Evaluation of PCR assays for the detection of Campylobacter fetus in bovine preputial scrapings and the identification of subspecies in South African field isolates
Journal of the South African Veterinary Association
Allerton Provincial Veterinary Laboratory, Private Bag X2, Cascades, 3202, South Africa; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
As a result of the high lability and slow growth of Campylobacter fetus subspecies, the laboratory diagnosis of bovine genital campylobacteriosis has always been difficult. This is especially true under South African conditions, where farms are far apart, laboratories are only present in major centres and there are high ambient temperatures. In order to overcome the short-comings associated with traditional diagnostic methods, the implementation of a molecular assay was sought. This work describes how a previously published PCR assay (MG3F/MG4R primers) was adapted, optimised and applied in the diagnostic laboratory to test preputial samples directly for the presence of Campylobacter fetus. Field evaluation of the assay revealed an analytical sensitivity and specificity of 85.7 % and 99 %, respectively. Subsequent genotyping and phenotyping of a diverse collection of South African field isolates revealed that South Africa has an unexpected and previously unreported high incidence of Campylobacter fetus subsp. venerealis biovar intermedius strains. These strains were not identified correctly by the subspecies-specific primer set evaluated. Until such time that cost- effective genotyping methods are available to diagnostic laboratories in South Africa, and other countries with these atypical Campylobacter fetus subsp. venerealis strains, the need for bacterial culture will persist. Identification to subspecies level of isolates at present remains dependent upon a single phenotypic criterion, namely tolerance to 1 % glycine.
article; bacterial strain; bacterium culture; Campylobacter fetus; controlled study; cost effectiveness analysis; cow; genotype; laboratory diagnosis; nonhuman; phenotype; polymerase chain reaction; prepuce; sensitivity and specificity; South Africa; Animals; Campylobacter fetus; Campylobacter Infections; Cattle; Cattle Diseases; Male; Polymerase Chain Reaction; South Africa; Bacteria (microorganisms); Bovinae; Campylobacter fetus; Campylobacter fetus subsp. fetus; Campylobacter fetus subsp. venerealis