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.