Publications by authors named "Bent Aalbaek"

45 Publications

Pathological and microbiological impact of a gentamicin-loaded biocomposite following limited or extensive debridement in a porcine model of osteomyelitis.

Bone Joint Res 2020 Jul 31;9(7):394-401. Epub 2020 Jul 31.

Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark.

Aims: CERAMENT|G is an absorbable gentamicin-loaded biocomposite used as an on-site vehicle of antimicrobials for the treatment of chronic osteomyelitis. The purpose of the present study was to investigate the sole effect of CERAMENT|G, i.e. without additional systemic antimicrobial therapy, in relation to a limited or extensive debridement of osteomyelitis lesions in a porcine model.

Methods: Osteomyelitis was induced in nine pigs by inoculation of 10 colony-forming units (CFUs) of into a drill hole in the right tibia. After one week, the pigs were allocated into three groups. Group A (n = 3) received no treatment during the study period (19 days). Groups B (n = 3) and C (n = 3) received limited or extensive debridement seven days postinoculation, respectively, followed by injection of CERAMENT|G into the bone voids. The pigs were euthanized ten (Group C) and 12 (Group B) days after the intervention.

Results: All animals presented confirmatory signs of bone infection post-mortem. The estimated amount of inflammation was substantially greater in Groups A and B compared to Group C. In both Groups B and C, peptide nucleic acid fluorescence in situ hybridization (PNA FISH) of CERAMENT|G and surrounding bone tissue revealed bacteria embedded in an opaque matrix, i.e. within biofilm. In addition, in Group C, the maximal measured post-mortem gentamicin concentrations in CERAMENT|G and surrounding bone tissue samples were 16.6 μg/ml and 6.2 μg/ml, respectively.

Conclusion: The present study demonstrates that CERAMENT|G cannot be used as a standalone alternative to extensive debridement or be used without the addition of systemic antimicrobials.Cite this article: 2020;9(7):394-401.
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http://dx.doi.org/10.1302/2046-3758.97.BJR-2020-0007.R1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393185PMC
July 2020

Urolithiasis and cystitis associated with Staphylococcus delphini group A and mortality in post-weaning mink kits (Neovison vison).

Vet Microbiol 2020 Jun 5;245:108706. Epub 2020 May 5.

Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 3, 1870 Frederiksberg C, Denmark.

Mortality of mink kits represents a significant loss to production. However, causes of post-weaning mortality in mink kits in modern Danish mink production systems are still relatively poorly documented. We performed a cross-sectional mortality study on eight Danish mink farms including 1893 post mortem examinations of mink kits found dead or euthanized. We assessed the prevalence of cystitis and urolithiasis leading to mortality. Gross pathological findings as well as animal characteristics were recorded and associations with post mortem microbiology (using culture and MaldiTof-MS Vitek MS system) were investigated. Cystitis and/or urolithiasis were associated with death in 33 % (n = 476) and 37 % (n = 166) of the examined mink kits in 2015 and 2017. On farm level, the prevalence of cystitis and/or urolithiasis leading to mortality varied from 0.25 % to 1.27 % with a low overall mortality of 0.9-4.5 %. The bacterial agent most frequently isolated in post mortem bladder swabs from mink with a post mortem diagnosis of urolithiasis and cystitis was Staphylococcus delphini group A (51/283) with a significant (p < 0.0001, CI = [19.5;4745.7]) association to gross pathological findings in the urinary tract. Staphylococcus delphini group A was cultured from 70 % of the skin swabs obtained from apparently healthy mink euthanized at pelting (n = 222). In conclusion urinary tract disease (cystitis and urolithiasis) was the most prevalent post mortem diagnosis during the growth period and was associated with Staphylococcus delphini group A.
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http://dx.doi.org/10.1016/j.vetmic.2020.108706DOI Listing
June 2020

Staphylococcus aureus infected embolic stroke upregulates Orm1 and Cxcl2 in a rat model of septic stroke pathology.

Neurol Res 2019 May 1;41(5):399-412. Epub 2019 Feb 1.

a Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Frederiksberg , Denmark.

Objective: Ischaemic brain lesions and brain abscesses are frequent in both human and animal cases of septic embolic stroke. However, existing models of brain infection do not reflect central aspects of septic embolic stroke. Our aim was to compare septic and non-septic embolic stroke in order to identify gene expressions, inflammatory mediators and brain damage in a rat model.

Methods: We created precisely located focal brain infarcts in a rat model of Staphylococcus aureus infected embolic stroke. To cause septic embolic stroke we used a fibrin-rich embolus with bacteria, while every rat in the control group received a non-infected embolus. 64 rats were randomized to receive sham-surgery, sterile embolic stroke or septic embolic stroke. All groups were compared for brain pathology, mortality, gene expressions and inflammatory mediators using histology and reverse transcription quantitative real-time PCR.

Results: Although infarct volumes did not differ, septic embolic stroke caused higher mortality than sterile embolic stroke (p=  0.002). Brain abscesses were observed only in the septic group. Approximately 400-500 fold increases were observed for Orm1 and Cxcl2 respectively (1.00E-08 < p < 1.92E-07) in the septic group compared to the sterile group, and these were the most dramatically regulated genes in septic embolic stroke compared to sterile embolic stroke.

Conclusions: Septic embolic stroke caused brain abscesses, increased mortality and upregulated Orm1 and Cxcl2 gene expressions compared to non-infected embolic stroke. The dramatic Orm1 increase observed in the septic group is unprecedented and suggests a significant biological role of Orm1 during septic neuroinflammation.
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http://dx.doi.org/10.1080/01616412.2019.1573455DOI Listing
May 2019

Dietary LPS traces influences disease expression of the diet-induced obese mouse.

Res Vet Sci 2019 Apr 8;123:195-203. Epub 2019 Jan 8.

University of Copenhagen, Faculty of Health and Medical Sciences, Department of Veterinary and Animal Sciences, Groennegaardsvej 15, DK 1870 Frederiksberg C, Denmark.

Lipopolysaccharides (LPS) from Gram negative bacteria are generally present in laboratory animal chow diets in unknown amounts, which has been correlated to significant immunological differences between animals receiving diets with either low or high "naturally" occurring LPS content. LPS in the blood stream has been linked to glucose intolerance through Toll-like receptor mediated release of pro-inflammatory cytokines, metabolic endotoxemia, adipose tissue inflammation. LPS uptake increases when co-administered with fat, therefore uncontrolled LPS levels in a high-fat diet may increase variation in development of disease when high-fat diets are used to induce obesity and type 2 diabetes. Three experiments were conducted, in which C57BL/6NTac mice received high-fat (60%) or low fat (10%) diets with or without LPS for 8 or 20 weeks investigating the short and long term effects. Three different doses of LPS were used to investigate dosage effect, and ampicillin to isolate the effect of dietary LPS. Dietary LPS increased LPS levels in the blood stream, and affected the level of glycated haemoglobin (HbA1c), a key parameter in this model, in a dose dependant manner (p < 0.05). There was a strong tendency toward slower glucose uptake in the LPS supplemented groups once obesity was established, but the differences disappeared after 20 weeks. A high-fat diet slightly increased serum LPS and altered ileal expression of il10 and tnfa (p < 0.05). In conclusion, LPS seems to affect the glucose metabolism in a time-dose dependant manner, and uncontrolled variation in LPS levels of a diet may therefore increase inter-study variation.
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http://dx.doi.org/10.1016/j.rvsc.2019.01.005DOI Listing
April 2019

Reclassification of Bisgaard taxon 37 and taxon 44 as Psittacicella melopsittaci gen. nov., sp. nov., Psittacicella hinzii sp. nov. and Psittacicella gerlachiana sp. nov. within Psittacicellaceae fam. nov. of the order Pasteurellales.

Int J Syst Evol Microbiol 2019 Feb 13;69(2):350-355. Epub 2018 Dec 13.

4​Department of Veterinary Animal Sciences, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark.

Bacteria isolated from lesions as well as apparently normal tissues of psittacine birds have previously been reported as taxon 37 and taxon 44 of Bisgaard. 16S rRNA gene sequence comparisons revealed a distant relationship to members of Pasteurellaceae at the species, genus and family levels. The polar lipid profile consisted of the major components phosphatidylethanolamine and phosphatidylglycerol. A new family Psittacicellaceae fam. nov. is proposed with the type genus Psittacicella gen. nov. The new genus Psittacicella includes the type species Psittacicella melopsittaci sp. nov. with type strain B96/4 (=CCUG 70858=DSM 105476), Psittacicella hinzii sp. nov. with type strain 111 (=CCUG 52861=CCM 8842) and Psittacicella gerlachiana sp. nov. with type strain EEAB3T1 (=CCUG 70857=DSM 105477). In addition to the major polar lipids, strain 111 possessed the non-identified aminophospholipids APL1 and APL2 and trace amounts of four lipids (L1-L4) whereas strain B94/4 showed the minor unidentified aminophospholipids APL3 and APL2 and trace amounts of unidentified lipid L3. These results demonstrate that strain B96/4 can be distinguished from 111 based on presence/absence of the unidentified lipids APL1 and APL3. The total polar lipid profile of strain EEAB3T1 differed from B96/4only in one minor lipid. Strain B96/4 can further be distinguished from 111 by acid formation from trehalose and raffinose and the α-glucosidase test. Strains 111 and EEAB3T1 can be separated based on acid formation from trehalose and the α-glucosidase test. Strains B96/4 and EEAB3T1 can be separated by acid formation from raffinose and eight signature indels in the RpoB protein.
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http://dx.doi.org/10.1099/ijsem.0.003133DOI Listing
February 2019

Gentamicin Susceptibility Test for Prevention of Bacterial Biofilms in Bone Tissue and on Implants.

Antimicrob Agents Chemother 2019 02 29;63(2). Epub 2019 Jan 29.

Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark.

The objective of this study was to set up an gentamicin susceptibility test for biofilm prevention in bone tissue and on implants. Twenty-five pigs were allocated to six groups. Pigs in group A ( = 6) were inoculated with saline. Pigs in groups B ( = 6), C ( = 3), D ( = 3), E ( = 3), and F ( = 4) were inoculated with 10 μl saline containing 10 CFU of Different concentrations based on the MIC of gentamicin for the specific strain were added to the 10-μl inoculum for groups C (160× MIC), D (1,600× MIC), E (16,000× MIC), and F (160,000× MIC). The inocula were injected into a predrilled tibial implant cavity, followed by insertion of a steel implant (2 by 15 mm). The pigs were euthanized after 5 days. , all the doses used were found to be bactericidal after up to 6 h. All implant cavities of pigs inoculated with bacteria and bacteria plus 160× MIC or 1,600× MIC of gentamicin were positive for In animals in each of groups E (16,000× MIC) and F (160,000× MIC), 2/3 and 1/4 of the implant cavities were positive, respectively. By grouping groups C and D (<10,000× MIC) and groups E and F (>10,000× MIC), a significant decrease in the number of implant-attached bacteria was seen only between the high-MIC-value group and group B. Histologically, it was demonstrated that 1,600×, 16,000×, and 160,000× MIC resulted in a peri-implant tissue reaction comparable to that in saline-inoculated animals. , the antimicrobial tolerance of the inoculated planktonic bacteria was increased by -specific factors of acute inflammation. This resulted in bacterial aggregation and biofilm formation, which further increased the gentamicin tolerance. Thus, susceptibility patterns might not reflect the actual susceptibility locally within a developing infectious area.
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http://dx.doi.org/10.1128/AAC.01889-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355599PMC
February 2019

Dam characteristics associated with pre-weaning diarrhea in mink (Neovison vison).

Acta Vet Scand 2018 Nov 12;60(1):73. Epub 2018 Nov 12.

Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 3, 1870, Frederiksberg C, Denmark.

Background: Pre-weaning diarrhea (PWD) in mink, also known as "sticky kits", is a frequently occurring syndrome in suckling mink kits on commercial mink farms. Outbreaks of PWD result in weakened kits, increased mortality and reduced growth and welfare as well as considerable economic losses for the farmers. The syndrome is regarded as multifactorial with a complex etiology, and studies have focused on associations with environment, management and dam characteristics. The present study was conducted from May to June 2015 and included 70 dams with mink litters with and without PWD. The aims were to examine associations between PWD and mastitis (bacterial infection and histological signs of inflammation or other lesions in the mammary gland), and to examine associations between PWD and other dam-related characteristics (age, litter size, body mass index, and weight and number of active mammary glands of the dam).

Results: Using multivariable mixed logistic regression analyses with farm id as a random intercept, we found that the odds for PWD in the litter were significantly higher in 1 year old dams versus > 1 year old (OR = 13.3, CI 2.0-90.2, P = 0.01), higher if litter size observed after birth was > 5 kits versus ≤ 5 kits (OR = 16.5, CI 2.2-123.7, P = 0.01), higher if the number of active mammary glands per kit was ≤ 1.5 versus > 1.5 glands per kit (OR = 6.5, CI 1.2-36.0), P = 0.03), and higher in farms with high prevalence of PWD versus low prevalence (OR = 16.8, CI 2.9-97.6, P = 0.002). There were no significant associations between PWD and bacterial infection, histological signs of inflammation or other lesions of the mammary gland, body mass index or weight of mammary gland per kit.

Conclusion: Pre-weaning diarrhea had a statistically significant association with age of the dam, litter size and the number of active mammary glands per kit. However, PWD was not associated with mastitis, body mass index and weight of mammary gland tissue per kit.
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http://dx.doi.org/10.1186/s13028-018-0427-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6233364PMC
November 2018

Characterization of Pasteurella multocida involved in rabbit infections.

Vet Microbiol 2018 Jan 21;213:66-72. Epub 2017 Nov 21.

Department of Veterinary Disease Biology, Faculty of Medical and Health Sciences, Stigbøjlen 4, 1870 Frederiksberg C, University of Copenhagen, Denmark.

In rabbit, P. multocida is considered a predominant pathogenic agent; despite this, few data on the molecular epidemiology are available so far. The aim of this work was to characterize P. multocida isolates from rabbit affected by various diseases in Italy. Comparison was made to reference strains from other countries. Thirty-nine isolates were tested using PCRs to detect the genes coding capsular antigens, virulence factors and lipopolysaccharide structures (LPS). Multilocus sequence typing (MLST) was performed and 19 STs registered that belonged to 9 clonal complexes. Italian isolates were all related to P. multocida subsp. P. multocida. Three sequence types dominated (ST9, ST50 and ST74). The isolates were assigned to capsular types A (20/39), D (9/39) and F (10/39), to virulence genes pfhA (13/39), hgbB (21/39) and pfhA+hgbB (4/39) (one without virulence factors) and the isolates either belonged to the LPS genotypes 3 (22/39) or 6 (17/39). The clonal relationships of the Italian strains from rabbit had similarity to previously reported rabbit isolates that belonged to ST9, ST74, ST204 and ST206, however, they differed from other rabbit references strains that belonged to six other STs. In particular, ST9 with capsular type F has been previously reported from diseased rabbit in Czech Republic and ST74 has been observed for older rabbit isolates. ST50 has probably been reported from Spain. ST9 and ST50 have previously also been reported from birds and pig, respectively, whereas ST74 has exclusively been reported from pig. It remains to be investigated if the isolates obtained from diseased rabbit in Italy represent introductions from other host or they are primarily of rabbit origin.
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http://dx.doi.org/10.1016/j.vetmic.2017.11.023DOI Listing
January 2018

Single-dose bone pharmacokinetics of vancomycin in a porcine implant-associated osteomyelitis model.

J Orthop Res 2018 04 22;36(4):1093-1098. Epub 2017 Nov 22.

Department of Orthopaedic Surgery, Aarhus University Hospital, Aarhus, Denmark.

The increasing incidence of orthopaedic methicillin-resistant Staphylococcus aureus (MRSA) infections represents a significant therapeutic challenge. Being effective against MRSA, the role of vancomycin may become more important in the orthopaedic setting in the years to come. Nonetheless, vancomycin bone and soft tissue penetration during infection remains unclear. In eight pigs, implant-associated osteomyelitis was induced on day 0, using a Staphylococcus aureus strain. Following administration of 1,000 mg of vancomycin on day 5, vancomycin concentrations were obtained with microdialysis for 8 h in the implant bone cavity, in cancellous bone adjacent to the implant cavity, in subcutaneous adipose tissue (SCT) adjacent to the implant cavity, and in healthy cancellous bone and healthy SCT in the contralateral leg. Venous blood samples were also obtained. The extent of infection and inflammation was evaluated by post-mortem computed tomography scans, C-reactive protein serum levels and cultures of blood and swabs. In relation to all the implant cavities, bone destruction was found. Ranging from 0.20 to 0.74, tissue penetration, expressed as the ratio of the area under the concentration-time curve from 0 to the last measured value, was incomplete for all compartments except for healthy SCT. The lowest penetration was found in the implant cavity. In conclusion, Staphylococcus aureus implant-associated osteomyelitis was found to reduce vancomycin bone penetration, especially in the implant cavity. These findings suggest that it may be unsafe to rely solely on vancomycin therapy when treating acute osteomyelitis. Particularly when metaphyseal cavities are present, surgical debridement seems necessary. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1093-1098, 2018.
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http://dx.doi.org/10.1002/jor.23776DOI Listing
April 2018

Colonization of the bovine uterus by Candida kefyr.

Acta Vet Scand 2017 Sep 16;59(1):61. Epub 2017 Sep 16.

Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 68, 1870, Frederiksberg, Denmark.

Background: While fungal infections of the bovine uterus are well-known diseases in pregnant cattle, very limited knowledge exists on the presence and significance of fungi in the uterus of non-pregnant cows. Presence of fungi in the uterine lumen of postpartum (pp) cows has been reported, but little attention has been paid to this as most studies of the bovine pp uterus have focused on bacteria.

Case Presentation: Microscopy of uterine lavage cytology slides of three cows from one herd revealed the presence of numerous yeast-like organisms, which were located either free in the fluid or within macrophages. Two of the cows were around 30 days pp, while the third was 7 months pp. None of the cows had been treated with antibiotics. Culturing of the flush samples was unsuccessful, but Sanger sequencing of DNA extracted from an endometrial biopsy of one of the cows revealed the presence of Candida kefyr (Kluyveromyces marxianus). Fluorescence in situ hybridization examination of endometrial tissue sections of two cows using probes targeting 18S rRNA of the K. marxianus group was performed and revealed the presence of yeast cells on the endometrium. Histology was performed and demonstrated hyphal and non-hyphal yeast-like organisms on the surface of endometrium and in the crypts. Tissue invasion was restricted to the superficial part of the epithelium and although endometrial inflammation was present, this was mild and considered as not being caused by the fungi. One of the cows became pregnant and delivered a normal calf at term, while the two others were not bred.

Conclusions: Candida kefyr is commonly isolated from milk of cows with mastitis, but has not been reported in association with other diseases of cattle. The infection was present as a monoculture in all three cows, but the fungi had only colonized the uterine lumen and the endometrial surface. Only a mild non-suppurative endometrial inflammation was present, but within the uterine luminal content, many macrophages having phagocytized yeast cells were present. Re-examination of the cows did not reveal a persistent infection, so the infection probably resolved spontaneously.
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http://dx.doi.org/10.1186/s13028-017-0329-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5603010PMC
September 2017

Rodentibacter gen. nov. including Rodentibacter pneumotropicus comb. nov., Rodentibacter heylii sp. nov., Rodentibacter myodis sp. nov., Rodentibacter ratti sp. nov., Rodentibacter heidelbergensis sp. nov., Rodentibacter trehalosifermentans sp. nov., Rodentibacter rarus sp. nov., Rodentibacter mrazii and two genomospecies.

Int J Syst Evol Microbiol 2017 Jun 20;67(6):1793-1806. Epub 2017 Jun 20.

Department of Veterinary Disease Biology, University of Copenhagen, 4 Stigbøjlen, DK-1870 Frederiksberg C, Denmark.

Rodentibacter gen. nov. is proposed based on isolation and phenotypic characterization of strains, predominantly from rodents. The strains showed 86 % or higher rpoB gene sequence similarity and indicated a genus-level relationship within Pasteurellaceae. The strains compared at 16S rRNA gene sequence level showed 93.8 % or higher similarity, and their genus-level relationship within Pasteurellaceae was confirmed by phenotypic analysis. The type species Rodentibacter pneumotropicus comb. nov. is reclassified from [Pasteurella] pneumotropica with type strain NCTC 8141T (=CCUG 12398T). Whole genomic comparison allowed the estimation of DNA-DNA renaturation. Rodentibacter heylii sp. nov. was proposed for a group that included the biovar Heyl of [Pasteurella] pneumotropica with the type strain ATCC 12555T (=CCUG 998T). A group was proposed as Rodentibacter ratti sp. nov., which included the taxon 22 of Bisgaard; the type strain is F75T (=CCUG 69665T=DSM 103977T). Taxon 41 of Bisgaard was proposed as Rodentibacter myodis sp. nov. with type strain Ac151T (=CCUG 69666T=DSM 103994T). Rodentibacter heidelbergensis sp. nov. included the type strain 1996025094T (=Ac69T) (=CCUG 69667T=DSM 103978T). A group strains of was proposed as Rodentibacter trehalosifermentans sp. nov. with type strain H1987082031T (=CCUG 69668T=DSM 104075T). Two strains including the reference strain of taxon 17 of Bisgaard that showed 16S rRNA gene similarity of 97.3 % were proposed as Rodentibacter rarus sp. nov. 2325/79T (=CCUG 17206T=DSM 103980T). Rodentibacter mrazii sp. nov. was proposed with type strain Ppn418T (Bisgaard taxon 21) (=CCUG 69669T=DSM 103979T). The eight species could be separated based on phenotypic characteristics such as NAD requirement, ornithine decarboxylase and indole formation, α-glucosidase, β-galactosidase and in acid formation from (+)-l-arabinose, (-)-d-ribose, (+)-d-xylose, myo-inositol, (-)-d-mannitol, lactose, melibiose and trehalose. Forty-six strains including taxon 48 of Bisgaard formed a monophyletic group by rpoB and 16S rRNA gene sequence analysis, but could not be separated phenotypically from R. pneumotropicus and R. heylii, and it was left as an unnamed genomospecies 1 of Rodentibacter with reference strain Ppn416. Another taxon that included 13 strains, mainly isolated from Apodemus sylvaticus, could not be separated phenotypically from R. pneumotropicus or R. heylii and was designated as genomospecies 2. Strain Ppn85 with 95 % or less rpoB gene sequence similarity and with 16S rRNA gene sequence similarity of 97 % or less to the other members of Rodentibacter was left as an unnamed singleton.
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http://dx.doi.org/10.1099/ijsem.0.001866DOI Listing
June 2017

Abortion and mortality in farm mink (Neovison vison) associated with feed-born Clostridium limosum.

Vet Microbiol 2017 May 18;203:229-233. Epub 2017 Mar 18.

National Food Institute, Technical University of Denmark, 2860, Søborg, Denmark.

Disease in mink clinically characterized by abortion and increased mortality among pregnant female mink on 28 Danish farms was observed during April and May 2015. Most of these farms suffered extensive disease problems, including a significant increase in the number of mated females without litters. Pathological, microbiological and molecular biological methods were applied to investigate the cause of disease. Necropsies of animals found dead revealed fragile and partially dissolved (liquefying) uterine tissue, with the presence of Gram positive rod-shaped bacteria. These slow growing bacteria were isolated by anaerobic culturing and identified as Clostridium limosum by both MALDI-TOF mass spectrometry analysis and 16S rRNA gene sequencing. All the performed tests for relevant differential diagnoses were negative. Foodborne disease was indicated because all the affected farms were served by the same feed factory. A specific PCR-based analysis was developed for positive identification of C. limosum and used to screen archived feed samples from the implicated feed factory. Both C. limosum 16S rRNA genes and C. limosum collagenase genes were identified in both mixed feed and more specifically in raw chicken carcass used as one of the components in the mixed feed, which was therefore identified as the most likely source of contamination. Based on the results of this investigation it is concluded that C. limosum can be associated with abortion and increased mortality in pregnant mink females and it is consequently recommended that raw materials contaminated with C. limosum should be avoided in mink feed, in particular during the whelping season.
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http://dx.doi.org/10.1016/j.vetmic.2017.03.017DOI Listing
May 2017

Novel porcine model of implant-associated osteomyelitis: A comprehensive analysis of local, regional, and systemic response.

J Orthop Res 2017 10 15;35(10):2211-2221. Epub 2017 Jan 15.

Department of Veterinary Disease Biology, University of Copenhagen, Ridebanevej 3, 1870, Frederiksberg C, Denmark.

Pigs are favorable experimental animals for infectious diseases in humans. However, implant-associated osteomyelitis (IAO) models in pigs have only been evaluated using high-inoculum infection (>10 CFU) models in 1975 and 1993. Therefore, the aim of this paper was to present a new low inoculum porcine model of human IAO based on 42 experimental pigs. The model was created by drilling an implant cavity in the tibial bone followed by insertion of a small steel implant and simultaneous inoculation of Staphylococcus aureus bacteria (n = 32) or saline (n = 10). The infected pigs were either inoculated with 10 CFU (n = 26) or 10 and 10 CFU (n = 6). All animals were euthanized 5 days after insertion of implants. Pigs receiving the high-inoculum infections showed a significantly higher volume of bone lesion, number of neutrophils around the implant, concentrations of acute phase proteins in serum, and enlargement of regional lymph nodes. A positive correlation was present between a high number of surrounding neutrophils and high values of all other parameters. Furthermore, a threshold of 40 neutrophils per 10 high power fields for the histopathological diagnosis of high grade IAO was defined.

In Conclusion: This paper describes a novel low-inoculum S. aureus porcine model of IAO which was demonstrated to be reliable, reproducible and discriminative to human IAO, and represents a requested and valuable tool in orthopedic research. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2211-2221, 2017.
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http://dx.doi.org/10.1002/jor.23505DOI Listing
October 2017

Early implant-associated osteomyelitis results in a peri-implanted bacterial reservoir.

APMIS 2017 Jan 5;125(1):38-45. Epub 2016 Oct 5.

Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg, Denmark.

Implant-associated osteomyelitis (IAO) is a common complication in orthopedic surgery. The aim of this study was to elucidate how deep IAO can go into the peri-implanted bone tissue within a week. The study was performed in a porcine model of IAO. A small steel implant and either 10 CFU/kg body weight of Staphylococcus aureus or saline was inserted into the right tibial bone of 12 pigs. The animals were consecutively killed on day 2, 4 and 6 following implantation. Bone tissue around the implant was histologically evaluated. Identification of S. aureus was performed immunohistochemically on tissue section and with scanning electron microscopy and peptide nucleic acid in situ hybridization on implants. The distance of the peri-implanted pathological bone area (PIBA), measured perpendicular to the implant, was significantly larger in infected animals compared to controls (p = 0.0014). The largest differences were seen after 4 and 6 days of inoculation, where PIBA measurements of up to 6 mm were observed. Positive S. aureus bacteria were identified on implants and from 25 μm to 6 mm into PIBA. This is important knowledge for optimizing outcomes of surgical debridement in osteomyelitis.
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http://dx.doi.org/10.1111/apm.12597DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5298028PMC
January 2017

High genotypic diversity among methicillin-resistant Staphylococcus pseudintermedius isolated from canine infections in Denmark.

BMC Vet Res 2016 Jun 29;12(1):131. Epub 2016 Jun 29.

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.

Background: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged globally in companion animals in the last decade. In Europe, the multidrug-resistant sequence type (ST)71 is widespread, but recently other clones have appeared. The objective of this study was to examine genotypic diversity and antimicrobial resistance of clinical MRSP isolates obtained from dogs, including dogs sampled on multiple occasions, in Denmark over a six-year period. For that purpose a total of 46 clinical MRSP isolates obtained from 36 dogs between 2009 and 2014 were subjected to antimicrobial susceptibility testing, multilocus-sequence typing (MLST) and SCCmec typing.

Results: Twenty-three sequence types were identified with ST71, mostly associated with SCCmec II-III, as the most common occurring in 13 dogs. Among the remaining 33 isolates, 19 belonged to clonal complex (CC)258 comprising ST258-SCCmec IV and its single- and double-locus variants. These were susceptible to 4-7 of the 22 antibiotics tested, whereas CC71 isolates were susceptible to only 2-5 antibiotics. Clone-specific differences were especially pronounced for fluoroquinolones and aminoglycosides with most CC71 isolates being resistant and almost all CC258 isolates being susceptible. Sixteen of the 19 CC258 isolates had oxacillin MICs of 0.5 g/L, whereas MICs for CC71 isolates were consistently above 4 g/L. Four of five dogs representing multiple isolates had distinct STs on different sampling events.

Conclusions: The overall genotypic diversity of MRSP is high in Denmark indicating multiple acquisitions of SCCmec into distinct clones, and mutational evolution, which appears to be particularly rapid for certain ancestral clones such as ST258. ST71-SCCmec II-III is the most common MRSP lineage and is typically multidrug-resistant. CC258-SCCmec IV isolates, which emerged in Denmark since 2012, display susceptibility to a wider range of antimicrobials. The isolation of distinct STs in individual dogs over time suggests repeated exposure or short-term genetic evolution of MRSP clones within patients.
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http://dx.doi.org/10.1186/s12917-016-0756-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4928297PMC
June 2016

Effects of Implant-Associated Osteomyelitis on Cefuroxime Bone Pharmacokinetics: Assessment in a Porcine Model.

J Bone Joint Surg Am 2016 Mar;98(5):363-9

Department of Orthopaedic Surgery (M.T. and K.S.) and Orthopaedic Research Unit (M.T., M.B., P.H., and K.S.), Aarhus University Hospital, Aarhus, Denmark.

Background: The prolonged antibiotic therapy that is often needed for successful management of osteomyelitis may be related to incomplete penetration of antibiotics into the target site. The objective of this study was to assess the effects of implant-associated osteomyelitis on cefuroxime penetration into bone.

Methods: Implant-associated osteomyelitis using a Staphylococcus aureus strain was induced in the right tibia in ten pigs. After five days and following administration of 1500 mg of cefuroxime, measurements of cefuroxime were obtained using microdialysis for eight hours in the implant-related bone cavity, in the adjacent infected cancellous bone and infected subcutaneous tissue, and in healthy cancellous bone and subcutaneous tissue in the contralateral leg. Measurements of the corresponding free plasma concentrations were also obtained. The extent of the infection was assessed by postmortem computed tomography (CT) scans and cultures of blood, swabs, and bone specimens.

Results: Bone destruction was found in the implant cavities. No structural bone changes in the adjacent infected cancellous bone were visible on CT scans. S. aureus was grown on culture of specimens from all implant cavities and from eight of ten swabs and seven of ten bone samples from the infected bone. The areas under the concentration-time curves for the different tissues differed significantly, with the lowest area under the curve found in the implant cavity (analysis of variance; p < 0.001). Although not as notable as for the implant cavity, cefuroxime penetration into infected cancellous bone was incomplete but comparable with that in healthy bone. Despite poorer tissue penetration, slightly increased time with concentrations above the minimal inhibitory concentration (MIC) was achieved in the implant cavity up to MICs of 2 mg/L compared with the other tissues, but the time was shorter for higher MICs.

Conclusions: Cefuroxime penetration into infected cancellous bone was incomplete but comparable with that in healthy bone. The destructive bone processes associated with acute osteomyelitis reduced cefuroxime penetration further.

Clinical Relevance: These findings support the general clinical perception that fast diagnosis and early initiation of antibiotics before the development of implant-associated cavities is important in nonsurgical management of acute osteomyelitis.
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http://dx.doi.org/10.2106/JBJS.O.00550DOI Listing
March 2016

Modelling severe Staphylococcus aureus sepsis in conscious pigs: are implications for animal welfare justified?

BMC Res Notes 2016 Feb 16;9:99. Epub 2016 Feb 16.

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.

Background: A porcine model of haematogenous Staphylococcus aureus sepsis has previously been established in our research group. In these studies, pigs developed severe sepsis including liver dysfunction during a 48 h study period. As pigs were awake during the study, animal welfare was challenged by the severity of induced disease, which in some cases necessitated humane euthanasia. A pilot study was therefore performed in order to establish the sufficient inoculum concentration and application protocol needed to produce signs of liver dysfunction within limits of our pre-defined humane endpoints.

Methods: Four pigs received 1 × 10(8) cfu/kg BW of S. aureus, and two controls were sham inoculated with saline. A fixed infusion rate of 3 mL/min was used, while the inoculum concentration, i.e., the dose volume, was changed between the pigs. The following dose volumes were used: 10 mL (n = 1), 20 mL (n = 2), and 30 mL (n = 1), corresponding to infusion durations of 3.33, 6.66, and 10 min at dose rates of 3 × 10(7), 1.5 × 10(7), and 1 × 10(7) cfu/min/kg BW, respectively. Blood samples were drawn for complete blood count, clinical chemistry, and inflammatory markers before and every 6 h after inoculation. Prior to euthanasia, a galactose elimination capacity test was performed to assess liver function. Pigs were euthanised 48 h post inoculation for necropsy and histopathological evaluation.

Results: While infusion times of 6.66 min, and higher, did not induce liver dysfunction (n = 3), the infusion time of 3.33 min (n = 1) caused alterations in parameters similar to what had been seen in our previous studies, i.e., increasing bilirubin and aspartate aminotransferase, as well as histopathological occurrence of intravascular fibrin split products in the liver. This pig was however euthanised after 30 h, according to humane endpoints.

Conclusions: A usable balance between scientific purpose and animal welfare could not be achieved, and we therefore find it hard to justify further use of this conscious porcine sepsis model. In order to make a model of translational relevance for human sepsis, we suggest that future model versions should use long-term anaesthesia.
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http://dx.doi.org/10.1186/s13104-016-1888-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755015PMC
February 2016

Whole-Genome Sequence of Staphylococcus aureus S54F9 Isolated from a Chronic Disseminated Porcine Lung Abscess and Used in Human Infection Models.

Genome Announc 2015 Oct 22;3(5). Epub 2015 Oct 22.

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark

We obtained a draft genome sequence of Staphylococcus aureus strain S54F9, which was isolated from a chronic disseminated porcine lung abscess and used in porcine infection models. Genes coding for a number of toxins, including enterotoxins and superantigen, were demonstrated in this strain.
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http://dx.doi.org/10.1128/genomeA.01207-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4611697PMC
October 2015

Reclassification of Actinobacillus muris as Muribacter muris gen. nov., comb. nov.

Int J Syst Evol Microbiol 2015 Oct 1;65(10):3344-3351. Epub 2015 Jul 1.

Department of Veterinary Disease Biology, VetSchool, University of Copenhagen, 4 Stigbøjlen, DK-1870 Frederiksberg C, Denmark.

To reinvestigate the taxonomy of [Actinobacillus] muris, 474 strains, mainly from mice and rats, were characterized by phenotype and 130 strains selected for genotypic characterization by 16S rRNA and partial rpoB gene sequencing. The type strain was further investigated by whole-genome sequencing. Phylogenetic analysis of the DNA sequences showed one monophyletic group with intragroup similarities of 96.7 and 97.2 % for the 16S rRNA and rpoB genes, respectively. The highest 16S rRNA gene sequence similarity to a taxon with a validly published name outside the group was 95.9 %, to the type strain of [Pasteurella] pneumotropica. The closest related taxon based on rpoB sequence comparison was 'Haemophilus influenzae-murium', with 88.4 % similarity. A new genus and a new combination, Muribacter muris gen. nov., comb. nov., are proposed based on a distinct phylogenetic position based on 16S rRNA and rpoB gene sequence comparisons, with major divergence from the existing genera of the family Pasteurellaceae. The new genus has the characteristics of [A.] muris with the emendation that acid formation from ( - )-d-mannitol and hydrolysis of aesculin are variable, while the α-glucosidase test is positive. There is no requirement for exogenously supplied NAD (V factor) for the majority of strains investigated; however, one strain was found to require NAD. The major fatty acids of the type strain of Muribacter muris were C14 : 0, C14 : 0 3-OH/iso-C16 : 1 I, C16 : 1ω7c and C16 : 0, which is in line with most genera of the Pasteurellaceae. The type strain of Muribacter muris is CCUG 16938T ( = NCTC 12432T = ATCC 49577T).
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http://dx.doi.org/10.1099/ijsem.0.000417DOI Listing
October 2015

Expression of acute phase proteins and inflammatory cytokines in mouse mammary gland following Staphylococcus aureus challenge and in response to milk accumulation.

J Dairy Res 2014 Nov 17;81(4):445-54. Epub 2014 Sep 17.

Department of Veterinary Clinical and Animal Science (IKVH), Faculty of Health and Medical Sciences,University of Copenhagen,Denmark.

We used a mouse model of pathogenic (Staphylococcus aureus) and non-pathogenic (teat sealing) mammary inflammation to investigate mRNA expression of several inflammatory cytokines and acute phase proteins (APP) in mammary tissue and liver, and the appearance of some of these factors in plasma and milk. The expression levels of IL1β and TNFα were markedly up-regulated in Staph. aureus-inoculated mammary tissue at 72 h, whilst IL6 was up-regulated to a lesser extent in a way which was not confined to the inoculated glands. APP expression was up-regulated at 48 and 72 h in both Staph. aureus-inoculated and teat-sealed mammary glands. These differences between cytokine and APP expression provide additional support for the contention that APPs are produced within the mammary tissue itself during inflammation, rather than in associated immune cells. We propose that measurement of cytokines and APP in combination might provide a tool for diagnostic discrimination between mastitis caused by pathogenic invasion and milk accumulation, and hence allow for better targeting of antibiotic therapy. In comparison with mammary expression, expression of cytokines in liver tissue was up-regulated to a similar or lesser extent, whilst expression of APP was up-regulated to a much greater extent. The first appearance of increased cytokine and APP concentrations in plasma and of milk amyloid A (MAA) in milk occurred in advance of the measurable up-regulation of expression, hence their origin cannot be stated with certainty.
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http://dx.doi.org/10.1017/S0022029914000454DOI Listing
November 2014

Porcine models of non-bacterial thrombotic endocarditis (NBTE) and infective endocarditis (IE) caused by Staphylococcus aureus: a preliminary study.

J Heart Valve Dis 2013 May;22(3):368-76

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.

Background And Aim Of The Study: Non-bacterial thrombotic endocarditis (NBTE) and, in particular, infective endocarditis (IE), are serious and potentially life-threatening diseases. An increasingly important agent of human IE is Staphylococcus aureus, which typically causes an acute endocarditis with high mortality. The study aim was to evaluate the pig as a model for non-bacterial as well as S. aureus-associated endocarditis, as these models would have several advantages compared to other laboratory animal models.

Methods: Fourteen animals underwent surgery with placement of a plastic catheter in the left side of the heart. Six of the pigs did not receive a bacterial inoculation and were used to study the development of NBTE. The remaining eight pigs were inoculated intravenously once or twice with S. aureus, 10(5)-10(7) cfu/kg body weight. Two bacterial strains were used: S54F9 (porcine) and NCTC8325-4 (human). Clinical examination, echocardiography and bacterial blood cultures were used to diagnose and monitor the development of endocarditis. Animals were euthanized at between two and 15 days after catheter placement, and tissue samples were collected for bacteriology and histopathology.

Results: Pigs inoculated with 10(7) cfu/kg of S. aureus strain S54F9 developed clinical, echocardiographic and pathologic signs of IE. All other pigs, except one, developed NBTE. Serial blood cultures withdrawn after inoculation were positive in animals with IE, and negative in all other animals.

Conclusion: S. aureus endocarditis was successfully induced in pigs with an indwelling cardiac catheter after intravenous inoculation of 10(7) cfu/kg of S. aureus strain S54F9. The model simulates typical pathological, clinical and diagnostic features seen in the human disease. Furthermore, NBTE was induced in all but one of the pigs without IE. Thus, the pig model can be used in future studies of the pathogenesis, diagnosis and therapy of NBTE and S. aureus endocarditis.
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May 2013

Embolic encephalitis in a porcine model of endocarditis.

In Vivo 2013 Sep-Oct;27(5):591-7

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 3, DK-1870 Frederiksberg, Denmark.

Background: Endocarditis is a severe disease in which neurological complications are frequent and associated with increased mortality and complex disease management. In the present study, the pig was evaluated as a model of embolic encephalitis as a complication of experimental infective endocarditis.

Materials And Methods: Brains from pigs with experimental Staphylococcus aureus-associated infective endocarditis (IE; n=2), experimental non-bacterial thrombotic endocarditis (NBTE; n=5), experimental S. aureus sepsis without endocarditis (SNE; n=3) and saline controls (n=3), were used. The brains were examined for lesions macroscopically, histologically and immunohistochemically.

Results: Lesions of focal encephalitis were found in the IE and SNE pigs, at considerably higher numbers in the IE pigs. Furthermore, microabscesses were common in the IE pigs, which fits the association between brain abscesses and S. aureus-associated endocarditis in humans.

Conclusion: Experimental porcine S. aureus-associated endocarditis is advantageous for studying neurological complications, such as brain abscess formation, as a result of endocardial bacterial seeding.
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May 2014

Systemic inflammatory response and local cytokine expression in porcine models of endocarditis.

APMIS 2014 Apr 24;122(4):292-300. Epub 2013 Jul 24.

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.

The knowledge of systemic inflammation and local cytokine expression in porcine endocarditis models is limited, though it could provide valuable information about the pathogenesis and comparability to human endocarditis. Analyses of bacteriology and hematology were performed on blood samples from pigs with non-bacterial thrombotic endocarditis (NBTE, n = 11), Staphylococcus aureus infective endocarditis (IE, n = 2), animals with S. aureus sepsis without endocarditis (n = 2) and controls (n = 2). Furthermore, immunohistochemistry was used to examine the local expression of IL-1β and IL-8. Bacterial blood cultures were continuously positive in IE pigs from inoculation to euthanasia, and negative in all other pigs at all times. The total white blood cell counts and total neutrophil counts were massively elevated in pigs with IE. Local IL-1β and IL-8 expression in IE pigs were moderate to high, and high, respectively. In addition, slight local expression of IL-1β and IL-8 was present in some NBTE pigs. In the IE model, both the systemic inflammatory response and the high local expression of IL-8 were comparable to the human disease. Furthermore, the results indicate IL-1β and IL-8 as important contributors in the endocarditis pathogenesis.
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http://dx.doi.org/10.1111/apm.12145DOI Listing
April 2014

Therapy of haematogenous osteomyelitis--a comparative study in a porcine model and Angolan children.

In Vivo 2013 May-Jun;27(3):305-12

Department of Veterinary Disease Biology, Faculty of Health and Medical Science, University of Copenhagen, Ridebanevej 3, 1870 Frederiksberg C, Denmark.

Background: It is generally accepted that surgery is necessary for the proper treatment of chronic haematogenous osteomyelitis (HO) in children. However, the correct timing of surgery and the technique most effective for debridement of infectious bone tissue is debated. Theoretically, large animal models of HO can be used for refinement and testing of surgical protocols. We report, to our knowledge for the first time, a porcine model of HO exposed to surgical treatment together with our surgical experiences with Angolan children suffering from chronic HO.

Materials And Methods: Surgically-debrided bone tissue from the children and pigs were analyzed microbiologically and histopathologically together with the entire operated bones from the pigs.

Results: It was illustrated that surgical intervention on porcine bones with experimentally-induced HO is representative of the handling of the condition in children. The porcine HO model can easily be used for refinement and application of surgical techniques used in order to cure children with HO.
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October 2013

A new technique for modeling of hematogenous osteomyelitis in pigs: inoculation into femoral artery.

J Invest Surg 2013 Jun 28;26(3):149-53. Epub 2012 Dec 28.

Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Frederiksberg, Denmark.

A new inoculation technique has been developed and applied in a porcine model of juvenile hematogenous osteomyelitis. Following the success of the model, we describe the inoculation technique in detail to enable its replication in future studies. The technique was based on an anatomical feature of the femoral artery that enables inoculation into the artery using a simple surgical procedure. Inoculation in the femoral artery is advantageous because the localization of lesions constitutes a discriminative model of the naturally occurring hematogenous osteomyelitis in long bones, usually involving femur and tibia in children. The procedure was performed under general anesthesia and consisted of five major steps: (1) Exposure of the right femoral artery, (2) retrograde catheterization, (3) inoculation of bacteria, (4) hemostasis of the arterial puncture site using compression, and (5) suturing of the wound in two layers.
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http://dx.doi.org/10.3109/08941939.2012.718043DOI Listing
June 2013

Latent class analysis of the diagnostic characteristics of PCR and conventional bacteriological culture in diagnosing intramammary infections caused by Staphylococcus aureus in dairy cows at dry off.

Acta Vet Scand 2012 Nov 20;54:65. Epub 2012 Nov 20.

Hushållningssällskapet Västernorrland, Trädgårdsgatan 7, Härnösand, Sweden.

Background: Staphylococcus aureus is one of the most common causes of intramammary infections in dairy cows at dry off. Reliable identification is important for disease management on herd level and for antimicrobial treatment of infected animals. Our objective was to evaluate the test characteristics of PathoProof ™ Mastitis PCR Assay and bacteriological culture (BC) in diagnosing bovine intramammary infections caused by S. aureus at dry off at different PCR cycle threshold (Ct)-value cut-offs.

Methods: Sterile quarter samples and non-sterile composite samples from 140 animals in seven herds were collected in connection with the dairy herd improvement (DHI) milk recording. All quarter samples were analyzed using BC whereas all composite samples were analyzed with PathoProof ™ Mastitis PCR Assay. Latent class analysis was used to estimate test properties for PCR and BC in the absence of a perfect reference test. The population was divided into two geographically divided subpopulations and the Hui-Walter 2-test 2-populations model applied to estimate Se, Sp for the two tests, and prevalence for the two subpopulations.

Results: The Se for PCR increased with increasing Ct-value cut-off, accompanied by a small decrease in Sp. For BC the Se decreased and Sp increased with increasing Ct-value cut-off. Most optimal test estimates for the real-time PCR assay were at a Ct-value cut-off of 37; 0.93 [95% posterior probability interval (PPI) 0.60-0.99] for Se and 0.95 [95% PPI 0.95-0.99] for Sp. At the same Ct-value cut-off, Se and Sp for BC were 0.83 [95% PPI 0.66-0.99] and 0.97 [95% PPI 0.91-0.99] respectively. Depending on the chosen PCR Ct-value cut-off, the prevalence in the subpopulations varied; the prevalence increased with increasing PCR Ct-value cut-offs.

Conclusion: Neither BC nor real-time PCR is a perfect test in detecting IMI in dairy cows at dry off. The changes in sensitivity and prevalence at different Ct-value cut-offs for both PCR and BC may indicate a change in the underlying disease definition. At low PCR Ct-value cut-offs the underlying disease definition may be a truly/heavily infected cow, whereas at higher PCR Ct-value cut-offs the disease definition may be a S. aureus positive cow.
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http://dx.doi.org/10.1186/1751-0147-54-65DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3537602PMC
November 2012

The use of sequential organ failure assessment parameters in an awake porcine model of severe Staphylococcus aureus sepsis.

APMIS 2012 Nov 15;120(11):909-21. Epub 2012 May 15.

Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark.

The human sequential organ failure assessment (SOFA) scoring system is used worldwide in intensive care units for assessing the extent of organ dysfunction/failure in patients with severe sepsis. An increasing number of septic cases are caused by Gram-positive bacteria as Staphylococcus aureus. The aim of the current study was to apply the human SOFA parameters in an awake, porcine model of severe S. aureus sepsis. Five pigs were inoculated intravenously with S. aureus and two control animals were sham-inoculated. Extensive clinical monitoring and sequential blood sampling was obtained and analysed for SOFA parameters. Dysfunction/failure was observed in the respiratory, haemostatic and hepatic system of all infected animals, together with initial cardiovascular dysfunction. The pulmonary system was the first to fail clinically, which corresponds with similar human findings, whereas the liver was affected earlier in pigs compared to humans. The use of human SOFA parameters was valuable in identifying dysfunctional/failing organs and showed consistency between this porcine model and human severe sepsis. Applying SOFA parameters in this model increased the relevance for comparison to clinical methods of evaluating human severe sepsis. Changes in SOFA parameters may in future porcine studies serve as a target for monitoring the effect of therapeutic intervention.
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http://dx.doi.org/10.1111/j.1600-0463.2012.02917.xDOI Listing
November 2012

Local osteogenic expression of cyclooxygenase-2 and systemic response in porcine models of osteomyelitis.

Prostaglandins Other Lipid Mediat 2012 Mar 14;97(3-4):103-8. Epub 2012 Jan 14.

Department of Veterinary Disease Biology, Faculty of Life Sciences, Copenhagen University, Ridebanevej 3, 1870 Frederiksberg C, Denmark.

It is suggested that cyclooxygenase 2 (COX-2) derived prostaglandins contributes to the progressive bone loss seen in osteomyelitis lesions. In the present study we examined the expression of COX-2 in bones from 23 pigs with experimental osteomyelitis. Osteomyelitis was induced with Staphylococcus aureus and groups of animals were euthanized following 6 h, 12 h, 24 h, 2 days, 5 days, 11 days and 15 days, respectively. Expression of COX-2 was evaluated immunohistochemically and combined with characterization of morphological changes in bone tissue. Furthermore, the serum concentrations of alkaline phosphatase and haptoglobin were measured. Extensive COX-2 expression by osteoblasts was present 2 days after inoculation together with many activated osteoclasts. Simultaneously, the serum concentration of alkaline phosphatase decreased whereas the haptoglobin concentration increased. This is the first in vivo study showing an early wave of COX-2 mediated bone resorption during osteomyelitis. Therefore, treatment aiming to reduce the break down of bone tissue directed by the COX-2 pathway might be suggested early in the course of the disease.
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http://dx.doi.org/10.1016/j.prostaglandins.2012.01.002DOI Listing
March 2012

A porcine model of acute, haematogenous, localized osteomyelitis due to Staphylococcus aureus: a pathomorphological study.

APMIS 2011 Feb 1;119(2):111-8. Epub 2010 Dec 1.

Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg, Denmark.

A porcine model of acute, haematogenous, localized osteomyelitis was established. Serial dilutions of Staphylococcus aureus [5-50-500-5000-50 000 CFU/kg body weight (BW) suspended in saline or saline alone] were inoculated into the right brachial artery of pigs (BW 15 kg) separated into six groups of two animals. During the infection, blood was collected for cultivation, and after the animals were killed from day 5 to 15, they were necropsied and tissues were sampled for histopathology. Animals receiving ≤500 CFU/kg BW were free of lesions. Pigs inoculated with 5000 and 50 000 CFU/kg BW only developed microabscesses in bones of the infected legs. In the centre of microabscesses, S. aureus was regularly demonstrated together with necrotic neutrophils. Often, bone lesions resulted in trabecular osteonecrosis. The present localized model of acute haematogenous osteomyelitis revealed a pattern of development and presence of lesions similar to the situation in children. Therefore, this model should be reliably applied in studies of this disease with respect to e.g. pathophysiology and pathomorphology. Moreover, because of the regional containment of the infection to a defined number of bones, the model should be applicable also for screening of new therapy strategies.
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http://dx.doi.org/10.1111/j.1600-0463.2010.02700.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3040840PMC
February 2011

Histologic and bacteriologic findings in valvular endocarditis of slaughter-age pigs.

J Vet Diagn Invest 2010 Nov;22(6):921-7

Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Ridebanevej 3, DK-1870 Frederiksberg C, Denmark.

Endocarditis lesions from 117 slaughter pigs were examined pathologically and etiologically in addition to 90 control hearts with cardiac valves. Lesions were located on the valves; however, the lesions had extended to the walls in 21 cases (18%). Lesions predominated on the mitral valve (59%). A total of 28 cases, from which no growth was obtained or a contamination flora was grown, were screened by fluorescence in situ hybridization (FISH) for bacteria (general bacterial probe) and probes specific for Streptococcus suis and Erysipelothrix rhusiopathiae, respectively. Using FISH, an additional 10 cases of endocarditis due to S. suis and E. rhusiopathiae were disclosed. Within lesions, streptococci predominated (53%) followed by E. rhusiopathiae (30%). Distinct features of both the lesions and the shape and localization of bacterial colonies were related to streptococci and E. rhusiopathiae. The propensity for streptococci to be localized on more than 1 valve in single hearts may be because S. suis-infected pigs tend to have been infected for a longer period compared with E. rhusiopathiae. Mineralization of endocarditis lesions was significantly associated with infection by streptococci, and was seen in 71% of the cases, whereas it was present in only 28% of lesions caused by E. rhusiopathiae. In addition, areas with mineralization were significantly correlated to the presence of a granulomatous reaction. Granulomatous endocarditis is likely a result of a foreign body reaction due to dystrophic mineralization. Local proliferation of valvular endothelial cells, found in 9 hearts in the current study, may increase the risk of developing thrombosing endocarditis in pigs.
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http://dx.doi.org/10.1177/104063871002200611DOI Listing
November 2010
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