E-Mail karger@karger.com Microbiology Chemotherapy 2012;58:482–491 DOI: 10.1159/000346529 Oxacillin Resistance and Antimicrobial Susceptibility Profile of Staphylococcus saprophyticus and Other Staphylococci Isolated from Patients with Urinary Tract Infection Adriano M. Ferreira  a, b Mariana F. Bonesso  a, b Alessandro L. Mondelli  c Carlos H. Camargo  c Maria de Lourdes R.S. Cunha  a, b   a  Department of Microbiology and Immunology, Botucatu Biosciences Institute, and Departments of b  Tropical Diseases and c  Internal Medicine, Botucatu School of Medicine, UNESP – Universidade Estadual Paulista, Botucatu, Brazil ommended by the Clinical and Laboratory Standards Insti- tute may overestimate oxacillin resistance in S. saprophyticus. Thus, changes in these guidelines are necessary for the cor- rect detection of this resistance. Copyright © 2013 S. Karger AG, Basel Introduction Urinary tract infection (UTI) is one of the most com- mon diseases in clinical practice [1–3] and the second most common infection in humans after respiratory traction infections [4, 5]. Staphylococcus saprophyticus is the second most frequent community-acquired caus- ative agent of acute UTI after Escherichia coli [6, 7]. This microorganism is isolated mainly from urine of sexually active young women [8–10] and induces symptoms that are undistinguishable from those caused by E. coli. There are also reports of septicemia and pyelonephritis caused by this microorganism [11, 12]. The pathogenicity of other coagulase-negative staphylococci (CoNS) in the urinary tract is generally uncertain, but the clinical sig- nificance of some CoNS species (S. haemolyticus, S. epi- Key Words Urinary tract infection · Susceptibility profile · Oxacillin resistance · Staphylococcus saprophyticus · mecA gene · Internal transcribed spacer-PCR Abstract Background: Staphylococcus saprophyticus is the second most frequent community-acquired causative agent of uri- nary tract infection (UTI). The objective of this study was to evaluate the susceptibility profile and resistance detection in Staphylococcus species. isolated from patients with UTI. Materials and Methods: The isolates were investigated us- ing 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, fol- lowed 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 ox- acillin resistance. Conclusions: The large number of oxacil- lin-resistant isolates indicates that the breakpoint value rec- Received: September 24, 2012 Accepted after revision: December 18, 2012 Published online: March 26, 2013 Maria de Lourdes Ribeiro de Souza da Cunha, PhD Departamento de Microbiologia e Imunologia Instituto de Biociências, UNESP – Universidade Estadual Paulista Caixa Postal 510, Botucatu, SP 18618-970 (Brazil) E-Mail cunhamlr @ ibb.unesp.br © 2013 S. Karger AG, Basel 0009–3157/13/0586–0482$38.00/0 www.karger.com/che