Evaluation of self-collected samples in contrast to practitioner-collected samples for detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis by polymerase chain reaction among women living in remote areas.Sex Transm Dis. 2002 Nov; 29(11):647-54.ST
Self-collected samples have been shown to be an acceptable and sensitive method for the detection by polymerase chain reaction (PCR) of sexually transmitted infections (STIs) among women. GOAL The goal of the study was to compare self-collected sampling methods to conventional practitioner endocervical sampling for the PCR detection of Chlamydia trachomatis and Neisseria gonorrhoeae to compare two self-collected sampling methods for the detection of T vaginalis by PCR.
Women (n = 318) from urban and remote areas of central Australia participated in the study when attending their health clinic for a check-up. They each provided a FVU sample, self-collected vaginal swab specimen, and tampon specimen. This was followed by a clinical examination by a practitioner, with collection of endocervical and high vaginal swabs for testing by conventional microscopy and culture for N gonorrhoeae and T vaginalis, respectively. The FVU, self-collected vaginal swab, tampon, and endocervical swab specimens were tested by Roche Cobas Amplicor for C trachomatis and N gonorrhoeae. The self-collected vaginal swab and tampon specimens were also tested by an in-house PCR method for the detection of T vaginalis.
In toto, C trachomatis was detected by PCR in 11.5%, N gonorrhoeae in 11.8%, and T vaginalis in 24.6%. Molecular diagnostics for N gonorrhoeae and T vaginalis were significantly more sensitive than traditional assays with microscopy and culture. For the detection of C trachomatis by PCR, tampons were the most sensitive (100.0%) and urine the least sensitive (72.7%) specimens (= 0.01). For the detection of by PCR, the self-collected tampon was the most sensitive specimen, followed by the endocervical swab, self-collected swab, and urine specimen, with sensitivities of 97.2%, 92.6%, 71.9%, and 31.2%, respectively. For detection of N gonorrhoeae, statistically significant differences were detected for urine versus tampon (< 0.0001), endocervical swab (< 0.001), and self-collected swab (= 0.01) and for self-collected swab versus tampon (= 0.01). Subsequent data collection showed that sensitivity of urine PCR for detection of N gonorrhoeae improved with freezing of urine specimens and shorter transport time. Tampons were also more sensitive than self-collected swabs for detection of T vaginalis (sensitivity of 100% versus 87.7%).
Self-collected specimens offer women in remote communities an acceptable and sensitive alternative method of testing for STIs. The low sensitivity of N gonorrhoeae PCR of urine specimens may reflect poor transport and storage conditions, which we have shown can be improved by freezing urine specimens and reducing transport delays.