Isolation of Escherichia coli O5 : H − , possessing genes for Shiga toxin 1, intimin-β and enterohaemolysin, from an intestinal biopsy from an adult case of bloody diarrhoea: evidence for two distinct O5 : H − pathotypes

Abstract

Two typical coliforms from an intestinal biopsy from an adult case of bloody diarrhoea carried genes encoding intimin-â, stx 1 and ehxA, and produced verocytotoxin 1 and enterohaemolysin in culture. Both were biochemically typical Escherichia coli O5 : H À , apart from producing urease. Such O5isolates represent a human pathogenic E. coli lineage. Case reportA 55-year-old man 3 months post autologous stem cell transplant for multiple myeloma presented to hospital with abrupt onset of bloody diarrhoea and fever (38 8C). He was commenced empirically on intravenous ciprofloxacin and metronidazole. General stool culture for commonly encountered enteric pathogens failed to yield a possible causative agent. Clostridium difficile toxin was not detected. A colonoscopy on the day of admission revealed multiple mucosal areas showing a granular erythematous appearance with changes predominating on the left side of the colon. A biopsy of the macroscopically abnormal area revealed numerous bacilli adhering and effacing the surface enterocytes with scant acute inflammatory cells, minor degenerative epithelial changes and focal epithelial sloughing (Fig. 1). The appearances were diagnosed as a bacterial colitis and the possibility of an attaching and effacing Escherichia coli (AEEC). Once the diagnosis was known, the antibiotics were ceased as ciprofloxacin has potential adverse effects. No further antibiotics were given and the patient improved over the next 3 days, the diarrhoea ceased and he went home.Regarding potential risk factors for exposure to Shiga toxinproducing E. coli (STEC), there was no recent travel history or contact with a farming environment. He worked in a food bar, where he sometimes ate cold peanuts and salami, and he had no knowledge of any reports of illness in any of the people who visited the shop around the time that his diarrhoea commenced. The studyThe biopsy material sent for microbiology was cultured for the presence of AEEC by smearing across the plates on MacConkey (MAC), sorbitol MacConkey (SMAC), and washed and unwashed sheep blood agars (WSBA and SBA). The majority of the colonies were coliform and of the same morphology, as well as a few staphylococci. The colonies all fermented lactose on MAC, sorbitol on SMAC, and were haemolytic on WSBA but not on SBA, suggesting a profuse growth of enterohaemolytic E. coli (Bettelheim, 1995) of similar phenotype. They were tested by the adaptation of the Denka-Seiken test ) and found to be verocytotoxigenic. Following standard previously described methods (Bettelheim et al., 2000) on two colonies, it was found that they were typical E. coli apart from being anaerogenic and urease producers. They were non-motile, and O serotyping showed them to belong to serogroup O5. Supernatants prepared from overnight growth in trypticase soy broth, when tested on Vero cells, gave the typical cytopathic effects of verocytotoxins at dilutions of up toAbbreviations: AEEC, attaching and effacing Escherichia coli; HUS, haemolytic uraemic syndrome; STEC, Shiga toxin-produc...

The Non-O157 Shiga-Toxigenic (Verocytotoxigenic)Escherichia coli; Under-Rated Pathogens

“…Pathotype B has been typically isolated from calves with diarrhea as well as healthy calves and possesses the Shiga-toxin subtype stx 1 , and produces enterohemolysin and does posses Intimin (Int-β subtype) Djordjevic et al 2004). Pathotype B rarely produces Shiga-toxin 2 and typically produces urease, which pathotype O and most other E. coli do not (Brett et al 2003a;Hornitzky et al 2005;Mercado et al 2004;Wieler et al 1996) and a strain of this pathotype B was isolated from an adult case of bloody diarrhea (McLean et al 2005). Such different pathotypes, may well be reflected among other STEC serotypes.…”

“…However, a number of observations suggest that strains belonging to apparently the same serotype O5:Hmay belong to two separate pathotypes, one ovine-derived: Pathotype O and one bovine-derived Pathotype B (McLean et al 2005). Pathotype O typically possesses the Shiga-toxin subtypes stx 1c /stx 1 + stx 2c and produces enterohemolysin but does not posses Intimin (Brett et al 2003b;Ramachandran et al 2001) is prevalent in healthy sheep as well as being the causative agent of a case of HUS (Starr et al 1998).…”

Shiga toxin-producingEscherichia coliand atypical enteropathogenicEscherichia colistrains isolated from healthy sheep of different populations in São Paulo, Brazil

“…2003). For example, STEC strains of serotype O5:H− are predominantly isolated from sheep and rarely from cattle, and show different genetic profiles among these species, suggesting the existence of different clonal populations of O5:H− (McLean et al. 2005).…”

“…There is mounting evidence that STEC serotypes that commonly inhabit the gastrointestinal tract of sheep are rarely isolated from other hosts (Beutin et al 1993(Beutin et al , 1997Djordjevic et al 2001Djordjevic et al , 2004Blanco et al 2003;Brett et al 2003;Urdahl et al 2003). For example, STEC strains of serotype O5:H) are predominantly isolated from sheep and rarely from cattle, and show different genetic profiles among these species, suggesting the existence of different clonal populations of O5:H) (McLean et al 2005).…”

Low-Density Macroarray Targeting Non-Locus of Enterocyte Effacement Effectors ( nle Genes) and Major Virulence Factors of Shiga Toxin-Producing Escherichia coli (STEC): a New Approach for Molecular Risk Assessment of STEC Isolates

“…Recent data from Enter-Net, a global surveillance consortium of 35 countries that tracks enteric infectious diseases, showed that the number of human cases of illness caused by non-O157 EHEC increased globally by 60.5% between 2000 and 2005, while at the same time the number of cases linked to EHEC O157 increased by only 13% (1). In the past few years, new serotypes of EHEC that differ from those previously known as typical and atypical EHEC have emerged (6,8,23,24,31). These EHEC strains were identified as important causes of food-borne infections in humans and were described as "new emerging EHEC.…”