Antibiotic resistance of ESBLs-producing Escherichia coli and Klebsiella pneumoniae isolates and risk factors for bloodstream infections

Abstract

Objective To investigate the antibiotic resistance of extended-spectrum-β-lactamases (ESBLs)-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K.pneumoniae) isolates and the risk factors of bloodstream infections caused by these strains. Methods Clinical data of 131 patients with E. coli or K. pneumoniae-induced bloodstream infections admitted in the Second Affiliated Hospital of Zhejiang Chinese Medical University during September 2009 and June 2014 were retrospectively analyzed. Species identification and antimicrobial susceptibility test were performed by Vitek 2 system, and ESBLs production was tested by standard disk diffusion method. Logistic regression analysis was performed to identify the risk factors of bloodstream infections induced by ESBLs-producing strains. Results Among 131 patients, 65 were infected with ESBLs-producing strains, and 66 were infected with non-ESBLs-producing strains. The resistance rates of ESBLs-producing strains were above 50% for penicillin, aztreonam and third/fourth generation cephalosporins, which were significantly higher than those of non-ESBLs producing strains. The resistance rates of ESBLs-producing E. coli and K. pneumoniae to carbapenems and piperacillin/tazobactam were 0-2.0%, 2.3% and 0-14.3%, 26.7%, respectively. The univariate analysis revealed that patients with exposure to cephalosporins in recent 3 months (χ2=18.322, P<0.01), prior infection with ESBLs-producing strains (χ2=14.610, P<0.01), indwelling catheter in recent 3 months (χ2=13.016, P<0.01), history of hospitalization in recent 3 months (χ2=11.269, P<0.01), exposure to quinolones in recent 3 months (χ2=10.638, P<0.01), nosocomial infection (χ2=8.205, P<0.01), history of indwelling deep venous catheter or percutaneous central catheter in recent 3 months (χ2=4.817, P<0.05) and exposure to glucocorticoid hormone in recent 3 months (χ2=4.265, P<0.05) were associated with infection of ESBLs-producing strains. Multivariate Logistic regression analysis revealed that exposure to quinolones in recent 3 months (OR=6.851, P<0.01), prior infection with ESBLs-producing strains (OR=6.344, P<0.01), exposure to cephalosporins in recent 3 months (OR=3.719, P<0.01), and indwelling catheter in recent 3 months (OR=3.180, P<0.05) were independent risk factors for ESBLs-producing E. coli or K. pneumoniae infection. Conclusions ESBLs-producing E. coli or K. pneumoniae isolates are highly resistant to most antibiotics, and multidrug-resistance is common. Carbapenems were still the most effective antibiotics against ESBLs-producing E. coli or K. pneumoniae infection. Rational use of cephalosporins and quinolones, strictly following aseptic technique in operation, strict use of indications for indwelling catheterization, and completely eradicating ESBLs-producing strains in previous infections may be helpful in reducing bloodstream infections by ESBLs-producing E. coli or K. pneumoniae. Key words: Beta-lactamases; Escherichia coli; Klebsiella pneumoniae; Bloodstream infection; Microbial sensitivity tests; Risk factors