Multidrug resistant enteroaggregative Escherichia coli diarrhoea in rural southern Indian population

Enteroaggregative Escherichia coli (EAEC) has been implicated in acute and persistent diarrhoea in children, adults, and in HIV/AIDS patients. Enteroaggregative Escherichia coli strains isolated from different parts of the world show a low to high level resistance to antimicrobial agents. The aim of the present study was to determine antimicrobial susceptibility in vitro among 64 EAEC strains isolated from children and adults with diarrhoea. 270 E. coli strains were isolated from children and adults. A total of 64 were identified as EAEC by multiplex PCR targeting 2 specific genes, AggR and EAST, from July 2006 to July 2007. Susceptibility to various antibiotics was checked using the Kirby Bauer disk diffusion method. Disk diffusion testing for 11 commonly used antimicrobial agents showed EAEC resistant to trimethoprim sulfamethoxazole, ampicillin and nalidixic acid. 75% of strains isolated showed multidrug resistance, i.e. resistance to >3 antimicrobial agents. Most of the isolates showing multidrug resistance were from children below 5 y of age. An increase in resistance of EAEC strains to quinolones was observed in the study. Our study indicated that EAEC resistance in southern India is much higher than that reported from other parts of country. Our study also showed that monitoring sensitivity to antibiotics commonly used in acute and persistent diarrhoea is necessary for optimum selection of effective antibiotics and elimination of antibiotics with little therapeutic value. Further clinical epidemiological and laboratory studies are needed to clarify these issues.