Epidemiology and properties of heat-stable enterotoxin-producing Escherichia coli serotype O169[ratio ]H41

Abstract

Enterotoxigenic Escherichia coli (ETEC) serotype O169:H41 organisms have become the most prevalent ETEC in Japan since the first outbreak in 1991. It was assumed that the outbreaks were due to clonal spread of this new ETEC serotype. The relationship of 32 strains isolated from 6 outbreaks were examined for biotype, antibiotic susceptibility, enterotoxigenicity, protein banding pattern, lipopolysaccharide banding pattern, plasmid analysis, and ribotyping. Further, the strains were examined by haemagglutination, surface hydrophobicity, and the ability to adhere to HEp-2 cells. The present study suggests that the outbreaks were caused by multiple clones of STp-producing O169:H41 since they showed differences in ribotype and outer membrane protein banding patterns. The strains did not agglutinate human or bovine red blood cells in a mannose-resistant manner. They adhered to HEp-2 cells in a manner resembling enteroaggregative E. coli. Five strains were examined by dot-blot tests for the colonization factor antigens CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS7, PCFO159, PCFO166 and CFA/III. Although four strains expressed CS6, no structure for CS6 was identified. A strain that the anti-CS6 MAbs did not react with could adhere to HEp-2 cells in mannose resistant manner; thus, it is unlikely that CS6 play an important role in the adhesion to the cells. Electron microscopy studies of the O169:H41 strains suggested that curly fimbriae, a possible new colonization factor, may be playing an important role in the adhesion of the bacteria to HEp-2 cells. In conclusion, outbreaks due to ETEC O169:H41 were caused by multiple clones, and the strains should be examined in detail for a possible new colonization factor.

Phylogenetic Comparisons Reveal Multiple Acquisitions of the Toxin Genes by Enterotoxigenic Escherichia coli Strains of Different Evolutionary Lineages

“…Previous phylogenetic investigations of ETEC using a variety of techniques have demonstrated similar results even though they were not placed within the context of the larger E. coli lineage. Thus, ETEC strains possessing the same CF-toxin genotypes often clustered together, suggesting that these strains had arisen by clonal expansion (33,42,43,51,59,61,64,65). However, in these same studies the CF-toxin genotypes were not strictly associated with phylogenetic clusters and closely related strains were also found to possess different CF-toxin profiles.…”

Prevalence of Diarrheagenic <i>Escherichia coli</i> in Foods and Fecal Specimens Obtained from Cattle, Pigs, Chickens, Asymptomatic Carriers, and Patients in Osaka and Hyogo, Japan

“…However, Ban et al recently found that the ETEC O169:H41 strain possesses genes encoding proteins homologous to the colonization factor K88 found in pig ETEC (38). Since ETEC O169:H41 is an emerging DEC in both Japan and the United States (13,39), ETEC originating from pigs may be transmitted to humans via meat and foods, just as STEC carried by cattle is transmitted via beef products and water polluted by feces.…”

“…Outbreaks due to the ETEC serogroup O169 have been increasing, and ETEC may be an emerging cause of food-borne diseases in Asia, Europe, and the U.S.A. (13)(14)(15)(16)(17).…”

A Comparative Genomic Analysis of Diverse Clonal Types of EnterotoxigenicEscherichia coliReveals Pathovar-Specific Conservation

“…Molec-ular studies have suggested that there is a difference in the virulence of ETEC strains producing two particular ST variants, STp and STh, with STh-producing strains seemingly being more pathogenic than their STp-producing counterparts (51,71). However, STp-producing ETEC strains are capable of causing disease in humans (47).…”