A novel gel-based method for self-collection and ambient temperature postal transport of urine for PCR detection of Chlamydia trachomatis S Bialasiewicz, 1 D M Whiley, 1 M Buhrer-Skinner, 3,4 C Bautista, 2 K Barker, 5 S Aitken, 5 R Gordon, 4 R Muller, 3 S B Lambert, 1 J Debattista, 6 M D Nissen, 1,2 T P Sloots 1,2 1 Queensland Paediatric Infectious Diseases Laboratory, Sir Albert Sakzewski Virus Research Centre, Royal Children’s Hospital and Health Service District, The University of Queensland, Clinical Medical Virology Centre, Queensland, Australia; 2 Microbiology Division, Queensland Health Pathology Service, Royal Brisbane Hospital Campus, Queensland, Australia; 3 Anton Breinl Centre for Public Health and Tropical Medicine, Townsville, Queensland, Australia; 4 Institute of Primary Health and Ambulatory Care, Townsville, Queensland, Australia; 5 Gold Coast Sexual Health Service, Miami, Queensland, Australia; 6 Sexual Health and HIV Service, Northside Health Service District, Queensland, Australia Correspondence to: Seweryn Bialasiewicz, Sir Albert Sakzewski Virus Research Centre, Building C28, Back Road, Herston, QLD 4029, Australia; seweryn@uq.edu.au Accepted 18 October 2008 Published Online First 12 November 2008 ABSTRACT Objectives: The aim of this study was to develop a novel urine transport method to be used in self-collection-based screening for Chlamydia trachomatis. The method needed to be suitable for C trachomatis PCR detection, be economical and suitable for transport by standard envelope mailing. Methods: An anhydrous gel composed of super- absorbent polymer and buffering agent was used to desiccate urine into a dry granulous state, which could subsequently be reconstituted upon arrival at a laboratory. DNA was then extracted from the reconstituted solution using the Roche MagNA Pure protocol for the detection of C trachomatis by PCR. Collections of urine specimens from three populations with widely differing chlamydia pre- valence (100%,n = 56; 47%, n = 70; 3%, n = 97) were used. We determined the gel method’s impact on C trachomatis PCR sensitivity and specificity using neat and gel-processed urine specimens. An equine herpes virus PCR was used to test for assay inhibition. Results: Overall, the sensitivity of the gel-based method ranged from 94.6–100% compared with neat urine, with a specificity of 100%. No PCR inhibition or decrease in analytical sensitivity was observed using the gel- processed extracts. Conclusions: The gel-based method was found to be suitable for the detection of C trachomatis by PCR. In addition, its ease of use, effectiveness at ambient temperature and low cost makes it well-suited for self- collection kits used in population-based C trachomatis screening, particularly for geographically and socially isolated individuals. Despite advances in diagnostic technology, Chlamydia trachomatis screening and disease control is still limited in some populations due to a variety of factors, including geographic isolation or an inability or unwillingness to access healthcare centres for diagnostic testing. 1–4 Unfortunately, this has maximum impact upon the groups most at risk of chlamydial infections, including young people under the age of 25 years, indigenous populations and men who have sex with men. 1–4 Over the past few years, an annual 20% increase in C trachomatis cases has been reported in Australia. 1 In response, the Australian National Sexually Transmitted Infections Strategy 2005–2008 report identified as a priority the need for increased testing of these at-risk populations, prompting the need to investigate alternative collection and testing methodologies. 15 The use of self-collected specimens, such as urine, vaginal swabs or tampons, which can be collected by individuals in their own homes can help increase the numbers of people using sexually transmitted infections (STIs) testing. 6 Several studies have successfully evaluated the use of home-collected and mailed urines for C trachomatis screening. 7–9 Such non-traditional methods of collection and transport would be ideal for facil- itating the extension of existing C trachomatis testing programmes. 15 However, there may be unforeseen obstacles that impair programme implementation and, consequently, need to be overcome, such as a need to refrigerate the sample, complexity of the collection method or additional costs associated with transport and mailing of liquids. We describe the development and evaluation of a novel super-absorbent polymer-based method for the self-collection and ambient temperature trans- port of urine, which is economical, easy to use and retains the high sensitivity of C trachomatis real- time polymerase chain reaction (rtPCR) detection. METHODS Gel matrix The gel matrix consisted of two reagents in equal parts: 0.5 g of the super-absorbent polymer Poly(acrylic acid), partial sodium salt-graft-poly(- ethylene oxide) (C 5 H 7 NaO 3 ) (Sigma-Aldrich, New South Wales, Australia) and 0.5 g of the buffering agent Tris base (NH 2 C(CH 2 OH) 3 ) (Sigma-Aldrich) in equal parts, the whole of which is further referred to as the ‘‘gel’’. In this evaluation, 3 ml of each urine specimen was added to a 10 ml tube containing 1 g of dry gel. In its anhydrous form, the polymer exists as complex folded chains of molecules. When urine is introduced, the water is adsorbed to the polymer, expanding and opening up the chains’ structures, which results in the gel swelling into a dry granular form while desiccating the urine. Consequently, the cells, proteins and DNA previously suspended within the urine are sequestered within the swollen gel matrix; thus, the transformation of the urine into a dry granular state allows urine samples to be packaged for standard envelope mailing without fear of leakage. Reconstitution of urine from the gel was achieved by adding 1.0 ml of 100% isopropanol followed by several vigorous inversions of the tube, which acted to liberate the bound water and re- suspend the cells and DNA. After 5 minutes Basic science 102 Sex Transm Infect 2009;85:102–105. doi:10.1136/sti.2008.032607