Isolation of the anaerobic intestinal spirochaete Brachyspira pilosicoli from long-term residents and Indonesian visitors to Perth, Western Australia

Abstract

Brachyspira pilosicoli is an anaerobic spirochaete that colonizes the large intestine of humans and various species of animals and birds. The spirochaete is an important enteric pathogen of pigs and poultry, but its pathogenic potential in humans is less clear. In the current study, the occurrence of B. pilosicoli in faecal samples from 766 individuals in two different population groups in Perth, Western Australia, was investigated by selective anaerobic culture. Of 586 individuals who were long-term residents of Perth, including children, elderly patients in care and in hospital and individuals with gastrointestinal disease, only one was culture positive. This person had a history of diverticulitis. In comparison, faeces from 17 of 180 (9.4 %) Indonesians who were short-or medium-term visitors to Perth were positive for B. pilosicoli. The culture-positive individuals had been in the city for between 10 days and 4.5 years (median 5 months). Resampling of subsets of the Indonesians indicated that all negative people remained negative and that some positive individuals remained positive after 5 months. Two individuals had pairs of isolates recovered after 4 and 5 months that had the same PFGE types, whilst another individual had isolates with two different PFGE types that were identified 2 months apart. Individuals who were culture-positive were likely to have been either colonized in Indonesia before arriving in Perth or infected in Perth following contact with other culture-positive Indonesians with whom they socialized. Colonization with B. pilosicoli was not significantly associated with clinical signs at the time the individuals were tested, although faeces with wet-clay consistency were 1.5 times more likely (confidence interval 0.55-4.6) than normal faeces to contain B. pilosicoli.

The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans

“…In a study of healthy immigrants to Western Australia, carriage was detected in 10.6% of the population, with the prevalence being significantly higher among individuals from the Middle East and from Africa than among individuals from other regions (170). In another study, a fecal carriage rate of 15% was found among 227 recent healthy immigrants to Australia (169).…”

“…In another study, a fecal carriage rate of 15% was found among 227 recent healthy immigrants to Australia (169). In the original study, feces from 17 of 180 (9.4%) Indonesians who either were short-term or medium-term visitors to Perth, Western Australia, were found to be culture positive for B. pilosicoli (170). The colonized individuals had lived in Perth for periods varying from 10 days to 4.5 years (with a median duration of 5 months).…”

“…When the Indonesian visitors to Perth subsequently were resampled at different times, all the people who had been culture negative remained negative, and a few individuals who had been positive remained so after 5 months (170). Pairs of isolates that were recovered from two individuals after 4 and 5 months had the same pulsed-field gel electrophoresis (PFGE) types, while two isolates with different PFGE types were recovered 2 months apart from the same individual.…”

“…Infection with B. pilosicoli in Aboriginal patients was significantly associated with having chronic diarrhea and with failure to thrive and being underweight in children. In another study, among 586 non-Aboriginal individuals who were long-term residents of Perth, Western Australia, including elderly patients in care or in hospital, children, and individuals with gastrointestinal disease, only one (elderly) person with a history of diverticulitis was culture positive for B. pilosicoli (170). Studies in Italy have successfully isolated B. pilosicoli from the feces of patients with gastrointestinal disease (7,171), although their ethnicity, travel history, and background were not described.…”

Evidence of homologous recombination as a driver of diversity in Brachyspira pilosicoli

“…A review collating global human clinical manifestations and prevalence of B. pilosicoli [2] cites that it is commonly found in faecal samples collected in the Middle East, Southeast Asia and rural Australia, but for example is less prevalent (~1.5 %) in urban parts of Australia [32], the UK and Belgium.…”