Synthesis of unusual thick pili by Escherichia coli of EPEC serogroup O119

Unique very thick pili were found in varying numbers on cells of five out of 11 clinical isolates of enteropathogenic Escherichia coli belonging to the classic EPEC serogroup O119. They were approximately 12.5 nm in diameter, which is thicker than any other known E. coli pilus type. Analysis of the plasmid profiles of the O119 isolates showed that one strain was plasmid-free while the remainder contained numerous plasmids with a wide range of sizes. The thick pilus determinants were located on a 140-kb non-transferrable plasmid. They were not associated with adherence or a putative 90-kb enteroadherence factor plasmid.     

Presence of type I-like fimbriae and thin filaments on diarrhoeagenic Escherichia coli

Abstract Type I-like fimbriae were found on more serotypes of diarrhoeagenic Escherichia coli than exprcted from previous observations. The fimbriae had long 2 nm thick filaments that appeared to extend from their tips, but thus far the thin filaments have not been clearly implicated in adhesion to gut epithelial cells.     

Frequency of indicator bacteria,Salmonella and diarrhoeagenic Escherichia coli pathotypes on ready‐to‐eat cooked vegetable salads from Mexican restaurants

The presence of coliform bacteria, faecal coliforms, Escherichia coli, diarrhoeagenic E. coli pathotypes (DEP) and Salmonella were determined in ready‐to‐eat cooked vegetable salads (RECS) from restaurants in Pachuca city, Mexico. The RECS were purchased from three types of restaurants: national chain restaurants (A), local restaurants (B) and small restaurants (C). Two restaurants for each A and B, and three for C, were included. Forty RECS samples were purchased at each A and B restaurant and 20 at each C restaurant. Of the overall total of 220 analysed samples, 100, 98·2, 72·3, 4·1 and 4·1% had coliform bacteria, faecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC). The EPEC, ETEC and STEC were isolated each from 1·4% of samples. No E. coli O157:H7 were detected in any STEC‐positive samples. The analysis of Kruskal–Wallis anova and median test of microbiological data showed that the microbiological quality of RECS did not differ between the different restaurants (P > 0·05).

Significance and Impact of the Study

This is the first report regarding microbiological quality and Salmonella, enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC) isolation from ready‐to‐eat cooked vegetable salads from Mexican restaurants. Ready‐to‐eat cooked vegetable salads could be an important factor contributing to the endemicity of EPEC, ETEC and STEC, and Salmonella caused gastroenteritis in Mexico.