Antimicrobial resistance in Canada

Abstract

Antibiotic resistance has increased rapidly during the last decade, creating a serious threat to the treatment of infectious diseases. Canada is no exception to this worldwide phenomenon. Data from the Canadian Nosocomial Infection Surveillance Program have revealed that the incidence of methicillin-resistant Staphylococcus aureus, as a proportion of S. aureus isolates, increased from 1% in 1995 to 8% by the end of 2000, and vancomycin-resistant enterococcus has been documented in all 10 provinces since the first reported outbreak in 1995. The prevalence of nonsusceptible Streptococcus pneumoniae in Canada in 2000 was found to be 12%. Human antimicrobial prescriptions, adjusted for differences in the population, declined 11% based on the total number of prescriptions dispensed between 1995 and 2000. There was also a 21% decrease in beta-lactam prescriptions during this same period. These data suggest that systematic efforts to reduce unnecessary prescribing of antimicrobials to outpatients in Canada, beginning after a national consensus conference in 1997, may be having an impact. There is, however, still a need for continued concerted efforts on a national, provincial and regional level to quell the rising tide of antibiotic resistance.

Fig. 1: The main genetic mechanisms leading to antibiotic resistance are genetic mutation (single point mutations or major deletions or rearrangements), expression of a latent resistance gene and acquisition of genes or DNA segments with resistance determinants. Some of the genes are inherited, some emerge through random mutations in bacterial DNA and some are imported from other bacteria. These genetic changes code for changes in binding proteins (a), ribosomes (b), membrane structure (c) or inactivating enzymes (d). Adapted with permission from Scientific American (1998;March:46-53). Photo: Christine Kenney

Fig. 2: Proportion of Staphylococcus aureus isolates reported as methicillin-resistant from hospitals in the United States (1986–1998) and Canada (1995–2000). Sources: US Centers for Disease Control and Prevention (CDC) data and Canadian Nosocomial Infection Surveillance Program (CNISP) data.

Fig. 3: Proportion of Enterococcus isolates from nosocomial infections reported as vancomycin-resistant enterococci (VRE) in the United States (1989–1998) and Canada (1995–2000). Sources: CDC data and data from the VRE Passive Reporting Network (1994–1998) and the VRE Incidence Surveillance Program (1999–2000) of the CNISP.

Fig. 4: Proportion of clinical Streptococcus pneumoniae strains reported as nonsusceptible (showing both intermediate-level and high-level resistance) to penicillin in the United States (1987–1997) and Canada (1988–2000). Sources: CDC data and Canadian Bacterial Surveillance Network data.