Comparison of first void urine and urogenital swab specimens for detection of Mycoplasma genitalium and Chlamydia trachomatis by polymerase chain reaction in patients attending a sexually transmitted disease clinic.

Abstract

The objective of this study was to compare urogenital swab specimens and first void urine (FVU) specimens from male and female patients at a sexually transmitted disease clinic for the detection of Mycoplasma genitalium and Chlamydia trachomatis infections using in-house, inhibitor-controlled polymerase chain reaction (PCR). Urethral swabs and FVU were collected from 1856 men and 753 women who also had a cervical swab collected. A positive diagnosis of infection was made if any 1 of the specimens tested positive and were confirmed in a second PCR assay targeting independent genes. M. genitalium DNA and C. trachomatis DNA were detected in 126 (6.8%) and 246 (13.3%) of the male sample sets and in 51 (6.8%) and 73 (9.7%) of the female specimen sets, respectively. Using our in-house PCR and sample preparation methods, FVU was found to be the most sensitive diagnostic specimen for both pathogens, but for optimal sensitivity, it should be supplemented with a cervical specimen in women. In a small subset of female FVUs, storage at -20 degrees C led to false-negative M. genitalium PCR results in 27% of specimens found positive when a sample preparation was performed before freezing. The age-specific prevalence of M. genitalium in men was almost constant between 18 and 45 years of age in contrast to C. trachomatis infections, which were more common in younger men. Urine appeared to be a better diagnostic specimen than the urethral swab for M. genitalium and C. trachomatis detection by PCR in this cohort of sexually transmitted disease clinic attendees but should be supplemented with a cervical specimen in women.