Evaluation of clinical algorithms for the diagnosis of gonococcal and chlamydial infections among men with urethral discharge or dysuria and women with vaginal discharge in Benin.

OBJECTIVE: To evaluate the validity of clinical algorithms proposed in Benin for the diagnosis of gonococcal or chlamydial infections among men with urethral discharge or dysuria and women with vaginal discharge consulting health services in Benin. These algorithms were adapted from those proposed by the World Health Organisation. METHODS: Consecutive patients with these symptoms were enrolled at three primary healthcare centres. The reference test for gonorrhoea was a combination of results from culture and polymerase chain reaction and chlamydial infection was ascertained by enzyme linked immunosorbent assay and PCR. In women, two algorithms were evaluated, one based on symptoms and risk assessment (algorithm A), the other relying also on speculum examination (algorithm B). The first algorithm evaluated in men relied on clinical examination only (algorithm C) whereas the other used microscopic examination of urethral smears (algorithm D). Sensitivity, specificity, and positive and negative predictive values of these algorithms were assessed using standard methods. RESULTS: In 192 women, the prevalence of gonococcal and chlamydial infections was 5.7% and 2.1% respectively (combined prevalence of 7.8%). The sensitivity, specificity, positive and negative predictive values of algorithm A (algorithm B) were respectively 86.7% (93.3%), 41.8% (34.5%), 11.2% (10.8%), and 97.4% (98.4%). In 105 men, the corresponding prevalences were 39.0% and 7.6% respectively (for a combined prevalence of 44.8%). The sensitivity, specificity, positive and negative predictive values of algorithm C (algorithm D) were respectively 91.5% (87.2%), 60.3% (67.2%), 65.2% (68.3%), and 89.7% (86.7%). CONCLUSION: A syndromic approach for the diagnosis of urethritis in men appears appropriate. In women, the diagnosis of gonococcal or chlamydial infection without specific laboratory tests, which are not easily affordable in developing countries, remains highly problematic.

Evaluation of a screening algorithm for the diagnosis of genital infections with Neisseria gonorrhoeae and Chlamydia trachomatis among female sexworkers in Bénin.

BACKGROUND AND OBJECTIVES: In developing countries, simple and cheap procedures for the diagnosis of sexually transmitted diseases (STDs) are urgently needed, especially for screening purposes in high risk groups. GOALS: To evaluate the sensitivity and specificity of a screening algorithm for STDs among 364 female sex workers in Bénin, in comparison with reference laboratory tests. STUDY DESIGN: The algorithm relied on the following criteria, which were evaluated in sequence: the presence of endocervical mucopus on visual inspection of the cervix, a positive swab test, or a microscopic examination of vaginal fluid showing more than 10 polymorphonuclear cells per field. The algorithm diagnosed an infection if any one of these criteria was fulfilled. True infectious status was determined by the combined results of culture for Neisseria gonorrhoeae, enzyme immunoassay for Chlamydia trachomatis, and polymerase chain reaction assays for both infections. RESULTS: Gonococcal or chlamydial infection was diagnosed in 39.8% of the study population according to the reference tests. The algorithm had a sensitivity of 57.9% and a specificity of 61.2%. In the presence of Candida sp or Trichomonas vaginalis, specificity decreased to 39.1%, but sensitivity increased to 67.5%. CONCLUSIONS: These results underscore the limitations of simple, nonlaboratory diagnostic tools for screening STDs in high-risk groups in developing countries. Further research is needed to increase the validity--especially the sensitivity--of these algorithms.