Decreased Susceptibility to Noncarbapenem Antimicrobials in Extended-Spectrum-β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Toronto, Canada

Abstract

Retrospective review from 11 Canadian hospitals showed increasing incidence of extended-spectrum ␤-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae from 0.12 per 1,000 inpatient days during 2005 to 0.47 per 1,000 inpatient days during 2009. By 2009, susceptibility rates of ESBL-positive E. coli/K. pneumoniae were as follows: ciprofloxacin, 12.8%/ 9.0%; TMP/SMX, 32.9%/12.2%; and nitrofurantoin, 83.8%/10.3%. Nosocomial and nonnosocomial ESBL-producing E. coli isolates had similar susceptibility profiles, while nonnosocomial ESBL-producing K. pneumoniae was associated with decreased ciprofloxacin (P ‫؍‬ 0.03) and nitrofurantoin (P < 0.001) susceptibilities. Multidrug-resistant Enterobacteriaceae strains have become a global concern. Increasing incidence of extended-spectrum ␤-lactamase-producing Enterobacteriaceae (ESBL-E) may be attributable, in part, to the successful clonal dissemination of the CTX-M-15 plasmid worldwide (2, 22). Carbapenem-resistant Enterobacteriaceae (CRE) are also emerging across the globe (3, 9, 15). Low prevalence rates (4.1%) of ESBL-producing E. coli have been described in Canada, predominantly due to CTX-M ␤-lactamases (23), and only sporadic cases of imported CRE have been reported (13,23).Infections due to ESBL-E are associated with increased morbidity, mortality, length of hospital stay, and cost (11). Therapeutic alternatives for ESBL-E are limited with increasing resistance to non-␤-lactam antibiotics (6), resulting in a high likelihood of inappropriate initial empirical therapy (8). Carbapenems continue to be the treatment choice for severe infections due to ESBL-E (16), but resistance to these agents is also emerging (9, 15).In light of these concerns regarding ESBL-E, a retrospective review of incidence rates and susceptibility profiles for ESBL-E was conducted in 11 large hospitals (five academic and six community) in Toronto, Canada, from 2005 to 2009. Participating hospital characteristics have been previously described (12). All ESBL-producing Ambler class A Escherichia coli and Klebsiella pneumoniae clinical isolates were included. Susceptibility testing was performed utilizing VITEK2 (bioMérieux, St. Laurent, Quebec, Canada) in 10 hospitals and Phoenix2 (Becton Dickenson, Mississauga, Ontario, Canada) in the remaining hospital. Isolates intermediate or resistant to an extended-spectrum cephalosporin (cefpodoxime, ceftriaxone, or ceftazidime) were confirmed as ESBL-E with double disk diffusion testing as per the 2009 CLSI standards (1). Mean incidence rates were calculated after each site was adjusted per 1,000 inpatient days. Only the first clinical isolate from any one patient was included. Isolates were defined as nosocomial if they were identified from cultures obtained 3 or more days after admission to the hospital in patients without a prior specimen yielding ESBL-E. Statistical analysis was performed utilizing the chi-squared test or the chi-squared test for trend, as well as a multivariate analysis (SAS 9.2; Cary, NC). Fig. 1. There were 1,994 E...

Association of Fluoroquinolone Resistance, Virulence Genes, and IncF Plasmids with Extended-Spectrum-β-Lactamase-Producing Escherichia coli Sequence Type 131 (ST131) and ST405 Clonal Groups

“…October 2013 Volume 57 Number 10 aac.asm.org 4739 trimethoprim-sulfamethoxazole (65%) (23). Similarly, 32 to 56% of isolates in our study exhibited MDR, except for those in the ST131-O16 group.…”

The Continuing Plague of Extended-spectrum β-lactamase–producing Enterobacteriaceae Infections

“…25,203,[229][230][231][232] Susceptibility rates from recent years, however, have been shown to be consistently low. 10,60,[232][233][234] In a prospective multicenter observational study of community-associated infections caused by ESBL-producing E coli from the United States, only 11% and 32% of the isolates were susceptible to fluoroquinolones and TMP-SMX, respectively, and 64% were resistant to both agents. 75 Nitrofurantoin and fosfomycin are 2 additional oral therapeutic options in ambulatory settings for mild to moderate ESBL UTIs.…”

The gut is the epicentre of antibiotic resistance

“…Gram-negative bacteria, in particular Enterobacteriaceae, have acquired or selected many genes of resistance in the past few years and are now often resistant to third-generation cephalosporins, since they carry extended-spectrum beta-lactamases (ESBLs)[5]. This mechanism of resistance initially emerged in Klebsiella pneumoniae but is now even more common in Escherichia coli , a micro-organism that lives in the human gut, generally in good intelligence with the host [6].…”