Utility of Direct Fluorescent Antibody Test for detection of Chlamydia trachomatis and its detection in male patients with non gonococcal urethritis in New Delhi

Introduction

Sexually transmitted chlamydial infections are prevalent throughout the world.[1] A substantial number of them are undetected because asymptomatic cases account for 70-80% of women and upto 50% of men.[2] Sequelae such as pelvic inflammatory disease (PID), ectopic pregnancy, tubal infertility, epididymitis, proctitis and arthritis have been costing heavily on health care resources demanding an urgent need for early and accurate diagnosis of chlamydial infections.

Serological tests including enzyme immunoassay are not of much value in the diagnosis of C.trachomatis because of their low sensitivity and because a positive antibody test does not always distinguish past from current infection.[1],[3] Conventional diagnosis based on culture has always been technically demanding, relatively expensive and restricted to a few specialised centres.

Data pertaining to genital tract chlamydial infections in India is scanty. A prevalence of 41 was reported in patients presenting with vaginal discharge and in another study the chlamydial antigen was demonstrated in 37.4% women with PID.[4],[5] Prevalence of C. trachomatis in asymptomatic pregnant women was found to be 21.3% in an antenatal clinic in New Delhi.[6] As far as ascertained, no reports are available in male patients except for a single study,[7] despite the fact that urethritis is one of the most common and important clinical manifestations of C.trachomatis infection in males. Hence we studied the clinico-epidemiologic profile and utility of DFA in the diagnosis of urethritis due to C.trachomatis in symptomatic male patients with dysuria.

Materials and Methods

Male patients with complaints of urethral discharge, and dysuria, presenting to the STD clinic of a tertiary care hospital in New Delhi, were interrogated and examined.

After a minimum 4 hours of urine holding, the urethral smears were taken for Gram stain, wet mount for candida and trichomonas with the help of a sterile cotton swab stick. Cases positive for C. albicans, Tvaginalis, or N. gonorrhoeae were excluded and only those showing polymorphs in gram stained urethral smears were included in the study group of thirty patients. None of them had received antibiotics in the last 2 months. For DFA test urethral smears were obtained in all the patients with dacron swab and the slides were labelled, stored at -20°C and then stained, according to Syva MicroTrak DFA test booklet, within 7 days of collection of specimen. A cut off line off 10 elementary bodies was taken as a positive result.

Results

The youngest and oldest patient was 20 years and 55 years old respectively, with the peak incidence (70%) in the age group of 21-25 years.

50% of them were emplo-yed, 46.6% were unmarried and most of them were sexually promiscuous (76.6%) with heterosexual practices (96.6%). Female commercial sex workers were the commonest source of infection (46.6%) al-though 33.3% acquired the infection through marital contact. History of past gonococcal ure-thritis was present in 20% of the patients.

Burning micturition and urethral dis-charge were the commonest complaints [Table - 1]. Majority of them presented with mild (66.6%), clear (76.6%) and thin (96.6%) discharge. Gram stained urethral smears revealed 5-7 polymor-phs/HPF in most (90%) of the patients. DFA test was found positive in 11 cases (36.6%) with a cut off line off 10 elementary bodies.

Discussion

C. trachomatis is believed to be an important etiological agent responsible for sexually transmitted genital tract infections and represents one of the major areas of investigative interest in recent years.

The epidemiological profile of chlamydial urethritis studied in male patients in our series revealed that the peak age group of the patients is 21-25 years. This is in conformity with earlier studies.[8],[9] Holmes noted that those with NGU belong to higher socio-economic strata and are less likely to be unemployed.[10] This is further substantiated in the present study as the majority of our patients were employed. Lack of financial resources may account for lower incidence of NGU in unemployed persons and students.

The fact that most of our patients were unmarried (46.6%) and sexually promiscuous (76.6%) points out to the fact that NGU occurs more commonly in unmarried individuals having high risk sexual behaviour. A similar view was expressed by Tchoudomirova et al.[9] Female commercial sex workers constituted an important source of infection (46.67%) in our series. Poor sex education, low income and social structure contribute to prostitution, which in turn promotes sexually transmitted diseases including NGU. Coinfection of gonorrhoea and NGU was noted in 15-35% of heterosexual males by Stamm and 20% of our patients had past history of gonococcal urethritis which further emphasises the fact that mixed infections occur commonly in patients with STDs.[11] Several studies including the present series, noted that burning micturition (93.3%) and urethral discharge (86.6%) are the most common complaints in chlamydial urethritis.[9],[12] Martin and Bowie have observed scanty and mucoid discharge in most cases of NGU and similarly in many of our patients the nature of urethral discharge was mild (66.6%), clear (76.6%) and thin (96.6%).[12]

Apart from conventional culture techniques, several studies as listed in table-I have proved that DFA is an important test aiding the diagnosis of chlamydial urethritis infectian.[13],[14],[15] However, it involves staining of the elementary bodies in epithelial cell scrapings from infected sites and requires a trained microscopist. It is the only diagnostic test that permits simultaneous assessment of specimen adequacy by visualisation of cuboidal columnar epithelial cells.[2] It does not require the maintenance of a cold chain for specimen shipment and provides results faster than culture. Thirty-six percent of our cases were proved chlamydia-positive with DFA test which corroborates with the incidence of C. trachomatis infection in NGU patients.[12] Nair et al also observed that DFA test is positive in 43.8% of NGU male patients.[2] When 10 or more elementary bodies are seen in a background of reddish-brown counterstained cells, the test becomes quite specific, although some bacteria can bind immunoglobulins to their surfaces and appear fluorescent specially in rectal specimens.[16],[17] Judson et al suggested that the monoclonal antibodies used in the MicroTrak kit react less intensely with A, I and J serotypes of C.trachomatis.[18]

More specific tests like PCR and LCR have been evaluated to detect C.trachomatis infection. However, these tests are quite expensive, time consuming and not easily available Based on the data observed in several earlier studies including the present series, it is clear that DFA test is one of the most appropriate and cost effective screening test for chlamydia detection. The easy applicability and immediate results are the additional advantages.

It is evident that C. trachomatis is an important cause of non gonococcal urethritis in male patients. Although the participating centre is not necessarily representative of the entire nation, it does help us to focus that antichlamydial therapy should be recommended empirically in this group if facilities for its detection are unavailable.