Oxacillin Resistance of <i>Staphylococcus aureus</i> Isolated from the University Hospital of Botucatu Medical School in Brazil

Abstract

Background: Oxacillin is the main drug used for the treatment of Staphylococcus aureus infections. However, resistance of S. aureus to oxacillin has become a major problem over recent decades. The aim of this study was to determine oxacillin resistance in S. aureus isolates obtained from the University Hospital of the Botucatu Medical School, Universidade Estadual Paulista, Brazil. Materials and Methods: A total of 102 isolates collected between 2002 and 2006 were analyzed by detection of the mecA gene, cefoxitin and oxacillin disk diffusion methods, screening test on Mueller-Hinton agar and E-test. Results: Forty-six (45.1%) isolates were mecA positive. The oxacillin disk diffusion method showed 86.9% sensitivity and 91.1% specificity. The screening method and cefoxitin disk diffusion presented a similar sensitivity (91.3%) and the same specificity. The E-test showed 97.8% sensitivity and the same specificity as observed for the other methods. Conclusions: The E-test yielded the best results compared to the other methods.

Prevalence of Methicillin-Resistant <b><i>Staphylococcus aureus</i></b>: Effect of Different Criteria for Elimination of Duplicates

“…Therefore, microbiology laboratories should provide accurate resistance data [13] adjusted for each individual clinical situation (site of the infection, inpatient, etc.) since there are significant differences within the same health district.…”

CA-MRSA: Epidemiology of a Pathogen of a Great Concern

“…There are several tests that detect phenotypic resistance to oxacillin, such as the E-test with oxacillin agar screening test, or Kirb-Bauer disk diffusion test, cefoxitin disk diffusion, determining the minimum inhibitory concentration (MIC) (Felten et al, 2002), latex agglutination test to detect PBP2a (Bressler et al, 2005;Martins et al 2010).…”

“…The same authors also tested the screening method on Mueller Hinton agar with 6µg/ml of oxacillin and 4% NaCl and found a sensitivity of 98% and specificity of 100%. Martins et al (2010) compared the screening methods of disk diffusion and E-test for detection of oxacillin resistance. They found that approximately 45% of samples were positive for the mecA gene, and the disk diffusion method with oxacillin disk showed a sensitivity of 86.9% and specificity 91.1%, respectively.…”

Epidemiological Aspects of Oxacillin-Resistant Staphylococcus spp.: The Use of Molecular Tools with Emphasis on MLST

“…As regards CoNS, 78.7% of the samples were resistant. At the Botucatu School of Medicine University Hospital -SP, approximately 45% of the S. aureus samples from hemocultures were positive for the mecA gene (Martins et al, 2010). In a study conducted at the neonatal intensive care unit of the same hospital, a total of 18% of MRSA samples was found (Pereira et al, 2009).…”