Urinary tract infections due to Staphylococcus saprophyticus biotype 3

Staphylococcus saprophyticus biotype 3 (Micrococcus subgroup 3 or M3) has usually been shown to be the second commonset cause of urinary tract infections in European women who are not in hospital. It generally causes pyuria and symptoms as severe as those caused by Escherichia coli. Unlike S. epidermidis it is seldom found as a contaminant in midstream urine specimens, and almost exclusively infects women in their reproductive years. However, S. saprophyticus is seldom differentiated from S. epidermidis in Canadian clinical laboratories. Urinary isolates of S. saprophyticus were presumptively differentiated from other coagulase-negative Micrococcaceae by their resistance to novobiocin as demonstrated by a simple disc susceptibility test that misidentified the infecting organism in only 3.4% of specimens. These novobiocin-resistant, coagulase-negative organisms caused similar proportions of the urinary tract infections in young women in York, England and Vancouver -- 6.6% and 6.9% respectively. In York these organisms were associated with significantly greater pyuria than novobiocin-sensitive organisms or bile-tolerant streptococci but not S. aureus or Enterobacteriaceae. In both communities novobiocin-sensitive, coagulase-negative Micrococcaceae were appreciably more resistant to penicillin than novobiocin-resistant organisms. Thus, differentiating S. saprophyticus from novobiocin-sensitive, coagulase-negative organisms provides information that is clinically useful, particularly for primary care practitioners working in the community or in outpatient clinics.