Chlamydia trachomatis load in population-based screening and STI-clinics: implications for screening policy

Area of Science:

• Infectious Diseases
• Microbiology
• Public Health

Background:

• Chlamydia trachomatis (CT) screening efficacy may be impacted by bacterial load differences between high-risk and general populations.
• Investigating CT bacterial load is crucial for understanding transmission dynamics and optimizing screening strategies.

Purpose of the Study:

• To compare the Chlamydia trachomatis (CT) bacterial load in high-risk individuals attending sexually transmitted infection (STI) clinics versus participants in population-based screening (PBS).
• To determine if higher CT bacterial loads in high-risk populations affect screening incentive efficacy.

Main Methods:

• Quantitative PCR was used to determine CT load in urine (men) and cervicovaginal swabs (women) from CT-positive individuals.
• Data from 889 CT-positive individuals (529 from PBS, 360 from STI clinics) were analyzed.
• Multinomial logistic regression assessed associations between cohort, symptoms, risk behavior, and human cell count with CT load.

Main Results:

• Both STI clinic attendees and PBS participants exhibited a similar range of CT bacterial loads.
• In men, STI clinic attendance, higher cell counts, and urethral discharge were associated with higher CT loads.
• In women, PBS participation and higher cell counts were associated with higher CT loads.

Conclusions:

• The bacterial load range of Chlamydia trachomatis is comparable between the general population and high-risk groups.
• Differences in CT load distribution by cohort and gender underscore the importance of population-based screening.
• Similar CT loads suggest comparable transmission and sequelae risks across populations.