Escherichia coli was the most commonly isolated pathogen in the Canadian Ward Surveillance Study 2007-2009 (3789 isolates). Susceptibility to cefazolin (34.1%), trimethoprim-sulfamethoxazole (73.8%), ciprofloxacin (78.4%), and levofloxacin (78.8%) was lowest. Susceptibility was above 90% for meropenem (100%), tigecycline (99.9%), piperacillin-tazobactam (97.6%), nitrofurantoin (96.9%), ceftazidime (95.6%), amoxicillin-clavulanate (94.9%), ceftriaxone (94.1%), cefoxitin (92.3%), and gentamicin (90.8%). Over the study period, there was a significant reduction in susceptibility to amoxicillin-clavulanate and trimethoprim-sulfamethoxazole for urinary tract isolates. Inpatient status was associated with greater resistance to nearly all antimicrobials including greater multidrug resistance (MDR). Increasing age was associated with resistance to fluoroquinolones, ceftriaxone, piperacillin-tazobactam, and MDR. Female gender was associated with susceptibility to fluoroquinolones and nitrofurantoin. In conclusion, greater antimicrobial resistance and MDR in E. coli were observed in inpatients, males, and with increasing age. The deterioration of susceptibility to trimethoprim-sulfamethoxazole continues with the greatest reduction in urinary isolates. Significant regional differences in resistance rates were apparent.
The purpose of this study was to analyse Canadian national surveillance data, specifically fluoroquinolone resistance, from 2007 to 2011 inclusive, to determine trends in resistance over time and to assess correlations with patient demographic factors.
All isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae collected by the 10 sites that participated in the annual CANWARD surveillance studies in each of the 5 years were included in this analysis. A multifactorial logistic regression model was used to determine the variables with significant impact on fluoroquinolone resistance.
The proportion of E. coli isolates resistant to ciprofloxacin increased significantly (P = 0.0005) between 2007 (20.0%) and 2011 (29.2%), although similar increases were not seen in K. pneumoniae, E. cloacae, P. aeruginosa and S. pneumoniae (tested against levofloxacin) (P > 0.05). Among isolates of S. aureus, there was a significant decrease in ciprofloxacin resistance from 34.4% in 2007 to 24.6% in 2011 (P
In vitro activity of ceftaroline-avibactam against gram-negative and gram-positive pathogens isolated from patients in Canadian hospitals from 2010 to 2012: results from the CANWARD surveillance study.
The in vitro activities of ceftaroline-avibactam, ceftaroline, and comparative agents were determined for a collection of bacterial pathogens frequently isolated from patients seeking care at 15 Canadian hospitals from January 2010 to December 2012. In total, 9,758 isolates were tested by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (document M07-A9, 2012), with MICs interpreted by using CLSI breakpoints (document M100-S23, 2013). Ceftaroline-avibactam demonstrated potent activity (MIC90, = 0.5 µg/ml) against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Morganella morganii, Citrobacter freundii, and Haemophilus influenzae; >99% of isolates of E. coli, K. pneumoniae, K. oxytoca, P. mirabilis, M. morganii, C. freundii, and H. influenzae were susceptible to ceftaroline-avibactam according to CLSI MIC interpretative criteria for ceftaroline. Ceftaroline was less active than ceftaroline-avibactam against all species of Enterobacteriaceae tested, with rates of susceptibility ranging from 93.9% (P. mirabilis) to 54.0% (S. marcescens). All isolates of methicillin-susceptible Staphylococcus aureus (MIC90, 0.25 µg/ml) and 99.6% of methicillin-resistant S. aureus isolates (MIC90, 1 µg/ml) were susceptible to ceftaroline; the addition of avibactam to ceftaroline did not alter its activity against staphylococci or streptococci. All isolates of Streptococcus pneumoniae (MIC90, 0.03 µg/ml), Streptococcus pyogenes (MIC90, = 0.03 µg/ml), and Streptococcus agalactiae (MIC90, 0.015 µg/ml) tested were susceptible to ceftaroline. We conclude that combining avibactam with ceftaroline expanded its spectrum of activity to include most isolates of Enterobacteriaceae resistant to third-generation cephalosporins, including extended-spectrum ß-lactamase (ESBL)- and AmpC-producing E. coli and ESBL-producing K. pneumoniae, while maintaining potent activity against staphylococci and streptococci.
Molecular epidemiology of extended-spectrum ß-lactamase-, AmpC ß-lactamase- and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae isolated from Canadian hospitals over a 5 year period: CANWARD 2007-11.
To assess the proportion of Escherichia coli and Klebsiella pneumoniae from Canadian hospitals that produce extended-spectrum ß-lactamases (ESBLs), AmpC ß-lactamases and carbapenemases, as well as to describe the patterns of antibiotic resistance and molecular characteristics of these organisms.
Some 5451 E. coli and 1659 K. pneumoniae were collected from 2007 to 2011 inclusive as part of the ongoing CANWARD national surveillance study. Antimicrobial susceptibility testing was performed to detect putative ESBL, AmpC and carbapenemase producers, which were then further characterized by PCR and sequencing to detect resistance genes. In addition, isolates were characterized by PFGE and an allele-specific PCR to detect isolates of sequence type (ST) 131.
The proportion of ESBL-producing E. coli (2007, 3.4%; 2011, 7.1%), AmpC-producing E. coli (2007, 0.7%; 2011, 2.9%) and ESBL-producing K. pneumoniae (2007, 1.5%; 2011, 4.0%) among the isolates collected increased during the study period. The majority of ESBL-producing E. coli (>95%), AmpC-producing E. coli (>97%) and ESBL-producing K. pneumoniae (>89%) remained susceptible to colistin, amikacin, ertapenem and meropenem. Isolates were generally unrelated by PFGE (
The national prevalence of extended-spectrum ß-lactamase (ESBL)-producing (2007: 3.4%, 2008: 4.9%, 2009: 4.3%) and AmpC ß-lactamase (AmpC)-producing (2007: 0.8%, 2008: 3.2%, 2009: 2.7%) Escherichia coli in Canadian hospitals have fluctuated from 2007 to 2009. Rates of co-resistance to non-lactam agents are elevated, and multidrug-resistant (MDR) phenotype were observed among E. coli strains producing ESBLs (83.3% MDR) and AmpCs (31.0%). The majority (>98%) of isolates remained susceptible to colistin, tigecycline, amikacin, and the carbapenems. CMY-2 encoding gene was detected in 52.9% of AmpC-producing strains, while bla(CTX-M-15) (65.2%) was the predominant ESBL genotype. A total of 50.3% of ESBL-producing E. coli and 21.4% of AmpC producers belonged to the ST131 clone. In conclusion, ESBL- and AmpC-producing E. coli are established in Canadian hospitals; and although the prevalence rates of these isolates remain low, they are often MDR and associated with the ST131 clone.