Publications by authors named "Maja Abram"

32 Publications

Diagnostic accuracy of three SARS-CoV2 antibody detection assays, neutralizing effect and longevity of serum antibodies.

J Virol Methods 2021 Apr 27;293:114173. Epub 2021 Apr 27.

Department of Infectious Diseases, Faculty of Medicine, University of Rijeka, Rijeka, Croatia; Clinic for Infectious Diseases, Clinical Hospital Center Rijeka, Rijeka, Croatia.

Evidence is currently insufficient to know whether SARS-CoV-2 antibodies (Abs) protect from future infection and how long immunity will last. The kinetics of the immune response to SARS-CoV-2 infection and role of serology in estimating individual protective immunity is yet to be established. We evaluated diagnostic performances of three serological assays - Abbott Architect CMIA IgG, bioMerieux VIDAS ELFA IgG/IgM, and Diesse Chorus ELISA IgG/IgM, and analyzed longevity and potential neutralizing effect of SARS-CoV-2 Abs in COVID-19 patients. Clinical sensitivities of assessed IgG tests two to three weeks post symptom onset (PSO) were very high: 96.77 % for Architect, 96.77 % for Chorus, and 100.00 % for VIDAS. Sensitivities of two assessed IgM assays were moderate: 74.07 % for Chorus, and 76.92 % for VIDAS. Specificities were excellent for all assessed IgG assays: 99.01 % for Architect and 100 % for Chorus and VIDAS. Chorus and VIDAS IgM assays also achieved excellent specificity of 99.01 % and 100 %, respectively. In most cases IgG Abs were still present eight months PSO. Neutralizing antibodies were detected in majority of serum samples from convalescent patients. Serum samples from severe COVID-19 patients had higher antibody titers and higher neutralizing activity. We observed a strong positive correlation among SARS-CoV-2 IgG antibody titer and neutralizing activity. The strongest positive correlation to neutralizing activity was found for VIDAS IgG assay.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jviromet.2021.114173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8078047PMC
April 2021

Does Fluoroquinolones and Third-Generation Cephalosporins Restriction Reverse Extended-Spectrum β-Lactamases Resistance Rates?

Microb Drug Resist 2021 Mar 19. Epub 2021 Mar 19.

Department of Clinical Pharmacology, Clinical Hospital Center Rijeka, Rijeka, Croatia.

To decrease the incidence and resistance rates of extended-spectrum β-lactamases (ESBL) (KP) by restriction of the use of third-generation cephalosporins (3GCs) and fluoroquinolones. Consumption of 3GCs, fluoroquinolones, and carbapenems in association with ertapenem and fluoroquinolone-resistant KP isolates, were analyzed in 21 months by autoregressive integrated moving average models. A follow-up analysis was performed 5 years later. Consumption of 3GCs decreased significantly during the postintervention period. Their restriction was associated with a decrease in ertapenem-resistant KP isolates by 17.5%. Fluoroquinolone, 3GCs, and carbapenem use did not significantly predict the percentage of ertapenem-resistant KP isolates. Fluoroquinolone, but not cephalosporin use, significantly predicted the percentage of fluoroquinolone-resistant isolates, with an increase of 1 defined daily dose (DDD) of fluoroquinolone/100 occupied bed-days (OBDs) corresponding to a 0.32% increase of fluoroquinolone-resistant isolates ( = 0.008). A decrease of 1 DDD of carbapenem/100 OBD was associated with a 16.94% increase of fluoroquinolone-resistant isolates ( = 0.007). Five years later, the consumption of all three antimicrobial classes increased significantly compared with the 2011-2013 period, whereas ertapenem-resistant KP rates significantly decreased. This study may bring a valuable contribution to the understanding of the intricate association between antibiotic consumption and bacterial resistance. Reporting a spectrum of different results could present a useful basis for more profound research of various interventions' effects.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/mdr.2020.0301DOI Listing
March 2021

Fecal microbiota transplantation - where are we?

Croat Med J 2021 Feb;62(1):52-58

Ivana Mikolašević, Department of Gastroenterology, Clinical Hospital Center Rijeka, Rijeka, Croatia,

View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7976890PMC
February 2021

Challenges to antimicrobial susceptibility testing of plant-derived polyphenolic compounds.

Arh Hig Rada Toksikol 2020 Dec 31;71(4):300-311. Epub 2020 Dec 31.

Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.

As multidrug resistance gains momentum, the last two decades have seen an ever-growing interest in the antimicrobial properties of plant extracts and plant-derived compounds. Most of the focus is on polyphenols - a large and diverse group of phytochemicals with strong antibacterial activity. Testing methods provide reliable results as long as they follow standard procedures. However, methods and procedures used in antimicrobial susceptibility testing (AST) are often too diverse to allow comparison of results. The lack of uniformity and comparability is much owed to the absence of guidelines. The focus of this review is to give a critical overview of different methods used in the assessment of polyphenols antimicrobial efficacy and to highlight the importance of their standardisation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2478/aiht-2020-71-3396DOI Listing
December 2020

Small intestinal bacterial overgrowth and non-alcoholic fatty liver disease diagnosed by transient elastography and liver biopsy.

Int J Clin Pract 2021 Apr 16;75(4):e13947. Epub 2021 Feb 16.

Department of Gastroenterology, UHC Rijeka, Rijeka, Croatia.

Background: We aimed to determine if there was a higher incidence of small intestinal bacterial overgrowth (SIBO) in non-alcoholic fatty liver disease (NAFLD) than in patients without NAFLD. Moreover, we assessed whether patients with significant fibrosis (SF) had a higher incidence of SIBO compared with patients with non-significant or no liver fibrosis.

Methods: NAFLD was diagnosed in 117 patients by using Fibroscan with a controlled attenuation parameter (CAP) as well as liver biopsy (LB). SIBO was defined by esophagogastroduodenoscopy with an aspiration of the descending duodenum.

Results: Patients with non-alcoholic steatohepatitis (NASH) and those with SF on LB had a significantly higher incidence of SIBO than patients without NASH and those without SF, respectively (P < .05). According to histological characteristics, there was a higher proportion of patients in the SIBO group with higher steatosis and fibrosis grade, lobular and portal inflammation, and ballooning grade (P < .001). In multivariate analysis, significant predictors associated with SF and NASH were type 2 diabetes mellitus (T2DM) and SIBO. Moreover, in multivariate analysis, significant predictors that were independently associated with SIBO were T2DM, fibrosis stage and ballooning grade (OR 8.80 (2.07-37.37), 2.50 (1.16-5.37) and 27.6 (6.41-119), respectively). The most commonly isolated were gram-negative bacteria, predominantly Escherichia coli and Klebsiella pneumoniae.

Conclusion: In this relatively large population of patients, we used a gold standard for both SIBO (quantitative culture of duodenum's descending part aspirate) and NAFLD (LB), and we demonstrated that NASH patients and those with SF had a higher incidence of SIBO. Moreover, significant predictors independently associated with SIBO were T2DM, fibrosis stage and ballooning grade. Although TE is a well-investigated method for steatosis and fibrosis detection, in our study, independent predictors of SIBO were histological characteristics of NAFLD, while elastographic parameters did not reach statistical significance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ijcp.13947DOI Listing
April 2021

Adhesion of Is Increased in Association with Foodborne Bacteria.

Microorganisms 2020 Jan 31;8(2). Epub 2020 Jan 31.

Department of Microbiology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20/1, HR-51000 Rijeka, Croatia.

The aim of this study was to evaluate NTCT 11168 adhesion to abiotic and biotic surfaces when grown in co-culture with ATCC 11229 and/or 4b. Adhesion of C. jejuni to polystyrene and to Caco-2 cells and castellanii was lower for at least 3 log CFU/mL compared to E. coli and L. monocytogenes. Electron micrographs of ultrathin sections revealed interactions of with host cells. In co-culture with and , adhesion of C. jejuni to all tested surfaces was significantly increased for more than 1 log CFU/mL. There was 10% higher aggregation for than for other pathogens, and high co-aggregation of co-cultures of C. jejuni with and . These data show that in co-cultures with and present significantly higher risk than as mono-cultures, which need to be taken into account in risk evaluation. adhesion is a prerequisite for their colonization, biofilm formation, and further contamination of the environment. survival under adverse conditions as a factor in their pathogenicity and depends on their adhesion to different surfaces, not only as individual strains, but also in co-cultures with other bacteria like and .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/microorganisms8020201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7074767PMC
January 2020

The Anti- Activity and Mechanisms of Pinocembrin Action.

Microorganisms 2019 Dec 10;7(12). Epub 2019 Dec 10.

Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.

We investigated the anti- activity of pinocembrin and its mechanism of action, as well as responses to pinocembrin treatment at the genetic and phenotypic levels, using NCTC 11168 and a multidrug efflux system repressor mutant (11168). At its minimal inhibitory concentration, pinocembrin significantly increased cell membrane permeability of . Interestingly, at sub-inhibitory concentrations, pinocembrin did not significantly alter membrane functionality and it increased bacterial fitness. Treatment with pinocembrin evoked decreased expression of ribosomal proteins and down-regulation of several NADH dehydrogenase I chain subunits and proteins involved in iron uptake. This suggests altered protein production and redox cycle and iron metabolism. Interestingly, the chelation of Fe ions during the treatment with pinocembrin increased survival, although there was no increase in the formation of reactive oxygen species. Pre-treatment of with sub-inhibitory concentrations of pinocembrin for 2 h resulted in a 1 log decrease in colony forming units in mice liver at 8 days post-infection, compared to untreated . These findings suggest that pinocembrin modulates the metabolic activity of and that pre-treatment of with pinocembrin influences its virulence potential in mice. This anti- potential of pinocembrin warrants further investigation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/microorganisms7120675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6955772PMC
December 2019

THE PREVALENCE OF ONYCHOMYCOSIS IN THE ZAGREB AREA - THE ROLE OF SABOURAUD AGAR WITHOUT CYCLOHEXIMIDE IN DIAGNOSIS AND THERAPY.

Acta Clin Croat 2018 Dec;57(4):726-735

1Department of Dermatovenereology, Sestre milosrdnice University Hospital Centre, Zagreb, Croatia; 2Department of Microbiology, School of Medicine, University of Rijeka, Rijeka, Croatia.

- Mycological analysis is considered the gold standard in the diagnosis of very common fungal diseases of nails. The purpose of the article is to present the prevalence of onychomycosis obtained by using direct microscopic examination (DME) and cultivation on Sabouraud media without cycloheximide. The quantitative retrospective research was conducted on 2706 patients of both sexes (mostly middle-aged to elderly) with various toenail lesions, who had undergone mycological analyses in the Mycological Laboratory of our Department of Dermatovenereology in 2013 and 2014. Analysis of the results obtained revealed that there were 35.4% of positive DME results; of these, there were 39.2% of dermatophytes, 59.1% of yeasts and 1.7% of molds. The percentage of dermatophytes ( spp.) was twice as high in men as in women. A considerable percentage (12%) of mixed isolates was also observed. Particularly worrisome was the high percentage (one-third) of suppressed and insufficiently developed dermatophytes (a possible indicator of inappropriate preparation of patients for mycological analysis). Cultivation on culture media without cycloheximide requires frequent inspections because of the fast-growing molds while not allowing sporulation for a great number of dermatophytes. However, it has certain advantages, i.e. it offers an insight into the wide range of the present fungi. As part of the biofilm, they can be potentially pathogenic in dystrophic nails under certain circumstances because, according to our results, the percentage of dermatophytes does not change substantially with aging; however, what does change is the percentage of molds, yeasts and mixed isolates.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.20471/acc.2018.57.04.15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6544114PMC
December 2018

Synergistic potential of Juniperus communis and Helichrysum italicum essential oils against nontuberculous mycobacteria.

J Med Microbiol 2019 May 27;68(5):703-710. Epub 2019 Mar 27.

Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.

Objective: The present study evaluated the possible synergistic antimycobacterial interactions of Juniperus communis and Helichrysum italicum essential oils (EO).

Methods: Antimycobacterial potential was tested against Mycobacterium avium and Mycobacterium intracellulare using broth and water dilution method and checkerboard synergy method. Antiadhesion and antibiofilm effect of EOs was evaluated on biotic (HeLa cells) and abiotic surface (polystyrene). To evaluate the possible mechanisms of action, cellular leakage of proteins and DNA was tested and structural changes were visualized with a transmission electron microscope.

Results: MIC, minimum bactericidal concentration (MBC) and minimal effective concentration (MEC) were 1.6 mg ml for J. communis EO and 3.2 mg ml for H. italicum EO against both mycobacteria. All combinations of EOs in checkerboard synergy method produced fractional inhibitory concentration index values ranging from 0.501 to 1.5, corresponding to synergistic, additive or indifferent effects. Mycobacterium avium showed a greater tendency to create biofilm but these EOs at subinhibitory concentrations (sMIC) effectively blocked the adhesion and the establishment of biofilm. The exposure of both mycobacteria to MICs and sMICs lead to significant morphological changes: acquired a swollen form, ghost-like cell, disorganized cytoplasm detached from the cell wall. OD value of supernatant for both mycobacteria exposed to EOs have confirmed that there is a leakage of cellular material.

Conclusion: The leakage of the cellular material is noticeably higher in sMIC, which is probably due to cell wall damage. sMIC of both EOs have an additive or synergistic effect, reducing MICs, limiting adhesion and preventing the formation of biofilms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1099/jmm.0.000962DOI Listing
May 2019

Antimycobacterial potential of the juniper berry essential oil in tap water.

Arh Hig Rada Toksikol 2018 Mar;69(1):46-54

2Department of Microbiology and Parasitology, University of Rijeka, Rijeka, Croatia.

Mycobacterium avium complex-related diseases are often associated with poorly maintained hot water systems. This calls for the development of new control strategies. The aim of this study was to investigate the activity of essential oils (EOs) from the Mediterranean plants, common juniper, immortelle, sage, lavandin, laurel, and white cedar against Mycobacterium avium ssp. avium, Mycobacterium intracellulare, and Mycobacterium gordonae in culturing broth and freshwater as their most common habitat. To do that, we developed a new method of water microdilution to determine their minimal effective concentrations (MEC). The most active EO was the one from the common juniper with the MEC of 1.6 mg mL-1. Gas chromatography / mass spectrometry the juniper EO identified monoterpenes (70.54 %) and sesquiterpenes (25.9 %) as dominant component groups. The main monoterpene hydrocarbons were α-pinene, sabinene, and β-pinene. The juniper EO significantly reduced the cell viability of M. intracellulare and M. gordonae at MEC, and of M. avium at 2xMEC. Microscopic analysis confirmed its inhibitory effect by revealing significant morphological changes in the cell membrane and cytoplasm of all three bacteria. The mode of action of the juniper EO on the cell membrane was confirmed by a marked leakage of intracellular material. Juniper EO has a great practical potential as a complementary or alternative water disinfectant in hot water systems such as baths, swimming pools, spa pools, hot tubs, or even foot baths/whirlpools.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2478/aiht-2018-69-3085DOI Listing
March 2018

Three New Strains in the Probiotic Toolbox against Gut Pathogen Serotype Typhimurium.

Food Technol Biotechnol 2017 Mar;55(1):48-54

University of Rijeka, Faculty of Medicine, Department of Microbiology and Parasitology,
Braće Branchetta 20, HR-51000 Rijeka, Croatia.

The benefits of probiotic bacteria have been widely explored. However, fermented foods and digestive system of humans and animals are an inexhaustible source of new potentially probiotic microorganisms. In this study we present three new strains isolated from different dairy products: cow's cheese, sheep's cheese and whey. In order to determine the antibacterial activity of yet unexplored strains against serotype Typhimurium, competition and co-culture tests were done. Furthermore, adhesion of these strains to Caco-2 cells and their influence on the adhesion of were tested. Results showed the potential probiotic activity of isolated strains. strains survived in the presence of 1% bile salts, they possessed acidification ability, antibacterial activity and significantly attenuated the growth of Typhimurium in brain heart infusion broth. All tested strains were able to adhere to Caco-2 cells and significantly impair the adhesion of Typhimurium. All three strains exhibited significant probiotic potential and anti- activity; therefore, further testing on models should follow.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.17113/ftb.55.01.17.4693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434365PMC
March 2017

Virulence genes and cytokine profile in systemic murine Campylobacter coli infection.

Virulence 2015 3;6(6):581-90. Epub 2015 Jun 3.

c Department of Microbiology ; Medical Faculty; University of Rijeka ; Rijeka , Croatia.

Campylobacter coli are one of the most common bacteria in bacterial gastroenteritis and acute enterocolitis in humans. However, relatively little is known regarding the mechanisms of pathogenesis and host response to C. coli infections. To investigate the influence of genetic changes, we first used PCR to demonstrate the presence of the known virulence genes cadF, virB11, cdtB, cdtC and ceuE in the clinical isolate C. coli 26536, which was isolated from the liver of infected BALB/c mice. Sequence analyses of the cadF, virB11, cdtB and ceuE genes in C. coli 26536 confirmed the stability in these virulence genes during their transmission through the host. We further investigated C. coli infection for the bacterial clearance from the liver and spleen of infected mice, and for their immune response. C. coli persisted well in both organs, with better survival in the liver. We also determined the levels of several pro-inflammatory cytokines (i.e., interleukin [IL]-6, IL-12, interferon-γ, tumor necrosis factor-α) and the anti-inflammatory cytokine IL-10 in plasma and in liver homogenates from the infected mice, using enzyme-linked immunosorbent assays. The lowest levels among these cytokines were for tumor necrosis factor-α in the plasma and IL-6 in the liver on days 1, 3 and 8 post-infection. The most pronounced production was for IL-10, in both plasma (days 1 and 8 post-infection) and liver (day 8 post-infection), which suggests that it has a role in healing of the organ inflammation. Our findings showed dynamic relationships between pro- and anti-inflammatory cytokines and thus contribute toward clarification of the healing processes involved in the resolution of C. coli infections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/21505594.2015.1042642DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720231PMC
June 2016

Mechanisms of Carbapenem Resistance in Multidrug-Resistant Clinical Isolates of Pseudomonas aeruginosa from a Croatian Hospital.

Microb Drug Resist 2015 Jun 7;21(3):261-9. Epub 2015 Jan 7.

1Department of Microbiology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.

Pseudomonas aeruginosa is an opportunistic pathogen, one of the leading causes of nosocomial infections such as pneumonia, urinary tract infections, and bacteraemia. The bacterial resistance to structurally unrelated antibiotics and its spread within hospitals limits the efficient antimicrobial options and patients' outcome. Carbapenems are important agents for the therapy of infections due to multidrug-resistant (MDR) P. aeruginosa; hence, the development of carbapenem resistance severely hampers effective therapeutic options. The aim of this investigation was to examine mechanisms of carbapenem resistance and genomic diversity in carbapenem-resistant MDR strains of P. aeruginosa, which caused an outbreak among patients in Clinical Hospital Rijeka. Most of the isolates showed decreased expression of porin that is important for the entry of carbapenems (oprD). Overexpression of MexAB-OprM, MexCD-OprJ, and MexEF-OprN efflux systems was observed in many of the isolates. Production of metallo-β-lactamases was not detected. Typing by pulsed-field gel electrophoresis discriminated the isolates into five clusters. The clonal distribution of the strains was related to the location of hospital departments where the isolates were collected, which implies that most of the infections were caused by spread of the epidemic strains within the hospital.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/mdr.2014.0172DOI Listing
June 2015

Stress response and virulence of heat-stressed Campylobacter jejuni.

Microbes Environ 2014 2;29(4):338-45. Epub 2014 Oct 2.

Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana.

Thermotolerant Campylobacter spp. frequently cause bacterial gastroenteritis in humans commonly infected through the consumption of undercooked poultry meat. We examined Campylobacter jejuni heat-stress responses in vitro after exposure to 48°C and 55°C. The in vivo modulation of its pathogenicity was also investigated using BALB/c mice intravenously infected with stressed C. jejuni. Regardless of the bacterial growth phase, the culturability and viability of C. jejuni in vitro was reduced after exposure to 55°C. This correlated with the altered protein profile and decreased virulence properties observed in vivo. Heat stress at 48°C elicited the transition to more resistant bacterial forms, independent of morphological changes or the appearance of shorter spiral and coccoid cells. This treatment did not cause marked changes in bacterial virulence properties in vivo. These results indicated that the characteristics and pathogenicity of C. jejuni in response to heat stress are temperature dependent. Further studies on the responses of C. jejuni to stresses used during food processing, as well as the modulation of its virulence, are important for a better understanding of its contamination and infective cycle, and will, thus, contribute to improved safety in the food production chain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1264/jsme2.ME14020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4262356PMC
December 2015

Sequence types 235, 111, and 132 predominate among multidrug-resistant pseudomonas aeruginosa clinical isolates in Croatia.

Antimicrob Agents Chemother 2014 Oct 28;58(10):6277-83. Epub 2014 Jul 28.

University Hospital for Infectious Diseases, Zagreb, Croatia.

A population analysis of 103 multidrug-resistant Pseudomonas aeruginosa isolates from Croatian hospitals was performed. Twelve sequence types (STs) were identified, with a predominance of international clones ST235 (serotype O11 [41%]), ST111 (serotype O12 [15%]), and ST132 (serotype O6 [11%]). Overexpression of the natural AmpC cephalosporinase was common (42%), but only a few ST235 or ST111 isolates produced VIM-1 or VIM-2 metallo-β-lactamases or PER-1 or GES-7 extended-spectrum β-lactamases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AAC.03116-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4187922PMC
October 2014

Dirofilaria repens infection in a ten-year-old boy from the Istria Peninsula: case report.

Acta Clin Croat 2013 Dec;52(4):533-6

Dirofilariasis is a zoonotic infection caused by worms belonging to the genus Dirofilaria. The disease is transmitted by mosquitoes and the hosts are usually dogs. Infections in humans are rare and they usually manifest as a subcutaneous nodule or a conjunctival form. We present a 10-year-old boy with a subcutaneous nodule on his left forearm, who was admitted to the hospital. On examination, the only significant findings were high levels of eosinophils. The pediatrician suspected dirofilariasis and the boy was referred to pediatric surgery. The whole lesion was surgically removed and histopathologic examination confirmed parasitic infection by Dirofilaria repens. Although human dirofilariasis is a rare disease, the number of reported cases has recently increased worldwide. The disease mainly occurs in southern European countries, but has also been described in eastern Europe, Central Asia and Sri Lanka. Croatia is one of the endemic areas for dirofilariasis, especially in the region of the Istria Peninsula. The case presented highlights the requirement for further monitoring of endemic areas in order to establish effective preventive measures.
View Article and Find Full Text PDF

Download full-text PDF

Source
December 2013

Superior induction and maintenance of protective CD8 T cells in mice infected with mouse cytomegalovirus vector expressing RAE-1γ.

Proc Natl Acad Sci U S A 2013 Oct 19;110(41):16550-5. Epub 2013 Sep 19.

Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia.

Due to a unique pattern of CD8 T-cell response induced by cytomegaloviruses (CMVs), live attenuated CMVs are attractive candidates for vaccine vectors for a number of clinically relevant infections and tumors. NKG2D is one of the most important activating NK cell receptors that plays a role in costimulation of CD8 T cells. Here we demonstrate that the expression of CD8 T-cell epitope of Listeria monocytogenes by a recombinant mouse CMV (MCMV) expressing the NKG2D ligand retinoic acid early-inducible protein 1-gamma (RAE-1γ) dramatically enhanced the effectiveness and longevity of epitope-specific CD8 T-cell response and conferred protection against a subsequent challenge infection with Listeria monocytogenes. Unexpectedly, the attenuated growth in vivo of the CMV vector expressing RAE-1γ and its capacity to enhance specific CD8 T-cell response were preserved even in mice lacking NKG2D, implying additional immune function for RAE-1γ beyond engagement of NKG2D. Thus, vectors expressing RAE-1γ represent a promising approach in the development of CD8 T-cell-based vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1310215110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799388PMC
October 2013

In vivo modulation of Campylobacter jejuni virulence in response to environmental stress.

Foodborne Pathog Dis 2013 Jun 2;10(6):566-72. Epub 2013 May 2.

Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.

Campylobacters have developed a number of mechanisms for responding to environmental conditions, although the different virulence properties of these cells following exposure to stress are still poorly understood. We analyzed in vitro stress responses and the consequent in vivo modulation of Campylobacter jejuni pathogenicity in BALB/c mice, as a result of the exposure of the C. jejuni to environmental stress (starvation, oxidative stress, heat shock). In vitro, the influence of starvation and oxidative stress was milder than that of heat shock, although the majority of the stress conditions influenced the survival of C. jejuni. During starvation, C. jejuni viability was maintained longer than its culturability. Additionally, starvation elicited transformation of stressed bacteria to coccoid forms. In contrast, bacteria exposed to oxygen remained culturable, but their viability decreased. Pre-starvation did not contribute to improved survival of C. jejuni cells during oxygen exposure. Changes in bacteria numbers and the levels of several cytokines (interleukins 6 and 10, tumor necrosis factor-α, interferon-γ) were followed in vivo, in liver homogenates from the mice intravenously infected with either control (untreated) or stressed C. jejuni. The systemic infection with the control or stressed C. jejuni occurred with different production dynamics of the cytokines investigated. Starvation was the most powerful stress factor, which significantly decreased infectious potential of C. jejuni during the first 3 days postinfection. The most pronounced differences in cytokine production were found in interferon-γ and interleukin-10 production, which indicates that these have roles in the immune response to C. jejuni infection. These in vivo studies of environmental impact on bacterial virulence reveal that microbial adaptation during stress challenge is crucial not just for pathogen survival out of the host, but also during host-pathogen interactions, and thus for the bacterial pathogenicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/fpd.2012.1298DOI Listing
June 2013

Listeriosis in pregnancy: case report and retrospective study.

J Matern Fetal Neonatal Med 2013 Feb 29;26(3):321-3. Epub 2012 Oct 29.

Department of Clinical Microbiology, University Hospital Rijeka, Rijeka, Croatia.

Background: Listeria monocytogenes usually causes mild maternal illness, but can be devastating to the fetus.

Case: Listeriosis in a pregnant patient successfully treated with empiric antibiotic therapy is described. After induced delivery, despite severe placental infection, a healthy infant was born. Additionally, archived placental specimens with similar pathological manifestation were evaluated for evidence of L. monocytogenes.

Conclusion: It is important to emphasize the value of associating maternal data and clinical and laboratory findings of the newborn with the pathologic placental findings to get better results in the etiologic diagnosis of the listeriosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3109/14767058.2012.733780DOI Listing
February 2013

Epidemiologic characteristics of human campylobacteriosis in the County Primorsko-goranska (Croatia), 2003-2007.

Coll Antropol 2011 Sep;35(3):847-53

University of Rijeka, School of Medicine, Department of Microbiology and Parasitology, Rijeka, Croatia.

The aim of the study was to investigate campylobacteriosis incidence in the County Primorsko-goranska (Croatia) between 2003 and 2007 and to find out possible connection with environmental factors (the average monthly temperature and total monthly precipitation). The data (number of stool samples examined, age and sex distribution of patients, monthly distribution of isolates and distribution of isolates according to the species) from the Laboratory for Diagnostics of Enteric Infections of the Teaching Institute of Public Health of the County Primorsko-goranska (Croatia) were analyzed retrospectively. During the observed period 30,164 stool samples were examined for Campylobacter spp. Campylobacters were identified in 1,242 (4.12%) samples. The overall annual campylobacter incidence rate was 81.3 +/- 21.9/100,000 population. Campylobacter jejuni was found in 1,093 (88%) and C. coli in 149 (12%) patients. Our findings showed age distribution of patients typical for developed countries. The patients were mostly children under 5 years (484.4 +/- 129.1/ 100,000, p < 0.001) and between 5 and 9 years of age (226.5 +/- 60.5/100,000, p < 0.05). Male consistently experienced higher rates, but the difference between genders was significant in the age groups from birth till late twentieth (p < 0.001). Campylobacter rates were significantly associated with monthly average temperatures (p < 0.05), but not with precipitation. Further investigations into the incidence of campylobacteriosis on the national level are necessary. The causes of the noticed monthly distribution, sources of infection and connection with the routes of transmission in humans need to be elucidated as well.
View Article and Find Full Text PDF

Download full-text PDF

Source
September 2011

Breast abscess in a man due to Salmonella enterica serotype Enteritidis.

J Clin Microbiol 2012 Jan 26;50(1):192-3. Epub 2011 Oct 26.

Infectious Diseases Department, Clinical Hospital Centre Rijeka, Rijeka, Croatia, and Department of Pathology, Faculty of Medicine, Rijeka, Croatia.

Nontyphoidal salmonellae can cause breast infection only exceptionally. A case of breast abscess in a 70-year-old man due to Salmonella enterica serotype Enteritidis (Salmonella Enteritidis) is reported. The infection was successfully treated with a combination of surgical and antibiotic treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/JCM.05361-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3256715PMC
January 2012

In vitro oxidative stress induced by conventional and self-ligating brackets.

Angle Orthod 2012 Mar 13;82(2):340-5. Epub 2011 Sep 13.

Department of Paediatric Dentistry and Orthodontics, School of Medicine, University of Rijeka, Rijeka, Croatia.

Objective: To determine the in vitro oxidative stress induced by conventional and self-ligating brackets made of different materials.

Materials And Methods: The concentration of oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) in DNA of murine fibroblast cells L929 after in vitro exposure to three types of conventional and four types of self-ligating brackets was assessed. To determine viability and changes in the number of cells before and after exposure, trypan blue dye was used. Analysis of variance (ANOVA) was used for statistical analysis.

Results: No significant difference in cell viability was noted between metal, ceramic, and polymeric conventional brackets, and self-ligating brackets made of combinations of those materials, but viability was significantly higher compared with positive controls (P < .05). The conventional sapphire ceramic bracket (Inspire Ice) showed high viability, the largest increase in the number of cells, and the lowest oxidative stress. A higher concentration of markers of oxidative stress was observed in full metal conventional and self-ligating brackets (MiniSprint and Speed) and in conventional polyurethane brackets (Quantum) compared with negative controls (P < .05).

Conclusion: All types of orthodontic brackets, regardless of the constituent materials, are a source of oxidative stress in vitro, but the highest stress was induced in the full metal and polyurethane brackets. Conventional ceramic brackets show the highest degree of biocompatibility compared with polymeric and metal brackets and self-ligating brackets made from combinations of these materials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2319/061811-395.1DOI Listing
March 2012

Listeria monocytogenes (delta-actA mutant) infection in tumor necrosis factor receptor p55-deficient neonatal mice.

Microb Pathog 2010 Oct 1;49(4):186-95. Epub 2010 Jun 1.

Department of Microbiology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.

Using TNF receptor 1 knock out (TNFR1KO) mice, we investigated the role played by TNFR1 in immune regulation during neonatal listeriosis. Induction of protective immune response in wild type pups resulted in the prompt control of infection with an attenuated DeltaactA mutant Listeria monocytogenes, accompanied by enhanced hepatic expression of mRNA for IFN-gamma, TNF-alpha, and IL-10. Conversely, the lack of TNFR1 signalling in TNFR1KO neonatal mice resulted in substantial changes in the profile of inflammatory mediators and ultimately fatal outcome of the infected pups. Despite remarkable increase in indoleamine 2, 3-dioxygenase (IDO) and inducible nitric oxide synthase (iNOS) mRNA detected in the liver of TNFR1KO mice, bacterial proliferation was unrestrained. Increased mRNA expression of IDO, iNOS, TNF-alpha, IFN-gamma, MCP-1, and MIP-1alpha was found in the spleens of infected KO mice, and in the brains mRNA encoding iNOS, IDO, IFN-gamma, IL-12p40, IL-10, and RANTES was also upregulated. Large necrotic lesions consisting of granulocytes and macrophages were scattered throughout the liver of these mice. TNFR1KO neonates were unable to clear neutrophils and switch from the innate immune response to a specific reaction mediated by T cells. These results prove that TNF-alpha signalling is crucial and irreplaceable in antilisterial protection during the neonatal period.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.micpath.2010.05.012DOI Listing
October 2010

[ISKRA guidelines on sore throat: diagnostic and therapeutic approach--Croatian national guidelines].

Lijec Vjesn 2009 Jul-Aug;131(7-8):181-91

Zavod za klinicku mikrobiologiju, Klinika za infektivne bolesti "Dr. Fran Mihaljević", Mirogojska 8, 10000 Zagreb.

Sore throat is most commonly caused by viruses, but when caused by bacteria, the most important is group A streptococcus (GAS). The aim of these guidelines is to determine optimal treatment for streptococcal sore throat and reasonable indications for tonsillectomy, as well as recommend how to differentiate streptococcal infection for which antibiotics are justified, from numerous other sore throats where antibiotics wont have a significant effect on disease course, but might contribute to bacterial resistance to antibiotics. The development of the guidelines was initiated by the Interdisciplinary Section for Antibiotic Resistance Control (ISKRA) of the Croatian Ministry of Health and Social Welfare in accordance with the principles of AGREE (Appraisal of Guidelines for Research and Evaluation) methodology which means that the guidelines are the result of consensus between all interested professional societies and institutions. For streptococcal sore throat diagnostics, the Working Group recommends evaluation of clinical presentation according to Centor criteria and for patients with Centor score 0-1, antibiotic therapy is not recommended nor bacteriological testing, while for patients with Centor score 2-4 bacteriological testing is recommended (rapid test or culture) as well as antibiotic therapy in case of positive result. The drug of choice for the treatment of streptococcal tonsillopharyngitis is oral penicillin taken for ten days (penicillin V) or in case of poor patient compliance benzathine penicillin G can be administered parenterally in a single dose. Other antibiotics (macrolides, clindamycin, cephalosporins, co-amoxiclav) are administered only in case of hypersensitivity to penicillin or in recurrent infections. Tonsillectomy is a widely accepted surgical procedure that decreases the number of sore throats in children and should be performed only if indications for this procedure are established. Absolute indications include five or more streptococcal infections per year, tonsillitis complications, permanent respiratory tract obstruction, obstructive sleep apnea syndrome and suspected tonsillar malignancy. Relative indications include chronic tonsillitis and occlusion disturbances.
View Article and Find Full Text PDF

Download full-text PDF

Source
December 2009

Stress response and pathogenic potential of Campylobacter jejuni cells exposed to starvation.

Res Microbiol 2009 Jun 27;160(5):345-52. Epub 2009 May 27.

Department of Food Science and Technology, University of Ljubljana, Jamnikarjeva, Slovenia.

Campylobacter jejuni is a Gram-negative, fragile, spiral bacterium, known worldwide to be a major cause of acute human enteritis. Like many other food-borne bacteria, campylobacters must be able to survive under diverse conditions both inside the host and in the environment. Understanding stress response mechanisms provides information necessary for improving food processing and strategies that enhance food safety as well as clarifying the pathogenesis of campylobacteriosis. We investigated the relation between stress response to starvation and pathogenic potential in C. jejuni. Starvation changed the morphology and physiology of C. jejuni cells. However, the lower metabolic activity of 5-h-starved culture was not a dormant state, but probably a viable but non-culturable (VBNC) form of the cells, since starved C. jejuni induced heat stress resistance. The health hazard potential of starved cells is still unclear. We showed that, in spite of starvation, C. jejuni survived in vitro within Caco-2 enterocites up to 4 days and caused systemic campylobacteriosis in vivo in a mouse model. However, bacterial numbers in investigated organs were significantly lower and the infection was resolved sooner. Our results show that nutrient insufficiency is responsible for C. jejuni transformation, influencing but not abolishing its survival and virulence properties while in the VBNC state.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.resmic.2009.05.002DOI Listing
June 2009

Survival of stress exposed Campylobacter jejuni in the murine macrophage J774 cell line.

Int J Food Microbiol 2009 Jan 17;129(1):68-73. Epub 2008 Nov 17.

Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.

Although campylobacters are relatively fragile and sensitive to environmental stresses, Campylobacter jejuni has evolved mechanisms for survival in diverse environments, both inside and outside the host. Their survival properties and pathogenic potential were assessed after subjecting food and clinical C. jejuni isolates to different stress conditions. After exposure to starvation (5 h and 15 h of nutrient depletion), a temperature shock (3 min at 55 degrees C) or oxidative stress (5 h and 15 h of atmospheric oxygen) we studied the culturability, viability and capability of adhesion, internalization and survival within the in vitro cell culture model using J774 murine macrophages. Starvation severely impaired C. jejuni culturability, particularly after 15 h of nutrient depletion. The number of viable cells decreased by 30-40%. Starved bacterial cells also showed a lower capability of adhesion, internalization and survival within macrophages. Despite the reduced culturability and viability of the heat treated cells, C. jejuni efficiently adhered to, and entered murine macrophages. However, the number of heat treated cells started to decrease more quickly than non-stressed cells. Within 24 h post infection all the cells were killed. The bacterial mechanisms involved in inactivating toxic oxygen products may enhance bacterial persistence through increased binding, entry and survival of both oxidatively stressed C. jejuni isolates inside the macrophages. Oxygen exposure increased the internalization and intracellular survival, although the cells cannot remain viable for extended periods within murine macrophages. However, any prolongation of survival in macrophages may increase the probability of transmission of bacteria in the host organism and have further implications in the pathogenesis of campylobacteriosis. This indicates that environmental stress conditions may be involved.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijfoodmicro.2008.11.010DOI Listing
January 2009

Environmental stress factors affecting survival and virulence of Campylobacter jejuni.

Microb Pathog 2007 Aug-Sep;43(2-3):120-5. Epub 2007 Apr 19.

Department of Microbiology, Medical Faculty, University of Rijeka, Brace Branchetta 20, HR-51000 Rijeka, Croatia.

Enteric pathogens are constantly exposed to stressful conditions in their natural habitat in the host and even more in the extra-host environment, including food processing. The aim of this study was to evaluate the effect of selected environmental stress factors: temperature shift, starvation and atmospheric oxygen concentration on culturability/viability of two Campylobacter jejuni isolates. Additionally, after stress exposure, in an in vitro cell culture model using Caco-2 cells, the adhesion, invasion and intracellular survival of C. jejuni were studied. Nutrient insufficiency was the most powerful stress factor which significantly affected C. jejuni culturability and viability, as well as, adhesion and invasion properties. Temperature elevation induced a transient growth arrest, and temporary loss of pathogenic potential as indicated by impaired adhesion and invasion efficiency of C. jejuni. However, bacteria recovered within 24-48h inside the Caco-2 cells. Oxidative stress neither affected C. jejuni growth nor reduced the binding and invasion into Caco-2 cells. Only 5h oxygen exposure increased the invasion capability and intraepithelial survival of the clinical isolate. Modulation of C. jejuni virulence in response to environmental stress factors may have further implications in the pathogenesis of campylobacteriosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.micpath.2007.03.004DOI Listing
September 2007

Systemic and local CC chemokines production in a murine model of Listeria monocytogenes infection.

Mediators Inflamm 2006 ;2006(3):54202

Department of Microbiology, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia.

Repeated intragastric inoculation of Listeria monocytogenes into BALB/c mice resulted in prolonged bacteraemia and severe hepatic infection. Bacteria could also be isolated from the brain tissue of all experimental mice. During the inflammatory process, chemokine concentrations typically increased at the local site in comparison to the systemic level. The liver-to-serum ratio was more pronounced in the case of macrophage inflammatory protein 1 alpha (MIP-1 alpha), suggesting its role in the inflammatory response in the liver. The ratio of brain-to-serum concentration of monocyte chemoattractant protein 1 (MCP-1) remained the same as in the control animals, while it was lower in the infected mice, both in the case MIP-1alpha and in the case of regulated on activation, normal T cell expressed and secreted (RANTES). This is in correlation with slight inflammatory infiltrates found in the brain tissue early in infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/MI/2006/54202DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1592594PMC
September 2006

Host resistance to primary and secondary Campylobacter jejuni infections in C57Bl/6 mice.

Microb Pathog 2006 Jan 1;40(1):35-9. Epub 2005 Dec 1.

Department of Microbiology, Medical Faculty, University of Rijeka, Braće Branchetta 20, HR-51000 Rijeka, Croatia.

Campylobacter jejuni has been known as a main causative agent of human enterocolitis for more than 30 years. This has prompted the research on defence mechanisms of the host involved. Although the humoral immune response to C. jejuni has been addressed in many studies, relatively little is known about the role of T lymphocytes in campylobacteriosis. The current study was based on in vivo T-cell subsets depletion to evaluate the role of CD4+ and CD8+ T lymphocytes in disseminated C. jejuni infection in C57BL/6 mice. Depletion of either CD8+ or CD4+ cells did not change the overall infection kinetics of primary campylobacteriosis. To assess the role of T cells in acquired immunity that develops during primary infection in C57BL/6 mice, in vivo depletions were performed during reinfection. Depletion of CD4+ cells did not have any effect on secondary infection kinetics, whereas depletion of CD8+ cells resulted in secondary liver infection that failed to resolve during the observed period. This study showed that both CD8+ and CD4+ T cells contribute to protection of C57BL/6 mice against C. jejuni. However, the predominant role resides in the CD8+ cell subpopulation. The exact mechanisms by which CD8+ cells operate during the course of campylobacteriosis will be the subject of our further research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.micpath.2005.10.004DOI Listing
January 2006

Salivary levels of tumor necrosis factor-alpha in oral lichen planus.

Mediators Inflamm 2004 Apr;13(2):131-3

Department of Oral Medicine, Medical Faculty, University of Rijeka, Croatia.

Objective: Oral lichen planus (OLP) is chronic inflammatory disease of the oral mucosa, presenting in various clinical forms. The etiology of OLP is still unknown but mounting evidence points to the immunologic basis of this disorder.

Aim: Our study was undertaken to quantify the salivary levels of pro-inflammatory tumor necrosis factor-alpha (TNF-alpha) in the reticular and the erosive/atrophic forms of OLP, compared with age-matched healthy control volunteers.

Subjects And Methods: Whole saliva from 40 patients with active lesions of OLP, as well as from 20 healthy persons, was investigated for the presence of TNF-alpha by enzyme immunoassay.

Results: Salivary TNF-alpha levels were significantly increased in patients with OLP in comparison with healthy subjects. The presence of TNF-alpha showed positive correlation to clinical forms of OLP, being significantly higher in the erosive/atrophic type than in the reticular type of disease.

Conclusion: Saliva provides an ideal medium for the detection of pro-inflammatory markers of the oral cavity. In patients with OLP, TNF-alpha levels in saliva are elevated, correlating with the severity of illness. Salivary TNF-alpha analysis may be a useful diagnostic tool and a potential prognostic marker in OLP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/09629350410001688530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1781548PMC
April 2004