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COMMENTS - HARPER ET AL - HPV ARTICLE
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Suzanne M. Garland, Melbourne, Australia Director, Microbiological Research, Royal Women's Hospital, Sepehr N. Tabrizi
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Harper et al., in a recent published prospective, longitudinal, randomised controlled trial, evaluated three techniques for self-sampling (two consecutive synthetic dacron swabs, single dacron swabs and tampon sample) by comparing to clinician directed ectocervical and endocervical samplings (1). They comprehensively evaluated potential variations in detection of HPV DNA (as determined by PCR) to factors such as menstrual cycle timing, recency of intercourse and time between samplings. As we described just over a decade ago, in comparison to physician collected endocervical scrape samples, tampons were an ideal specimen for HPV DNA detection, and unaffected by the quartile of the menstrual cycle (2-4). In the Harper et al. study, a single self-collected swab or tampon resulted in a significant reduction in detection of HPV DNA as compared to two consecutive self collected swabs or a physician collected endocervical and ectocervical swab. This is in sharp contrast to our findings where there was no difference between the tampon and clinician-collected specimens (2). Furthermore in evaluating the tampon for diagnosis of other sexually transmitted infections (STIs), we found the tampon to be more sensitive for detection (by polymerase chain reaction) of Neisseria gonorrhoeae and Trichomonas vaginalis, although for Chlamydia trachomatis, the sample type does not seem to matter significantly (5-9). Possible explanations for the difference in the performance of the tampon as a self-collected sampler in the above study as compared to our findings may lie in the preparation and processing of the tampon itself. Firstly, the tampon has a larger surface area than a regular swab and consequently collects more clinical material (2) which can become adherent to the absorbent material of the tampon. Optimal recovery of cells requires manual squeezing rather than vortexing or centrifugation. We note that Harper et al. place the tampons into PreservCyt (Thinprep) fluid, which fixes cells. In our experience once tampons are in this fluid, cells can be very difficult to retrieve (data not published). In addition, as we have demonstrated previously, extracting DNA is an important key step in detecting a particular pathogen’s DNA and in contrast to no extraction or a crude DNA lysis (6). The lack of detail in their methods does not allow one to determine how this step was performed (1). A comparison of the different tampon methods would be required to adequately address these differences in performance. Suzanne M. Garland & Sepehr N. Tabrizi References: 1. Harper DM, Longacre MR, Noll WW, et al. Factors affecting the detection of human papilloma virus. Ann Fam Med 2003;1(4):221-227 2. Fairley CK, Chen S, Tabrizi S, Quinn MA, McNeil JJ, Garland SM. Tampons: A novel patient-administered method for the assessment of genital human papillomavirus infection. J Infect Dis. 1992;165(6):1103-1106 3. Fairley CK, Chen S, Tabrizi SN, Quinn MA, Garland SM. Influence of quartile of the menstrual cycle on pellet volume of specimens from tampons and isolation of human papillomavirus. J Infect Dis. 1992;166(5):1199-1200 4. Fairley CK, Robinson PM, Chen S, Tabrizi SN, Garland SM. The detection of HPV DNA, the size of tampon specimens and the menstrual cycle. Genitourin Med. 1994;70(3):171-174 5. Tabrizi SN, Paterson B, Fairley CK, Bowden FJ, Garland SM. A self -administered technique for the detection of sexually transmitted diseases in remote communities. J Infect Dis. 1997;176(1):289-292 6. Knox J, Tabrizi SN, Miller P, Petoumenos K, Law M, Chen S, Garland SM. 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 Lving in Remote Areas. Sexually Transmitted Diseases Journal, 2002; 29:647-654. 7. Bowden FJ, Paterson BA, Tabrizi SN, Fairley CK, Garland SM. Using self-administered tampons to diagnose STDs. AIDS Patient Care & STDs. 1998;12(1):29-32 8. Tabrizi SN, Paterson BA, Fairley CK, Bowden FJ, Garland SM. Comparison of tampon and urine as self-administered methods of specimen collection in the detection of Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis in women. Int J STD AIDS. 1998;9(6):347-349 9. Sullivan E, Abel M, Koro K, Kaldor J, Kaun K, Grice A, Garland SM, Tabrizi S, Chen S, Poumerol G, O’Leary M, Taleo H. Prevalence of sexually transmitted infections among antenatal women in Vanuatu, 1999-2000. Sexually Transmitted Diseases 2003; 30(4): 362-366. Competing interests: None declared |
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Francisco Garcia, Tucson Arizona, USA Director Division of Gynecology, University of Arizona
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Dr. Harper and her team provide important insight into the practical limitations of potential self-sampling HPV-based strategies for cervical cancer and its precursors. Their finding that recent sexual intercourse or timing of the collection in relation to the menstrual cycle do not adversely affect the detection of HPV (potential False Positives)is particularly notable and has very practical implications for proposed self-sampling regimes in developing world settings. This important study addresses a very basic and often overlooked issue in this debate. Competing interests: None declared |
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