|313-1||Molecular Characterization of Staphylococcus aureus Isolates in Northeast Brazil|
|Autores:||Ana Carolina de Oliveira Luz (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães / UFPE - Universidade Federal de Pernambuco) ; Thiago Ferreira de Barros (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães) ; Mariana Andrade Figueiredo (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães / UFPE - Universidade Federal de Pernambuco) ; Tereza Cristina Leal-balbino (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães) |
Introduction: Staphylococcus aureus is a major pathogen associated with serious community-acquired and nosocomial diseases in Brazil and worldwide. In hospital units, resistant strains can be dispersed among healthcare workers, patients and in the environment. The bacteria can produce a wide variety of exoproteins that contributes to its ability to colonize and cause diseases in hosts, including the toxic shock syndrome toxin-1 (TSST-1), exfoliative toxins (ETs), and several enterotoxins responsible for food poisoning (SEA-SEE and SEG-SEO). Methodology: the Polymerase Chain Reaction (PCR) was used to determine the presence of the genes responsible for TSST-1, ETA, ETB and enterotoxins in 80 clinical isolates, in which 28 were considered methicillin-resistant (MRSA) and 52 methicillin-sensitive (MSSA), from different sources of infection in patients from a public hospital in Northeast Brazil. Results: Of 80 isolates, none showed the genes sed, see and etb. However, all isolates were positive for at least one of the remaining genes investigated, most isolates had between 6 and 10 toxin genes. It was found that 11,2% of isolates were positive for sea, 5% seb, 3,7% sec, 98,7% seg, 12,5% seh, 82,5% sei, 50% sej, 67,5% sek, 62,5% sel, 90% sem, 80% sen, and 88,7% for seo. Three isolates harbored the tst gene, and only one isolate had eta gene. The association seg + sei + sem + sen + seo observed in 65% of isolates is attributed to the presence of the enterotoxin gene cluster (egc). Discussion: The present data showed that the frequencies of seg-seo genes were higher than the others enterotoxin genes, refuting the idea that only classic enterotoxins (sea-see) can cause diseases. Although observed in low frequency, the classic toxins are recognized as important cause of food poisoning. In addition, the presence of more than one toxigenic gene in the same bacteria increases its pathogenicity. PFGE, MLST, spa and SCCmec typing were performed and suggest that some isolates of S. aureus are circulating in all sectors of the hospital, demonstrating a severe public health problem in our region. Conclusions: Our results indicate a high frequency of MRSA (35%) isolates carrying toxigenic genes in public hospital units of Northeast Brazil, which can cause serious nosocomial diseases. The data contribute for the knowledge of the S. aureus in our region.
Palavras-chave: Staphylococcus aureus, Exotoxins, MRSA