Abstract:
Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of infectious diarrhea in children.
There are no licensed vaccines against ETEC. This study aimed at characterizing Escherichia coli for ETEC
enterotoxins and colonization factors from children < 5 years with acute diarrhea and had not taken antibiotics prior
to seeking medical attention at the hospital.
Methods: A total of 225 randomly selected archived E. coli strains originally isolated from 225 children with acute
diarrhea were cultured. DNA was extracted and screened by multiplex polymerase chain reaction (PCR) for three
ETEC toxins. All positives were then screened for 11 colonization factors by PCR.
Results: Out of 225 E. coli strains tested, 23 (10.2%) were ETEC. Heat-stable toxin (ST) gene was detected in 16
(69.6%). ETEC isolates with heat-stable toxin of human origin (STh) and heat-stable toxin of porcine origin (STp)
distributed as 11 (68.8%) and 5 (31.2%) respectively. Heat-labile toxin gene (LT) was detected in 5 (21.7%) of the
ETEC isolates. Both ST and LT toxin genes were detected in 2 (8.7%) of the ETEC isolates. CF genes were detected in
14 (60.9%) ETEC strains with a majority having CS6 6 (42.9%) gene followed by a combination of CFA/I + CS21 gene
detected in 3 (21.4%). CS14, CS3, CS7 and a combination of CS5 + CS6, CS2 + CS3 genes were detected equally in 1
(7.1%) ETEC isolate each. CFA/I, CS4, CS5, CS2, CS17/19, CS1/PCFO71 and CS21 genes tested were not detected. We
did not detect CF genes in 9 (39.1%) ETEC isolates. More CFs were associated with ETEC strains with ST genes.
Conclusion: ETEC strains with ST genes were the most common and had the most associated CFs. A majority of
ETEC strains had CS6 gene. In 9 (39.1%) of the evaluated ETEC isolates, we did not detect an identifiable CF.
