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Multidrug Resistance in Large-plasmid-associated Presumptive Enterohaemorrhagic Escherichia Coli Isolated from Contaminated Lake Water

Zakir Hossain
Industrial Microbiology Section, Institute of Food Science and Technology,Bangladesh Council of Scientific and Industrial Research, Dhaka, Bangladesh

Papia Sultana
Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet, Bangladesh

Sudipta Deb
Department of Microbiology, Stamford University, Dhaka, Bangladesh

Monzur Morshed Ahmed
Industrial Microbiology Section, Institute of Food Science and Technology,Bangladesh Council of Scientific and Industrial Research, Dhaka, Bangladesh

Abstract/ Executive Summary:

To determine the presence of enterohaemorrhagic Escherichia coli (EHEC), 50 water samples of three different lakes in Dhaka, Bangladesh were studied. A total of 90 strains were examined thoroughly to isolate sorbitol non-fermenting (NSF) E. coli. Twelve of 90 isolates (13.3%) from 5 samples were found to be sorbitol nonfermenter, which were further screened for rhamnose, cellobiose and sucrose fermentation. Eleven (12.2%) of 90 isolates also tested negative for cellobiose and sucrose fermentation, while only 3 (3.3%) of them were found to be rhamnose non-fermenting. Biochemical tests confirmed that 91.7% (11 of 12) of NSF strains were indole positive. Eleven NSF E. coli isolates survived at 45.5°C and mostly produced gas by fermentation within 24h. After antimicrobial susceptibility testing, 91.7% (n=11) of these isolates were found resistant to cephalexin, ampicillin and amoxicillin. Ceftazidime and nalidixic acid resistance was also observed in 75% (9 of 12) and 58.3% (7 of 12) isolates, respectively. Plasmid profile analysis revealed that nine (75%) strains harboured large plasmids of >35.8-140 megadaltons (MDa), four (33.3%) of which contained 60-MDa plasmid. Also, the large-plasmid-associated strains shared common behaviour in antimicrobial resistance and eight (88.9%) of these were resistant to four or more antibiotics. Our data suggest a possible association of source water contamination in Bangladesh with multidrug-resistant (MDR) EHEC, which is alarming to public health.

Keywords: EHEC, water, sorbitol non-fermenting E. coli, large plasmid, MDR, public health

Location: Industrial Microbiology Section, Institute of Food Science and Technology,Bangladesh Council of Scientific and Industrial Research, Dhaka

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Water quality

Objectives:

To investigate the occurrence of EHEC in the water used for drinking, swimming and other necessities.

Methodology:

E. coli ATCC 8739 and E. coli O157:H7 NCTC 12079 were used in all experiments throughout this study as appropriate control strains (ATCC, American Type Culture Collection, USA; NCTC, National Collection of Type Cultures, United Kingdom). ATCC 8739 (Microbiologics®, USA), as a non-toxigenic and non-plasmid containing strain20, was obtained from the Microbial Reference Culture Collection of the Food Microbiology Laboratory, BCSIR, and the NCTC 12079 strain was kindly provided by the Department of Microbiology, University of Dhaka, Bangladesh. Other bacterial strains, such as Bacillus cereus, Pseudomonas aeruginosa, Salmonella typhi and Vibrio cholerae used as controls in certain biochemical tests were previously isolated from the environment and maintained in the laboratory, where this study was conducted. To validate the efficiency of an EC-broth mediated lactose fermentation step before using EMB and MacConkey agar media for confirmation of E. coli in this study, the percentages of sensitivity and specificity were calculated as follows: % Sensitivity = True positives x 100 / (True positives + False negatives); % Specificity = True negatives x 100 / (True negatives + False positives)

Source of Information: Bangladesh J Microbiol, Volume 28, Number 1, June 2011, pp 33-40

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In the present study, we have successfully isolated nine large-plasmid containing strains, which showed remarkable resistance to a panel of carefully chosen antibiotics. An attempt has been made to establish a relationship of these plasmids with antibiotic resistance among the strains. Overall findings also report a possible association of EHEC with the lake water contamination in Dhaka. Further assays are being carried out to confirm these results. This study refers to the first survey of shiga-toxin producing E. coli in the source water of Bangladesh.

Knowledge Management: Journal