A 10 year surveillance for antimicrobial susceptibility of Escherichia coli and Klebsiella pneumoniae in community- and hospital-associated intra-abdominal infections in China
ABSTRACT The objective of this study was to investigate the susceptibility of hospital- and community-associated Escherichia coli and Klebsiella pneumoniae isolated from patients with intra-abdominal infections in China. From 2002 to 2011, the minimum inhibitory concentrations (MICs) of 12 antibiotics against 3,074 E. coli and 1,025 K. pneumoniae from 23 centers located in 16 cities were determined by the broth microdilution method. During the ten-year study period, ertapenem, imipenem, amikacin and piperacillin-tazobactam retained high and stable activity against E .coli and K. pneumoniae isolates regardless of their source (hospital-associated [HA] or community-associated [CA]) and extended-spectrum beta-lactamase (ESBL) production. However, the susceptibility of E. coli to cephalosporins and ampicillin-sulbactam decreased dramatically during the ten years, especially for the CA isolates. Fluoroquinolones showed low activity against E. coli. During the whole study period, the ESBL rates for E. coli isolates from IAIs increased from 36.1% in 2002-2003 to 68.1% in 2010-2011 (P<0.001). Correspondingly, the ESBL rates in HA isolates increased from 52.2% in 2002-2003 to70.0% in 2010-2011 (P=0.001), and in CA isolates from 19.1% in 2002-2003 to 61.6% in 2010-2011 (P<0.001). The ESBL-positive rate in K. pneumoniae remained between 30.1-39.3% of the total isolates with no significant change during the ten years. In conclusion, carbapenems retained the highest susceptibility rates against HA and CA E. coli and K. pneumoniae. High prevalence of ESBL in HA E. coli and fast-growing resistance in CA E. coli severely limit the empirical use of the third- and fourth-generation cephalosporins in the therapy of intra-abdominal infections.
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ABSTRACT: Background In order to investigate the epidemiology, molecular characteristics, and distribution of extended-spectrum ß-lactamase (ESBL)- and AmpC-producing Escherichia coli from community-onset infections in Chinese county hospitals.Methods E. coli isolates were collected from patients with community-onset infections in 30 county hospitals. ESBL activity was confirmed by double-disc diffusion. Genetic confirmation and molecular typing of ESBL- and AmpC-producing isolates was determined by PCR and DNA sequencing. ESBL-positive isolates were further characterised by multi-locus sequence typing.ResultsOf 550 E. coli isolates, 256 (46.5%) carried ESBL genes and all were of the CTX-M type. The prevalence of ESBL-producing strains varied from 30.2% to 57.0% across different regions of China. Overall, 12 bla CTX-M subtypes were detected; the most abundant were bla CTX-M-14 (163/256 isolates, 64.5%), bla CTX-M-55(47/256, 18.4%), and bla CTX-M-15 (31/256, 12.1%). CMY-2-like AmpC ß-lactamases were detected in 11 strains, three of which co-existed with bla CTX-M. A total of 64 sequence types (STs) were detected in 256 ESBL-producing strains, including nine that were new. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%).Conclusions This study revealed that the widespread prevalence of ESBLs among outpatient infections has reached a high level in county hospitals. The CTX-M genotype was most dominant, comprising a variety of subtypes. This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China. No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.BMC Infectious Diseases 12/2014; 14(1):659. DOI:10.1186/s12879-014-0659-0 · 2.56 Impact Factor
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ABSTRACT: The aim of this study was to investigate the trends and the diversity of CTX-M types of extended-spectrum β-lactamase (ESBL) in Escherichia coli isolated from food animals in China over a ten-year period. From 2003 to 2012, 2815 E. coli isolates collected from diseased animals (chickens, pigs, and waterfowl) were screened for the prevalence of CTX-M genes. CTX-M-positive isolates were tested for their susceptibilities to 10 antimicrobial agents and the clonal relationship of CTX-M-producing E. coli isolates was also assessed. Overall, 677 (20.1%) of the 2815 E. coli isolates carried CTX-M genes. Eighteen different types of CTX-M ESBLs were identified, with CTX-M-14, CTX-M-55, and CTX-M-65 being the most dominant genotypes. The occurrence of CTX-M-producing E. coli increased significantly from 5.7% in 2003-2005 to 35.3% in 2009-2012 (p<0.0001). High genetic heterogeneities were observed in the CTX-M-producing E. coli isolates. Most CTX-M-producing strains were also resistant to other classes of antimicrobials. Compared to isolates carrying CTX-M-9 subgroup of ESBLs, isolates carrying CTX-M-1 subgroup ESBLs showed significantly higher resistance rates to ceftazidime, amikacin, and fosfomycin (p<0.01). The study reported the dramatic increase of CTX-M ESBLs in E. coli isolated from animals overtime in China. The increasing incidence of CTX-M-55 with high hydrolytic activity against ceftazidime and the widely spread co-resistance in CTX-M-producing isolates alarm the serious antimicrobial resistance situation in China and highlight the need for urgent control strategies to limit the dissemination of those resistant genes in China.Veterinary Microbiology 06/2014; 172(3-4). DOI:10.1016/j.vetmic.2014.06.013 · 2.73 Impact Factor
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ABSTRACT: Ceftolozane MIC50/MIC90 values were 4/8 μg/ml when tested against 26 CTX-M-14-type-producing isolates, and 64/>64 μg/ml against 219 CTX-M-15-type-producing isolates. Addition of 4 μg/ml tazobactam lowered ceftolozane MIC50/MIC90 values to ≤0.25/0.5 μg/ml by broth microdilution and Etest. Zone diameters for a ceftolozane-tazobactam disk were 23-29 mm for 92.2% of the isolates.Journal of Clinical Microbiology 08/2014; 58(11). DOI:10.1128/JCM.02357-14 · 4.23 Impact Factor