Which laboratory tests are essential for the diagnosis of STIs in a primary care setting?

In a primary care setting, essential laboratory tests for the diagnosis of sexually transmitted infections (STIs) include:

• Chlamydia and Gonorrhoea testing: Nucleic acid amplification tests (NAATs) on urine samples or swabs from relevant sites (genital, rectal, or throat) are standard for detecting these infections ¹,².
• Syphilis testing: A full syphilis screen usually involves a combination of treponemal tests (such as enzyme immunoassay [EIA] or chemiluminescent assay [CLIA]) and non-treponemal tests (such as rapid plasma reagin [RPR] or Venereal Disease Research Laboratory [VDRL] test) to confirm diagnosis and stage the disease ¹.
• Herpes simplex virus (HSV) testing: Virology swabs from active lesions (genital, extragenital, or oral) for PCR testing are recommended if lesions are present to exclude herpes simplex infection ¹.
• Hepatitis B and C testing: Serological tests for hepatitis B surface antigen and hepatitis C antibody, with reflex PCR testing for hepatitis C RNA if antibody positive, are essential for people at risk ³.
• HIV testing: HIV antibody/antigen combination tests are recommended, with rapid or laboratory-based assays available; testing should be offered routinely to those at risk ⁴.

Offering a full sexual health screen including HIV testing alongside syphilis and other STI tests is recommended because individuals at risk for one STI are often at risk for others ¹,².