En reconstruction mammaire : intérêt du dépistage du portage de Staphylococcus aureus dans la prévention de l’infection du site opératoire

National audienceThe incidence of prosthesis infections after breast reconstruction is of the order of 4% to 13% according to the literature. In surgical patients, Staphylococcus aureus (S. aureus) is the bacterial species most often responsible for surgical site infections. In cardiac surgery, screening for carriage of S. aureus and preoperative decontamination are carried out routinely before prosthetic surgery. We retrospectively reviewed data from patients at our institution between January 2011 and December 2013. Our series showed that the prosthesis infection rates were in the range of 5.92% in 2008 with an ISO rate of S. aureus 3.61%. Routine screening for prosthetic reconstructions was performed to assess the impact of preoperative decontamination patients in carriers of S. aureus. This screening was done in 381 patients: 17.8% of patients were carriers of S. aureus ; 11 patients have an ISO (or an incidence rate of 2.88%) ; 5 patients have an ISO S. aureus (an incidence of S. aureus ISO 1.3%). The introduction of the screening process, allowed a drop of 5.92% ISO rate at 1.46% with a passage of S. aureus SSI rates of 3, 60% to 0.72%. In the near future, studies are needed to confirm these encouraging results, to demonstrate the efficacy of preoperative decontamination in carriers of S. aureus patients before laying prosthesis

Prevalence of oropharyngeal beta-lactamase-producing Capnocytophaga spp. in pediatric oncology patients over a ten-year period

BACKGROUND: The aim of this study was to evaluate the prevalence of beta-lactamase-producing Capnocytophaga isolates in young children hospitalized in the Pediatric Oncology Department of Hôpital Sud (Rennes, France) over a ten-year period (1993–2002). METHODS: In neutropenic children, a periodic survey of the oral cavity allows a predictive evaluation of the risk of systemic infections by Capnocytophaga spp. In 449 children with cancer, 3,053 samples were collected by oral swabbing and plated on TBBP agar. The susceptibility of Capnocytophaga isolates to five beta-lactams was determined. RESULTS: A total of 440 strains of Capnocytophaga spp. were isolated, 309 (70%) of which were beta-lactamase producers. The beta-lactamase-producing strains were all resistant to cefazolin, 86% to amoxicillin, and 63% to ceftazidime. The proportion of strains resistant to third-generation cephalosporins remained high throughout the ten-year study, while susceptibility to imipenem and amoxicillin combined with clavulanic acid was always conserved. CONCLUSION: These results highlight the risk of antibiotic failure in Capnocytophaga infections and the importance of monitoring immunosuppressed patients and testing for antibiotic susceptibility and beta-lactamase production

Biofilms as a mechanism of bacterial resistance.

International audienceInside the biofilm, antimicrobial agents must overcome high cell density, an increased number of resistant mutants, substance delivery, molecular exchanges, such as high levels of beta-lactamases or inducers of efflux pump expression, and specific adaptive cells, so-called persisters. The environment within the biofilm modulates the response to antibiotics, especially when the SOS response or DNA repair systems are involved. Exposure to subinhibitory concentrations of antibiotics can enhance biofilm formation and mutagenesis. Thus, a global response to cell stress seems to be responsible for antibiotic-induced biofilm formation

Bacterial Persistence in Biofilms and Antibiotics Mechanisms Involved

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Recent Developments for the Detection of Escherichia Coli Biosensors Based on Nano-Objects-A Review

International audienceAdvances in nanotechnology have made it possible in recent years to develop strategies for rapid and sensitive detection of pathogenic bacteria using new nanomaterials and the development of electronic nano-sensors. The detection of bacteria still faces problems such as long analysis time and complexity of the process. An alternative method is the use of biosensors, which combines a biological recognition mechanism with a physical transduction technique. Thus, a number of methods and manufacturing technologies have been developed in order to achieve performance in sensitivity, detection limit, label-free detection or real-time analysis. This review aims to focus on the state of the art of biosensors for the recognition elements of Escherichia coli in label-free biosensors with a particular focus on the beneficial use of nanomaterials and nano-objects for detection. Among the recent related biosensors based on nano-objects for E. coli detection, the technologies and measurement techniques are detailed by comparing their performances detection in terms of concentration range and detection limit. Detection becomes more sensitive and more flexible using nanoparticles as markers, and real-time electrical detection methods are dominant in comparison with optical ones. The lowest detection limit can be achieved for sensors based on metal (gold or silver nanoparticles) with optical detection techniques in contrast with electrical detection methods using measurement conductance

Role of DNA gyrase and topoisomerase IV mutations in fluoroquinolone resistance of Capnocytophaga spp. clinical isolates and laboratory mutants

International audienceObjectives: Capnocytophaga spp. are often reported to cause bacteraemia and extra-oral infections and are characterized by their significant contribution to resistance to beta-lactam and macrolide-lincosamide-streptogramin antibiotics in the human oral microbiota. The implication of mutations in the quinolone resistance-determining region (QRDR) of DNA gyrase A and B (gyrA and gyrB) and topoisomerase IV (parC and parE) of fluoroquinolone (FQ)-resistant Capnocytophaga spp., hitherto unknown, was explored in this study.Methods: Two reference strains (Capnocytophaga gingivalis ATCC 33624 and Capnocytophaga sputigena ATCC 33612) and four Capnocytophaga spp. isolated from clinical samples were studied. Nine in vitro FQ-resistant mutants, derived from two reference strains and one FQ-susceptible clinical isolate, were selected by successive inoculations onto medium containing levofloxacin. MICs of ofloxacin, norfloxacin, ciprofloxacin, levofloxacin and moxifloxacin were determined. The presumed QRDRs of GyrA, GyrB, ParC and ParE from Capnocytophaga spp. were determined by sequence homology to Bacteroides fragilis and Escherichia coli. PCR primers were designed to amplify the presumed QRDR genetic region of Capnocytophaga spp. and sequence analyses were performed using the BLAST program at the National Center for Biotechnology Information. Results and conclusions: gyrA mutations leading to a substitution from amino acid position 80 to 86 were systematically detected in Capnocytophaga spp. with ciprofloxacin MIC >1 mg/L and considered as the primary target of FQs. No mutational alteration in the QRDR of gyrB was detected. Other mutations in parC and parE led to spontaneous amino acid substitutions of DNA topoisomerase IV subunit B with no alteration in FQ susceptibility

Capnocytophaga spp. involvement in bone infections: a review.

International audienceCapnocytophaga are commensal gliding bacteria that are isolated from human and animal oral flora and are responsible for infections both in immunocompromised and immunocompetent hosts. Accumulation of microbial plaque, loss of collagen attachment, and alveolar bone resorption around the tooth can lead to local Capnocytophaga spp. bone infections. These capnophilic bacteria, from oral sources or following domestic animal bites, are also causative agents of bacteraemia and systemic infections as well as osteomyelitis, septic arthritis, and infections on implants and devices. The present literature review describes the main aetiologies of bone infections due to Capnocytophaga spp., the cellular mechanisms involved, methods used for diagnosis, antimicrobial susceptibility, and effective treatments

Role of a short tandem leucine/arginine repeat in strong mutator phenotype acquisition in a clinical isolate of Salmonella Typhimurium.

International audienceIn this prospective study, a strong mutator strain of Salmonella Typhimurium was isolated from a collection of 130 human clinical strains of Salmonella. Sequence analysis of the mutS, mutL, and mutH genes, which encode three proteins that are essential for initiation of methyl-directed DNA mismatch repair, revealed insertion of a short tandem repeat (STR) of leucine/alanine in the histidine kinase-like ATPase domain of MutL. The role of this STR in the acquisition of the strong mutator phenotype was confirmed by the construction of an isogenic mutant (6bpinsmutL) from a normomutator strain of Salmonella Heidelberg. This result adds to the sparse body of knowledge about strong mutators and highlights the role of this STR as a hotspot for the acquisition of a strong mutator phenotype in Salmonella

Emergence of resistance to antibacterial agents: the role of quaternary ammonium compounds--a critical review.

International audienceQuaternary ammonium compounds (QACs) are widely distributed in hospitals, industry and cosmetics. Little attention has been focused on the potential impact of QACs on the emergence of antibiotic resistance in patients and the environment. To assess this issue, we conducted a literature review on QAC chemical structure, fields of application, mechanism of action, susceptibility testing, prevalence, and co- or cross-resistance to antibiotics. Special attention was paid to the effects of QACs on microflora; in particular, the issue of the potential of QACs for applying selective pressure on multiple-antibiotic-resistant organisms was raised. It was found that there is a lack of standardised procedures for interpreting susceptibility test results. QACs have different impacts on the minimum inhibitory concentrations of antibacterials depending on the antibacterial compound investigated, the resistance genes involved, the measuring methodology and the interpretative criteria. The unmet needs for adequate detection of reduced susceptibility to QACs and antibiotics include (i) a consensus definition for resistance, (ii) epidemiological cut-off values and (iii) clinical resistance breakpoints. This review advocates the design of international guidelines for QAC use

Silicon Nanowires based bio-sensors for the detection of Bacteria

International audienc