Antibiotic resistance and plasmid transfer capacity in biofilm formed with a CTX-M-15-producing Klebsiella pneumoniae isolate.

International audienceTo characterize a CTX-M-15-producing Klebsiella pneumoniae isolate that was identified during an outbreak involving 16 patients who had undergone endoscopic retrograde cholangiopancreatography between December 2008 and August 2009. The strain was also detected in one endoscope used for these examinations. Disc diffusion assays, MICs and isoelectric focusing were used to characterize the plasmidic CTX-M-15 β-lactamase. PCRs were used to check for the presence of genes associated with virulence or antibiotic resistance. Antibiotic tolerance tests and plasmid transfer were carried out in both planktonic and biofilm conditions. The strain belonged to sequence type 14 and to the virulent capsular serotype K2, but produced little glucuronic acid. It contained a 62.5 kb conjugative plasmid carrying the bla(CTX-M-15), bla(OXA-1) and aac(6')-Ib-cr genes and harboured few virulence genes (uge, wabG, kfu and mrkD). The strain was highly resistant to cefotaxime (MIC 516 mg/L) and the presence of this antibiotic at sub-MIC concentrations enhanced biofilm formation. The isolate was susceptible to ofloxacin (MIC 2 mg/L), but the bactericidal effect of this antibiotic was greater in planktonic cultures and 6 h old biofilm than in 24 or 48 h old biofilms. The K. pneumoniae strain was notable for its ability to transfer its plasmid, especially in biofilm conditions, in which the rate of plasmid transfer was about 0.5/donor. These findings demonstrate the ability of this strain to survive in a hospital environment and to transfer its extended-spectrum β-lactamase-encoding plasmid

Assessment on experimental bacterial biofilms and in clinical practice of the efficacy of sampling solutions for microbiological testing of endoscopes

International audienceOpinions differ on the value of microbiological testing of endoscopes, which varies according to the technique used. We compared the efficacy on bacterial biofilms of sampling solutions used for the surveillance of the contamination of endoscope channels. To compare efficacy, we used an experimental model of a 48-h Pseudomonas biofilm grown on endoscope internal tubing. Sampling of this experimental biofilm was performed with a Tween 80-lecithin-based solution, saline, and sterile water. We also performed a randomized prospective study during routine clinical practice in our hospital sampling randomly with two different solutions the endoscopes after reprocessing. Biofilm recovery expressed as a logarithmic ratio of bacteria recovered on bacteria initially present in biofilm was significantly more effective with the Tween 80-lecithin-based solution than with saline solution (P = 0.002) and sterile water (P = 0.002). There was no significant difference between saline and sterile water. In the randomized clinical study, the rates of endoscopes that were contaminated with the Tween 80-lecithin-based sampling solution and the saline were 8/25 and 1/25, respectively (P = 0.02), and the mean numbers of bacteria recovered were 281 and 19 CFU/100 ml (P = 0.001), respectively. In conclusion, the efficiency and therefore the value of the monitoring of endoscope reprocessing by microbiological cultures is dependent on the sampling solutions used. A sampling solution with a tensioactive action is more efficient than saline in detecting biofilm contamination of endoscopes

Prevention and treatment of biofilm-related infections on invasive medical devices

À ce jour, la thèse n’a pas été déposée. L’Université Clermont Auvergne est donc dans l’impossibilité d’en assurer le traitement, la conservation et la diffusion.To date, this thesis has not been deposited. The Université Clermont Auvergne is therefore unable to ensure its processing, conservation and dissemination

Evolution structurale et émergence en France des enzymes de type CTX-M

CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

An epidemiological study of enteric viruses in sewage with molecular characterization by RT-PCR and sequence analysis.

International audienceThe aim of this study was to assess the presence and seasonal frequency of various enteric viruses in wastewater treatment. The detection of astrovirus, norovirus, enterovirus, hepatitis A virus (HAV) and rotavirus was carried out by molecular analyses in concentrated water samples collected over 18 months at the entrance and exit of an activated sludge sewage treatment plant. The reverse transcriptase-polymerase chain reaction (RT-PCR) results were confirmed by sequencing, and comparative phylogenetic analysis was performed on the isolated strains. Genomes of human astrovirus and human rotavirus were identified in 26/29 and 11/29 samples of raw sewage, respectively, and in 12/29 and 13/29 treated effluent samples, respectively. Some rotavirus sequences detected in environmental samples were very close to those of clinical strains. Noroviruses, enteroviruses and HAV were not detected during the study period. This could be related to the small sample volume, to the sensitivity of the detection methods or to local epidemiological situations. Frequent detection of viral RNA, whether infectious or not, in the exit effluent of sewage treatment indicates wide dispersion of enteric viruses in the environment. Consequently, viral contamination resulting from the use of these treated waters is a risk that needs to be addressed

Bloodstream infection after positive catheter cultures: what are the risks in the intensive care unit when catheters are routinely cultured on removal?

International audienceOBJECTIVES: The aim of the study was to assess whether an isolated positive catheter culture is predictive of a subsequent bloodstream infection in intensive care unit patients. DESIGN: Retrospective clinical study between 2000 and 2007. SETTING: Intensive care unit of a university hospital. SUBJECTS: All arterial, central venous, and dialysis catheters yielding selected pathogenic microorganisms from isolated positive catheter cultures. Positive catheter culture was defined by a catheter tip culture performed with the Brun-Buisson technique yielding ≥103 colony-forming units/mL; isolated positive catheter culture by a positive catheter culture without concomitant bloodstream infection due to the microorganism of the positive catheter culture evidenced within 48 hrs before or after catheter removal; and subsequent bloodstream infection by a bloodstream infection developing between 48 hrs and 30 days after catheter removal and due to a selected pathogenic microorganism of an isolated positive catheter culture. Active antibiotic therapy was active if at least one of the antibiotics administered was effective against the selected pathogenic microorganism of the positive catheter culture. INTERVENTION: None. MEASUREMENT AND MAIN RESULTS: The end point of the study was the ratio of the number of subsequent bloodstream infections to that of selected pathogenic microorganisms isolated from positive catheter culture 30 days after catheter removal. A total of 138 isolated positive catheter cultures for 149 selected pathogenic micro-organisms was included in the study. Only two cases (1.3%) of subsequent bloodstream infection were evidenced, one resulting from Escherichia coli and the other from Staphylococcus epidermidis. The incidence of subsequent bloodstream infection did not differ with regard to the presence or absence of active antibiotics at catheter removal: zero of 23 vs. two of 121 (p = 1), respectively. CONCLUSIONS: Our results suggest that the risk of subsequent bloodstream infection in intensive care unit patients when the Brun-Buisson technique is used to define isolated positive catheter culture is low

A prospective study on the pathogenesis of catheter-associated bacteriuria in critically ill patients

International audienceBackground: Updating the pathogenesis of catheter-associated bacteriuria (CA-bacteriuria) in the intensive care unit (ICU) is needed to adapt prevention strategies. Our aim was to determine whether the main pathway of CAbacteriuria in ICU patients was endoluminal or exoluminal. In a prospective study, quantitative urine cultures were sampled from catheter sampling sites, collector bags and the catheter outer surface near the meatus from days 1 to 15 after catheterization. The endoluminal pathway was CA-bacteriuria (defined as 10 2 CFU/mL) first in collector bags and then in catheters. The exoluminal pathway was CA-bacteriuria first in catheters, on day 1 in early cases and after day 1 in late cases. Results: Of 64 included patients, 20 had CA-bacteriuria. Means of catheterization days and incidence density were 6.81 days and 55.2/1000 catheter-days. Of 26 microorganisms identified, 12 (46.2%) were Gram positive cocci, 8 (30.8%) Gram negative bacilli and 6 yeasts. Three (11.5%) CA-bacteriuria were endoluminal and 23 (88.5%) exoluminal, of which 10 (38.5%) were early and 13 (50%) late. Molecular comparison confirmed culture findings. A quality audit showed good compliance with guidelines. Conclusion: The exoluminal pathway of CA-bacteriuria in ICU patients predominated and surprisingly occurred early despite good implementation of guidelines. This finding should be considered in guidelines for prevention of CA-bacteriuria

Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis.

Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1) to nanostructure acrylonitrile-butadiene-styrene (ABS), a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2) to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3) to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion