Surveillance de la colonisation par Candida glabrata en réanimation chirurgicale (épidemiologie moléculaire et sensibilité aux antifongiques)

BESANCON-BU Médecine pharmacie (250562102) / SudocSudocFranceF

Rapid antibiotic susceptibility testing on blood cultures using MALDI-TOF MS.

Antibiotic resistance is a major public health problem requiring the early optimization of antibiotic prescriptions. Matrix-Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry (MALDI-TOF MS) has been shown to accurately identify bacteria from positive blood culture. Here, we developed a rapid detection of Escherichia coli resistance to amoxicillin (AMX) and cefotaxime (CTX) from positive blood culture based on MALDI-TOF MS. Potential sparing of broad-spectrum antibiotics was also evaluated. We tested 103 E. coli-positive blood cultures. Blood cultures were subculture 1-hour in antibiotic-free rich liquid media before further incubation with and without AMX for 2.5 h or CTX for 2 h. Protein extracts associated with an internal control were spotted on a MALDI-TOF target and spectra were analyzed with the MBT-ASTRA prototype software (Bruker Daltonik GmbH, Bremen, Germany). Bacterial growth ratio was calculated from the AUC spectra obtained in the presence and absence of the antibiotic and compared to a threshold which classified E. coli as susceptible or resistant. Results were interpreted with MICs determined using agar dilution method as reference technique. MBT-ASTRA recognized 95% and 84% of the AMX- and CTX-susceptible isolates, respectively. Overall, quantitative analysis of mass spectra allows susceptibility testing within 4 hours after the positivity of blood culture with E. coli. At the first report of positive blood culture, MALDI-TOF MS would then provide the prescribers with the bacterial identification and the susceptibility to AMX and CTX, thus limiting the use of broad-spectrum compounds

Can MALDI-TOF Mass Spectrometry Reasonably Type Bacteria?

International audienceBacterial typing is crucial to tackle the spread of bacterial pathogens but current methods are time-consuming and costly. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been recently integrated into the microbiology laboratory workflow for a quick and low-cost microbial species identification. Independent research groups have successfully redirected the original function of this technology from their primary purpose to discriminate subgroups within pathogen species. However, identical bacterial subgroups could be identified by unrelated peaks by independent methods, thus limiting their robustness and exportability. We propose several guidelines that could improve the performance of MALDI-TOF MS-based typing methods for use as a first-line epidemiological tool

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry identifies Pseudomonas aeruginosa high-risk clones.

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Rapid, sensitive and specific detection of OXA-48-like-producing Enterobacteriaceae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

International audience: The emergence of Enterobacteriaceae producing the class D carbapenemase OXA-48 has become a public health concern, particularly in southern Europe and in the Mediterranean area. The existing MALDI-TOF MS assays that detect carbapenemase activity have disregarded the Enterobacteriaceae producing OXA-48-like enzymes. Here, we assessed the ability of an optimized MALDI-TOF MS imipenem hydrolysis assay to detect OXA-48-like-producing Enterobacteriaceae. We tested 372 non duplicate isolates of Enterobacteriaceae from 9 species, among which 92 harbored a blaOXA-48-like gene and 180 were non-susceptible to ertapenem. The vast majority (98.9%) of the OXA-48-like producers were detected and 97.8% of the ertapenem non-susceptible isolates were correctly classified. From the agar plate to the final result, the turnaround time of the test was 90min. This quick, easy and accurate MALDI-TOF MS test can expedite the implementation of hygiene measures to prevent dissemination of OXA-48-like-producing Enterobacteriaceae and limit outbreaks

Matrix-assisted laser desorption ionization-time of flight Mass spectrometry can detect Staphylococcus aureus clonal complex 398.

International audienceWithin the last decade methicillin-resistant Staphylococcus aureus belonging to CC398 has become a worldwide threat associated with livestock. More recently, methicillin-susceptible S. aureus (MSSA) belonging to CC398 have been increasingly reported as a cause of invasive infections in patients without livestock contact. It appears therefore necessary to implement a convenient tool for the surveillance this emerging pathogen. We evaluated the MALDI-TOF MS as a tool for rapid detection of S. aureus CC398. We used 626 S. aureus isolates characterized by a CC398-specific PCR, to constitute independent training (300 isolates including 60 isolates CC398) and validation sets (326 isolates including 82 isolates CC398). Fifteen peak biomarkers of CC398 were identified from the mass spectra of the training set. Ninety four % (307 of 326) of strains of the validation set were well assigned with an overall sensitivity of 93% and a specificity of 95%. Six CC398 and 13 non-CC398 isolates were misclassified. With MALDI-TOF MS, clinical laboratories could rapidly detect S. aureus CC398 associated with a higher mortality in hospitalized patients

mcr-1-like detection in commensal Escherichia coli and Salmonella spp. from food-producing animals at slaughter in Europe.

International audienceWe evaluate here the presence of the mcr-1-like and mcr-2 genes in Escherichia coli and Salmonella spp. isolated from healthy food-producing animals at slaughter between 2002 and 2014 in Europe. Isolates were retrieved from cattle, pig and chicken from 11 European countries of production. The susceptibility to colistin and antibiotics used in human medicine was determined by agar dilution. Colistin-resistant isolates were PCR-screened for mcr genes. mcr-positive isolates were typed by Pulsed-Field Gel Electrophoresis (PFGE) and Multi-Locus Sequence Typing. Among the 10,206 E. coli and 1774 Salmonella spp. isolated from cattle, pigs and chickens, 148 E. coli and 92 Salmonella spp. isolates were resistant to colistin. We found mcr-1-like gene in 68 (0.7%) E. coli and 2 (0.1%) Salmonella isolates whereas none of the isolates tested positive for mcr-2. MCR-1-like-positive E. coli were isolated from 2008 to 2014 in chicken (n=44, 1.2%) and pigs (n=24, 0.7%). The presence of mcr-1-like varied from 0 to 4.0% depending on the year and the animal species. mcr-1-like-positive isolates came from animals originating from Germany (n=38), Spain (n=23), The Netherlands (n=5), and France (n=4). They were distributed in 63 different PFGE types and 37 different STs, with ST10 being the most prevalent. The two mcr-1-like-positive Salmonella spp. were isolated from France and Germany from a pig and a chicken, respectively. mcr-1-like gene is present in food-producing animals at slaughter in European countries with the highest occurrence in chickens. The high clonal diversity of E. coli underlines the evidence for horizontal transfer of mcr-1-like genes

Matrix-assisted laser desorption ionization-time of flight mass spectrometry assigns Escherichia coli to the phylogroups A, B1, B2 and D.

International audience: Escherichia coli classification into phylogroups reflects the diversity of their pathogenicity and their ecological niche, B2 isolates being the most virulent among extra-intestinal strains. MALDI-TOF MS allows a quick, automated, simple and inexpensive bacterial identification. We evaluated the MALDI-TOF MS as a tool for E. coli phylogroup differentiation. We used 656 E. coli isolates, previously assigned to phylogroup A, B1, B2, and D by multiplex PCR, to constitute independent training and validation sets. We then defined two phylogrouping strategies, both validated on spectra obtained by the 'direct transfer method'. The first strategy used the MALDI Biotyper software (Bruker Daltonik) that identified a single peak shift between isolates of phylogroup B2 and those of groups A, B1 and D. It accurately classified 89% of the isolates. The second strategy used the ClinProTools software (Bruker Daltonik) and was based on three successive models. The model 1 adequately differentiated 92% of phylogroup B2-isolates from those belonging to phylogroups A, B1, D. The model 2 adequately discriminated 87% of phylogroup D-isolates from those of phylogroups A and B1. The model 3 correctly sorted 69% of A and B1-isolates. We concluded that clinical laboratories could routinely and very quickly assign E. coli isolates to phylogroups with MALDI-TOF MS. These methods could (i) expedite the detection of the most virulent strains belonging to phylogroup B2 and (ii) be a first-line tool to monitor the epidemiology of extra-intestinal pathogenic E. coli

Hospital-diagnosed infections with Escherichia coli clonal group ST131 are mostly acquired in the community

International audienceAbstract The worldwide spread of E. coli ST131 has significantly contributed to the dissemination of E. coli producing extended-spectrum β-lactamases (ESBL). In a French University hospital, we assessed the molecular features of ESBL-producing E. coli and identified risk factors in patients for colonization or infection with E. coli ST131. Over a 2-year period (2015–2017), each patient with at least one clinical isolate or one screening isolate positive with ESBL-producing E. coli were included (n = 491). The ST131 clonal group accounted for 17.5% (n = 86) of all ESBL-producing E. coli and represented 57.3% isolates of phylogroup B2. FimH -based sub-typing showed that 79.1% (68/86) of ST131 isolates were fimH30, among which 67.6% (n = 46), 20.6% (n = 14) and 11.8% (n = 8) isolates harbored genes encoding the ESBL CTX-M-15, CTX-M-27, and CTX-M-14, respectively. The multivariate analysis identified two factors independently associated with ST131 ESBL-producing E. coli isolates: infection (Odds ratio [OR] = 1.887, 95% confidence interval [CI]: 1.143–3.115; p = 0.013) and community acquisition (OR = 2.220, 95% CI: 1.335–3.693; p = 0.002). In conclusion, our study confirmed the predominance of ST131 clonal group among ESBL-producing E. coli and the difficulty to identify common risk factors associated with carriage of this pandemic clonal group

Increasing incidence of bloodstream infections due to Staphylococcus aureus clonal complex 398 in a French hospital between 2010 and 2017

International audienceThe epidemiology of Staphylococcus aureus is changing and several surveillances worldwide have evidenced an increasing incidence of S. aureus bloodstream infections (BSIs). Here, we described the long-term epidemiology of the emergent clonal group CC398 among S. aureus isolated from BSIs in our French university hospital between 2010 and 2017. Each patient with at least one blood culture positive with S. aureus during the study period was included (N = 1455). Cefoxitin susceptibility was determined using the disk diffusion method according to EUCAST recommendations. CC398 isolates were first screened from the whole S. aureus collection with a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) typing method confirmed by a CC398-specific PCR. In our hospital, the incidence of hospital- and community-acquired BSIs due to S. aureus and MSSA increased in parallel between 2010 and 2017 while that of BSIs with MRSA decreased. The prevalence of CC398 isolates among S. aureus from BSIs increased from 3.6 in 2010 to 20.2% in 2017 (p < 0.05). CC398-MRSA emerged but remains very sparse. Our data suggested that CC398-MSSA disseminates in the community. We showed here the emergence and the diffusion of CC398-MSSA, a subclone associated with invasive infections, in our hospital. The monitoring of this particular human-adapted S. aureus clone is needed and genomic studies will have to identify the determinants of its diffusion