Resistance Detection and Susceptibility Profile in Staphylococcus spp. Isolated from Patients with Urinary Tract Infection (UTI)

Abstract

UTI is one of the most common infections in clinical practice and S. saprophyticus is the second most frequent agent affecting the community. We identified Staphylococcus spp. and assessed its susceptibility profile in samples from UTI patients. The identification was done by means of the simplified method of biochemical tests and the highest percentage of resistance was to oxacillin (78.0%). Of the 18 mecA-positive staphylococci, 15 (83.3%) were resistant to cefoxitin and oxacillin disks simultaneously. Among 57 S. saprophyticus, 7 (12.3%) were resistant to the cefoxitin disk and none of them had the gene mecA, whereas 56 (98.2%) showed resistance to the oxacillin disk and 2 had the gene mecA, both with SCCmec type IV. Although cefoxitin disk and detection of the gene mecA are more sensitive to detect resistance to oxacillin, the oxacillin disk presented better results for S. saprophyticus probably due to a hyperproduction of beta-lactamase, a change in a PBP other than PBP2a, or even a cutoff suggested by CLSI that overestimates the resistance to oxacillin for S. saprophyticus.