Mailed, home-obtained urine specimens: a reliable screening approach for detecting asymptomatic Chlamydia trachomatis infections

Abstract

The use of mailed, home-obtained urine specimens could facilitate screening programs for the detection of asymptomatic Chlamydia trachomatis infections. Since transport time could have an adverse effect on the sensitivity of C. trachomatis detection by PCR, the influence of DNA degradation on amplification was monitored over the course of 1 week. Therefore, urine specimens were aliquoted on the day of collection or arrival. Two groups of urine specimens were investigated. Group I contains first-void C. trachomatis-positive and -negative urine samples. DNA degradation was monitored in group I samples for 7 days at room temperature (RT) and at 4 degrees C by amplifying different lengths of the human beta-globin gene and the C. trachomatis plasmid target. DNA degradation was observed only for the larger human beta-globin fragments at days 5 to 7 at RT. In contrast, at 4 degrees C all targets could be amplified. Urine specimens were also frozen and thawed before aliquoting to mimic freezing during transport. This resulted in a lower sensitivity for the detection of C. trachomatis after thawing and 3 to 4 days at RT. In addition, mailed, home-obtained C. trachomatis-positive urine specimens (group II) were analyzed for 7 days after arrival by two commercially available C. trachomatis detection systems (PCR and ligase chain reaction [LCR]). The C. trachomatis plasmid target in mailed, home-obtained urine specimens could be amplified by both PCR and LCR after 1 week of storage and/or transport at RT. In conclusion, our findings indicate that mailed, home-obtained urine specimens are suitable for the sensitive detection of asymptomatic C. trachomatis infections by amplification methods, even if the transport time is up to 1 week at RT. These findings support the feasibility and validity of screening programs based on mailed, home-obtained urine specimens. Larger studies should be initiated to confirm our results.

FIG. 1

Monitoring of DNA degradation in urine specimens (group I) by PCR for 7 days. (1A and 1B) Results of PCR for the detection of the human β-globin gene in a urine specimen stored at room temperature and 4°C, respectively. (2A and 2B) Results of PCR for the detection of the C. trachomatis plasmid target in a C. trachomatis-positive urine specimen stored at room temperature and 4°C, respectively. (3A and 3B). Results of PCR for the detection of the C. trachomatis plasmid target in a C. trachomatis-positive urine specimen which was initially frozen and thawed and subsequently stored at room temperature and 4°C, respectively. The marker (lanes M) is pUC 19 HinfI. The different amplimer lengths are indicated with arrows.