Abstract
Escherichia coli (E. coli) is one of the most frequent and lethal causes of bloodstream infections (BSIs). We carried out a retrospective multicenter study on antimicrobial resistance and phylogenetic background of clinical E. coli isolates recovered from bloodstream in three hospitals in Shanghai. E. coli isolates causing BSIs were consecutively collected between Sept 2013 and Sept 2014. Ninety isolates randomly selected (30 from each hospital) were enrolled in the study. Antimicrobial susceptibility testing was performed by disk diffusion. PCR was used to detect antimicrobial resistance genes coding for β-lactamases (TEM, CTX-M, OXA, etc.), carbapenemases (IMP, VIM, KPC, NDM-1 and OXA-48), and phylogenetic groups. eBURST was applied for analysis of multi-locus sequence typing (MLST). The resistance rates for penicillins, second-generation cephalosporins, fluoroquinolone and tetracyclines were high (>60%). Sixty-one of the 90 (67.8%) strains enrolled produced ESBLs and no carbapenemases were found. Molecular analysis showed that CTX-M-15 (25/61), CTX-M-14 (18/61) and CTX-M-55 (9/61) were the most common ESBLs. Phylogenetic group B2 predominated (43.3%) and exhibited the highest rates of ESBLs production. ST131 (20/90) was the most common sequence type and almost assigned to phylogenetic group B2 (19/20). The following sequence types were ST405 (8/90) and ST69 (5/90). Among 61 ESBL-producers isolates, B2 (26, 42.6%) and ST131 (18, 29.5%) were also the most common phylogenetic group and sequence type. Genetic diversity showed no evidence suggesting a spread of these antimicrobial resistant isolates in the three hospitals. In order to provide more comprehensive and reliable epidemiological information for preventing further dissemination, well-designed and continuous surveillance with more hospitals participating was important.
Highlights
Bloodstream infections (BSIs) has been associated with major fatality and prolonged hospital stay for a long period[1]
In the same period from 2002 to 2009, the proportion among all E. coli of E. coli resistant to third-generation cephalosporins increased significantly from 1.7% to 8% according to EARS-Net[4]
Data from Mohnarin showed the positive rate of ESBL-producing E. coli from BSIs (EC-BSI) had increased from 70.2% to 72.6% during 2009–2012[9]
Summary
Bloodstream infections (BSIs) has been associated with major fatality and prolonged hospital stay for a long period[1]. Escherichia coli (E. coli) has emerged as the most common causative gram-negative bacterium [3,4,5,6,7], but even worse, the incidence was keep rising. European Antibiotic Resistance Monitoring Network (EARS-Net) has noted an alarming 71% increase of E. coli BSIs from 2002 to 2009[4]. In China, the proportion of E. coli from BSIs (EC-BSI) has jumped from 19.8% to 23.0% during 2010–2012 in accordance with statistics from the Ministry of Health National Antimicrobial Resistance Investigation Net (Mohnarin)[8, 9]. In the same period from 2002 to 2009, the proportion among all E. coli of E. coli resistant to third-generation cephalosporins increased significantly from 1.7% to 8% according to EARS-Net[4]. What’s worse, the therapeutic treatment and cost of E. coli BSIs has been threatened due to the resistant organisms [13, 14]
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