Methicillin-resistant Staphylococcus aureus in Rio de Janeiro hospitals: dissemination of the USA400/ST1 and USA800/ST5 SCCmec type IV and USA100/ST5 SCCmec type II lineages in a public institution and polyclonal presence in a private one.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infections have changed since certain non-multiresistant MRSA lineages have emerged in hospitals. In this study, 99 MRSA isolates, 77 from a public and 22 from a private hospital, were characterized.

Methods: Isolates were tested for antimicrobial susceptibility, whereas staphylococcal chromosomal cassette mec (SCCmec) typing and Panton-Valentine leukocidin genes were assessed by polymerase chain reaction.

A combination of methods to evaluate biofilm production may help to determine the clinical relevance of Staphylococcus in blood cultures.

Staphylococcus is the most prevalent pathogen causing bacteremia and many of its isolates possess the ability to form biofilm. In this study Staphylococcus isolates from the blood of patients with bacteremia were analyzed by two biofilm detection phenotypic methods: Congo red agar (CRA) and microtiter-plate adherence (MPA) in relation to the presence of ica genes, detected by PCR. Their oxacillin susceptibility was also evaluated.