Background: Perinatal diagnostic screening with molecular-based tests and treatment of Chlamydia trachomatis (CT), Neisseria gonorrhoea (NG) and Trichomonas vaginalis (TV) is an important strategy for reducing their associated morbidity and negative sequelae. We conducted an analysis to determine postnatal prevalence and perinatal incidence of CT, NG, and TV, and their associated factors among HIV-infected pregnant women in South Africa. Methods: Our cohort consisted of HIV-infected women accessing antenatal care in three public-sector clinics. Women who presented for their first antenatal care (ANC) visit were screened for urogenital CT, NG and TV infection using the Xpert® assay (intervention group). Those presenting for a later ANC visit were managed for STIs syndromically (control group). Intervention group participants were given definitive treatment based on the Xpert® result and underwent multiple rounds of test-of-cure at 21-day intervals until their infection was cleared or they had a birth outcome. Both intervention and control group participants were screened for CT, NG, and TV infection with Xpert® during the first postnatal visit. Results: Six hundred and forty participants were tested for CT, NG, and TV postnatally (331 intervention and 309 control). Overall prevalence of CT, NG, and TV was 15.5%; control group women had significantly higher STI prevalence (20.4%, 95%CI: 16.3%-25.3%, p-value=0.001) than intervention group women (10.9%, 95%CI: 7.9%-14.7%). STI incidence among intervention group participants who tested negative at baseline was 15.3/100 person-years (95%CI: 9.4-24.9) and 24.8/100 person-years (13.3-46.1) among intervention group participants who cleared their STI before delivery. Antenatal diagnostic screening was associated with reduced CT-infection (aOR=0.42, 95% CI: 0.21-0.83) and TV-infection (aOR=0.17, 95%CI: 0.05-0.65) postnatally. Conclusion: Our results suggest that diagnostic testing and treatment of STIs during pregnancy may reduce the prevalence of STIs during pregnancy. Carefully planned randomised trials are needed to assess the effect of different STI screening modalities on morbidity during pregnancy.

03 / POSTNATAL PREVALENCE AND INCIDENCE OF CHLAMYDIA TRACHOMATIS, NEISSERIA GONORRHOEA AND TRICHOMONAS VAGINALIS AND FACTORS ASSOCIATED WITH INFECTION AQUISITION AMONG HIV-INFECTED PREGNANT WOMEN IN SOUTH AFRICA