Abstract
An increased incidence of nosocomial and community-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has been observed worldwide. The molecular characterization of MRSA has played an important role in demonstrating the existence of internationally disseminated clones. The use of molecular biology methods in the surveillance programs has enabled the tracking of MRSA spread within and among hospitals. These data are useful to alert nosocomial infection control programs about the potential introduction of these epidemic clones in their areas. Four MRSA blood culture isolates from patients hospitalized at two hospitals in the city of São Paulo, Brazil, were analyzed; one of them was community acquired. The isolates were characterized as SCCmec, mecA and PVL by PCR, pulsed-field gel electrophoresis (PFGE) profile and molecular sequence typing (MLST) genotyping. The isolates presented type IV SCCmec, and none proved to be positive for PVL. The isolates showed a PFGE profile similar to the pediatric clone. MLST genotyping demonstrated that the isolates belonged to clonal complex 5 (CC5), showing a new yqiL allele gene, resulting in a new sequence typing (ST) (1176). Our results showed that strains of MRSA carrying a new ST are emerging in community and nosocomial infections, including bacteremia, in São Paulo, Brazil.
Highlights
Staphylococcus aureus has been the most important pathogen related to nosocomial infections in Brazil and remains the main agent isolated from community-acquired infections in most countries [1]
The molecular characterization of methicillin-resistant S. aureus (MRSA) has been conducted primarily by pulsed-field gel electrophoresis (PFGE) and plasmid analysis, which showed the existence of internationally disseminated clones, reflecting epidemiological and geographical relatedness [5]
The study was carried out using selected bloodstream MRSA isolates obtained from a patient with communityacquired pneumonia admitted to a private general hospital in 2006 (A26151), from 2 patients with nosocomial infection admitted to a public university hospital in 2004 (A13357 and A14711), and from a patient with nosocomial infection admitted to a public general hospital in 2007 (A30988)
Summary
Staphylococcus aureus has been the most important pathogen related to nosocomial infections in Brazil and remains the main agent isolated from community-acquired infections in most countries [1]. After the description of the Brazilian epidemic clone (BEC) in 1992 [4], other studies further demonstrated the persistence of this microorganism in Brazilian hospitals [3] In these studies, the molecular characterization of methicillin-resistant S. aureus (MRSA) has been conducted primarily by pulsed-field gel electrophoresis (PFGE) and plasmid analysis, which showed the existence of internationally disseminated clones, reflecting epidemiological and geographical relatedness [5]. The MLST data obtained can be used to answer basic questions about the evolution and biology of the population of bacterial species [7]. Such information can be of help, for example, in the development of more efficient vaccines against pathogenic microorganisms or for the planning and implementation of epidemiological measures. The aim of the present study was to detect MRSA gene rearrangements with subsequent acquisition or loss of genetic determinants through different molecular typing techniques, including SCCmec typing, PFGE, and MLST
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