Entero-adherent Escherichia coli is an important diarrhoeagenic agent in infants aged below 6 months in Calcutta, India.

Escherichia coli adherent to HEp-2 and HeLa cells were isolated from the faeces of 43 (19.7%) of 218 hospitalised infants aged below 6 months with acute diarrhoea. No conventional virulence factors, including enterotoxin production--heat-labile (LT) or heat-stable (ST), the verotoxin (VT) or shiga-like toxin (SLT)--or the invasive phenotype (determined by the Sereny test) could be detected among these isolates. Out of the 43 isolates, 16 (37.2%) were of the known enteropathogenic O:K serogroups--enteropathogenic E. coli (EPEC). The remaining 27 (62.8%) isolates showed different types of adherence to HEp-2 and HeLa cells which was diffuse (40.7%), localised (37.0%), or both (22.3%); they were identified as entero-adherent E. coli (EAEC). The EAEC isolates adhered to HEp-2 and HeLa cells in the presence of mannose, lactose, fucose, galactose, and fetuin, indicating that adhesion was not specific for these sugars or glycoprotein. Haemagglutination and the salt aggregation test (SAT) did not correlate with patterns of adherence. The results of this study indicate that LA-EAEC is an important aetiological agent of acute diarrhoea in infants aged below 6 months in Calcutta.