A comparison of ThinPrep against four non-volatile transport media for HPV testing at or near the point of care

The Xpert HPV Test is used at point of care for cervical screening in a number of low and middle income countries (LMIC). It is validated for use with ThinPrep-PreservCyt transport medium which has a high methanol content and is therefore classified as a dangerous good for shipping, making cost, transportation and use challenging within LMIC. We compared the performance of ThinPrep against four non-volatile commercially available media for human papillomavirus (HPV) point of care testing. Ten-fold serial dilutions were prepared using three HPV cell lines each positive for 16, 18 or 31 and with each suspended in five different media types. The media types consisted of Phosphate Buffered Saline (ThermoFisher Scientific, USA), Sigma Virocult (Medical Wire and Equipment, UK), MSwab (Copan, Italy) Xpert Transport Media (Cepheid, USA) and ThinPrep-PreservCyt (Hologic, USA). A total of 105 Xpert HPV tests were conducted in a laboratory setting, with seven 10-fold dilutions of each of the three HPV genotypes tested in all five media types. The lowest HPV 10-fold dilution detected for any media, or cell line was the fifth dilution. MSwab was the only medium to detect HPV to the fifth dilution across all three cell types. MSwab transport media may be a suitable alternative to ThinPrep for Xpert HPV point of care testing. A field based, head to head comparison of both media types using the Xpert HPV assay is warranted to confirm these laboratory based findings.

PERPETRATION OF VIOLENCE BY FEMALE SEX WORKERS IN PAPUA NEW GUINEA: 'WE WILL CRUSH THEIR BONES'

There is a small but important body of literature on female sex workers' (FSWs) violence towards others, but little of that focused on low- and middle-income countries. Drawn from a larger biobehavioural study of FSWs in three cities in Papua New Guinea, we analyse the interviews from 19 FSWs who reported having perpetrated physical violence towards four major groups: (1) ex-husbands; (2) clients; (3) other sex workers and (4) other people (mainly women). Our study demonstrates that FSWs' use of violence arises from a complex set of social, material and gendered circumstances and cannot be addressed in isolation from other aspects of their lives.

A diagnostic evaluation of a molecular assay used for testing and treating anorectal chlamydia and gonorrhoea infections at the point-of-care in Papua New Guinea

OBJECTIVES

Papua New Guinea has among the highest prevalences of sexually transmissible infections (STIs) globally with no services able to accurately test for anorectal Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections. Here we prospectively evaluated the diagnostic performance of a molecular CT/NG assay used at the point-of-care (POC) with the aim of enhancing anorectal STI screening and same-day treatment.

METHODS

Men who have sex with men, transgender women and female sex workers taking part in Papua New Guinea's first large-scale biobehavioural study were enrolled and asked to provide a self-collected anorectal swab for POC GeneXpert CT/NG testing. Same-day treatment was offered if positive. A convenience sample of 396 unique and randomly selected samples were transported to Australia for comparison using the Cobas 4800 CT/NG test (Roche Molecular Diagnostics, Pleasanton, CA, USA).

RESULTS

A total of 326 samples provided valid results by Cobas whereas 70 samples provided invalid results suggesting inhibition. The positive, negative and overall percentage agreements of GeneXpert CT/NG for the detection of C. trachomatis were 96.7% (95% CI 92.3%-98.9%), 95.5% (95% CI 91.3%-98.0%) and 96.0% (95% CI 93.3%-97.8%), and for N. gonorrhoeae were 93.0% (95% CI 86.1%-97.1%), 100.0% (95% CI 98.3%-100.0%) and 97.8% (95% CI 95.6%-99.1%), respectively.

CONCLUSIONS

The overall rate of agreement between the GeneXpert and Cobas CT/NG assays was high with 96.0% for C. trachomatis and 97.8% for N. gonorrhoeae. Results from this study data suggest that the GeneXpert CT/NG assay is suitable for testing self-collected anorectal specimens at the POC and that same-day treatment was feasible.

Evaluation of self-collected vaginal specimens for the detection of high-risk human papillomavirus infection and the prediction of high-grade cervical intraepithelial lesions in a high-burden, low-resource setting

OBJECTIVES

To compare the performance of self-collected vaginal (V) specimens with clinician-collected cervical (C) specimens for detection of high-risk human papillomavirus (hrHPV) and cervical disease using the Cepheid Xpert HPV, Roche Cobas 4800 HPV and Hologic Aptima HPV assays.

METHODS

Women aged 30-59 years (n = 1005) were recruited at two clinics in Papua New Guinea, and they provided specimens for testing at point-of-care using the Xpert HPV Test, and for subsequent testing using the Cobas HPV (n = 981) and Aptima HPV (n = 983) assays. Liquid-based cytology was performed on C specimens to predict underlying high-grade squamous intraepithelial lesions (HSIL). V specimen results of each assay were evaluated against a constructed reference standard and for detection of HSIL or worse.

RESULTS

There was substantial (κ >0.6) agreement in hrHPV detection between V and C specimens across all three assays. The sensitivity, specificity, and positive and negative predictive values of Xpert HPV using self-collected V specimens for the detection of HPV type 16 according to the constructed reference standard were 92.1%, 93.1%, 63.6% and 98.9%, respectively; compared with 90.4%, 94.3%, 67.8% and 98.7% for Cobas 4800 HPV; and 63.2%, 97.2%, 75.0% and 95.3% for Aptima HPV. Similar results were observed for all hrHPV types (combined) and for HPV types 18/45, on all three assays. The detection of any hrHPV using self-collected specimens had high sensitivity (86%-92%), specificity (87%-94%) and negative predictive value (>98%) on all assays for HSIL positivity.

CONCLUSIONS

Xpert HPV, using self-collected vaginal specimens, has sufficient accuracy for use in point-of-care 'test-and-treat' cervical screening strategies in high-burden, low-resource settings.

A reliable and easy to transport quality control method for chlamydia and gonorrhoea molecular point of care testing

Quality control (QC) is an essential component of point-of-care testing programs. In the context of a randomised-controlled trial (TTANGO) using GeneXpert (Xpert) Chlamydia trachomatis and Neisseria gonorrhoeae (CT/NG) point-of-care testing in remote areas of Australia, we aimed to develop and utilise a stable positive control material. Bacterial cultures of CT and NG were resuspended together to provide cycle threshold (C_t) values of approximately 25 cycles for both CT and NG when tested on the Xpert CT/NG assay. These positive control suspensions were dried in aliquots, heat inactivated, and then provided to 12 participating health services as research-only QC samples in kit form. At each service, a QC sample was resuspended and tested each month on the Xpert. QC results, including Xpert C_t values, were analysed from each site over 30 months and we calculated costs per QC sample. Overall, at 12 health services there were 89 QC samples tested (average of 8 tests per site per year). Mean C_t values for the 89 controls samples were 25.25 cycles (SD = 1.15) for CT, 24.04 cycles (SD = 1.400) for one NG target and 23.35 cycles (SD = 1.55) for the other NG target. No significant differences in C_t value for CT or NG controls were observed over a trial period of 30 months. Positive QC samples for research use in a trial of a molecular point-of-care assay were inexpensive to produce and stable when stored at 2-8°C. For routine use, additional requirements such as meeting National Association of Testing Authority (NATA) regulations and Therapeutic Goods Administration (TGA) approval will need to be achieved.

A preliminary evaluation of a new GeneXpert (Gx) molecular point-of-care test for the detection of Trichomonas vaginalis

OBJECTIVES

Global concerns regarding the prevalence, asymptomatic nature and burden of disease associated with Trichomonas vaginalis (TV) continue. The lack of a portable molecular point-of-care assay to detect this infectious disease has meant that many remote or low-resource settings still need to rely on delayed results from central laboratories and/or syndromic management as treatment strategies. We evaluated the new GeneXpert (Gx) TV nucleic acid amplification test (NAAT) compared with an in-house laboratory NAAT to determine whether it would be suitable for use at the point of care.

METHODS

In a state-based laboratory and using their in-house NAAT, we selected the first 60 urine samples that were positive and the first 60 that were negative (n=120) in the study period for Gx TV testing in order to reduce collection delays and avoid the freezing of samples.

RESULTS

Positive percentage agreement between the Gx TV and NAAT was 95.0% (95% CI 86.1% to 99.0%), negative percentage agreement was 100.0% (95% CI 93.5% to 100.0%) and overall percentage agreement was 97.4% (95% CI 92.5% to 99.5%). Three discordant results were detected with each being close to the cycle threshold of detection using the in-house NAAT assay.

CONCLUSIONS

Findings suggest the Gx TV assay is easy to use and has suitable overall agreement for sexually transmissible infection (STI) testing at the point of care. It may be used in combination with the Gx CT/NG assay to test for all three STIs simultaneously using this portable and modular-based NAAT platform.

Public health implications of molecular point-of-care testing for chlamydia and gonorrhoea in remote primary care services in Australia: a qualitative study

OBJECTIVES

With accurate molecular tests now available for diagnosis of chlamydia and gonorrhoea (Chlamydia trachomatis (CT)/Neisseria gonorrhoeae (NG)) at the point-of-care (POC), we aimed to explore the public health implications (benefits and barriers) of their integration into remote primary care in Australia.

METHODS

Qualitative interviews were conducted with a purposively selected group of 18 key informants reflecting sexual health, primary care, remote Aboriginal health and laboratory expertise.

RESULTS

Participants believed that POC testing may decrease community prevalence of sexually transmitted infections (STIs), and associated morbidity by reducing the time to treatment and infectious period and expediting partner notification. Also, POC testing could improve acceptability of STI testing, increase testing coverage and result in more targeted prescribing, thereby minimising the risk of antibiotic resistance. Conversely, some felt the immediacy of diagnosis could deter certain young people from being tested. Participants also noted that POC testing may reduce the completeness of communicable disease surveillance data given the current dependence on reporting from pathology laboratories. Others expressed concern about the need to maintain and improve the flow of NG antibiotic sensitivity data, already compromised by the shift to nucleic acid-based testing. This is particularly relevant to remote areas where culture viability is problematic.

CONCLUSIONS

Results indicate a high level of support from clinicians and public health practitioners for wider access to CT/NG POC tests citing potential benefits, including earlier, more accurate treatment decisions and reductions in ongoing transmission. However, the data also highlight the need for new systems to avoid adverse impact on disease surveillance.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry: ACTRN12613000808741.

Field evaluation of the CRT and ACON chlamydia point-of-care tests in a tropical, low-resource setting

OBJECTIVE

To evaluate the clinical performance of two chlamydia point-of-care (POC) tests compared with a gold standard nucleic acid amplification testing (NAAT).

METHODS

Tests evaluated were the Chlamydia Rapid Test (CRT), Diagnostics for the Real World and the ACON Chlamydia Rapid Test Device, ACON Laboratories (ACON). Overall 226 men and 225 women in Port Vila, Vanuatu, participated in this prospective study in 2010. NAAT and POC testing was performed on samples of male urine and female vaginal swabs for 156 men and 223 women (CRT), and 133 men and 75 women (ACON).

RESULTS

The sensitivity and specificity of the CRT in men were 41.4% (95% CI 23.5% to 61.1%) and 89.0% (95% CI 82.2% to 93.8%), respectively, and in women 74.2% (95% CI 61.5% to 84.5%) and 95.7% (95% CI 91.3% to 98.2%), respectively; for ACON, they were 43.8% (95% CI 19.8% to 70.1%) and 98.3% (95% CI 93.9% to 99.8%) in men, and in women 66.7% (95% CI 22.3% to 95.7%) and 91.3% (95% CI 82.0% to 96.7%), respectively. Both tests were (absolutely) insensitive at organism loads less than 1000 (log=3) per mL or per swab; the CRT sensitivity was significantly lower at loads less than, compared with those greater than, 100 000 (log=5) per mL or per swab.

CONCLUSIONS

The performance of both CRT and ACON is well below the levels stated by the manufacturers. The evaluated tests are unlikely to be helpful in clinical settings due to the high proportion of false-negatives that will go untreated and false-positives that will result in overtreatment and potential adverse social consequences.