Serotype-Specific Prevalence of Escherichia coli Strains with EPEC Adherence Factor Genes in Infants with and without Diarrhea in Sao Paulo, Brazil

Abstract
To examine interrelationships of classic enteropathogenic Escherichia coli (EPEC) serotypes, EPEC adherence factor (EAF) genes, and diarrheal disease, E. coli were studied from stools of 500 infants +) E. coli of three common classic EPEC serotypes (O111:H, odds ratio [OR] 36.0; O111:H2, OR 55.0; O119:H6, OR 3.7) were individually strongly associated with diarrhea, as were EAF+ strains of less common classic serotypes combined (OR 5.3). Among EPEC serogroups, neither EAP+ strains of nonclassic serotypes (OR 1.8) nor EAF strains of classic (OR 2.2) or nonclassic (OR 1.4) serotypes were significantly associated with diarrhea. At least one EAF+ non-EPEC serogroup serotype (O88:H25) may represent an unrecognized EPEC serotype. Serotype-specific variation in the association of EAF+E. coli with diarrhea suggests that other factors are also important in determining virulence; thus, both EAF detection and E. coli serotyping are desirable in studying the etiology of diarrheal disease.