Preliminary results from a Dutch study suggest that a commercial assay for chlamydial heat shock protein 60 (cHSP60) predicts severity of infection in women. At the very least the assay should ensure comparable results among laboratories.

Investigators tested the assay with serum from women well defined for Chlamydia trachomatis infection and disease of the fallopian tubes against results previously obtained with a CT-pELISA IgG assay. Three groups were tested: 21 women confirmed to have no tubal disease (group 1), 86 pregnant women with unknown tubal disease (group 2), and 21 women with confirmed tubal disease (group 3).

The cHSP60 assay performed similarly to the IgG assay, identifying a rising proportion of positives across groups 1–3 (cHSP60: 5%; 16%; 27%; IgG: 19%; 40%; 64%, respectively), which increased for subgroups positive in the IgG assay (25%, 35%, and 43% across groups 1–3), though the trend was not significant. In the IgG negative subgroup, in group 2, the assay produced only 4% positives. Median titres in the cHSP60 assay increased across groups 1–3, as expected for a response linked to disease severity. However, the new assay may identify a different subgroup as it identified only 40% of women with confirmed tubal disease positive in the IgG assay.

In house cHSP60 assays are widely used to detect C trachomatis infection, and their potential for predicting disease severity has driven the need for a standardised commercial assay. Further testing—of more subjects with different degrees of disease—will be needed to confirm its potential.