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

Chemotherapy. 2012;58(6):482-91. doi: 10.1159/000346529. Epub 2013 Mar 26.

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 species. isolated from patients with UTI.

Materials 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 Clinical and Laboratory Standards Institute may overestimate oxacillin resistance in S. saprophyticus. Thus, changes in these guidelines are necessary for the correct detection of this resistance.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Disk Diffusion Antimicrobial Tests / methods
  • Drug Resistance, Bacterial
  • Humans
  • Oxacillin / pharmacology*
  • Practice Guidelines as Topic
  • Sensitivity and Specificity
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / microbiology
  • Staphylococcus / drug effects*
  • Staphylococcus / isolation & purification
  • Staphylococcus saprophyticus / drug effects*
  • Staphylococcus saprophyticus / isolation & purification
  • Urinary Tract Infections / drug therapy
  • Urinary Tract Infections / microbiology

Substances

  • Anti-Bacterial Agents
  • Oxacillin