Emergence of penicillin-resistant Streptococcus pneumoniae–southern Ontario, Canada, 1993-1994

Streptococcus pneumoniae is a leading cause of infectious disease-related illness and death in the United States, accounting for an estimated 3000 cases of meningitis, 50,000 cases of bacteremia, 50,000 cases of pneumonia, and 7 million cases of acute otitis media each year. Penicillin has been the antibiotic of choice for the treatment of infections caused by S. pneumoniae; since the mid-1980s, the prevalence of penicillin-resistant S. pneumoniae has increased substantially worldwide. In Canada, a strain of pneumococcus with reduced susceptibility to penicillin was first reported in 1974; based on surveys during 1977-1990, rates of resistance to penicillin were 2.4%, 1.5%, and 1.3% in the provinces of Alberta, Ontario, and Quebec, respectively. To determine whether the prevalence of penicillin resistance had increased among pneumococcal isolates, investigators from the University of Toronto tested the susceptibility of strains collected from a Toronto hospital and from a surrounding region in southern Ontario during June-December 1993 and March-June 1994. This report summarizes the results of this investigation.