Detection of Chlamydia psittaci in free-ranging koalas (Phascolarctos cinereus): DNA hybridization and immuno-slot blot analyses.

DNA-slot hybridization and immuno-slot blot analyses were compared for the detection of Chlamydia psittaci in crude swab material from free-ranging koalas. Immuno-slot blot analysis detected chlamydiae in 43 out of 68 koalas, with the sensitivity of the assay varying from 52 to 73% depending on the site of infection. Gene probe analysis was also used employing a genus-specific probe pCKO-10 isolated from a koala chlamydial gene library (ocular strain) and a plasmid probe pCKU cloned from a urogenital strain. The sensitivity of these two assays was comparable and they were considerably more efficient than the immuno-slot blot method for the detection of chlamydiae. Comparison of these data with a cell-culture method of detection, previously used with the same samples, demonstrated that gene probe analysis detected more positives than observed with cell culture. However, this appears to reflect more on the condition of the swab material rather than the sensitivity of the method.