BRISBANE, AUSTRALIA – Self-collected penile-meatal swabs perform as well as urethral swabs for the detection of chlamydia, gonorrhea, trichomoniasis, and Mycoplasma genitalium, but are more acceptable to men, according to a case-control study.
Findings presented at the World STI & HIV Congress 2015 showed there were no statistically significant differences in accuracy between the self-collected penile swabs and clinician-collected urethral swabs in nucleic acid amplification testing (NAAT).
Dr. Charlotte A. Gaydos
The study enrolled 203 men attending an STI clinic in Baltimore, who were undergoing urethral swabs and who were then invited to perform their own penile swab.
The swabs were placed in separate transport medium and were tested separately with NAAT for four organisms: Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium.
• For Chlamydia trachomatis, the self-collected penile swab showed a sensitivity of 96.8% and specificity of 98.8%, with no statistically significant difference from urethral swabs (P = .625).
• For Neisseria gonorrhoeae, the penile swab had a sensitivity of 100% and specificity of 98.9%, with no statistically significant difference from urethral swabs (P = .248).
• For Trichomonas vaginalis, the sensitivity was 85% and specificity was 96.8%, with no statistically significant difference from urethral swabs (P = .344).
• For Mycoplasma genitalium the sensitivity was 79.3% and specificity was 99.4%, with no statistically significant difference from urethral swabs (P = .70).
Charlotte A. Gaydos, Dr.P.H., director of the Johns Hopkins Center for the Development of Point of Care Tests for Sexually Transmitted Diseases in Baltimore, said that despite the men’s initial concerns about undergoing another swab after the discomfort of the urethral swab, all of them preferred the self-collected penile swab.
“We think that in the future such self-collected penile swabs could expedite express visits, for example, in an STD clinic,” Dr. Gaydos said. “The swab also shows promise as being one swab type that could be tested for four different STIs.”
An audience member raised the possibility that the penile swab specimen could have been inadvertently contaminated with biological material brought up from the prior urethral swab. Dr. Gaydos acknowledged the lack of randomization in terms of the timing of each swab could have affected the results.
She also pointed out that the study was done in largely symptomatic rather than asymptomatic men, and a trial is needed to address the randomization issue and also to explore the approach in asymptomatic men.
“We do feel that we are with the penile swab where we were 10 years ago with the self-collected vaginal swab,” Dr. Gaydos said in an interview. “We hope it will generate more interest in the self-collected penile swab, because the urethral is painful.”
Dr. Gaydos reported research funding and lectureships with Becton Dickinson, Gen-Probe/Hologic, Abbott Molecular Diagnostics, Siemens Healthcare Diagnostics, Sekisui, and Cepheid.