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Canadian Journal of Infectious Diseases
Volume 6, Issue 3, Pages 157-160
Brief Report

Emergence of Penicillin-Resistant Streptococcus Pneumoniae in Southern Ontario, 1993–94

Andrew E Simor,1,2,3 Anita Rachlis,1 Lisa Louie,1 Janet Goodfellow,1 and Marie Louie1,2,3

1Departments of Microbiology and Medicine, Sunnybrook Health Science Centre, University of Toronto, Canada
2Med-Chem Laboratories, Canada
3Flemingdon Medical Laboratory, Toronto, Ontario, Canada

Received 13 December 1994; Accepted 10 February 1995

Copyright © 1995 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective: To determine the prevalence of resistance of Streptococcus pneumoniae to penicillin and other antimicrobial agents in metropolitan Toronto.

Design: 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.