Population genetic analysis of Serpulina pilosicoli and its molecular epidemiology in villages in the Eastern Highlands of Papua New Guinea

Abstract

The population genetics of Serpulina pilosicoli and its molecular epidemiology in villages in the Eastern Highlands province of Papua New Guinea were investigated. Multilocus enzyme electrophoresis (MLEE) was used to analyse 164 isolates from humans and animals. These were divided into 33 electrophoretic types (ETs), four of which contained 65% of the isolates. The mean genetic diversity (n = number of ETs) for 145 human isolates was 0.18, and the mean number of alleles at five polymorphic loci was 2.6. The species appeared to be recombinant, as there was a lack of linkage disequilibrium, and 25% of all the possible combinations of alleles was present in the population. PFGE analysis using the enzymes MluI and Sall divided 157 of the isolates into 99 PFGE types, demonstrating the existence of considerable strain diversity in a geographically restricted area. The two techniques were in excellent agreement; however, PFGE was more discriminatory for strain typing than was MLEE. Nine out of 19 (474%) culture-positive individuals were colonized by the same PFGE type of 5. pilosicoli when retested after 6 weeks. For three individuals, the PFGE profiles of the second isolate differed from the first in only one or two DNA bands, while the other seven individuals were colonized with distinct PFGE types on each occasion. In two cases, strains with the same PFGE pattern were isolated from humans and dogs, suggesting that crossspecies transmission of 5. pilosicoli may occur naturally and that the infection can be zoonotic.

Carriage of intestinal spirochaetes by humans: epidemiological data from Western Australia

“…Digestion of DNA with MluI gave 9-16 DNA bands. Using this enzyme, 37 distinct banding patterns were obtained for the 39 isolates plus 6 control isolates, confirming previous observations that B. pilosicoli is genetically heterogeneous [17][18][19]. Isolates from Aboriginals, migrants and control strains were widely distributed throughout the dendrogram produced from analysis of MluI patterns (not shown).…”

Colonization and risk factors for Brachyspira aalborgi and Brachyspira pilosicoli in humans and dogs on tea estates in Assam, India

“…3 % (4/76 dogs), compared to 22 . 8% in humans [36]. The low prevalence in dogs in that study, as in the present study, suggests that they are unlikely to be a significant reservoir of B. pilosicoli infection for humans in developing communities.…”

“…The low prevalence in dogs in that study, as in the present study, suggests that they are unlikely to be a significant reservoir of B. pilosicoli infection for humans in developing communities. Indeed, in such settings, it is likely that dogs become colonized with B. pilosicoli following consumption of contaminated human faeces [9,36].…”

Brachyspira research – special issue on colonic spirochaetes of medical and veterinary significance

“…Colonization was associated with the use of well water, and affected individuals had an increased chance of having wet faeces. This study confirms that colonization with B. pilosicoli is common in humans in developing communities (Trott et al, 1998) and that the spirochaete may present a considerable burden on human health in many regions.…”