Discussion
The strategy of presumptive antibiotic treatment for chlamydia and gonorrhea of all patients at high risk for infection who are unlikely to return for a follow-up evaluation was recommended by the CDC and implemented by the PBCHD. In a study comparing positive cultures and the likelihood of receiving treatment for gonorrhea and chlamydia infection, 20% of patients with positive screening cultures for either infection did not return to the clinic for treatment within 30 days of initial presentation. Among those who did return, 30% did so more than 2 weeks after their initial visit. This strategy was developed at least in part because of the lack of availability of a rapid and accurate test. In addition, the nonspecific clinical findings and frequently asymptomatic nature of these diseases contribute to inaccuracies in clinical judgment about which patients to treat.
These circumstances have led to undertreatment of those who require treatment and overtreatment of those who do not require treatment. Several retrospective studies have addressed the issue of rates of positive results among those not given presumptive antibiotic treatment on the day of the initial visit. To the best of our knowledge, however, data are sparse concerning empirical antibiotic treatment for suspected infections in the absence of laboratory-proven disease. In a study conducted in an emergency department setting, 88.3% of women initially treated for one or both diseases had negative results, whereas 38.3% of patients with a positive test result were untreated on their initial visit. Levitt et al suggested the possibility of not testing those given antibiotic treatment and redirecting the expenses for testing to clinical settings where women would be more likely to be asymptomatic.
The limitation of this approach would be that without chlamydia testing, there would be no surveillance data to evaluate trends in prevalence and no recommendation to treat contacts if the index case was positive. In contrast, our study was conducted at an outpatient local health department clinic, where patients present as part of a contact investigation for the treatment of symptoms or for testing because of high-risk behaviors. Another study evaluated empiric treatment for chlamydia in an urban safety net primary care clinic. Among the patients with symptoms of an STI, 37% tested positive, whereas 9.3% of those tested had a positive culture result and never received treatment. These patients were medically underserved; however, the study used a regular primary care site as opposed to a public health unit for high-risk patients dedicated to the management of STIs. In a study conducted in an emergency department, patients were presumptively treated based on clinical findings suggesting cervicitis or pelvic inflammatory disease. Only 1.8% and 9.3% of those treated for cervicitis and 4.4% and 10% of those treated for pelvic inflammatory disease had positive cultures for Neisseria gonorrhea and C. trachomatis, respectively. It has also been suggested that treating patients with negative results with antibiotics can create unnecessary emotional trauma secondary to the social stigmas of STIs, especially for someone who needs to inform his or her partner of that treatment was received. Patients with negative test results from the Riviera Beach STD Clinic were not contacted and were told about their negative test results only if they opted to return for follow-up. (Those with positive results are automatically located by PBCHD staff for partner elicitation and follow-up services.)
Presumptive antibiotic treatment of patients with negative results raises issues of antibiotic resistance, adverse effects, and drug costs. If treatment is a one-time occurrence for a presumed infection, it seems unlikely that a single dose will lead to antibiotic resistance. Patients who present multiple times for testing or treatment at the PBCHD may receive antibiotic treatment numerous times per year. Such circumstances may have contributed to antimicrobial resistance of endogenous microbial flora to these antibiotics. Such concerns about possible overuse of antibiotics, however, must be weighed against the likelihood that without same-day treatment, infected patients will continue to transmit disease. The increased rates of transmission and morbidities of patients who are positive and lost to follow up if antibiotic treatment is withheld seem to far outweigh the issues of adverse effects and drug costs. This is especially important because >30% of the patients treated had positive pretreatment culture results; as such, presumptive antibiotic treatment prevented both their individual complications and further transmission to subsequent sexual contacts.
These results should be viewed in the context of the quality of the test used for diagnosing these diseases and the specimen-collecting technique of the healthcare provider. The chlamydia and gonorrhea NAAT uses a polymerase chain reaction–amplified test from genital swabs, the sensitivity of which is 90% to 95% and the specificity is 98% to 100%. Such results can be available within 24 to 48 hours. Because of this time delay, there is a clear need for rapid and simple point-of-care diagnostic testing, with results available within 20 minutes while patients are still at the clinic. The availability of such a test would allow rapid and effective treatment of asymptomatic patients with positive results, which would reduce prevalence and complications of chlamydia and gonorrhea and may even reduce the incidence of human immunodeficiency virus infection. During the time that these data were collected, available rapid tests were considered to have sensitivities that were too low to be recommended in universal screening programs. Nonetheless, the performance of the new point-of-care chlamydia rapid test developed at the Diagnostic Development Unit of the University of Cambridge suggests that it would be an effective, same-day diagnostic and screening tool for chlamydia infection in women.
One major strength of this study is the large sample size, which provides stable estimates of the percentages of negative tests among patients who were given antibiotic treatment. One major limitation is the lack of an appropriate comparison group and, as a consequence, a lack of information about provider treatment rationale in deciding whether to treat. Thus, we were unable to evaluate the overall number tested within this time period or the subpopulation tested but not given treatment. In addition, there may be false-negative laboratory results because of provider collection techniques, test specificity, or from infections caused by other organisms. Testing was provided only for chlamydia and gonorrhea and there are other common infections that can cause urogenital infection that could have been missed, such as bacterial vaginosis or trichomonas. Finally, these findings may be limited in their generalizability to other racial/ethnic groups, although this may reflect the race/ethnicity frequencies of attendees at STI clinics. In addition, Gram stain microscopy or other means of diagnosing urethritis were not conducted; as such, these findings cannot be generalized to clinics conducting these tests.
Despite these and other possible limitations, we believe the most plausible interpretation of this dataset to be that implementation by the STD Clinic of the PBCHD of the CDC guidelines results in antibiotic treatment of approximately two-thirds of patients with negative NAAT results for chlamydia, gonorrhea, or both diseases. Our study failed to identify any demographic or clinical factors, such as the presence of self-reported symptoms, which could be used to better target treatment of particular subgroups that would benefit most from antibiotic treatment. Further research is necessary and should include analytical studies designed a priori to test various hypotheses formulated from these data. These findings suggest the need to develop strategies to maximize treatment of patients with positive test results and minimize the exposure to antibiotics of patients with negative test results. One possible option is to explore the clinical and public health utility of newer testing and treatment methodologies in development.