Resumo

The genus Staphylococcus is involved in infections of great importance for human health. Staphylococcus species can be classified into coagulase-positive staphylococci, as S. aureus, and coagulase-negative staphylococci (CNS), which comprise different species normally involved in infectious processes in immunocompromised patients or patients using catheters. The main class of drugs used for the treatment of staphylococcal infections is the β-lactams. However, a large number of S. aureus and CNS nosocomial isolates are resistant to these drugs. Methicillin resistance is encoded by the mecA gene, which is inserted in the SCCmec cassette. This cassette is a mobile genetic element classified in eight different types and several subtypes. The aim of this study was to detect the resistance to oxacillin in Staphylococcus sp. isolated from hospital environment. Fourteen Staphylococcus sp. were obtained from environment of an intensive care unit of São Lucas Hospital (HSL-PUCRS) during three months. The samples were collected using a swab from bed, doorknob, gloves and floor. The swabs were spread on Chapman agar and the manitol positive strains were classified according Gram method. The Gram positives Staphylococcus were tested for coagulase production. The resistance to oxacillin in coagulase-negative strains was determined by the detection of mecA gene by PCR, as well as all strains were spread on BHI agar with 6% oxacillin. Among ten strains that grew in BHI agar with oxacillin, nine presented the mecA gene. Only three isolates were positives for mecA gene and did not grow in the BHI agar with oxacillin. Therefore, the majority of coagulase-negative Staphylococcus strains isolated from hospital environment showed the SCCmec, which can be transmitted to other species of Staphylococcus, S. aureus for example, by horizontal gene transfer.