Antimicrobial Resistance in Urinary Tract Pathogens in Canada from 2007 to 2009: CANWARD Surveillance Study.
Antimicrob Agents Chemother. 2011 May 2;
Authors: Karlowsky JA, Lagacé-Wiens PR, Simner PJ, Decorby MR, Adam HJ, Walkty A, Hoban DJ, Zhanel GG
From January 2007 to December 2009 an annual Canadian national surveillance study (CANWARD) tested 2943 urinary culture pathogens for antimicrobial susceptibilities following Clinical and Laboratory Standards Institute (CLSI) guidelines. The most frequently isolated urinary pathogens (n, % of all isolates) were Escherichia coli (1581, 54%), enterococci (410, 14%), Klebsiella pneumoniae (274, 9%), Proteus mirabilis (122, 4%), Pseudomonas aeruginosa (100, 3%), and Staphylococcus aureus (80, 3%). Rates of susceptibility to trimethoprim-sulfamethoxazole (SXT) were 78%, 86%, 84%, and 93%, respectively, for E. coli, K. pneumoniae, P. mirabilis, and S. aureus. Rates of susceptibility to nitrofurantoin were 96%, 97%, 33%, and 100%, respectively, for E. coli, enterococci, K. pneumoniae, and S. aureus. Rates of susceptibility to ciprofloxacin were 81%, 40%, 86%, 81%, 66%, and 41%, respectively, for E. coli, enterococci, K. pneumoniae, P. mirabilis, P. aeruginosa, and S. aureus. Statistical analysis of resistance rates (resistant plus intermediate isolates) by year for E. coli over the three year study period demonstrated that increased resistance rates occurred only for amoxicillin-clavulanate (from 1.8% to 6.6%; P <0.001) and for SXT (from 18.6 to 24.3%; P = 0.02). For isolates of E. coli, in a multivariate logistic regression model, hospital location was independently associated with resistance to ciprofloxacin (P = 0.026) with higher rates of resistance observed in inpatient areas (medical, surgical, and intensive care unit wards). Increased age was also associated with resistance to ciprofloxacin (P< 0.001) and with resistance to two or more commonly prescribed oral agents (amoxicillin-clavulanate, ciprofloxacin, nitrofurantoin, SXT) (P = 0.005). We conclude that frequently prescribed empiric agents for urinary tract infections, such as SXT and ciprofloxacin, demonstrate lowered in vitro susceptibilities when tested against recent clinical isolates.
PMID: 21537027 [PubMed - as supplied by publisher]