Enteropathogenic Escherichia coli serotype O111:HNT isolated from preterm neonates in Nairobi, Kenya

Abstract

This investigation was initiated as a consequence of several cases of diarrhea in a nursery ward for preterm babies in Nairobi, Kenya. Ten lactose-positive colonies were isolated from the stools of each of 30 neonates, regardless of whether they had diarrhea; 229 strains were identified as Escherichia coli and 65 strains were identified as Klebsiella pneumoniae. Six strains were lost during laboratory handling. No other bacterial, viral, or parasitic enteropathogens were identified. Using synthetic alkaline phosphatase-labeled probes, the bacterial isolates were found to be negative for the presence of genes coding for heat-stable and heat-labile enterotoxins. Seventy-eight E. coli strains isolated from a total of 13 neonates possessed the E. coli enteropathogenic adhesion factor (EAF) gene, as demonstrated by the use of a cloned radiolabeled DNA fragment probe. These strains possessed similar plasmid profiles constituting a core plasmid profile, and while all adhered to HeLa cells, none produced Vero cell cytotoxins. The EAF gene was located on a 65-megadalton plasmid. Serotyping showed the strains to be of serogroup 0111 and serotype H nontypable, a well known enteropathogenic type. Five neonates died during the outbreak, and the fatality rate was 30.7% (4 of 13) for neonates infected with EAF-positive E. coli strains compared with 7.7% (1 of 13) for neonates from whom only EAF-negative E. coli strains were isolated. K. pneumoniae only was isolated from five neonates.

Antimicrobial resistance of enteropathogenic Escherichia coli strains from a nosocomial outbreak in Kenya

“…The lactose-positive colonies were selected at random from each plate and later identified to species level (6). Two hundred and twentynine strains were identified as E. coli (24), and seventy-eight hybridized with the EAF probe and belonged to one plasmid profile group. The EAF gene was located on a 65-MDa plasmid (24).…”

“…Two hundred and twentynine strains were identified as E. coli (24), and seventy-eight hybridized with the EAF probe and belonged to one plasmid profile group. The EAF gene was located on a 65-MDa plasmid (24). These were strains of serotype 01 1 l:HNT, not cytotoxic and did not adhere to cell cultures (24).…”

“…The EAF gene was located on a 65-MDa plasmid (24). These were strains of serotype 01 1 l:HNT, not cytotoxic and did not adhere to cell cultures (24). All the 294 strains were negative for LT and ST (24) using DNA probes (30).…”

“…The role of antibiotics in the treatment of EPEC infections is not clear; most studies have failed t o show any benefit (9). A n outbreak of diarrhea due t o EPEC occurred in a hospital ward in Nairobi, Kenya (24). The bacterial strains isolated from this outbreak belonged to several different plasmid profile groups (25).…”

“…Antibiotics can select strains with both antibiotic resistance and virulent genes, especially if both types of genes are located on the same genetic element such as plasmids (1 3,27). The enteroadherence factor (EAF) gene of the EPEC strains is located on a plasmid that could possess antimicrobial resistance genes (14,24). The transfer of these plasmids in vitro to E. coli K12 strains in the presence of antibiotics has been demonstrated (21).…”