PREVALENCE AND ASSOCIATION OF THE LONGUS PILUS STRUCTURAL GENE (LNGA)WITH COLONIZATION FACTOR ANTIGENS, ENTEROTOXIN TYPES, AND SEROTYPES OF ENTEROTOXIGENIC ESCHERICHIA-COLI

Human enterotoxigenic Escherichia coli (ETEC) produces a plasmid-encod ed type IV pilus termed longus (fdr long pilus). Regardless of the geo graphic origins of ETEC strains, the longus structural gene lngA was f ound to have the highest level of association with ETEC producing colo nization factor antigen (CFA) CFA/II, followed by ETEC producing CFA/I and CFA/IV. ETEC bearing the less prevalent CFA/III and putative colo nization factors and ETEC negative for CFA and putative colonization f actor also contained lngA-related sequences. lngA was found in a consi derable number of ETEC serotypes and was more often associated with ET EC producing heat-stable enterotoxins than with ETEC producing both he at-labile and heat-stable enterotoxins or heat-labile enterotoxin alon e. lngA was found more often in strains isolated from children with di arrhea than in strains from healthy children, suggesting an associatio n with intestinal disease. We conclude that longus is a widely distrib uted antigenic determinant in ETEC that is highly associated with know n plasmid-encoded virulence factors, namely, CFAs and enterotoxins. A longus-specific probe may be a helpful epidemiological tool to assist in the identification of ETEC.