title: Emergence of penicillin-resistant Streptococcus pneumoniae in southern Ontario, 1993-94.
abstract: OBJECTIVE
  To determine the prevalence of resistance of Streptococcus pneumoniae to penicillin and other antimicrobial agents in metropolitan Toronto.
  
  
  METHODS
  Consecutive pneumococcal isolates from different patients were obtained from two private community-based laboratories and from patients assessed in the emergency department of a tertiary-care teaching hospital in Toronto, Ontario between June and December 1993, and between March and October 1994. In vitro susceptibility testing was done by broth microdilution in accordance with National Committee for Clinical Laboratory Standards guidelines.
  
  
  RESULTS
  Twenty (7.3±3.1%) of 274 pneumococcal isolates were resistant to penicillin; six (30%) isolates had high-level resistance (minimal inhibitory concentration [mic] 2.0 μg/mL or greater); and 14 isolates had intermediate resistance (mic 0.1 to 1.0 μg/mL). Penicillin-resistant strains were also frequently resistant to tetracycline (55%), cotrimoxazole (50%), erythromycin (40%) and cefuroxime (35%). Resistant strains comprised several serotypes: 19F (six isolates), 9V (three), 23F (three), and one each of 6A, 6B, 14, and 19A; four isolates were nontypeable.
  
  
  CONCLUSIONS
  There has been a recent emergence of penicillin-resistant S pneumoniae in southern Ontario. National and regional surveillance is warranted to determine the extent of the problem elsewhere in Canada.
authors.affiliation: Departments of Microbiology and Medicine, Sunnybrook Health Science Centre, University of Toronto; Med-Chem Laboratories; and Flemingdon Medical Laboratory, Toronto, Ontario.
authors.forename: A E
authors.initials: AE
authors.lastname: Simor
authors.forename: A
authors.initials: A
authors.lastname: Rachlis
authors.forename: L
authors.initials: L
authors.lastname: Louie
authors.forename: J
authors.initials: J
authors.lastname: Goodfellow
authors.forename: M
authors.initials: M
authors.lastname: Louie