Publications by authors named "Simone Ambretti"

72 Publications

Performance of PhenoMatrix for the detection of Group B Streptococcus from recto-vaginal swabs.

Diagn Microbiol Infect Dis 2021 May 13;101(1):115427. Epub 2021 May 13.

Microbiology Unit, IRCCS S.Orsola-Malpighi Hospital, Bologna, Italy.

We assessed the performance of PhenoMatrix digital imaging software in detection of Group B Streptococcus from recto-vaginal swabs plated on a specific chromogenic medium, using the WASP automated processor. PhenoMatrix algorithm showed a sensitivity of 100% and a specificity of 64.5%. False-positive results were mainly due to commensal viridans streptococci.
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http://dx.doi.org/10.1016/j.diagmicrobio.2021.115427DOI Listing
May 2021

Epidemiology of Meropenem/Vaborbactam Resistance in KPC-Producing Causing Bloodstream Infections in Northern Italy, 2018.

Antibiotics (Basel) 2021 May 6;10(5). Epub 2021 May 6.

Operative Unit of Clinical Microbiology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy.

Meropenem/Vaborbactam (MEM-VAB) is a novel carbapenem- β-lactamase inhibitor active against KPC-producing Enterobacteria. Herein, we evaluate the incidence of meropenem/vaborbactam-resistance among KPC-producing (KPC-Kp) bloodstream infection in a large Italian hospital. Meropenem/vaborbactam-resistance was found in 8% ( = 5) KPC-Kp, while 5% ( = 3) strains exhibited cross-resistance to ceftazidime/avibactam (CAZ-AVI). Genomic analysis revealed that meropenem/vaborbactam-resistance was associated with truncated OmpK35 and insertion of glycine and aspartic acid within OmpK36 at position 134-135 (GD134-135). Notably, no specific mutation was associated to cross-resistance. No specific antimicrobial treatment was related to favorable clinical outcomes, while cross-resistance was not associated to higher clinical and/or microbiological failures. Our study indicated that resistance to meropenem/vaborbactam was due to porins mutations and is associated with reduced susceptibility to both ceftazidime/avibactam and carbapenems.
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http://dx.doi.org/10.3390/antibiotics10050536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8148119PMC
May 2021

Respiratory bacterial co-infections in intensive care unit-hospitalized COVID-19 patients: Conventional culture vs BioFire FilmArray pneumonia Plus panel.

J Microbiol Methods 2021 07 29;186:106259. Epub 2021 May 29.

Microbiology Unit, IRCCS S.Orsola-Malpighi Hospital, Via Massarenti n 9, Bologna, Italy.

The prevalence and microbiology of concomitant respiratory bacterial infections in patients with SARS-CoV-2 infection are not yet fully understood. In this retrospective study, we assessed respiratory bacterial co-infections in lower respiratory tract samples taken from intensive care unit-hospitalized COVID-19 patients, by comparing the conventional culture approach to an innovative molecular diagnostic technology. A total of 230 lower respiratory tract samples (i.e., bronchial aspirates or bronchoalveolar lavages) were taken from 178 critically ill COVID-19 patients. Each sample was processed by a semi-quantitative culture and by a multiplex PCR panel (FilmArray Pneumonia Plus panel), allowing rapid detection of a wide range of clinically relevant pathogens and a limited number of antimicrobial resistance markers. More than 30% of samples showed a positive bacterial culture, with Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus the most detected pathogens. FilmArray showed an overall sensitivity and specificity of 89.6% and 98.3%, respectively, with a negative predictive value of 99.7%. The molecular test significantly reduced the turn-around-time (TAT) and increased the rates of microbial detection. Most cases missed by culture were characterized by low bacterial loads (10-10 copies/mL). FilmArray missed a list of pathogens not included in the molecular panel, especially Stenotrophomonas maltophilia (8 cases). FilmArray can be useful to detect bacterial pathogens in lower respiratory tract specimens of COVID-19 patients, with a significant decrease of TAT. The test is particularly useful to rule out bacterial co-infections and avoid the inappropriate prescription of antibiotics.
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http://dx.doi.org/10.1016/j.mimet.2021.106259DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8164500PMC
July 2021

The lower respiratory tract microbiome of critically ill patients with COVID-19.

Sci Rep 2021 05 12;11(1):10103. Epub 2021 May 12.

Operative Unit of Clinical Microbiology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 9 via G. Massarenti, 40138, Bologna, Italy.

COVID-19 infection may predispose to secondary bacterial infection which is associated with poor clinical outcome especially among critically ill patients. We aimed to characterize the lower respiratory tract bacterial microbiome of COVID-19 critically ill patients in comparison to COVID-19-negative patients. We performed a 16S rRNA profiling on bronchoalveolar lavage (BAL) samples collected between April and May 2020 from 24 COVID-19 critically ill subjects and 24 patients with non-COVID-19 pneumonia. Lung microbiome of critically ill patients with COVID-19 was characterized by a different bacterial diversity (PERMANOVA on weighted and unweighted UniFrac Pr(> F) = 0.001) compared to COVID-19-negative patients with pneumonia. Pseudomonas alcaligenes, Clostridium hiranonis, Acinetobacter schindleri, Sphingobacterium spp., Acinetobacter spp. and Enterobacteriaceae, characterized lung microbiome of COVID-19 critically ill patients (LDA score > 2), while COVID-19-negative patients showed a higher abundance of lung commensal bacteria (Haemophilus influenzae, Veillonella dispar, Granulicatella spp., Porphyromonas spp., and Streptococcus spp.). The incidence rate (IR) of infections during COVID-19 pandemic showed a significant increase of carbapenem-resistant Acinetobacter baumannii (CR-Ab) infection. In conclusion, SARS-CoV-2 infection and antibiotic pressure may predispose critically ill patients to bacterial superinfection due to opportunistic multidrug resistant pathogens.
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http://dx.doi.org/10.1038/s41598-021-89516-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8115177PMC
May 2021

Epidemiologic case investigation on the zoonotic transmission of Staphylococcus aureus infection from goat to veterinarians.

Zoonoses Public Health 2021 May 5. Epub 2021 May 5.

Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.

Staphylococcus aureus infection led to a case of goat abortion, and four veterinarians contracted S. aureus infection from the goat during and after the abortion. Three veterinarians assisted a doe during the dystocic delivery of a dead foetus. Seventy-two hours after the dystocia, which ended with the goat's death, the veterinarians who assisted during the kidding and the veterinarian who performed the necropsy showed the presence of multiple, isolated, painful pustules 1-5 mm in diameter located along their forearms and knees. S. aureus was isolated from the pustules of the veterinarians, the placenta and uterus of the goat, the organs (brain, thymus gland, abomasum, liver and spleen) of the foetus, the scrotum and eye swabs of the buck, and mammary pustules of another goat from the same herd. Histological analysis revealed purulent metritis and inflammation of the placental cotyledons. Additional investigations eliminated the chances of other infections. S. aureus isolates recovered from the veterinarians, goats, foetus and buck were sensitive to the tested anti-microbials and did not encode staphylococcal enterotoxin genes (sea, ser, sep, see, seg and sei). The isolates were closely related, as indicated by the results of Fourier-transform infrared spectroscopy and comparative whole-genome sequencing analysis. The results of this study clearly support the hypothesis that an episode of professional zoonosis was caused by S. aureus infection during the abortion and also highlight the need for bacterial subtyping in epidemiological surveys.
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http://dx.doi.org/10.1111/zph.12836DOI Listing
May 2021

Classification of of the (Para-)Typhoid Fever Group by Fourier-Transform Infrared (FTIR) Spectroscopy.

Microorganisms 2021 Apr 15;9(4). Epub 2021 Apr 15.

Infectious Disease Department, Bernhard Nocht Institute for Tropical Medicine Hamburg, 20359 Hamburg, Germany.

Typhoidal and para-typhoidal are major causes of bacteraemia in resource-limited countries. Diagnostic alternatives to laborious and resource-demanding serotyping are essential. Fourier transform infrared spectroscopy (FTIRS) is a rapidly developing and simple bacterial typing technology. In this study, we assessed the discriminatory power of the FTIRS-based IR Biotyper (Bruker Daltonik GmbH, Bremen, Germany), for the rapid and reliable identification of biochemically confirmed typhoid and paratyphoid fever-associated isolates. In total, 359 isolates, comprising 30 . Typhi, 23 . Paratyphi A, 23 . Paratyphi B, and 7 . Paratyphi C, respectively and other phylogenetically closely related serovars belonging to the serogroups O:2, O:4, O:7 and O:9 were tested. The strains were derived from clinical, environmental and food samples collected at different European sites. Applying artificial neural networks, specific automated classifiers were built to discriminate typhoidal serovars from non-typhoidal serovars within each of the four serogroups. The accuracy of the classifiers was 99.9%, 87.0%, 99.5% and 99.0% for Typhi, Paratyphi A, B and Paratyphi C, respectively. The IR Biotyper is a promising tool for fast and reliable detection of typhoidal . Hence, IR biotyping may serve as a suitable alternative to conventional approaches for surveillance and diagnostic purposes.
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http://dx.doi.org/10.3390/microorganisms9040853DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8071548PMC
April 2021

Carbapenem resistant bacteria in Intensive Care Unit during COVID-19 pandemic: multicenter before-after cross sectional study.

Infect Control Hosp Epidemiol 2021 Apr 16:1-25. Epub 2021 Apr 16.

Infectious Diseases Unit, Department of Medical and Surgical Sciences, Policlinico Sant'Orsola, Bologna, Italy.

Objectives: To assess the incidence of colonization and infection with carbapenemase producing Enterobacteriaceae (CPE) and carbapenem resistant Acinetobacter baumannii (CR-Ab) in the ICUs of our city hospitals before and during COVID-19 pandemic.

Methods: Multicentre before-after cross sectional study to compare the rates of colonization and infection with CPE and/or CR-Ab in two study periods, period 1 (Jan-Apr 2019) and period 2 (Jan-Apr 2020). Incidence rate ratios (IRR) and 95% CI of weekly colonization and infection rates for each period were compared for the two study periods with Poisson regression. Weekly trends in the incidence of colonization or infection for each study period were summarized using local weighted (Loess) regression.

Results: There was no significant change in either IRR and weekly trend in CPE colonization and infection during the two study periods. A shift from KPC to other CPE mechanisms (OXA-48 and VIM) was observed during period 2. Compared to period 1, during period 2 the IRR of colonization and infection with CR-Ab increased of 7.5 and 5.5-fold, respectively. Genome sequencing showed that all CR-Ab strains belonged to the CC92/IC2 clonal lineage. Clinical strains clustered closely into a single monophyletic group in one of the three centres, whereas segregated in two different clusters in the other two centres, strongly appoints for the occurrence of horizontal transmission.

Conclusion: Our findings remark the need of pursuing infection control activities targeted against the spread of antimicrobial resistance intra and inter hospitals during COVID-19 pandemic, and if necessary re-modulating them according to the new organizational structures imposed by the pandemic.
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http://dx.doi.org/10.1017/ice.2021.144DOI Listing
April 2021

Breakthrough invasive fungal infection after liver transplantation in patients on targeted antifungal prophylaxis: A prospective multicentre study.

Transpl Infect Dis 2021 Mar 26:e13608. Epub 2021 Mar 26.

Division of Infectious Diseases, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy.

Objective: To investigate the rate of and the risk factors for breakthrough-IFI (b-IFI) after orthotopic liver transplantation (OLT) according to the new definition proposed by Mycoses-Study-Group-Education-and-Research-Consortium (MSG-ERC) and the European-Confederation-of-Medical-Mycology (ECMM).

Methods: Multicenter prospective study of adult patients who underwent OLT at three Italian hospitals, from January 2015 to December 2018. Targeted antifungal prophylaxis (TAP) protocol was developed and shared among participating centers. Follow-up was 1-year after OLT. B-IFI was defined as infection occurring during exposure to antifungal prophylaxis. Risk factors for b-IFI were analyzed among patients exposed to prophylaxis by univariable analysis.

Results: We enrolled 485 OLT patients. Overall compliance to TAP protocol was 64.3%, 220 patients received antifungal prophylaxis, 172 according to TAP protocol. Twenty-nine patients were diagnosed of IFI within 1 year after OLT. Of them, 11 presented with b-IFI within 17 (IQR 11-33) and 16 (IQR 4-30) days from OLT and from antifungal onset, respectively. Then out of 11 patients with b-IFI were classified as having high risk of IFI and were receiving anti-mould prophylaxis, nine with echinocandins and one with polyenes. Comparison of patients with and without b-IFI showed significant differences for prior Candida colonization, need of renal replacement therapy after OLT, re-operation, and CMV infection (whole blood CMV-DNA >100 000 copies/mL). Although non-significant, a higher rate of b-IFI in patients on echinocandins was observed (8.2% vs 1.8%, P = .06).

Conclusions: We observed 5% of b-IFI among OLT patients exposed to antifungal prophylaxis. The impact of echinocandins on b-IFI risk in this setting should be further explored.
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http://dx.doi.org/10.1111/tid.13608DOI Listing
March 2021

Rapid identification and detection of β-lactamase-producing Enterobacteriaceae from positive blood cultures by MALDI-TOF/MS.

J Glob Antimicrob Resist 2021 Mar 2;24:270-274. Epub 2021 Jan 2.

Operative Unit of Clinical Microbiology, IRCCS S. Orsola-Malpighi University Hospital, Bologna, Italy; Microbiology, DIMES, University of Bologna, Bologna, Italy.

Objectives: Current evidence suggests that early diagnosis of sepsis and timely detection of antimicrobial resistance are crucial to improve mortality rates among patients. The aim of this study was to evaluate a rapid method for the identification of Gram-negative bacteria from positive blood cultures (BCs), combined with the detection of extended spectrum β-lactamases (ESβL) and carbapenemases production, by means of MALDI-TOF/MS analysis.

Methods: During the study, all BCs positive for Gram-negative rods were selected. Starting from bacterial pellets obtained directly from BC broths, species identification and hydrolysis assays were achieved through MALDI-TOF/MS (Bruker). In particular, we performed a hydrolysis assays of cefotaxime (CTX) and ertapenem (ERT) for the rapid detection of resistance via ESβL and carbapenemases, respectively. These results were compared with the routine workflow, including BC subcultures and confirmation phenotypic methods. Finally, a comparison of the turnaround-time (TAT) between the two protocols was conducted.

Results: Overall, 185 BCs positive for Enterobacteriaceae were collected. In terms of species identification, we observed a concordance of 95.9% comparing MALDI-TOF/MS results to the subculture-based method. The sensitivity and specificity for CTX hydrolysis assay were 91.1% and 92%, respectively; ERT hydrolysis assay showed a sensitivity of 96.2% and a specificity of 99.2%. The TAT of the proposed MALDI TOF/MS-based protocol was significantly lower compared with the routine workflow (P <  0.0001).

Conclusions: The proposed protocol can provide reliable bacterial identification and data concerning β-lactam resistance in only 3 hours, positively improving management of patients in terms of antimicrobial stewardship.
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http://dx.doi.org/10.1016/j.jgar.2020.12.015DOI Listing
March 2021

Ceftolozane-Tazobactam Treatment of Hypervirulent Multidrug Resistant Infections in Neutropenic Patients.

Microorganisms 2020 Dec 21;8(12). Epub 2020 Dec 21.

Institute of Hematology "Seràgnoli", IRCCS-Azienda Ospedaliero Policlinico Sant'Orsola-Universitaria di Bologna, 40138 Bologna, Italy.

The effectiveness of ceftolozane/tazobactam for the treatment of infections in neutropenic patients caused by hypervirulent multidrug-resistant (MDR) has not been previously reported. We identified seven cases of MDR infection in neutropenic patients over a four-month period within the same hematology ward. Four cases were associated with rapid progression despite piperacillin-tazobactam or meropenem therapy, and three patients developed sepsis or extensive skin/soft tissue necrosis. In three of the four cases, patients were empirically switched from meropenem to ceftolozane/avibactam before carbapenem susceptibility test results were available, and all four patients underwent extensive surgical debridement or amputation of affected tissues and survived. Further investigation revealed a common bathroom source of MDR clonal subtypes ST175 and ST235 that harbored genes for type III secretion system expression and elaboration of ExoU or ExoS exotoxin. We conclude that ceftolozane/tazobactam plus early source control was critical for control of rapidly progressing skin and soft infection in these neutropenic patients caused by highly virulent ST175 and ST235 clones of MDR .
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http://dx.doi.org/10.3390/microorganisms8122055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767535PMC
December 2020

Rapid Sepsityper in clinical routine: 2 years' successful experience.

J Med Microbiol 2020 Dec 6;69(12):1398-1404. Epub 2020 Nov 6.

Operative Unit of Microbiology, University Hospital Policlinico Sant'Orsola-Malpighi, Bologna, Italy.

Rapid identification of the causative agent of sepsis is crucial for patient outcomes.. The Sepsityper sample preparation method enables direct microbial identification of positive blood culture samples via matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS).. The implementation of the Sepsityper method in the routine practice could represent a fundamental tool to achieve a prompt identification of the causative agent of bloodstream infections, and therefore accelerate the adoption of the proper antibiotic treatment. In this study, the novel rapid workflow of the MALDI Biotypr Sepsityper kit (Bruker Daltonik GmbH, Germany) was evaluated using routine samples from a 2-year period (=6918), and dedicated optimized protocols for the microbial groups that were more difficult to identify were developed. Moreover, the use of the residual bacterial pellet to perform susceptibility testing using different methods (commercial broth microdilution, disc diffusion, gradient diffusion) was investigated. The rapid Sepsityper protocol allowed the identification of 5470/6338 (86.3 %) monomicrobial samples at species level, with very good performance for all of the clinically most significant pathogens (2510/2592 enterobacteria, 631/669 and 223/246 enterococci were identified). , and yeasts were the most troublesome to identify, but the application of specific optimized protocols significantly improved their rate of identification (from 14.7-71.5 %, 47.8-89.7 % and 37.1-89.5 %, respectively). Specificity was 100 % (no identification was made for the false-positive samples). Further, the residual pellet proved to be suitable to investigate susceptibility to antimicrobials, enabling us to simplify the workflow and shorten the time to report. The Rapid Sepsityper workflow proved to be a reliable sample preparation method for identification and susceptibility testing directly from positive blood cultures, providing novel approaches for accelerated diagnostics of bloodstream infections.
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http://dx.doi.org/10.1099/jmm.0.001268DOI Listing
December 2020

The Italian arm of the PREPARE study: an international project to evaluate and license a maternal vaccine against group B streptococcus.

Ital J Pediatr 2020 Oct 28;46(1):160. Epub 2020 Oct 28.

Paediatric Infectious Diseases Research Group, St George's University of London, London, UK.

Background: Group B streptococcus (GBS) is a leading cause of sepsis, pneumonia and meningitis in infants, with long term neurodevelopmental sequelae. GBS may be associated with poor pregnancy outcomes, including spontaneous abortion, stillbirth and preterm birth. Intrapartum antibiotic prophylaxis (IAP) is currently the only way to prevent early-onset disease (presenting at 0 to 6 days of life), although it has no impact on the disease presenting over 6 days of life and its implementation is challenging in resource poor countries. A maternal vaccine against GBS could reduce all GBS manifestations as well as improve pregnancy outcomes, even in low-income countries.

Main Body: The term "PREPARE" designates an international project aimed at developing a maternal vaccination platform to test vaccines against neonatal GBS infections by maternal immunization. It is a non-profit, multi-center, interventional and experimental study (promoted by the St George University of London. [UK]) with the aim of developing a maternal vaccination platform, determining pregnancy outcomes, and defining the extent of GBS infections in children and mothers in Africa. PREPARE also aims to estimate the protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa and to conduct two trials on candidate GBS vaccines. PREPARE consists of 6 work packages. In four European countries (Italy, UK, Netherlands, France) the recruitment of cases and controls will start in 2020 and will end in 2022. The Italian PREPARE network includes 41 centers. The Italian network aims to collect: GBS isolates from infants with invasive disease, maternal and neonatal sera (cases); cord sera and GBS strains from colonized mothers whose infants do not develop GBS infection (controls).

Short Conclusion: PREPARE will contribute information on protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa. The vaccine that will be tested by the PREPARE study could be an effective strategy to prevent GBS disease.
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http://dx.doi.org/10.1186/s13052-020-00923-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594470PMC
October 2020

Epidemiology of invasive pulmonary aspergillosis among COVID-19 intubated patients: a prospective study.

Clin Infect Dis 2020 Jul 28. Epub 2020 Jul 28.

Infectious Diseases Unit, Department of Medical and Surgical Sciences, Policlinico Sant'Orsola, Bologna, Italy.

Background: In this study we evaluated the incidence of invasive pulmonary aspergillosis among intubated patients with critical coronavirus disease 2019 (COVID-19) and evaluated different case definitions of invasive aspergillosis.

Methods: Prospective, multicentre study on adult patients with microbiologically confirmed COVID-19 receiving mechanical ventilation. All included participants underwent screening protocol for invasive pulmonary aspergillosis with bronchoalveolar lavage galactomannan and cultures performed on admission at 7 days and in case of clinical deterioration. Cases were classified as coronavirus associated pulmonary aspergillosis (CAPA) according to previous consensus definitions. The new definition was compared with putative invasive pulmonary aspergillosis (PIPA).

Results: A total of 108 patients were enrolled. Probable CAPA was diagnosed in 30 (27.7%) of patients after a median of 4 (2-8) days from intensive care unit (ICU) admission. Kaplan-Meier curves showed a significant higher 30-day mortality rate from ICU admission among patients with either CAPA (44% vs 19%, p= 0.002) or PIPA (74% vs 26%, p<0.001) when compared with patients not fulfilling criteria for aspergillosis. The association between CAPA [OR 3.53 (95%CI 1.29-9.67), P=0.014] or PIPA [OR 11.60 (95%CI 3.24-41.29) p<0.001] with 30-day mortality from ICU admission was confirmed even after adjustment for confounders with a logistic regression model. Among patients with CAPA receiving voriconazole treatment (13 patients, 43%) A trend toward lower mortality (46% vs 59% p=0.30) and reduction of galactomannan index in consecutive samples was observed.

Conclusion: We found a high incidence of CAPA among critically ill COVID-19 patients and that its occurrence seems to change the natural history of disease.
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http://dx.doi.org/10.1093/cid/ciaa1065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7454393PMC
July 2020

Antibiotic susceptibility testing of anaerobic bacteria by broth microdilution method using the MICRONAUT-S Anaerobes MIC plates.

Anaerobe 2020 Jun 24;63:102217. Epub 2020 May 24.

University Hospital of Bologna-Policlinico Sant'Orsola-Malpighi, Operative Unit of Microbiology, via Massarenti, 9, Bologna, Italy.

Susceptibility profiles of anaerobic bacteria to antibiotics have become unpredictable, thus reliable and user-friendly methods for routine susceptibility testing are needed. In this study, we evaluated the MICRONAUT-S Anaerobes MIC test plate, a commercially available broth microdilution method, and suitable for clinical microbiology routine testing. We analyzed a collection of 300 consecutive clinically significant isolates, including 149 Gram-positive and 151 Gram-negative strains. The performance of the MICRONAUT-S Anaerobes MIC plate was compared to that of a gradient diffusion method (current laboratory standard), calculating the essential and the categorial agreement. 99.7% (299/300) of the strains included in this study successfully grew in the MICRONAUT-S Anaerobes MIC plate (73% of them after 24 h of incubation), while 1 Porphyromonas uenoni isolate didn't grow. It showed a high concordance with the gradient diffusion method. Overall essential and categorical agreements resulted >95% and >97%, respectively, and only a low rate of errors was observed. Beyond the very good analytical performance, several technical advantages in comparison with the gradient diffusion method were observed, that contribute to make the MICRONAUT-S Anaerobes panels suitable for an easy implementation into laboratory routine.
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http://dx.doi.org/10.1016/j.anaerobe.2020.102217DOI Listing
June 2020

Diffuse primary cutaneous infection by in a liver transplant recipient with pulmonary nocardiosis: Importance of prompt identification for clinical resolution.

Med Mycol Case Rep 2020 Jun 4;28:42-45. Epub 2020 May 4.

Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Via Massarenti 9, 40138, Bologna, Italy.

Fungal infections are rare in the general population but are an emerging cause of disease in immunosuppressed patients, especially solid organ transplant recipients. Here, we report the case of a female Caucasian liver transplant patient who developed pulmonary nocardiosis two months after an episode of liver rejection. At the time of lung nocardiosis, she was being treated with tacrolimus and corticosteroids and suffered from diffuse papular skin lesions. She was initially suspected of having a cutaneous nocardial infection but culture examination revealed the presence of a dematiaceous fungus; . The prompt identification of the fungus and administration of oral Voriconazole resolved the skin infection with complete remission.
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http://dx.doi.org/10.1016/j.mmcr.2020.04.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218148PMC
June 2020

Evaluation of the MBT STAR-Carba Assay for the Detection of Carbapenemase Production in and with a Large Collection of Routine Isolates from Plate Cultures and Patient-Derived Positive Blood Cultures.

Microb Drug Resist 2020 Nov 15;26(11):1298-1306. Epub 2020 May 15.

Unit of Microbiology, University Hospital Sant'Orsola-Malpighi of Bologna, Bologna, Italy.

The spread of carbapenemase-producing is a major public health concern worldwide, and methods for their prompt and reliable detection are highly demanded for therapeutic and hygiene control purposes. In this study, we evaluate the MBT STAR-Carba assay (Bruker Daltonik) to detect the carbapenemase production in clinical and surveillance isolates from plate cultures and directly from patient-derived positive blood cultures bottles. Overall,  = 1,307 samples were analyzed ( = 900 plate cultures, and  = 407 positive blood cultures, using the bacterial pellet obtained with the Sepsityper Kit; Bruker Daltonik), including  = 793 carbapenemase producers ( = 579 carbapenemase,  = 161 metallo-beta-lactamases,  = 45 OXA-48, and eight isolates harboring two different enzymes),  = 239 carbapenem-resistant noncarbapenemase producers, and  = 275 carbapenem-susceptible strains. The STAR-Carba assay detected 657/661 (99.4%) carbapenemase producers from plate cultures, and 132/132 (100%) from positive blood cultures. Specificity resulted in 100% for carbapenem-susceptible strains, and 91.6% for carbapenem-resistant strains resulted negative for carbapenamase production with the routine methods used in this study. In this study, the MBT STAR-Carba assay proved to be a highly reliable method for the detection of carbapenemase-producing , regardless of the enzyme family, and from both plate cultures and positive blood culture bottles.
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http://dx.doi.org/10.1089/mdr.2019.0466DOI Listing
November 2020

Evaluation of five carbapenemase detection assays for Enterobacteriaceae harbouring blaKPC variants associated with ceftazidime/avibactam resistance.

J Antimicrob Chemother 2020 07;75(7):2010-2013

Operative Unit of Clinical Microbiology, S. Orsola-Malpighi University Hospital, Bologna, Italy.

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http://dx.doi.org/10.1093/jac/dkaa079DOI Listing
July 2020

Impact on Mortality of a Bundle for the Management of Enterococcal Bloodstream Infection.

Open Forum Infect Dis 2019 Dec 4;6(12):ofz473. Epub 2019 Nov 4.

Infectious Diseases Unit, Department of Medical and Surgical Sciences, Sant'Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy.

Objective: In this study, we evaluated the effectiveness of a management bundle for bloodstream infection (E-BSI).

Method: This was a single-center, quasi-experimental (pre/post) study. In the prephase (January 2014 to December 2015), patients with monomicrobial E-BSI were retrospectively enrolled. During the post- or intervention phase (January 2016 to December 2017), all patients with incident E-BSI were prospectively enrolled in a nonmandatory intervention arm comprising infectious disease consultation, echocardiography, follow-up blood cultures, and early targeted antibiotic treatment. Patients were followed up to 1 year after E-BSI. The primary outcome was 30-day mortality.

Results: Overall, 368 patients were enrolled, with 173 in the prephase and 195 in the postphase. The entire bundle was applied in 15% and 61% patients during the pre- and postphase, respectively ( < .001). Patients enrolled in the postphase had a significant lower 30-day mortality rate (20% vs 32%, = .0042). At multivariate analysis, factors independently associated to mortality were age (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.00-1.05), intensive care unit admission (HR, 2.51; 95% CI, 1.18-3.89), and healthcare-associated (HR, 2.32; 95% CI, 1.05-5.16) and hospital-acquired infection (HR, 2.85; 95% CI, 1.34-4.76), whereas being enrolled in the postphase period (HR, 0.49; 95% CI, 0.32-0.75) was associated with improved survival. Results were consistent also in the subgroups with severe sepsis (HR, 0.37; 95% CI, 0.16-0.90) or healthcare-associated infections (HR, 0.53; 95% CI, 0.31-0.93). A significantly lower 1-year mortality was observed in patients enrolled in the postphase period (50% vs 68%, < .001).

Conclusions: The introduction of a bundle for the management of E-BSI was associated with improved 30-day and 1-year survival.
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http://dx.doi.org/10.1093/ofid/ofz473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047956PMC
December 2019

Effect of Alternative Pasteurization Techniques on Human Milk's Bioactive Proteins.

J Pediatr Gastroenterol Nutr 2020 04;70(4):508-512

Department of Medical and Surgical Sciences, Neonatal Intensive Care Unit, AOU Bologna, University of Bologna, Bologna.

Objectives: Human milk (HM) feeding leads to improved outcome for preterm infants. When mother's milk is unavailable, pasteurized donor HM (DHM) is the recommended alternative over formula. The Holder pasteurization (HoP) method is universally performed in HM banks; however, it is known to impair several functional HM components. The aim of this study was to compare the efficacy of HoP with 2 innovative processing methods (high-temperature short-time [HTST] pasteurization and high-pressure processing [HPP]) in preserving some bioactive HM protein components.

Methods: HM samples from donors of the Bologna HM bank were collected and divided into 4 subsamples: 1 was kept raw, and each of the others was processed using a different technique (HoP, HTST, and HPP at 600 MPa for 3 minutes). Total protein content, secretory immunoglobulin A (sIgA), and lactoferrin contents were compared.

Results: Both HM lactoferrin and sIgA content were negatively affected, but to a different extent, by each method: sIgA was preserved by HTST, with only HPP leading to a significant reduction (-38.8%); lactoferrin content was strongly reduced by HoP (-87.5%) and HTST (-83.5%), and preserved by HPP. Variations in protein profile were seen for all processing methods, being more relevant for HoP, followed by HTST and, finally, by HPP. All the 3 methods lowered the untreated HM microbial counts to undetectable levels, in accordance with national guidelines.

Conclusions: Both HTST and HPP better preserved the original HM protein profile, compared to HoP. They, however, affected differently some bioactive HM components involved in immune response and antibacterial activity.
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http://dx.doi.org/10.1097/MPG.0000000000002598DOI Listing
April 2020

Prognostic Utility of the New Definition of Difficult-to-Treat Resistance Among Patients With Gram-Negative Bloodstream Infections.

Open Forum Infect Dis 2019 Dec 12;6(12):ofz505. Epub 2019 Dec 12.

Infectious Diseases Unit, Department of Medical and Surgical Sciences, Policlinico Sant'Orsola Malpighi, University of Bologna, Bologna, Italy.

Background: To compare the prognostic utility of the new definition of difficult-to-treat resistance (DTR) vs established definitions in a cohort of patients with Gram-negative bloodstream infections (GNBSIs).

Methods: This was a retrospective single-center study of adult patients with monomicrobial GNBSI, hospitalized from 2013 to 2016. DTR was defined as isolate demonstrating intermediate or resistant phenotype to all reported agents in the carbapenem, beta-lactam, and fluoroquinolone classes. Carbapenem resistance (CR) was defined according to 2015 Centers for Disease Control and Prevention criteria. Each isolate was further classified according to the Magiorakos et al. criteria as non-multidrug-resistant (non-MDR), MDR, extensively drug-resistant (XDR), or pan-drug-resistant (PDR). The primary outcome was all-cause 30-day mortality.

Results: Overall, 1576 patients were analyzed. Enterobacteriaceae accounted for 88.7% of BSIs, with (n = 941) and (n = 326) being the most common pathogens. was the most common nonfermentative bacteria (n = 130, 8.2%). Overall, 11% of strains were defined as DTR and 13% as CR. Episodes were further classified as non-MDR (68.8%), MDR (21.9%), XDR (8.8%), and PDR (0.4%). The prevalence rates of DTR, CR, and XDR were similar among Enterobacteriaceae and , whereas they differed in . All the analyzed resistance definitions significantly improved prediction of 30-day mortality when introduced into a baseline multivariate model, to a similar degree: 9%, 10%, and 11% for DTR, Magiorakos, and CR definitions, respectively.

Conclusions: DTR seems a promising tool to identify challenging GNBSIs, mainly those due to . With the availability of new agents for CR infections, further multicenter assessments of DTR are needed.
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http://dx.doi.org/10.1093/ofid/ofz505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6916520PMC
December 2019

Epidemiology and complications of late-onset sepsis: an Italian area-based study.

PLoS One 2019 22;14(11):e0225407. Epub 2019 Nov 22.

Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale, Azienda Ospedaliero-Universitaria S. Orsola-Malpighi-Università di Bologna, Bologna, Italy.

Background: Most studies regarding late-onset sepsis (LOS) address selected populations (i.e., neonates with low birth weight or extremely preterm neonates). Studying all age groups is more suitable to assess the burden of single pathogens and their clinical relevance.

Methods: This is a retrospective regional study involving paediatric departments and NICUs in Emilia-Romagna (Italy). Regional laboratory databases were searched from 2009 to 2012. Records of infants (aged 4 to 90 days) with a positive blood or cerebrospinal fluid (CSF) culture were retrospectively reviewed and analysed according to acquisition mode (whether hospital- or community-acquired).

Results: During the study period, there were 146,682 live births (LBs), with 296 patients experiencing 331 episodes of LOS (incidence rate: 2.3/1000 LBs). Brain lesions upon discharge from the hospital were found in 12.3% (40/296) of cases, with death occurring in 7.1% (23/296; 0.14/1000 LBs). With respect to full-term neonates, extremely preterm or extremely low birth weight neonates had very high risk of LOS and related mortality (> 100- and > 800-fold higher respectively). Hospital-acquired LOS (n = 209) was significantly associated with very low birth weight, extremely preterm birth, pneumonia, mechanical ventilation, and death (p< 0.01). At multivariate logistic regression analysis, catecholamine support (OR = 3.2), central venous line before LOS (OR = 14.9), and meningitis (OR = 44.7) were associated with brain lesions or death in hospital-acquired LOS (area under the ROC curve 0.81, H-L p = 0.41). Commonly identified pathogens included coagulase-negative staphylococci (CoNS n = 71, 21.4%), Escherichia coli (n = 50, 15.1%), Staphylococcus aureus (n = 41, 12.4%) and Enterobacteriaceae (n = 41, 12.4%). Group B streptococcus was the predominant cause of meningitis (16 of 38 cases, 42%). Most pathogens were sensitive to first line antibiotics.

Conclusions: This study provides the first Italian data regarding late-onset sepsis (LOS) in all gestational age groups. Compared to full-term neonates, very high rates of LOS and mortality occurred in neonates with a lower birth weight and gestational age. Group B streptococcus was the leading cause of meningitis. Excluding CoNS, the predominant pathogens were Escherichia coli and Staphylococcus aureus. Neonates with hospital-acquired LOS had a worse outcome. Antibiotic associations, recommended for empirical treatment of hospital- or community-acquired LOS, were adequate.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0225407PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874360PMC
March 2020

Rectal screening for carbapenemase-producing Enterobacteriaceae: a proposed workflow.

J Glob Antimicrob Resist 2020 06 19;21:86-90. Epub 2019 Oct 19.

Microbiology Unit, S. Orsola-Malpighi Hospital, Via Massarenti 9, Bologna, Italy.

Objectives: Active screening is a crucial element for the prevention of carbapenemase-producing Enterobacteriaceae (CPE) transmission in healthcare settings. Here we propose a culture-based protocol for rectal swab CPE screening that combines CPE detection with identification of the carbapenemase type.

Methods: The workflow integrates an automatic digital analysis of selective chromogenic media (WASPLab®; Copan), with subsequent rapid tests for the confirmation of carbapenemase production [i.e. detection of Klebsiella pneumoniae carbapenemase (KPC)-specific peak by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) or a multiplex immunochromatographic assay identifying the five commonest carbapenemase types]. To evaluate the performance of this protocol in depth, data for 21 162 rectal swabs submitted for CPE screening to the Microbiology Unit of S. Orsola-Malpighi Hospital (Bologna, Italy) were analysed.

Results: Considering its ability to correctly segregate plates with/without Enterobacteriaceae, WASPLab Image Analysis Software showed globally a sensitivity and specificity of 100% and 79.4%, respectively. Of the plates with bacterial growth (n = 901), 693 (76.9%) were found to be positive for CPE by MALDI-TOF/MS (KPC-specific peak for K. pneumoniae) or by immunochromatographic assay. Only 2.8% (16/570) of KPC-positive K. pneumoniae strains were missed by the specific MALDI-TOF/MS algorithm, being detected by the immunochromatographic assay. The mean turnaround time needed from sample arrival to the final report ranged between 18 and 24 h, representing a significant time saving compared with manual reading.

Conclusion: This workflow proved to be fast and reliable, being particularly suitable for areas endemic for KPC-producing K. pneumoniae and for high-throughput laboratories.
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http://dx.doi.org/10.1016/j.jgar.2019.10.012DOI Listing
June 2020

Genomic characterization of a Klebsiella pneumoniae ST1519 resistant to ceftazidime/avibactam carrying a novel KPC variant (KPC-36).

Int J Antimicrob Agents 2020 01 5;55(1):105816. Epub 2019 Oct 5.

Operative Unit of Clinical Microbiology, S. Orsola-Malpighi University Hospital, Bologna, Italy; University of Bologna, Bologna, Italy.

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http://dx.doi.org/10.1016/j.ijantimicag.2019.09.020DOI Listing
January 2020

Screening for carriage of carbapenem-resistant Enterobacteriaceae in settings of high endemicity: a position paper from an Italian working group on CRE infections.

Antimicrob Resist Infect Control 2019 13;8:136. Epub 2019 Aug 13.

6Department of Experimental and Clinical Medicine, University of Florence, and Clinical Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy.

Introduction: A variety of national and international guidelines exist around the management of carbapenem resistant Enterobacteriaceae (CREs), but some of these are several years old and do not reflect current epidemiology and they also do not necessarily give pragmatic advice around active surveillance of CREs in countries with a high burden of cases and limited resources. This paper aims to provide a best practice position paper to guide active surveillance in a variety of scenarios in these settings, and discusses which patients should be screened, what methods could be used for screening, and how results might influence infection prevention interventions.

Methods: This paper was developed as a result of a series of meetings of expert opinion leaders representing the major infectious disease and infection prevention societies in Italy and having the endorsement of AMCLI (Italian Association of Clinical Microbiology) and SITA (Italian Society for Anti-infective Therapy). There was no attempt to undertake a full systematic review of the evidence, as it was felt that this was inadequate to inform a pragmatic view on the best way forward based on current epidemiology and infection rates.

Key Recommendations: Key recommendations focus on the urgent need to promote measures to prevent transmission and infection, focusing on high risk patients and clinical areas, as well as outbreak situations. Active surveillance leading to appropriate infection prevention precautions plays a major role in this.

Conclusions: There are limited national or international guidelines giving pragmatic advice on the most appropriate measures for active surveillance and management of colonized patients in a high-burden setting such as Italy. While individual hospitals and regions will need to formulate their own policies based on local epidemiology, this position paper attempts to highlight current best practice in this area and provide pragmatic advice for clinicians, infection prevention staff, and healthcare managers.
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http://dx.doi.org/10.1186/s13756-019-0591-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6693230PMC
June 2020

Comparative serum bactericidal activity of meropenem-based combination regimens against extended-spectrum beta-lactamase and KPC-producing Klebsiella pneumoniae.

Eur J Clin Microbiol Infect Dis 2019 Oct 6;38(10):1925-1931. Epub 2019 Jul 6.

Department of Medical Sciences and Surgery, Operative Unit of Infectious Diseases, S.Orsola-Malpighi University Hospital, Bologna, Italy.

Combination therapies are frequently used in the treatment of multidrug-resistant Klebsiella pneumoniae infection without consensus regarding which combination is the most effective. We compared bactericidal titres from sera collected from critically ill patients receiving meropenem plus tigecycline (n = 5), meropenem plus colistin (n = 5), or meropenem, colistin and tigecycline (n = 5) against K. pneumoniae isolates that included ESBL-producing (n = 7) and KPC-producing strains (n = 14) with varying sensitivity patterns to colistin and tigecycline. Meropenem concentrations (C) were measured in all samples by LC-MS/MS, and indexed to respective pathogen MICs to explore differences in patterns of bactericidal activity for two versus three drug combination regimens. All combination regimens achieved higher SBTs against ESBL (median reciprocal titre 128, IQR 32-256) versus KPC (4, IQR 2-32) strains. Sera from patients treated with meropenem-colistin yielded higher median SBTs (256, IQR 64-512) than either meropenem-tigecycline (32, IQR 8-256; P < 0.001). The addition of tigecycline was associated with a lower probability of achieving a reciprocal SBT above 8 when meropenem concentrations were below the MIC (P = 0.04). Although the clinical significance is unknown, sera from patients receiving tigecycline-based combination regimens produce lower serum bactericidal titres against ESBL or KPC-producing K. pneumoniae. SBTs may represent a useful complimentary endpoint for comparing pharmacodynamics of combinations regimens for MDR Enterobacteriaceae.
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http://dx.doi.org/10.1007/s10096-019-03628-6DOI Listing
October 2019

Risk factors for group B streptococcus early-onset disease: an Italian, area-based, case-control study.

J Matern Fetal Neonatal Med 2020 Jul 17;33(14):2480-2486. Epub 2019 Jul 17.

Unità Operativa di Terapia Intensiva Neonatale, Dipartimento Integrato Materno-Infantile, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy.

Intrapartum antibiotic prophylaxis (IAP) prevents group B streptococcus (GBS) early-onset disease (EOD). No European study evaluates the relative impact of risk factors (RFs) for EOD after a screening-based strategy and widespread IAP use We aimed to evaluate the risks of EOD in an Italian region where a screening-based strategy for preventing EOD was implemented. Cases of EOD born at or above 35 weeks' gestation were reviewed and matched with controls. There were 109 cases of EOD among 532,154 live births. Most cases had negative GBS prenatal screening (56/91, 61.5%) and were unexposed to IAP (86/109, 78.9%). At multivariate analysis, GBS bacteriuria ( = 6.99), positive prenatal screening ( = 13.7) and maternal intrapartum fever ( = 188.3) were associated with an increased risk of EOD, whereas intrapartum beta-lactam antibiotics were associated with a decreased risk of EOD (≥4 h:  = 0.008; <4 h:  = 0.04). Neonates born to nonfebrile, GBS positive pregnant women, receiving beta-lactam antibiotics had very low probability of EOD, particularly if IAP was adequate. GBS positive prenatal screening, GBS bacteriuria and intrapartum fever are associated with EOD. Intrapartum beta-lactam antibiotics reduce the probability of EOD in neonates born to nonfebrile mothers.
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http://dx.doi.org/10.1080/14767058.2019.1628943DOI Listing
July 2020

In vitro synergistic activity of meropenem/vaborbactam in combination with ceftazidime/avibactam against KPC-producing Klebsiella pneumoniae.

J Antimicrob Chemother 2019 05;74(5):1457-1459

Operative Unit of Clinical Microbiology, St Orsola-Malpighi University Hospital, Bologna, Italy.

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http://dx.doi.org/10.1093/jac/dky557DOI Listing
May 2019

Risk factors for treatment failure in patients receiving β-lactam/β-lactamase inhibitor combinations for Enterobacteriaceae bloodstream infection: A retrospective, single-centre, cohort study.

Int J Antimicrob Agents 2019 May 9;53(5):574-581. Epub 2019 Jan 9.

Infectious Diseases Unit, Department of Medical and Surgical Sciences, Policlinico Sant'Orsola Malpighi, University of Bologna, Via Massarenti 11, 40137 Bologna, Italy.

The aim of this study was to investigate risk factors for treatment failure in patients receiving in vitro-active therapy with β-lactam/β-lactamase inhibitor (BL/BLI) for Enterobacteriaceae bloodstream infection (E-BSI). This was a retrospective, single-centre study of patients diagnosed with E-BSI at an Italian centre over a 4-year period. Exclusion criteria were age <18 years, clinical data unavailable, polymicrobial BSI, failure to receive in vitro-active therapy and death within 72 h from drawing the index blood culture. Patients who received BL/BLI as appropriate empirical and/or definitive therapy for ≥50% of the total treatment duration were selected. The primary endpoint was all-cause 30-day mortality. The secondary endpoint was 90-day relapse. Of 1319 eligible patients, 835 were selected. A total of 714 received BL/BLI as appropriate empirical therapy, of whom 522 remained on BL/BLI as definitive therapy and 192 shifted to another antibiotic for <50% of the treatment duration; 121 received BL/BLI as definitive therapy only. Non-susceptibility to extended-spectrum cephalosporins (NS-ESCs) was detected in 207 episodes (24.8%). All-cause 30-day mortality was 6.8%. In multivariate analysis adjusted for NS-ESC, independent predictors of mortality were Charlson comorbidity index, septic shock, Proteus spp. and CVC-related BSI, whilst urinary source was a protective factor. The 90-day relapse rate was 4.2%. Immunosuppression was the main independent predictor for relapse. BL/BLI was the most common antibiotic administered to patients with E-BSI in this cohort. Among patients appropriately treated with BL/BLI, failure rates were low and were primarily associated with underlying diseases, clinical severity at BSI onset and infection source.
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http://dx.doi.org/10.1016/j.ijantimicag.2019.01.005DOI Listing
May 2019

A Full MALDI-Based Approach to Detect Plasmid-Encoded KPC-Producing .

Front Microbiol 2018 23;9:2854. Epub 2018 Nov 23.

Department of Medical Microbiology, MVZ Dr. Eberhard & Partner Dortmund, Dortmund, Germany.

KPC-producing represents a severe public health concern worldwide. The rapid detection of these isolates is of fundamental importance for the adoption of proper antibiotic treatment and infection control measures, and new applications of MALDI-TOF MS technology fit this purpose. In this study, we present a full MALDI-based approach to detect plasmid-encoded KPC-producing strains, accomplished by the automated detection of a KPC-specific peak (at 11,109 m/z) by a specific algorithm integrated into the MALDI Biotyper system (Bruker Daltonik), and the confirmation of carbapenemase activity by STAR-Carba imipenem hydrolysis assay. A total of 6209 isolates from Italy and Germany were investigated for the presence of the KPC-related peak, and a subset of them ( = 243) underwent confirmation of carbapenemase activity by STAR-Carba assay. The novel approach was further applied directly to positive blood culture bottles ( = 204), using the bacterial pellet obtained with Sepsityper kit (Bruker Daltonik). The novel approach enabled a reliable and very fast detection of KPC-producing strains, from colonies as well as directly from positive blood cultures. The automated peak detection enabled the instant detection of KPC-producing during the routine identification process, with excellent specificity (100%) and a good sensitivity (85.1%). The sensitivity is likely mainly related to the prevalence of the specific plasmid harboring clones among all the KPC-producing circulating strains. STAR-Carba carbapenemase confirmation showed 100% sensitivity and specificity, both from colonies and from positive blood cultures.
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http://dx.doi.org/10.3389/fmicb.2018.02854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6277887PMC
November 2018

Impact of meropenem on Klebsiella pneumoniae metabolism.

PLoS One 2018 15;13(11):e0207478. Epub 2018 Nov 15.

Microbiology, DIMES, University of Bologna, Bologna, Italy.

The aim of this study was to analyze the metabolome of several Klebsiella pneumoniae strains characterized by different resistance patterns. A total of 59 bacterial strains (27 carbapenemase-negative and 32 carbapenemase-positive) were included and their metabolic features were assessed in basal conditions. Moreover, 8 isolates (4 wild-type and 4 KPC-producers) were randomly selected to evaluate the impact of sub-lethal concentrations of meropenem on bacterial metabolism. The metabolomic analysis was performed by 1H-NMR spectroscopy both on filtered supernatants and cell lysates. A total of 40 and 20 molecules were quantified in the intracellular and the extracellular metabolome, respectively. While in basal conditions only five metabolites showed significant differences between carbapenemase-positive and negative strains, the use of meropenem had a profound impact on the whole bacterial metabolism. In the intracellular compartment, a reduction of different overflow metabolites and organic acids (e.g. formate, acetate, isobutyrate) was noticed, whereas, in the extracellular metabolome, the levels of several organic acids (e.g. succinate, acetate, formate, lactate) and amino acids (aspartate, threonine, lysine, alanine) were modified by meropenem stimulation. Interestingly, carbapenemase-positive and negative strains reacted differently to meropenem in terms of number and type of perturbed metabolites. In wild-type strains, meropenem had great impact on the metabolic pathways related to methane metabolism and alanine, aspartate and glutamate metabolism, whereas in KPC-producers the effect was predominant on pyruvate metabolism. The knowledge about the bacterial metabolic profiles could help to set up innovative diagnostic methods and new antimicrobial strategies to fight the global crisis against carbapenemase-positive K. pneumoniae.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207478PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237392PMC
April 2019