Attaching and effacing lesions in the intestines of an adult goat associated with natural infection with Escherichia coli O145

THERE have been few reports of attaching and effacing Escherichia coli (AEEC) infections in goats. A severe outbreak was recorded by Drolet and others (1994) affecting neonatal goat kids, of which 21 of 34 born alive died after having diarrhoea. A further case (Duhamel and others 1992) involved a goat approximately two months old, with severe diarrhoea of three weeks’ duration. This animal was part of a drug toxicity trial, which may have been an exacerbating factor. This short communication describes a naturally occurring infection with AEEC in an adult goat with diarrhoea. Nine adult diary goats out of a herd of 300 had died over the course of a month with a history of milk drop, anorexia and weakness followed by death within a few days. The 10th animal, a three-year-old Saanen cross nanny which showed similar clinical signs, was submitted to the Veterinary Laboratories Agency (VLA) – Langford for examination. The animal was depressed, remained recumbent during clinical examination and had mild diarrhoea. Blood samples were collected for routine haematological and biochemical analysis. Haematological examination indicated dehydration, with a packed-cell volume of 0·53 litre/litre (reference range 0·24 to 0·39 litre/litre). The blood urea level was 94·7 mmol/litre (reference range 4·0 to 8·6 mmol/litre) and there was a raised blood creatine kinase level of 1083 U/litre at 37°C (reference range 0 to 100 U/litre), consistent with muscle damage due to recumbency. The remaining parameters were within normal limits. The goat was euthanased by intravenous pentobarbitone injection and a postmortem examination was performed immediately. At postmortem examination the carcase weighed 77 kg and had a large amount of abdominal fat. No gross lesions were identified in the gastrointestinal tract. The rumen contained a large volume of pale straw-coloured fluid and a little roughage. The contents of the abomasum were fluid. The small and large intestines contained a moderate amount of yellow, watery fluid and the mucosa appeared normal. The rectal contents were semisolid. The kidneys appeared slightly enlarged, and the uterus contained excess clear fluid consistent with pseudopregnancy. No other abnormalities were detected. Samples of the small and large intestinal contents, liver, heart blood and brain were collected for routine bacteriological examination. Smears of small intestinal mucosa were stained using Gram’s stain. Ten colonies of E coli selected at random from sweeps of the contents taken from the large and small intestines were subcultured onto Dorset’s egg slopes for preliminary typing as described by Pearson and others (1999). Samples of the duodenum, jejunum, ileum and colon were fixed immediately in 10 per cent neutral-buffered formalin; the tissues were processed routinely to paraffin wax, and 4 μm sections were stained with haematoxylin and eosin. For peroxidase-antiperoxidase (PAP) immunostaining, additional 4 μm sections of the ileum and colon were mounted on organosilane-coated slides and incubated at room temperature with commercially available rabbit anti-O45, anti-O71 and anti-O145 antisera (Prolabs) at a dilution of 1/1000. These antisera were selected after preliminary analysis of the E coli isolates recovered from the goats. Goat anti-rabbit antiserum (Sigma), rabbit PAP (Dako) and diaminobenzidine were then applied sequentially. Sections incubated with normal rabbit serum (diluted 1/500 and 1/1000) and rabbit anti-O157 and anti-O26 antisera were used as controls. For electron microscopic studies, a small area of the ileum was cut from the paraffin wax block and processed as described by Pearson and others (1989). Bacteriological culture of the small and large intestinal contents produced a heavy, pure growth of coliforms. Salmonella species were not isolated using specific culture techniques. The 10 randomly selected coliform colonies were tested using the multiplex PCR described by Meng and others (1997). Seven isolates possessed the eae gene, encoding the 94 kDa outer membrane protein intimin, but none was positive for stx or stx2, the genes encoding Shiga-like toxins. Five of the seven eae-positive isolates were identified as E coli O145, one as E coli O45 and one as E coli O71. Following immunostaining, the five E coli O145 isolates were analysed further by the genetic methods of Cookson and others (2002) and each was found to possess genes encoding the β-intimin subtype and CNF1 and CNF2 cytotoxins. There were no significant isolates following culture of heart blood, liver or brain. Clostridia-like organisms were not identified in Gram-stained smears of the small intestinal contents. Histological examination of the duodenum and jejunum revealed moderate separation of the villous epithelium from the lamina propria, associated with early autolytic changes, but the villi were otherwise normal. In the ileum, severe stunting and fusion of villi, with flattening of the mucosa and an irregular epithelial surface, was observed (Fig 1). Adherent bacteria were present as multifocal colonies of variable size on the mucosal surface. In the colon, a few areas of focal, irregular surface epithelium were seen, some of which were associated with adherent bacteria similar to those observed in the ileum. Examination of the kidneys revealed a marked ectasia of the distal convoluted tubules, with many of them containing oxalate casts. Sparse neutrophil foci were present in a few tubules. Immunostained ileum and colon sections demonstrated bacterial expression of E coli O145 antigen (Fig 2), but E coli O45 and O71 staining was not identified. Electron microscopy of the ileum confirmed that these bacteria were associated with attachingeffacing (AE) lesions (Fig 3). Veterinary Record (2004) 155, 807-808