Molecular characterization of enterotoxigenic Escherichia coli toxins and colonization factors in children under five years with acute diarrhea attending Kisii Teaching and Referral Hospital, Kenya

Abstract

Background 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.

Characteristics of Pathogenic Escherichia coli Associated with Diarrhea in Children under Five Years in Northwestern Ethiopia

“…In our study, 33.3% of ETEC isolates produced heat-stable toxins (STs), 12.8% produced heat-labile toxins (LTs), and 7.7% produced both enterotoxins. These findings are consistent with those of a study conducted in Kenya [ 70 ] and Indonesia [ 71 ], where ST toxins were the most common, followed by LT, and both enterotoxins were the least common. In contrast, studies from Iran [ 72 ] and Bolivia [ 73 ] found that LT toxins were detected at a higher rate than ST toxins.…”

Molecular detection of Enterotoxigenic Escherichia coli Toxins and Colonization Factors from Diarrheic Children in Pediatric Teaching Hospital, Sulaymaniyah, Iraq

“…The discrepancy between our findings and those of other studies could be attributable of variation in CF expression by ETEC in different geographical regions, as well as differences in laboratory methods/primers used to identify CFs [46]. In addition, due to sub cultured repeatedly or storage for long term, the plasmid containing the CF genes has been lost [44]. Decreasing the expression of CF genes, a mutation inside the genetic locus, and expression of a CF not covered by the primers used in the PCR panel [6], [57], [58].…”

“…Variations in our results with other researches could be related to changes in primers utilized, geographical considerations, population targeted, and sample size [44]. In nine of the 12 research conducted in Africa, 22 of 34 investigations in Asia, and three of six studies in Latin America and the Caribbean, ETEC was being the first or second most often isolated pathogen [45].…”

Multidrug-resistant and clonal dispersion of enterotoxigenic Escherichia coli from ready-to-eat meat products in Duhok province, Iraq

“…ETEC strains are characterized by heat-labile (LT) and/or heat-stable (ST) enterotoxins which are plasmid-encoded (6,7). In developing nations, enterotoxigenic E. coli is a known causal agent of diarrhea in travelers and children (8,9).…”