EAEC

Enteroaggregative Escherichia coli (EAEC) is a diarrheagenic pathotype of Escherichia coli associated with acute and persistent diarrhea in children, travelers, and adults in both developing and developed regions. EAEC strains characteristically adhere to intestinal epithelial cells in a stacked-brick, aggregative pattern, a phenotype used in some laboratory assays to identify the pathotype.

Pathogenesis and virulence factors are heterogeneous. Many EAEC strains carry the pAA plasmid, which includes the aggR transcriptional regulator and genes for aggregative adherence fimbriae (AAF) that mediate adherence to the intestinal mucosa. The plasmid also encodes dispersin (aap) and a transport system (Aat) important for secreting virulence factors. This combination promotes biofilm formation and prolonged colonization. Atypical EAEC strains lack the pAA plasmid and aggR but may possess other virulence genes and can still cause disease.

Clinical presentation typically includes watery, sometimes persistent diarrhea with abdominal cramps; in children, malnutrition and growth impairment may accompany infection. Extraintestinal infections are uncommon but have been reported.

Diagnosis relies on a combination of clinical suspicion and laboratory testing. Traditional identification used HEp-2 cell adherence patterns; modern approaches often rely on PCR detection of EAEC-associated virulence genes (such as aggR and aatA) and, when available, detection of the dispersin gene (aap) and AAF-related markers.

Treatment is mainly supportive, focusing on rehydration and electrolyte management. Antibiotics are considered for severe or persistent cases, with selection guided by local resistance patterns; resistance to several agents has been described.

Prevention centers on standard diarrheal disease measures: good hygiene, safe drinking water, proper food handling, and exclusive breastfeeding when possible. There is currently no widely available EAEC vaccine.