Is coexisting chlamydial infection more common in gonococcal infections with serogroup WI?

Over a 4-year period a total of 8974 women were screened for Neisseria gonorrhoeae and Chlamydia trachomatis. There were 489 cases of cervical gonorrhoea, 261 serogroup WI and 228 serogroup WII/III. A total of 169 (34.6%) cases had a dual infection with C. trachomatis, 92 from the WI serogroup and 77 from the WII/III. Using Fisher's exact test, no statistically significant difference was observed in the rates of chlamydial carriage between the two serogroups (P = 0.39). These findings are at odds with previously reported data, which suggested a biological interaction resulting in a positive correlation between colonization with serogroup WI and C. trachomatis. Possible reasons for the difference between the findings are discussed.