Methicillin-Resistant Staphylococcus capitis with Reduced Vancomycin Susceptibility Causes Late-Onset Sepsis in Intensive Care Neonates

isolated from the blood of NICU infants and compared these data to adult patients. element, and constantly showed either vancomycin resistance (37.5%) or heteroresistance (62.5%). Conversely, the isolates that were collected outside of the NICU were genetically diverse and displayed much lower rates of vancomycin resistance and heteroresistance (7.7% and 23.1%, respectively). strains has spread into several French NICUs. These isolates exhibit reduced susceptibility to vancomycin, which is the most widely used antimicrobial agent in the NICU setting

ETUDE DU POLYMORPHISME DE RESTRICTION DES GENES PBP2B ET PBP2X DE SOUCHES DE STREPTOCOCCCUS PNEUMONIAE DE SENSIBILITE DIMINUEE A LA PENICILLINE (DES BIOL. MED.)

LYON1-BU Santé (693882101) / SudocSudocFranceF

INTERETS D'UNE TECHNIQUE DE PCR DANS LES INFECTIONS A BRUCELLA (DES BIOL. MED.)

LYON1-BU Santé (693882101) / SudocSudocFranceF

Distribution des principaux gènes de résistance aux aminosides chez les entérobactéries et corrélation génotype-phénotype

LYON1-BU Santé (693882101) / SudocSudocFranceF

Emergence des beta-lactamases à spectre étendu CTX-M en région Rhône-Alpes

LYON1-BU Santé (693882101) / SudocSudocFranceF

Dépistage biologique des mycoplasmes urogénitaux au cours du deuxième trimestre de grossesse

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Evaluation of the BD GeneOhm methicillin-resistant Staphylococcus aureus (MRSA) assay as a method for detection of MRSA isolates, using a large collection of European and North African isolates

International audienceUsing a large collection of European and North African methicillin-resistant Staphylococcus aureus (MRSA) isolates with a variety of genetic backgrounds and staphylococcal cassette chromosome mec (SCCmec) types, we evaluated the reliability of the BD GeneOhm MRSA assay. Results revealed high performance of this test for detecting MRSA strains provided from Europe and North Africa (98.3%)

Evaluation of a commercial immunochromatographic assay for rapid routine identification of PBP2a-positive Staphylococcus aureus and coagulase-negative staphylococci

International audienceWe evaluated the performance of an immunochromatographic assay (PBP2a Culture Colony Test - Alere\texttrademark), detecting protein-binding penicillin 2a on staphylococci primary isolates in only 6minutes. The assay is highly sensitive for the direct detection of MRSA on various culture media whereas it requires cefoxitin induction for methicillin-resistant coagulase-negative staphylococci

Staphylococcus epidermidis in orthopedic device infections: the role of bacterial internalization in human osteoblasts and biofilm formation

International audienceBACKGROUND: Staphylococcus epidermidis orthopedic device infections are caused by direct inoculation of commensal flora during surgery and remain rare, although S. epidermidis carriage is likely universal. We wondered whether S. epidermidis orthopedic device infection strains might constitute a sub-population of commensal isolates with specific virulence ability. Biofilm formation and invasion of osteoblasts by S. aureus contribute to bone and joint infection recurrence by protecting bacteria from the host-immune system and most antibiotics. We aimed to determine whether S. epidermidis orthopedic device infection isolates could be distinguished from commensal strains by their ability to invade osteoblasts and form biofilms. MATERIALS AND METHODS: Orthopedic device infection S. epidermidis strains (n?=?15) were compared to nasal carriage isolates (n?=?22). Osteoblast invasion was evaluated in an ex vivo infection model using MG63 osteoblastic cells co-cultured for 2 hours with bacteria. Adhesion of S. epidermidis to osteoblasts was explored by a flow cytometric approach, and internalized bacteria were quantified by plating cell lysates after selective killing of extra-cellular bacteria with gentamicin. Early and mature biofilm formations were evaluated by a crystal violet microtitration plate assay and the Biofilm Ring Test method. RESULTS: No difference was observed between commensal and infective strains in their ability to invade osteoblasts (internalization rate 308+/-631 and 347+/-431 CFU/well, respectively). This low internalization rate correlated with a low ability to adhere to osteoblasts. No difference was observed for biofilm formation between the two groups. CONCLUSION: Osteoblast invasion and biofilm formation levels failed to distinguish S. epidermidis orthopedic device infection strains from commensal isolates. This study provides the first assessment of the interaction between S. epidermidis strains isolated from orthopedic device infections and osteoblasts, and suggests that bone cell invasion is not a major pathophysiological mechanism in S. epidermidis orthopedic device infections, contrary to what is observed for S. aureus

PSMs of hypervirulent Staphylococcus aureus act as intracellular toxins that kill infected osteoblasts.

Epidemic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is associated with more severe and acute forms of osteomyelitis than healthcare-associated (HA-) MRSA. Although S. aureus is now recognized as a facultative intracellular pathogen, the contribution of osteoblast invasion by CA-MRSA to the pathogenesis of osteomyelitis is unknown. Using an ex vivo model of intracellular infection of human osteoblasts, we demonstrated that CA-MRSA strains of diverse lineages share an enhanced ability to kill infected osteoblasts compared to HA-MRSA. Cytotoxicity comparisons of CA-MRSA isogenic deletion mutants revealed that phenol-soluble modulins (PSMs), a class of membrane-damaging exoproteins that are expressed at higher levels in CA-MRSA than in HA-MRSA, are involved in this osteoblast killing, whereas other major CA-MRSA virulence determinants, the Panton-Valentine leukocidin and alpha-toxin, are not involved. Similarly, functional agr and sarA regulators, which control the expression of PSMs and alpha-toxin, were required for the expression of the intracellular cytotoxic phenotype by CA-MRSA, whereas the saeRS regulator, which controls the expression of alpha-toxin but not PSMs, had no impact on cytotoxicity. Finally, PSM transcript levels determined by quantitative reverse-transcriptase PCR were significantly higher in CA-MRSA than in HA-MRSA strains and associated with cell damage in MRSA-infected osteoblasts. These findings provide new insights into the pathogenesis of severe CA-MRSA osteomyelitis and unravel a novel virulence strategy of CA-MRSA, based on the invasion and subsequent killing of osteoblasts by PSMs acting as intracellular toxins