THE LABORATORY DIAGNOSIS OF MALE CHLAMYDIA-TRACHOMATIS INFECTIONS - A TIME FOR CHANGE

We carried out a two-phased study comparing the effectiveness of first-catch early morning urine (FCU) samples against urethral swabs for the detection of C. trachomatis in men. Four hundred and seventeen new and re-booked consecutive men, who attended the Department of Genito-Urinary Medicine, Bristol, having held their urine overnight, were recruited. Patients who had received antimicrobial chemotherapy in the preceding 2 months were excluded. Early morning FCU samples were obtained from 208 men followed by urethral swabs for the detection of C. trachomatis (phase 1) and this order of collection was reversed for the remaining 209 patients (phase 2). A last-catch urine (LCU) was also obtained from all patients. All urethral and urine samples were examined by an amplified enzyme immunoassay (IDEIA, Dako Diagnostics Ltd). Initially, discordant samples were critically examined by direct immunofluorescence (Syva, 'Microtrak') which was used as the 'gold' standard in this study. We have shown that overall 42 and 4·7% of our symptomatic and asymptomatic male patients respectively were positive for C. trachomatis antigen by IDEIA. Furthermore 86·4 and 91·0% (phases 1 and 2) of the total C. trachomatis positive samples were detected by examination of an FCU sample. In contrast only 66·0 and 65·5 % (phases 1 and 2) of the total positives were identified by examination of an urethral swab. These results show that an FCU sample not only has the advantage of being a non-invasive procedure but is also a very sensitive method, compared to swabbing the urethra for the detection of C. trachomatis. This study also demonstrates that flushing of the urethra on voiding, although resulting in a significant number of false-negative LCU urine samples, does not appear to affect the detection of C. trachomatis from urethral swabs. © 1992 The British Society for the Study of Infection.