title: Vancomycin heteroresistance and biofilm formation in Staphylococcus epidermidis from food.
abstract: Staphylococcus epidermidis CNBL 7032 is a heteroresistant strain, with subpopulations resistant to vancomycin concentrations up to 32 mg l (-1), which was isolated from cured pork meat. The mechanisms of glycopeptide resistance in this strain were investigated in this study. S. epidermidis CNBL 7032 does not harbour enterococcal transmissible vancomycin-resistance genes. Transmission electron microscopy revealed that resistant subpopulations have a thicker cell wall, and that the increase in cell wall thickness is proportional to vancomycin concentration in the growth medium. Scanning electron microscopy showed that S. epidermidis CNBL 7032 forms a biofilm-like structure when grown in the presence of vancomycin. This food isolate harbours the gene atlE, coding for an autolysin with an adhesive function, which is involved in the first phase of biofilm formation. This study has demonstrated an interaction between atlE expression, biofilm formation and glycopeptide antibiotic resistance; transcription analysis demonstrated that the expression of atlE increased proportionally with the vancomycin concentration in the culture. Insertional inactivation of atlE confirmed the role of the AtlE autolysin in biofilm and vancomycin resistance.
authors.affiliation: Istituto di Microbiologia, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29100 Piacenza, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Gazzola
authors.affiliation: Istituto di Microbiologia, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29100 Piacenza, Italy.
authors.forename: Pier Sandro
authors.initials: PS
authors.lastname: Cocconcelli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D002473:Cell Wall / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000235:genetics; D005516:Food Microbiology; D005519:Food Preservation; D015964:Gene Expression Regulation, Bacterial; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000648:ultrastructure; D014158:Transcription, Genetic; D014640:Vancomycin / Q000494:pharmacology; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D014640:Vancomycin; D009238:N-Acetylmuramoyl-L-alanine Amidase