title: A combination of methods to evaluate biofilm production may help to determine the clinical relevance of Staphylococcus in blood cultures.
abstract: 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. Among 127 isolates evaluated, 47 were S. aureus and 80 were coagulase negative staphylococci (CNS). Seventy-four (58.3%) isolates were mecA gene positive (27.7%S. aureus and 76.3% CNS isolates). Among the 40 S. aureus isolates which were positive for the ica genes, 25 (62.5%) were positive in MPA and 27 (67.5%) in CRA, whereas both methods combined detected 34 (85%) isolates as biofilm producers. Among 12 S. epidermidis isolates carrying ica genes, 8 were positive in MPA and 5 in CRA. The combination of CRA and MPA methods provided a better prediction of the presence of ica genes in S. aureus isolates than did either method alone.
authors.affiliation: Department of Medical Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro Marcilio Dias Naval Hospital, Rio de Janeiro, Brazil.
authors.forename: Natalia Lopes Pontes
authors.initials: NL
authors.lastname: Iorio
authors.forename: Ana Paula da Cruz Neves
authors.initials: AP
authors.lastname: Lopes
authors.forename: Ricardo Pinto
authors.initials: RP
authors.lastname: Schuenck
authors.forename: Ariane Guimarães
authors.initials: AG
authors.lastname: Barcellos
authors.forename: André Nogueira
authors.initials: AN
authors.lastname: Olendzki
authors.forename: Guillermo Lopez
authors.initials: GL
authors.lastname: Lopez
authors.forename: Kátia Regina Netto
authors.initials: KR
authors.lastname: dos Santos
mesh_terms: D000362:Agar; D016470:Bacteremia / Q000382:microbiology*; D001422:Bacterial Adhesion; D001431:Bacteriological Techniques / Q000379:methods*; D018441:Biofilms; D003224:Congo Red; D006801:Humans; D013210:Staphylococcus / Q000166:cytology / Q000502:physiology*
chemical_list: D003224:Congo Red; D000362:Agar