The prevalence of Chlamydia trachomatis in a young sexually-active population.

A prospective study was conducted over the December 11 1985-May 29 1986 period to determine the prevalence of "Chlamydia trachomatis" among 1000 sexually-active women at Melbournes (Australia) Family Planning Association Clinic. An epidemiological and clinical history was recorded on a code sheet for study participants. Patients ages weights coitarches numbers of sexual partners during the last 12 months and lengths of association with their present partners were recorded along with current contraceptive usage and the results of the last Papanicolaou smear-test. Patients also were asked about the presence of any symptoms of sexually-transmitted disease (STD). The appearance of the cervix was ascertained on speculum examination. Cervical specimens were taken from all women for microbiological assessment. 995 patients completed the patient record form. In 994 of these women satisfactory swabs were taken for microbiological examination. The patients ranged in age from 15-50 years with a mean age of 25.4. The age at 1st intercourse (coitarche) ranged from 12-30 years and the number of sexual partners during the last 12 months from none to more than 10 partners. 573 (57.6%) women were using oral contraceptives (OCs) 141 (14.2%) no contraception 101 (10.2%) an IUD 118 (11.9%) a barrier method and the remainder a progestagen-only pill an injectable contraceptive agent sterilization or natural contraceptive methods. The previous cervical cytology was available for 775 (77.9%) women; 625 (80.6%) of these showed no abnormal cells. Of the 150 smear-tests that showed some abnormality only 10 tests demonstrated dysplastic lesions. The rest were indicative of infection or a benign abnormality. Of the 994 cervical swabs 51 (5.1%) swabs grew Chlamydia trachomatis. 42 swabs gave positive results of both immunofluorescence staining and culture; 9 swabs gave positive results of culture alone. An association between other factors and the presence or absence of Chlamydia was determined. When the ages of patients were compared patients whose swabs gave positive results for Chlamydia were significantly younger than those whose swabs gave negative results. The women whose swabs gave positive results for Chlamydia began intercourse at a significantly younger age. The prevalence of Chlamydia trachomatis in a young sexually-active population was 5.1%; the group with multiple partner was identified as being at high risk (9.3% positive results). In trying to identify women with an increased risk of carrying Chlamydia 5 factors appeared relevant: younger age at coitarche; a younger age; more than 1 sexual partner during the previous 12 months; symptoms of urethritis; and the presence of cervical ectopy.