Quantitative aspects of chlamydial infection of the cervix.

In 580 women with Chlamydia trachonmatis infection of the cervix, the degree of the infection was assessed by counting the number of chlamydial inclusions which developed in McCoy cell monolayers inoculated with cervical swab material under standardised conditions. In 34% of these women inclusion counts were <100 per monolayer whereas in 36% the counts were greater than or equal to 1000. Clinical features in each of these groups were compared to see if certain factors could be identified as the cause, or the result, of high-grade rather than low-grade infection. A significant association was found between high inclusion counts and the presence of cervical mucopus or cervical ectopy. Oral contraceptives acted additively with ectopy but had no significant effect alone. Concurrent gonorrhoea did not affect the degree of chlamydial infection. High inclusion counts were more common in women under 20 years of age than in older women.