Chlamydia pecorum infection is a threat to the health of free-ranging koalas (Phascolarctos cinereus) in Australia. Utilising an extensive sample archive we determined the prevalence of C. pecorum in koalas within six regions of Victoria, Australia. The ompA genotypes of the detected C. pecorum were characterised to better understand the epidemiology of this pathogen in Victorian koalas. Despite many studies in northern Australia (i.e. Queensland and New South Wales), prior Chlamydia studies in Victorian koalas are limited. We detected C. pecorum in 125/820 (15%) urogenital swabs, but in only one ocular swab. Nucleotide sequencing of the molecular marker C. pecorum ompA, revealed that the majority (90/114) of C. pecorum samples typed were genotype B. This genotype has not been reported in northern koalas. In general, Chlamydia infection in Victorian koalas is associated with milder clinical signs compared to infection in koalas in northern populations. Although disease pathogenesis is likely to be multifactorial, the high prevalence of genotype B in Victoria may suggest it is less pathogenic. All but three koalas had C. pecorum genotypes unique to southern koala populations (i.e. Victoria and South Australia). These included a novel C. pecorum ompA genotype and two genotypes associated with livestock. Regression analysis determined that significant factors for the presence of C. pecorum infection were sex and geographic location. The presence of 'wet bottom' in males, and the presence of reproductive tract pathology in females, were significantly associated with C. pecorum infection suggesting variation in clinical disease manifestations between sexes.
Journal of Medical Microbiology / Vol. 65, pp.420-428