Background Sentinel STI surveillance with clinicians exists since 2000. STI within HIV patients triggered STI surveillance in ARC, specialised in care of HIV patients and patients at risk. No STI-HIV screening guidelines exist. STI is a driving force for HIV epidemics.

Methods STI surveillance registers STI episodes, including questions on HIV serology, HIV testing and risk behaviour. HIV testing circumstances are analysed in both networks.

Results In 2011, 744 STI patients were registered by the network of clinicians and 250 STI coinfected HIV patients by the ARC.

HIV testing circumstances are known for 95% of the STI patients from the clinicians network. 51% was tested during STI consultation, 19% were never tested, being postponed, refused or not proposed. The remaining 30% was tested previously of whom 49% was HIV negative and not retested.

Within the clinicians network, HIV serology was reported in 79% of the cases: 21% are HIV positive of whom 14% discovered their seropositivity at STI consultation.

Within the ARC, 7% of the coinfected HIV patients discovered their HIV positivity simultaneously with the STI diagnosis. Among STI patients in the ARC with at first negative/unknown HIV status, 57% was tested for STI-HIV simultaneously: 15% were found HIV positive. 11% of the seronegative STI patients were not retested. For the other 32% of the STI patients, their HIV status remains unknown.

Conclusions Surveillance of STI in both networks shows that HIV testing is not always performed during STI consultation, the HIV status may remain unknown and/or patients are not retested. Nevertheless, HIV positivity and STI are regularly found simultaneously.

Knowing the HIV status of STI patients and screening HIV patients for STI is important for reducing HIV-STI transmission. National STI-HIV screening guidelines should be developed and implemented.

Besides screening, condom use remains the most important preventive factor.