Oxacillin resistance and antimicrobial susceptibility profile of Staphylococcus saprophyticus and other staphylococci isolated from patients with urinary tract infection

• Grant number: 12/25108-6
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: January 01, 2013
• End date: June 30, 2013
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Maria de Lourdes Ribeiro de Souza da Cunha
• Grantee: Maria de Lourdes Ribeiro de Souza da Cunha
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• City of the host institution: Botucatu

Abstract

Background: Staphylococcus saprophyticus is the second most frequent community-acquired causative agent of urinary tract infection (UTI). The objective of this study was to evaluate the susceptibility profile and resistance detection in Staphylococcus spp. isolated from patients with UTI. Material and Methods: The isolates were investigated using the disk diffusion method, Vitek I system, E-test®, and detection of the mecA gene. Results: Most isolates (76.2%) were resistant to oxacillin by the disk diffusion method, followed by those resistant to penicillin (72.2%). The oxacillin disk diffusion method, E-test® and Vitek I method showed higher sensitivity (94.4%) and lower specificity (28.9%, 26.5% and 24.0%, respectively) than the cefoxitin disk diffusion test (sensitivity: 83.5%, specificity: 85.5%) for the detection of oxacillin resistance. Conclusions: The large number of oxacillin-resistant isolates indicates that the breakpoint value recommended by the CLSI may overestimate oxacillin resistance in S. saprophyticus. Thus, changes in these guidelines are necessary for the correct detection of this resistance. (AU)