Repeated Chlamydia trachomatis genital infections in adolescent women

Abstract

Background: Repeated Chlamydia trachomatis infections are common among young sexually active women. The relative frequency of reinfection and antibiotic treatment failure is undefined.

Methods: Adolescent women enrolled in a longitudinal cohort had behavioral and sexually transmitted infection assessments performed every 3 months, including amplification tests for C. trachomatis, ompA genotyping, and interviews and diary entries to document sex partner-specific coitus and event-specific condom use. Repeated infections were classified as reinfection or treatment failure by use of an algorithm. All infections for which treatment outcomes were known were used to estimate the effectiveness of antibiotic use.

Results: We observed 478 episodes of infection among 210 study participants; 176 women remained uninfected. The incidence rate was 34 episodes/100 woman-years. Of the women who were infected, 121 experienced 1 repeated infections, forming 268 episode pairs; 183 pairs had complete data available and were classified using the algorithm. Of the repeated infections, 84.2% were definite, probable, or possible reinfections; 13.7% were probable or possible treatment failures; and 2.2% persisted without documented treatment. For 318 evaluable infections, we estimated 92.2% effectiveness of antibiotic use.

Conclusions: Most repeated chlamydial infections in this high-incidence cohort were reinfections, but repeated infections resulting from treatment failures occurred as well. Our results have implications for male screening and partner notification programs and suggest the need for improved antibiotic therapies.

Figure 1. Examples of infection episodes

Q=quarterly visits; W=weekly home visits for sample collections; empty boxes=chlamydia test negative; hatched boxes=chlamydia test positive; letters in boxes=genotype; missing boxes=missing weekly samples; inverted triangles=azithromycin treatment; hearts=unprotected coitus. Brackets above each example encompass an infection episode. A. Incident infection defined by ≥3 weekly tests in the absence of a positive quarterly test, apparent spontaneous resolution but treated at subsequent quarterly visit; B. Infection detected at a quarterly visit and 1^st weekly collection with treatment and clearance; C. infection detected at a quarterly visit with delayed treatment but then prompt clearance; D. A symptomatic incident infection emerging in weekly collection period and treated at the subsequent quarterly clinic visit; E. Infection detected at quarterly visit, treatment within 2 weeks and clearance; then subsequent unprotected coitus with untreated partner infected with same genotype resulting in repeat incident infection; then treatment of participant and partner with clearance.

Figure 2. Repeat infection classification algorithm

^aThree paired episodes were not classified because each involved mixed infections that could not be resolved into same/different: F → F/Ja; D/Ja → D2; D → D/F ^bThree episode pairs with all coitus reported as condom protected were separated by multiple negative chlamydia tests, making treatment failure less likely: 1 quarterly and 9 weekly tests over 6.7months; 5 quarterly and 19 weekly tests over 17.9 months and 4 quarterly and 32 weekly tests over 13.2 months.