of asymptomatic persons in the context of screening. Unfortunately, many clinicians fail to appreciate that no single laboratory test is optimal for use in all settings.

"Syndromic diagnosis," which utilizes the patient's history, results of physical examination, and rapid laboratory tests, can be utilized for the diagnosis of clinical syndromes. This allows appropriate treatment for infected individuals in a single visit. This approach is relatively inexpensive when compared to conducting specific laboratory testing. Unfortunately, syndromic diagnosis is not always specific even though, for many of the syndromes, only one or two STD pathogens are usually the cause. The major curable STD syndromes in adults include urethritis in males; vaginal discharge, cervicitis, and pelvic inflammatory disease in women; and genital ulcers in both men and women. In clinical practice in the United States, it is common to initiate syndromic treatment for urethritis in men and cervicitis and pelvic inflammatory disease in women (while results of laboratory testing are pending), using treatments effective against all of the common bacteria that can cause these syndromes. For genital ulcers and vaginal discharge, it is more common to perform rapid tests before initiating treatment. Since syndromic treatment, by definition, is used only for persons with symptoms or signs of a clinical syndrome, this approach is not useful in detecting mild or asymptomatic infection. It should also be noted that, like any diagnostic test, the predictive value and therefore diagnostic utility of syndromic diagnosis will vary with the prevalence of the disease being tested for in the population. In low-prevalence populations, construing all cervicitis or urethritis to represent an STD may result in a large number of false positive diagnoses, unnecessary treatment, and potential psychological distress.

Laboratory testing for specific causative infectious agents is necessary for the detection of minimally symptomatic and asymptomatic individuals. There are STDs, such as gonorrhea, for which the antimicrobial resistance patterns of the pathogen are important. The isolation of the pathogen permits a determination of sensitivity or resistance to appropriate antibiotics. In addition, laboratory isolation of the pathogen allows specific testing for epidemiological purposes to track the spread of infection in a population. Although analyses of antimicrobial resistance patterns for STDs are seldom used to guide individual treatment, they are essential to develop community-based treatment guidelines. Unfortunately, some specific laboratory tests are often not available at clinical sites other than dedicated STD clinics and, even when available, the test results are often not available during the initial patient visit. In addition, the expense of these tests may limit their availability and utility.

Specific laboratory tests often guide therapeutic decisions. Ideally, the test could distinguish between past and present infection. The adequacy of specimens collected and specimen transport conditions are important modifiers of test performance. For example, there may be nonpathogenic microorganisms present in some of the sites being sampled, and specimens must be managed to preserve the

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