Quantitative culture of endocervical Chlamydia trachomatis

Abstract

We examined the number of Chlamydia trachomatis inclusions produced in the initial passage of cell cultures of endocervical specimens from 1,231 women with positive chlamydial cultures who attended a sexually transmitted diseases clinic. Youth, white race, oral contraceptive use, and concurrent infection by Neisseria gonorrhoeae were associated with high chlamydial inclusion counts. Youth, white race, and oral contraceptive use were independent determinants of a high chlamydial inclusion count in women without concurrent gonorrhea but not in women with gonorrhea. Results of our study suggest that the degree of chlamydial excretion from the infected cervix may be influenced by characteristics of the patient being tested and may affect the ability to detect C. trachomatis in different patient groups.

PIP: The relationships between selected epidemiological variables and the number of organisms detected in 1st passage in cell culture of specimens obtained from patients at an Indiana sexually transmitted disease clinic who were infected with Chlamydia trachomatis was investigated. Endocervical C trachomatis was detected in the initial passage of cell culture in 1300 (25%) of the 5276 eligible women. 599 (46%) of these infected women were also infected with Neisseria gonorrhoeae. 1769 (34%) were oral contraceptive (OC) users and 780 (60%) were black. Inclusion count data were obtained for only 1231 chlamydia-infected women given the need to exclude pregnant women and IUD users. The inclusion count distribution was as follows: less than or equal to 100 IFU/ml, 25%; 101-1000 IFU/ml, 40%; 1001-10,000 IFU/ml, 21%; and over 10,000 IFU/ml, 14%. Multivariate analysis of these counts identified young age (under 20 years), current OC use, and concurrent gonorrhea as the most significant risk factors for endocervical C trachomatis. The cervical signs of ectopy, mucopus, and friability were also associated with chlamydial infection. Among women with gonorrhea, only concurrent trichomoniasis was associated with the inclusion count. A history of prior sexually transmitted diseases or the presence of concurrent infection with trichomoniasis were associated with lower inclusion counts. Since the degree of detectability of chlamydial excretion may be affected by certain patient characteristics such as those identified in this study, possible bias in chlamydial detection tests must be considered.