Comparative analysis of syndromic and PCR-based diagnostic assay reveals misdiagnosis/ overtreatment for trichomoniasis based on subjective judgment in symptomatic patients.

BACKGROUND

Trichomoniasis, a sexually transmitted disease (STD), is caused by Trichomonas vaginalis in both men and women. Screening of trichomoniasis is problematic in resource challenged settings as currently available, inexpensive diagnostic methods are of low sensitivity and/or specificity. In India, National AIDS Control organization (NACO) recommended syndromic case management (SCM) for treatment. The objective of the present study was to compare the utility of the NACO-NACP III Algorithms for STI/RTI treatment used by clinicians with PCR based diagnosis.

METHODS

Patients visiting Department of Obstetrics & Gynecology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi from January 2011 to June 2014 were enrolled in the study to compare the diagnostic efficiency of PCR-based assays against SCM. Based on SCM, patients (n = 820) were treated with antibiotics using pre-packed STI/RTI kits (sexually transmitted infection/reproductive tract infection; procured by National AIDS Control/State AIDS Control Society (NACO/SACS), Ministry of Health and Family Welfare, Govt of India.) under National AIDS Control Programme (NACP III) for syndromic case management (SCM). Ectocervical dry swab samples were also obtained from these patients and out of that 634 samples were tested by PCR. Total genomic DNA was extracted from these samples and used as template for PCR amplification using pfoB, gyrA and orf1 gene specific primers for diagnosis of T. vaginalis (TV), Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) respectively.

RESULTS

Out of 6000 patients who visited OPD, 820 (14 %) female patients reported vaginal discharge and were recommended antibiotic treatment for one or more pathogens namely, TV, CT, NG and Candida or for co-infection. On the basis of signs & symptoms and NACO guidelines, the following distribution of various infections was observed: TV (46 %), CT (20 %), coinfection with TV and CT (12 %), coinfection with CT and NG (11 %), coinfection with TV, CT and Candida (7 %) and coinfection with TV and NG (2 %). Others were infected with NG alone (1 %), coinfected with TV and Candida (0.4 %) and 0.3 % were coinfected with CT, NG and Candida. Based on PCR method, 110 (17 %) women tested positive for one or more of these three pathogens while 524 (83 %) women were negative for any of these three pathogens but could be positive for other STIs not tested in this study. Since all the patients (634) were given antibiotics, we estimate that the over-treatment was 85 % while 524 (83 %) patients were also misdiagnosed by SCM.

CONCLUSIONS

The over-treatment and inaccurate diagnosis of pathogens due to subjective judgment based on syndromic approach in symptomatic women is a large economic wastage and may also contribute towards increased resistance. The misdiagnosed patients will also serve as a reservoir for transmission of pathogens to their sexual partner.