Colonization of 8-week-old conventionally reared goats by Escherichia coli O157:H7 after oral inoculation

Enterohaemorrhagic Escherichia coli O157 : H7 infections of man have been associated with consumption of unpasteurized goat's milk and direct contact with kid goats on petting farms, yet little is known about colonization of goats with this organism. To assess the contribution of flagella and intimin of E coli O157 : H7 in colonization of the goat, 8-week-old conventionally reared goats were inoculated orally in separate experiments with 1 X 10(10) c.f.u. of a non-verotoxigenic strain of E coli O157: H7 (strain NCTC 12900 Nal(r)), an aflagellate derivative (DMB1) and an intimin-deficient derivative (DMB2). At 24 In after inoculation, the three E coli O157 : H7 strains were shed at approximately 5 X 1 04 c.f.u. (g faeces)(-1) from all animals. Significantly fewer intimin-deficient bacteria were shed only on days 2 (P = 0(.)003) and 4 (P = 0(.)014), whereas from day 7 to 29 there were no differences. Tissues from three animals inoculated with wild-type E coli O157 : H7 strain NCTC 12900 Nalr were sampled at 24,48 and 96 In after inoculation and the organism was cultured from the large intestine of all three animals and from the duodenum and ileum of the animal examined at 96 h. Tissues were examined histologically but attaching-effacing (AE) lesions were not observed at any intestinal site of the animals examined at 24 or 48 In. However, the animal examined at 96 h, which had uniquely shed approximately 1 x 10(7) E coli O157: H7 (g faeces)(-1) for the preceding 3 days, showed a heavy, diffuse infection with cryptosporidia. and abundant, multifocal AE lesions in the distal colon, rectum and at the recto-anal junction. These AE lesions were confirmed by immunohistochemistry to be associated with E coli O157: H7.

Contribution of fimbriae and flagella of Salmonella enteritidis to colonization and invasion of chicks

Isogenic mutants of Salmonella enteritidis defective for the elaboration of fimbrial types SEF14, SEF17, SEF21 and flagella were used to study the contribution these organelles made to colonization, invasion and lateral transfer in young chicks. The caecum, liver and spleen were colonized within 24 h following oral inoculation of 1-day-old chicks with 10(5) wild-type S. enteritidis strain LA5. However, for some mutants, the numbers of organisms recovered from internal organs was reduced significantly, particularly at 24 h post-inoculum, which supported the hypothesis that the organelles contribute to invasion and dissemination to internal organs. Specifically, mutations affecting SEF17, SEF21 and flagella contributed to a delay in colonization of the spleen, and those affecting SEF21 and flagella delayed colonization of the liver. Lower numbers of bacteria were recovered from the caecum with mutants deficient in elaboration of SEF21. Sentinel birds were colonized by LA5 or EAV40 (14(-), 17(-), 21(-), fla(-)) directly from the environment within 2 days, although a consistent slight delay was observed with the multiple mutant. Overall, our data suggest a collective role for SEF17, SEF21 and flagella, but not SEF14, in the early stages of colonization and invasion of young chicks by S. enteritidis, but these surface appendages appear unnecessary for colonization of birds from their immediate environment.

Oral treatment of chickens with Lactobacillus reuteri LM1 reduces Brachyspira pilosicoli-induced pathology

Avian intestinal spirochaetosis (AIS) results from the colonization of the caeca and colon of poultry by pathogenic Brachyspira, notably Brachyspira pilosicoli. Following the ban on the use of antibiotic growth promoters in the European Union in 2006, the number of cases of AIS has increased, which, alongside emerging antimicrobial resistance in Brachyspira, has driven renewed interest in alternative intervention strategies. Lactobacillus-based probiotics have been shown to protect against infection with common enteric pathogens in livestock. Our previous studies have shown that Lactobacillus reuteri LM1 antagonizes aspects of the pathobiology of Brachyspira in vitro. Here, we showed that L. reuteri LM1 mitigates the clinical symptoms of AIS in chickens experimentally challenged with B. pilosicoli. Two groups of 15 commercial laying hens were challenged experimentally by oral gavage with B. pilosicoli B2904 at 18 weeks of age; one group received unsupplemented drinking water and the other received L. reuteri LM1 in drinking water from 1 week prior to challenge with Brachyspira and thereafter for the duration of the study. This treatment regime was protective. Specifically, B. pilosicoli was detected by culture in fewer birds, bird weights were higher, faecal moisture contents were significantly lower (P<0.05) and egg production as assessed by egg weight and faecal staining score was improved (P<0.05). Also, at post-mortem examination, significantly fewer B. pilosicoli were recovered from treated birds (P<0.05), with only mild–moderate histopathological changes observed. These data suggest that L. reuteri LM1 may be a useful tool in the control of AIS.