Chlamydial co-infection among patients with gonorrhoea.

The objective was to determine how often gonococcal (GC) infection is accompanied by chlamydial co-infection and to determine risk factors for dual infection. All GC-positive cultures were identified between 24 April and 9 September 1998, among patients seen at the three genitourinary medicine (GUM) clinics across the Chelsea and Westminster Directorate. Chlamydia trachomatis was diagnosed using an enzyme-linked immunosorbent assay (ELISA) (Dade-Behring). One hundred and fifty-three episodes of gonorrhoea were identified. Information on chlamydial infection was available for 149 cases of GC of whom 16 (10.7%) were found to be co-infected with C. trachomatis. In univariate analysis, chlamydial co-infection was exclusively diagnosed in heterosexuals, and was more likely to be diagnosed among females, in younger individuals and in individuals of black Caribbean ethnic group. In multivariable analyses, however, only the sex and age of the individual were independently associated with chlamydial co-infection. The rate of co-infection was 10.7%. Independent risk factors were being less than 20 years old and being female.