Comparison of nine antigen detection kits for diagnosis of urogenital infections due to Chlamydia psittaci in koalas.

Chlamydia psittaci is the major cause of infectious disease in the koala (Phascolarctos cinereus). It causes four disease syndromes in the koala, namely, conjunctivitis, rhinitis, cystitis, and infertility (females only). Diagnosis of chlamydial infections in koalas relies primarily on isolation of the organism in cell culture. Serology has generally not been useful, and little use has previously been made of the commercially available antigen detection kits. We examined the sensitivity, specificity, and usefulness of three direct fluorescent-antibody kits (Vet-IF [Cell Labs], IMAGEN [Celltech], Chlamydia-Direct IF [Bio Merieux]) and six antigen detection enzyme-linked immunosorbent assay (ELISA) kits (Clearview [Unipath], Surecell [Kodak], Pathfinder [Kallestad], Chlamydia-EIA [Pharmacia], Chlamydiazyme [Abbott], IDEIA [Celltech]) for the detection of urogenital infections in koalas. Laboratory studies showed that the direct fluorescent-antibody kits were the least sensitive in this case and did not detect fewer than 10(4) elementary bodies per ml, while most ELISA kits detected between 130 and 600 elementary bodies per ml. Field study results showed that the Clearview kit was the most sensitive (91%) compared with the IDEIA (88%) and the Surecell (73%) kits. All three kits were more sensitive than cell culture (36%), highlighting viability loss problems that occur during transport. This study showed that the Clearview kit is sensitive, specific, and easy to use for the detection of type II (urogenital) C. psittaci from koalas in the field and warrants further evaluation.