Nucleic acid amplification tests, such as PCR and LCR, are increasingly being utilized for diagnosis of many infections and will likely be considered the standard for diagnosis of STDs in the future. Chlamydial, gonorrhea, and HIV diagnostic tests from one or more manufacturers are currently approved by the Food and Drug Administration. Prototype tests for the diagnosis of syphilis, genital herpes, human papillomavirus, trichomonas, and most other sexually transmitted pathogens are in various stages of development. Because these assays amplify genetic material from infectious organisms, their specificity can approach 100 percent if the proper genetic sequences are selected for the test; their sensitivity is a function of the amplification process. In certain situations, such as when tests are performed soon after therapy, false positive results may be a problem. Nucleic acid amplification tests have been as sensitive as culture for several STDs, and the detection of some pathogens such as chlamydial and herpes virus has been improved by these tests. The causative pathogens of human papillomavirus and syphilis cannot be cultured but can be detected using these sensitive techniques. In addition, the sensitivity of these tests has enabled clinicians to use more easily collected specimens for diagnosis, such as simple urine and vaginal swabs, rather than specimens obtained by more invasive sampling techniques. Lastly, the tests are not dependent on the presence of viable organisms in the specimen; therefore, handling and transport of specimens are relatively easy.
The diagnosis of an STD should lead to either curative and/or preventive therapy for the infected individual. Although ideal therapy does not exist for many infections, highly effective antimicrobial therapy is available for all bacterial STDs as well as those caused by protozoa and ectoparasites (CDC, 1993a). They are administered to eradicate infection and to prevent its complications. In contrast, drugs for viral STDs have largely been limited to alleviating symptoms because they cannot eradicate the organism. However, many viral STDs (e.g., HIV infection, genital herpes, hepatitis B virus infection) are increasingly being viewed as suppressible infections with new therapies. These treatments suppress viral replication and thereby reduce transmission and may be considered to be a viable approach for preventing STDs.
Utilization of antimicrobial drugs is guided by both syndromic and etiologic diagnoses. The STD Treatment Guidelines published by the CDC provide the current standards for therapy of STDs (CDC, 1993a). A significant barrier to appropriate treatment is failure to comply with a full course of medication. To address this problem, effective single-dose therapy for several STDs (e.g., chancroid, gonorrhea, syphilis, trichomoniasis) has been available for some time, and single-does therapy for chlamydial infection has recently become available. These single-dose regimens have been shown to be as effective as multiple-dose regimens