Time from Treatment to Re-infection with Chlamydia trachomatis or Neisseria gonorrhoeae in Patients with and without Co-infection

Background:
C.trachomatis (CT) and N.gonorrhoeae (GC) infections are increasing in many populations in the U.S. despite active STI control efforts. Data from Canadian public health efforts suggest a significant proportion of CT infections are re-infections in the same individuals. Understanding factors that may increase risk of re-infection is critical to development of effective control strategies.

Objective:
To describe rates of CT and GC re-infection in clients co-infected compared to those with single infections.

Method:
Data from June 2005 were used to identify a cohort of individuals infected with CT and/or GC reported from STD*MIS database in Central Indiana. Kaplan-Meier estimates of time to re-infection were compared for those with & without co-infection (á=.05).

Result:
627 & 303 clients were diagnosed with CT &/or GC, respectively. 114 clients were infected with both organisms (CT-18.1% & GC- 37.6%). Mean time to re-infection for
CT-clients originally co-infected or CT only: 241 days(± 47.1) and 302 days (± 19.3). Mean time to re-infection for
GC-clients originally co-infected or GC only: 285 days
(± 51.9) and 273 days (± 32.8). Of the 513 and 189 persons infected with CT or GC only, 65 (12.7%) and 27 (14.3%) were re-infected within 1 year. Of the 114 co-infected, 13 (11.4%) were re-infected within 1 year. These differences were not statistically significant. Cox regression analysis with covariants did not reveal additional significant factors.

Conclusion:
Infection with both CT and GC is common: >1/3 of those with GC also have CT. However, co-infection w/CT & GC does not appear to decrease time to re-infection in this cohort.

Implications:
Although understanding re-infection is critical to care & management of STIs, analysis of co-infection does not appear to provide clinicians with additional information regarding future risk. Further analysis of an expanded cohort related to infections beyond first re-infection will be performed to verify findings.