Resistance Pattern and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC) Strains Isolated in Bangladesh

Abstract

BackgroundEnterotoxigenic Escherichia coli (ETEC) is a common cause of bacterial infection leading to acute watery diarrhea in infants and young children as well as in travellers to ETEC endemic countries. Ciprofloxacin is a broad-spectrum antimicrobial agent nowadays used for the treatment of diarrhea. This study aimed to characterize ciprofloxacin resistant ETEC strains isolated from diarrheal patients in Bangladesh.MethodsA total of 8580 stool specimens from diarrheal patients attending the icddr,b Dhaka hospital was screened for ETEC between 2005 and 2009. PCR and Ganglioside GM1- Enzyme Linked Immuno sorbent Assay (ELISA) was used for detection of Heat labile (LT) and Heat stable (ST) toxins of ETEC. Antimicrobial susceptibilities for commonly used antibiotics and the minimum inhibitory concentration (MIC) of nalidixic acid, ciprofloxacin and azithromycin were examined. DNA sequencing of representative ciprofloxacin resistant strains was performed to analyze mutations of the quinolone resistance-determining region of gyrA, gyrB, parC and parE. PCR was used for the detection of qnr, a plasmid mediated ciprofloxacin resistance gene. Clonal variations among ciprofloxacin resistant (CipR) and ciprofloxacin susceptible (CipS) strains were determined by Pulsed-field gel electrophoresis (PFGE).ResultsAmong 1067 (12%) ETEC isolates identified, 42% produced LT/ST, 28% ST and 30% LT alone. Forty nine percent (n = 523) of the ETEC strains expressed one or more of the 13 tested colonization factors (CFs) as determined by dot blot immunoassay. Antibiotic resistance of the ETEC strains was observed as follows: ampicillin 66%, azithromycin 27%, ciprofloxacin 27%, ceftriazone 13%, cotrimaxazole 46%, doxycycline 44%, erythromycin 96%, nalidixic acid 83%, norfloxacin 27%, streptomycin 48% and tetracycline 42%. Resistance to ciprofloxacin increased from 13% in 2005 to 34% in 2009. None of the strains was resistant to mecillinam. The MIC of the nalidixic acid and ciprofloxacin of representative CipR strains were 256 μg/ml and 32μg/ml respectively. A single mutation (Ser83-Leu) in gyrA was observed in the nalidixic acid resistant ETEC strains. In contrast, double mutation in gyrA (Ser83-Leu, Asp87-Asn) and a single mutation in parC (Glu84-Ly) were found in ciprofloxacin resistant strains. Mutation of gyrB was not found in either the nalidixic acid or ciprofloxacin resistant strains. None of the ciprofloxacin resistant strains was found to be positive for the qnr gene. Diverse clones were identified from all ciprofloxacin resistant strains by PFGE analysis in both CF positive and CF negative ETEC strains.ConclusionEmergence of ciprofloxacin resistant ETEC strains results in a major challenge in current treatment strategies of ETEC diarrhea.

Drivers of antimicrobial resistance amongst intestinalEscherichia coliisolated from children in South Asia and sub-Saharan Africa

“…The high AMR frequencies for first-line drugs, in particular penicillins, detected in this study are similar to reports of other intestinal, extra-intestinal and environmental isolates of E. coli 22,37 . Of note, the high levels of ciprofloxacin-resistance found in this study at the Asian sites corresponded to high levels reported in clinical cases in India, Bangladesh and Pakistan 17,18,21,23,24,38 . Further, while ESBL-producing aEPEC were detected in this study in Asia, the frequency of these was lower than those reported from hospitals in both Asia and Africa 18,21,31,38 .…”

“…While limited AMR data for E. coli are available from the seven countries where the GEMS sites were located, there are no national surveillance data from any of these countries. Furthermore, AMR data on E. coli in these countries predominately pertain to E. coli causing extra-intestinal infections and to a limited number of drugs, mainly third-generation cephalosporins and fluoroquinolones 21,[23][24][25]31 . Here we present the first comprehensive AMR phenotypic data and molecular characterization for multiple antimicrobials, detecting several common mobile elements mediating the AMR including small plasmids, class I integrons with different cassettes and transposons including Tn6029, Tn10 and Tn1721 ( Fig S3).…”

“…Of greatest concern are multi-drug resistant (MDR) E. coli (non-susceptible to one or more agents in at least three antimicrobial categories) 16 , particularly those that are fluoroquinolone resistant and/or produce extended-spectrum beta-lactamases (ESBL). While several recent studies have reported increases in ESBLs 17,18 , gentamicin 19,20 , ciprofloxacin [20][21][22][23][24] and revealed diverse AMR profiles, these data have largely come from E. coli responsible for disease in hospital settings. Thus, there remain significant gaps in knowledge of the prevalence of AMR in human intestinal E. coli populations globally, particularly in the developing nations of sub-Saharan Africa and South Asia 25 .…”

Emergence of Resistance to Quinolones and β-Lactam Antibiotics in Enteroaggregative and Enterotoxigenic Escherichia coli Causing Traveler’s Diarrhea

“…This reflects the situation of antimicrobial resistance in different countries in Latin America versus Southeast Asia/India. Southeast Asia and India present high rates of resistance to the most available and inexpensive antibiotics, including quinolones, whereas in Latin America, ETEC and EAEC strains remain susceptible to these antimicrobial agents (13)(14)(15)(16)(17)(18)(19). The high prevalence of quinolone-resistant EAEC and ETEC isolates from Southeast Asia and India is worthy of mention, with rates of resistance for ciprofloxacin at higher than 40% for both EAEC and ETEC.…”

Outbreak of CTX-M-15-Producing Enterotoxigenic Escherichia coli O159:H20 in the Republic of Korea in 2016

“…Most cases of ETEC-induced acute diarrhea are self-limiting; however, because prolonged diarrhea can result in severe dehydration, which is a high-risk factor for mortality, antimicrobials are sometimes considered for the treatment of ETEC infections such as traveler's diarrhea (1). However, the emergence of ETEC infections exhibiting drug resistance to available antimicrobials complicates treatment and leads to public health concerns (1,4,5). Here, we describe the first outbreak caused by cefotaxime-resistant ETEC O159:H20 strains at a high school in Incheon, Republic of Korea.…”