Background:
Young women are at especially high risk for sexually transmitted infections (STI). Chlamydia trachomatis (C. trachomatis) is the most commonly diagnosed bacterial STI in this population.

Objective:
To determine patterns of repeat C. trachomatis infections after an initial diagnosis in a cohort of young women using multiple sources of data.

Method:
From 1998 – 2002, 411 adolescent women ages 14 to 19 years were recruited from 10 community-based health centers and followed for 23,318 person-months (average 4.7 years per person) using a variety of methods including urine-based screening for C. trachomatis infections, face-to-face interviews, medical record reviews, and a review of state health department reports of C. trachomatis infections. Repeat infections were defined as a diagnosis that occurred more than 30 days after an initial diagnosis.

Result:
The sample was an average 17.3 years of age, and 40% black and 36% Latina. A total of 216 (53%) participants were diagnosed with C. trachomatis during the study period, and 123 (30% of total sample and 57% of those with initial infections) were diagnosed with repeat C. trachomatis. Over half of all diagnoses made were repeat infections (53% = 241/456). The rate of repeat infections was 42.1 per 1,000 person-months. The median time to repeat infection was 5.2 months. Younger (age 14-16 years) and older adolescents (17-19 years) had similar frequencies of repeat infections.

Conclusion:
Repeat C. trachomatis infections comprise a substantial health burden in young women. Using multiple data sources, we found higher estimates than previously reported.

Implications:
Repeat C. trachomatis infections are of clinical and public health concern because of the link to pelvic inflammatory disease, chronic pelvic pain, and infertility. Treatment guidelines include a recommendation to advise all women with C. trachomatis infections to be re-screened 3-4 months after treatment; the results of this study underscore its importance.