Multiple Antibiotic Resistance Index of Escherichia Coli Isolated from Drinking Water Sources in Ado-Ekiti, Nigeria

Waterborne diseases are among the leading cause of morbidity and mortality in developing countries and could
result from feacal contamination of surface water serving as source of drinking water in rural communities. The
presence of Escherichia coli in water is an indication of faecal contamination. Hence, investigation on the incidence
of antibiotic-resistant E. coli of different drinking water sources in Ado-Ekiti, Nigeria was carried out from June to
November, 2011. Water samples were collected from different water sources (surface drinking water, water dams,
shallow wells and commercial processed water) in Ado-Ekiti metropolis and analysed for microbiological quality.
Escherichia coli strains were isolated from the water samples on Eosin methylene blue (EMB-agar). Two hundred
and twenty eighty (228) strains were isolated from all the water sources and screened against eight antibiotics
namely: amoxicillin, augmentin,gentamicin, cotrimoxazole, nitrofurantoin, nalixidic acid, ofloxacin and tetracycline.
The mean antibiotic resistance patterns exhibited by the isolates were augmentin (91.7%), tetracycline (73.0%),
nitrofurantoin (62.2%), cotrimoxazole (61.1%), gentamicin (45.0%) , nalixidic acid (38.7%), and ofloxacin (9.2%).
Eleven (11) randomly selected antibiotic resistant E.coli strains that showed multiple resistance patterns were
screened for plasmid, out of which ten (10) were found to harbour one or more plasmids of sizes 23.13kbp, 2.37kbp
and 2.98kbp. High levels of MAR-index ranging from 0.81 to 3.08 as against low risk value of 0.2 could be an
indication that all the water sources were of high public health risk in the study areas. Hence this study revealed the
need for adequate water sanitation programme especially for rural communities to prevent outbreak of antibioticresistant
waterborne infections.