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Aim: The clinical presentation of four children and adolescents (two males and two females with a mean age of 12.4 years; range 9-16 years) with colorectal spirochetosis is discussed., Results: Symptoms included persistent diarrhea (n = 2), rectal bleeding (n = 1) and abdominal pain (n = 2). In all patients, colorectal spirochetosis was an unanticipated finding on colonic histology, and the presence of spirochetes was confirmed by the use of electron microscopy. Spirochetes were identified as Brachyspira aalborgi by using PCR amplification of the bacterial 16S rRNA and nicotinamide adenine dinucleotide oxidase sequences in all four patients. No other enteric pathogens were found., Conclusions: Although all patients appeared to respond to antibiotic treatment, the clinical significance of B. aalborgi as a human pathogen requires further investigation.

Detection of multiple pathogens, particularly a combination of viruses and bacteria, is infrequently documented in outbreaks of gastroenteritis. This paper reports the presence of Norwalk-like virus (NLV) and enterohaemorrhagic verotoxin-producing Escherichia coli in one individual, and NLV and verotoxin-producing Aeromonas sobria in another individual, both part of a large gastroenteritis outbreak. The causes of gastroenteritis in such outbreaks may be more complex than previously thought.

A 6-week-old child with acute urinary tract infection caused by Shiga toxin-producing Escherichia coli (STEC) O5:H-developed hemolytic-uremic syndrome (HUS). Molecular and phenotypic analysis of the urinary isolate indicated that it lacked uropathic properties and that it was probably of intestinal origin. Nevertheless, the patient did not experience a diarrheal prodrome, nor was STEC or Shiga toxin detected in his feces at any time. Examination of the patient's serum pointed to recent infection with E. coli O5, with no evidence of exposure to E. coli O157, O111, or O26. A review of 13 previously reported cases of HUS associated with acute urinary tract infection indicated that this was the first case of nondiarrheal HUS in which infection with the most common STEC serogroups was specifically excluded. This case illustrates the need to investigate patients with nondiarrheal HUS for infection with STEC.

The ability to cause attaching and effacing (AE) lesions in intestinal epithelial cells is an essential virulence trait of enteropathogenic E. coli (EPEC) that requires several chromosomal genes acting in concert with one another. In this study, we show that the ability to cause AE lesions can be transferred by conjugal mating from a high frequency recombinant (Hfr) derivative of a rabbit EPEC strain, E. coli RDEC-1, to a strain of E. coli K-12. Although the recipient acquired a considerable amount of donor DNA during the transfer process, it expressed the AE phenotype phenotype only weakly. The findings suggest the AE is a multigene phenomenon, the genes for which may not reside on a single region of the bacterial chromosome.

Assays to quantify bacterial invasion of epithelial cells generally fail to take account of the ability of the bacteria to adhere to the cells prior to invasion. We have developed a modified invasion assay to allow for this factor. We then used the assay to investigate diarrhoeagenic strains of Escherichia coli with differing ability to adhere to and invade HEp-2 epithelial cells. The results showed that enteroinvasive strains of E. coli were the most invasive variety, followed in order by enteropathogenic E. coli and enterotoxigenic E. coli. These findings correspond to what is known of the ability of the bacteria to invade the intestinal tract in vivo. The results also indicated that adhesins of diarrhoeagenic E. coli play no direct role in invasion, although they may facilitate invasion indirectly by promoting initial contact between bacteria and animal cells.