Neisseria gonorrhoeae vaccines: a contemporary overview.

Neisseria gonorrhoeae infection is an important public health issue, with an annual global incidence of 87 million. N. gonorrhoeae infection causes significant morbidity and can have serious long-term impacts on reproductive and neonatal health and may rarely cause life-threatening disease. Global rates of N. gonorrhoeae infection have increased over the past 20 years. Importantly, rates of antimicrobial resistance to key antimicrobials also continue to increase, with the United States Centers for Disease Control and Prevention identifying drug-resistant N. gonorrhoeae as an urgent threat to public health. This review summarizes the current evidence for N. gonorrhoeae vaccines, including historical clinical trials, key N. gonorrhoeae vaccine preclinical studies, and studies of the impact of Neisseria meningitidis vaccines on N. gonorrhoeae infection. A comprehensive survey of potential vaccine antigens, including those identified through traditional vaccine immunogenicity approaches, as well as those identified using more contemporary reverse vaccinology approaches, are also described. Finally, the potential epidemiological impacts of a N. gonorrhoeae vaccine and research priorities for further vaccine development are described.

Prevalence of cefixime-resistant Neisseria gonorrhoeae in Melbourne, Australia, 2021-2022.

While ceftriaxone remains the first-line treatment for gonorrhoea, the US CDC recommended cefixime as a second-line treatment in 2021. We tested 1176 Neisseria gonorrhoeae isolates among clients attending the Melbourne Sexual Health Centre in 2021-2022. The prevalence of cefixime resistance was 6.3% (74/1176), azithromycin resistance was 4.9% (58/1176) and ceftriaxone resistance was 0% (0/1176). Cefixime resistance was the highest among women (16.4%, 10/61), followed by men-who-have-sex-with-women (6.4%, 7/109), and men-who-have-sex-with-men (5.8%, 57/982). The prevalence of cefixime-resistant N. gonorrhoeae exceeds the threshold of the 5% resistance level recommended by the World Health Organization; and thus, cefixime treatment would have limited benefits in Australia.

Evaluation of artificial intelligence-powered screening for sexually transmitted infections-related skin lesions using clinical images and metadata.

BACKGROUND: Sexually transmitted infections (STIs) pose a significant global public health challenge. Early diagnosis and treatment reduce STI transmission, but rely on recognising symptoms and care-seeking behaviour of the individual. Digital health software that distinguishes STI skin conditions could improve health-seeking behaviour. We developed and evaluated a deep learning model to differentiate STIs from non-STIs based on clinical images and symptoms. METHODS: We used 4913 clinical images of genital lesions and metadata from the Melbourne Sexual Health Centre collected during 2010-2023. We developed two binary classification models to distinguish STIs from non-STIs: (1) a convolutional neural network (CNN) using images only and (2) an integrated model combining both CNN and fully connected neural network (FCN) using images and metadata. We evaluated the model performance by the area under the ROC curve (AUC) and assessed metadata contributions to the Image-only model. RESULTS: Our study included 1583 STI and 3330 non-STI images. Common STI diagnoses were syphilis (34.6%), genital warts (24.5%) and herpes (19.4%), while most non-STIs (80.3%) were conditions such as dermatitis, lichen sclerosis and balanitis. In both STI and non-STI groups, the most frequently observed groups were 25-34 years (48.6% and 38.2%, respectively) and heterosexual males (60.3% and 45.9%, respectively). The Image-only model showed a reasonable performance with an AUC of 0.859 (SD 0.013). The Image + Metadata model achieved a significantly higher AUC of 0.893 (SD 0.018) compared to the Image-only model (p < 0.01). Out of 21 metadata, the integration of demographic and dermatological metadata led to the most significant improvement in model performance, increasing AUC by 6.7% compared to the baseline Image-only model. CONCLUSIONS: The Image + Metadata model outperformed the Image-only model in distinguishing STIs from other skin conditions. Using it as a screening tool in a clinical setting may require further development and evaluation with larger datasets.

STI pathogens in the oropharynx: update on screening and treatment.

PURPOSE OF REVIEW: The rise in antimicrobial resistance in several STI pathogens such as Neisseria gonorrhoeae has become a public health threat as only one first-line treatment remains. Reducing screening interval for gonorrhoea and chlamydia in high-prevalence populations has been proposed to address antimicrobial stewardship, but this remains controversial. This review aimed to revisit the epidemiology of infections at the oropharynx and review the current screening recommendations and treatment guidelines in different populations. RECENT FINDINGS: Emerging evidence suggests that the oropharynx is the primary anatomical site for gonorrhoea transmission but maybe not for chlamydia transmission. Most international guidelines recommend 3-monthly oropharyngeal gonorrhoea and chlamydia screening for high-prevalence populations (e.g. men who have sex with men) but not low-prevalence populations (e.g. heterosexuals) given the clinical and public health benefits of screening in low-prevalence populations are still unclear. Doxycycline remains the first-line treatment for oropharyngeal chlamydia in most guidelines. However, some countries have moved from dual therapy (ceftriaxone and azithromycin) to monotherapy (ceftriaxone) for oropharyngeal gonorrhoea treatment to address antimicrobial stewardship. SUMMARY: The transmission of gonorrhoea and chlamydia is still not fully understood. Further work will be required to evaluate the benefits and harms of reducing screening in high-prevalence populations.

Annual hepatitis C testing and positive tests among gay and bisexual men in Australia from 2016 to 2022: a serial cross-sectional analysis of sentinel surveillance data.

OBJECTIVE: Guidelines recommend annual hepatitis C virus (HCV) testing for gay and bisexual men (GBM) with HIV and GBM prescribed HIV pre-exposure prophylaxis (PrEP). However, there is a limited understanding of HCV testing among GBM. We aimed to examine trends in HCV testing and positivity from 2016 to 2022. METHODS: Using sentinel surveillance data, we examined the proportion of GBM with at least one test and the proportion with a positive test in each year for HCV antibody testing among GBM with no previous HCV positive test, HCV RNA testing among GBM with a positive antibody test but no previous positive RNA test (naïve RNA testing), and HCV RNA testing among people who had a previous RNA positive test and a subsequent negative test (RNA follow-up testing). Trends were examined using logistic regression from 2016 to 2019 and 2020 to 2022. RESULTS: Among GBM with HIV, from 2016 to 2019 antibody testing was stable averaging 55% tested annually. Declines were observed for both naïve HCV RNA testing (75.4%-41.4%: p<0.001) and follow-up HCV RNA testing (70.1%-44.5%: p<0.001). Test positivity declined for HCV antibody tests (2.0%-1.3%: p=0.001), HCV RNA naïve tests (75.4%-41.4%: p<0.001) and HCV RNA follow-up tests (11.3%-3.3%: p=0.001). There were minimal or no significant trends from 2020 to 2022.Among GBM prescribed PrEP, antibody testing declined from 2016 to 2019 (79.4%-69.4%: p<0.001) and was stable from 2020 to 2022. Naïve and follow-up HCV RNA testing was stable with an average of 55% and 60% tested each year, respectively. From 2016-2019, the proportion positive from HCV RNA naïve tests declined (44.1%-27.5%: p<0.046) with no significant change thereafter. Positive follow-up HCV RNA tests fluctuated with no or one new positive test among this group in most years. CONCLUSION: The proportion of GBM with positive HCV tests has declined, however a substantial proportion are not tested annually. A renewed focus on HCV testing, and treatment where required, is warranted to achieve HCV elimination among GBM in Australia.

Hepatitis C virus reinfection incidence among gay and bisexual men with HIV in Australia from 2016 to 2020.

BACKGROUND: There is some concern that hepatitis C virus (HCV) reinfection might impact HCV micro-elimination efforts among gay and bisexual men (GBM) with HIV. However, there is a limited understanding of reinfection incidence in the context of unrestricted government-funded HCV treatment. We aimed to estimate HCV reinfection incidence among GBM with HIV in Australia from 2016 to 2020. METHODS: Data were from 39 clinics participating in ACCESS, a sentinel surveillance network for blood borne viruses and sexually transmissible infections across Australia. GBM with HIV who had evidence of treatment or spontaneous clearance with at least one positive HCV RNA test, a subsequent negative HCV RNA test, and at least one additional HCV RNA test between 1st January 2016 and 31st December 2020 were eligible for inclusion. A new HCV RNA positive test and/or detectable viral load was defined as a reinfection. Generalised linear modelling was used to examine trends in reinfection. RESULTS: Among 12 213 GBM with HIV who had at least one HCV test, 540 were included in the reinfection incidence analysis, of whom 38 (7%) had evidence of reinfection during the observation period. Over 1124 person-years of follow-up, the overall rate of reinfection was 3.4/100PY (95% CI 2.5-4.6). HCV reinfection incidence declined on average 30% per calendar year (Incidence Rate Ratio 0.70, 95% CI 0.54-0.91). CONCLUSION: HCV reinfection incidence has declined among GBM with HIV in Australia since government-funded unrestricted DAAs were made available. Ongoing HCV RNA testing following cure and prompt treatment for anyone newly diagnosed is warranted to sustain this.

Condom Failure Among HIV-Negative Men in Serodiscordant Relationships in Australia, Brazil, and Thailand.

Condoms continue to be used by many gay, bisexual, and other men who have sex with men (GBM) to reduce the risk of HIV transmission. However this is impacted by condom failure events, defined here as condom breakage and slippage. In a prospective, observational cohort study of 343 HIV serodiscordant male couples recruited through high HIV caseload clinics and hospitals between 2012 and 2016 in Australia, Brazil, and Thailand, condom failure rates and associated factors were analysed, including with the study partner versus other sexual partners. There were 717 reported instances of condom failure from an estimated total of 25,831 sex acts with condoms, from over 588.4 participant years of follow up. Of the HIV-negative partners (n = 343) in the study, more than a third (n = 117, 36.7%) reported at least one instance of condom failure with any partner type during study follow-up. Condom failure with their study partner was reported by 91/343 (26.5%) HIV-negative partners, compared with 43/343 (12.5%) who reported condom failure with other partners. In total, there were 86 events where the HIV-negative partner experienced ano-receptive condom failure with ejaculation, representing 12.0% of all failure events. In multivariable analysis, compared to Australia, HIV-negative men in Brazil reported a higher incidence risk rate of condom failure (IRR = 1.64, 95%CI 1.01-2.68, p = 0.046) and HIV-negative men who reported anal sex with other partners reported an increased risk of condom failure compared with men who only had sex with their study partner (IRR = 1.89, 95%CI 1.08-3.33, p = 0.025). Although at least one event of condom failure was reported by a significant proportion of participants, overall condom failure events represented a small proportion of the total condom protected sex acts.

Ignored and undervalued in public health: a systematic review of health state utility values associated with syphilis infection.

BACKGROUND: Syphilis is a sexually transmitted infection causing significant global morbidity and mortality. To inform policymaking and economic evaluation studies for syphilis, we summarised utility and disability weights for health states associated with syphilis. METHODS: We conducted a systematic review, searching six databases for economic evaluations and primary valuation studies related to syphilis from January 2000 to February 2022. We extracted health state utility values or disability weights, including identification of how these were derived. The study was registered in the international prospective register of systematic reviews (PROSPERO, CRD42021230035). FINDINGS: Of 3401 studies screened, 22 economic evaluations, two primary studies providing condition-specific measures, and 13 burden of disease studies were included. Fifteen economic evaluations reported outcomes as disability-adjusted life years (DALYs) and seven reported quality-adjusted life years (QALYs). Fourteen of 15 economic evaluations that used DALYS based their values on the original Global Burden of Disease (GBD) study from 1990 (published in 1996). For the seven QALY-related economic evaluations, the methodology varied between studies, with some studies using assumptions and others creating utility weights or converting them from disability weights. INTERPRETATION: We found a limited evidence base for the valuation of health states for syphilis, a lack of transparency for the development of existing health state utility values, and inconsistencies in the application of these values to estimate DALYs and QALYs. Further research is required to expand the evidence base so that policymakers can access accurate and well-informed economic evaluations to allocate resources to address syphilis and implement syphilis programs that are cost-effective.

Management of acute sexual assault presenting to a large Australian sexual health clinic in 2012-2021: a retrospective clinical audit.

Background The incidence of sexual assault continues to rise in Australia. This study aimed to describe the nature of assault, HIV/STI positivity, and its management at a sexual health clinic. Methods We performed a chart review of 516 sexual assault cases presenting to Melbourne Sexual Health Centre between 2012 and 2021, collecting data on victim demographics, details of assault, HIV/STI testing and positivity, police involvement, and offer of counselling. Results We included 516 cases: 124 males (24.0%); 384 females (74.4%); and eight transgender (1.6%) victims. The proportion of assault cases presenting to Melbourne Sexual Health Centre increased from 0.1% (37/37,070) in 2012 to 0.2% (56/36,514) in 2021 (P trend =0.006). HIV post-exposure prophylaxis was prescribed for 64.5% (80/124) of males and 12.5% (48/384) of females. Among victims, 69.4% (358/516) were tested for HIV and no one tested positive, while 71.9% (371/516) were tested for syphilis, with 1.6% (6/371) positive. Gonorrhoea and chlamydia were tested at the oropharynx (44.8% [231/516] vs 28.7% [148/516]), genitals (83.7% [432/516] vs 92.4% [477/516]) and anorectum (35.3% [182/516] vs 35.3% [182/516]). Positivity for gonorrhoea and chlamydia were: 2.6% (6/231) vs 2.0% (3/148) at oropharynx, 1.4% (6/432) vs 2.9% (14/477) at genitals, and 5.5% (10/182) vs 7.1% (13/182) at anorectum. According to clinical records, 25.2% (130/516) of victims sought police involvement, and 71.7% (370/516) were offered counselling. Conclusions Sexual assault was an uncommon presentation at Melbourne Sexual Health Centre, with diverse circumstances surrounding assault; however, clinical documentation varied, indicating a need for a standard primary care protocol for clients presenting with acute sexual assault.

A typology of HIV self-testing support systems: a scoping review.

To maximise the benefits of HIV self-testing (HIVST), it is critical to support self-testers in the testing process and ensure that they access appropriate prevention and care. To summarise systems and tools supporting HIVST (hereafter, 'support systems') and categorise them for future analysis, we synthesised the global data on HIVST support systems and proposed a typology. We searched five databases for articles reporting on one or more HIVST support systems and included 314 publications from 224 studies. Across 189 studies, there were 539 reports of systems supporting HIVST use; while across 115 studies, there were 171 reports of systems supporting result interpretation. Most commonly, these were pictorial instructions, followed by in-person demonstrations and in-person assistance while self-testing or reading self-test results. Less commonly, virtual interventions were also identified, including online video conferencing and smartphone apps. Smartphone-based automated result readers have been used in the USA, China, and South Africa. Across 173 studies, there were 987 reports of systems supporting post-test linkage to care; most commonly, these were in-person referrals/counselling, written referrals, and phone helplines. In the USA, Bluetooth beacons have been trialled to monitor self-test use and facilitate follow-up. We found that, globally, HIVST support systems use a range of methods, including static media, virtual tools, and in-person engagement. In-person and printed approaches were more common than virtual tools. Other considerations, such as linguistic and cultural appropriateness, may also be important in the development of effective HIVST programs.

Chlamydia retesting remains low among young women in Australia: an observational study using sentinel surveillance data, 2018-2022.

BACKGROUND: Chlamydia remains the most notified bacterial sexually transmissible infection in Australia with guidelines recommending testing for re-infection at 3months post treatment. This paper aimed to determine chlamydia retesting and repeat positivity rates within 2-4months among young women in Australia, and to evaluate what factors increase or decrease the likelihood of retesting. METHODS: Chlamydia retesting rates among 16-29-year-old women were analysed from Australian Collaboration for Coordinated Enhanced Sentinel Surveillance of sexually transmissible infection and bloodborne virus (ACCESS) sentinel surveillance data (n =62 sites). Among women with at least one positive test between 1 January 2018 and 31 August 2022, retesting counts and proportions within 2-4months were calculated. Logistic regression was performed to assess factors associated with retesting within 2-4months. RESULTS: Among 8758 women who were positive before 31 August 2022 to allow time for follow up, 1423 (16.2%) were retested within 2-4months, of whom 179 (12.6%) tested positive. The odds of retesting within 2-4months were 25% lower if tested in a coronavirus disease 2019 (COVID-9) pandemic year (2020-2022) (aOR=0.75; 95% CI 0.59-0.95). Among 9140 women with a positive test before 30 November 2022, 397 (4.3%) were retested too early (within 7days to 1month) and 81 (20.4%) of those were positive. CONCLUSIONS: Chlamydia retesting rates remain low with around a sixth of women retested within 2-4months in line with guidelines. Re-infection is common with around one in eight retesting positive. An increase in retesting is required to reduce the risk of reproductive complications and onward transmission.

Factors Associated With Recent Decline in Anal Health Among Older Gay and Bisexual Men: A Cross-sectional Analysis.

ABSTRACT: We investigated factors associated with "worse than usual" anal health among gay and bisexual men aged ≥35 years recruited to a longitudinal study of anal human papillomavirus infection/lesions from September 2010 to August 2015.Among 616 participants (median age 49 years; 36% HIV-positive), 42 (6.8%) reported worse than usual anal health in the last 4 weeks. Associated factors included spending less time with gay friends (odds ratio [OR] = 2.25, 95% CI = 1.06-4.77), most time "feeling down"(OR = 9.17, 95% CI = 2.94-28.59), reduced libido (OR = 2.90, 95% CI = 1.52-5.52), current anal symptoms (OR = 6.55, 95% CI = 2.54-16.90), recent anal wart diagnosis (OR = 4.33, 95% CI = 1.98-9.49), and fear of developing anal cancer (OR = 9.34, 95% CI = 4.52-19.28).Concerns regarding anal health should be routinely discussed by clinicians, and potentially associated psychosocial, physical, and sexual issues further explored.

Cost-effectiveness of resistance-guided therapy for Mycoplasma genitalium in Australia.

The recommended first-line treatment for Mycoplasma genitalium infections is azithromycin. However, the prevalence of macrolide resistance for M. genitalium has increased to more than 50% worldwide. In 2013, Australia introduced a resistance-guided therapy (RGT) strategy to manage M. genitalium infections. This study assesses the cost-effectiveness of the RGT approach compared to no RGT (i.e., without macrolide resistance profile test) in women, men who have sex with men (MSM), and men who have sex with women (MSW) in Australia. We constructed dynamic transmission models of M. genitalium infections in women, MSM, and MSW in Australia, each with a population of 100,000. These models compared the costs and quality-adjusted life-years (QALYs) gained between RGT and no RGT scenarios from a healthcare perspective over ten years. All costs are reported in 2022 Australian dollars (Australian $). In our model, RGT is cost saving in women and MSM, with the incremental net monetary benefit of $1.3 million and $17.9 million, respectively. In MSW, the RGT approach is not cost-effective, with an incremental cost-effectiveness ratio of -$106.96 per QALY gained. RGT is cost saving compared to no RGT for M. genitalium infections in women and MSM, supporting its adoption as the national management strategy for these two population groups.

Validation of self-reported human papillomavirus vaccination in young adult men who have sex with men.

The Victorian Government introduced a time-limited human papillomavirus (HPV) catch-up program for gay, bisexual, and other men who have sex with men (GBMSM) aged ≤ 26 years in 2017-2019. We conducted a retrospective observational study to examine the accuracy of the self-report of HPV vaccination status using computer-assisted self-interviewing versus their immunization history via electronic health records. We included GBMSM aged 23-30 years visiting the Melbourne Sexual Health Centre (MSHC) in 2020-2021 because they were age-eligible for the HPV catch-up program in Victoria, Australia. Individuals who were unsure about their vaccination status were categorized as 'unvaccinated'. Of the 1,786 eligible men, 1,665 men self-reported their HPV vaccination status: 48.8% (n = 812) vaccinated, 17.4% (n = 289) unvaccinated, and 33.9% (n = 564) unsure. Self-reported HPV vaccination had a sensitivity of 61.3% (95%CI: 58.3 to 64.2%; 661/1079), a specificity of 74.2% (95%CI: 70.5 to 77.7%; 435/586), a positive predictive value of 81.4% (95%CI: 78.6 to 84.0%; 661/812), a negative predictive value of 51.0% (95%CI: 47.6 to 54.4%; 435/853), and an accuracy of 52.6% (95%CI: 50.1 to 55.0%). Our results showed that only half of GBMSM know and report their HPV vaccination status correctly. Novel approaches such as digital vaccine passports may be useful for individuals to accurately report their vaccination status to guide accurate clinical decisions and management.

Changes in HIV post-exposure prophylaxis prescriptions before and after the introduction of HIV pre-exposure prophylaxis at a sexual health clinic in Melbourne, Australia, 2011-2021.

OBJECTIVE: HIV pre-exposure prophylaxis (PrEP) became available in Victoria, Australia, in 2016. We examined non-occupational post-exposure prophylaxis (nPEP) usage among gay, bisexual and other men who have sex with men (MSM) before and after PrEP became available. METHODS: We included MSM attending Melbourne Sexual Health Centre for nPEP between 2011 and 2021. We analysed three periods: the 'pre-PrEP' (01 Jan 2011 to 25 Jul 2016), 'PrEP before COVID-19' (26 Jul 2016 to 31 Dec 2019), and 'PrEP during COVID-19' (01 Jan 2020 to 31 Dec 2021). RESULTS: There were 222,978 consultations for MSM; 8292 (3.7%) were nPEP consultations. The proportion of nPEP consultations increased from 3.3% (3093/94263) in the pre-PrEP period to 4.3% (3843/89251) in the PrEP before COVID-19 period then dropped to 3.4% (1356/39464) during the COVID-19 period. Compared to Australian-born MSM, MSM born in Central/South America (adjusted odds ratio [aOR]: 1.75; 95% confidence interval [CI]: 1.27-2.40) had the highest odds of accessing nPEP, followed by Asian-born MSM (aOR: 1.47; 95% CI: 1.27-1.71) after adjusting for PrEP availability and COVID-19. Those newly arrived in Australia in ≤4 years had higher odds (aOR: 1.14; 95% CI: 1.05-1.22) of accessing nPEP than those living in Australia for >4 years. CONCLUSION: nPEP prescriptions declined with PrEP availability. Newly arrived overseas-born MSM who are unlikely to have access to subsidised PrEP have a higher demand of nPEP. IMPLICATIONS FOR PUBLIC HEALTH: Increasing PrEP education and ensuring equal access is vital in the drive to reduce new HIV diagnoses.

Identifying Individuals at High Risk for HIV and Sexually Transmitted Infections With an Artificial Intelligence-Based Risk Assessment Tool.

Background: We have previously developed an artificial intelligence-based risk assessment tool to identify the individual risk of HIV and sexually transmitted infections (STIs) in a sexual health clinical setting. Based on this tool, this study aims to determine the optimal risk score thresholds to identify individuals at high risk for HIV/STIs. Methods: Using 2008-2022 data from 216 252 HIV, 227 995 syphilis, 262 599 gonorrhea, and 320 355 chlamydia consultations at a sexual health center, we applied MySTIRisk machine learning models to estimate infection risk scores. Optimal cutoffs for determining high-risk individuals were determined using Youden's index. Results: The HIV risk score cutoff for high risk was 0.56, with 86.0% sensitivity (95% CI, 82.9%-88.7%) and 65.6% specificity (95% CI, 65.4%-65.8%). Thirty-five percent of participants were classified as high risk, which accounted for 86% of HIV cases. The corresponding cutoffs were 0.49 for syphilis (sensitivity, 77.6%; 95% CI, 76.2%-78.9%; specificity, 78.1%; 95% CI, 77.9%-78.3%), 0.52 for gonorrhea (sensitivity, 78.3%; 95% CI, 77.6%-78.9%; specificity, 71.9%; 95% CI, 71.7%-72.0%), and 0.47 for chlamydia (sensitivity, 68.8%; 95% CI, 68.3%-69.4%; specificity, 63.7%; 95% CI, 63.5%-63.8%). High-risk groups identified using these thresholds accounted for 78% of syphilis, 78% of gonorrhea, and 69% of chlamydia cases. The odds of positivity were significantly higher in the high-risk group than otherwise across all infections: 11.4 (95% CI, 9.3-14.8) times for HIV, 12.3 (95% CI, 11.4-13.3) for syphilis, 9.2 (95% CI, 8.8-9.6) for gonorrhea, and 3.9 (95% CI, 3.8-4.0) for chlamydia. Conclusions: Risk scores generated by the AI-based risk assessment tool MySTIRisk, together with Youden's index, are effective in determining high-risk subgroups for HIV/STIs. The thresholds can aid targeted HIV/STI screening and prevention.

Clinical features-based machine learning models to separate sexually transmitted infections from other skin diagnoses.

INTRODUCTION: Many sexual health services are overwhelmed and cannot cater for all the individuals who present with sexually transmitted infections (STIs). Digital health software that separates STIs from non-STIs could improve the efficiency of clinical services. We developed and evaluated a machine learning model that predicts whether patients have an STI based on their clinical features. METHODS: We manually extracted 25 demographic features and clinical features from 1315 clinical records in the electronic health record system at Melbourne Sexual Health Center. We examined 16 machine learning models to predict a binary outcome of an STI or a non-STI diagnosis. We evaluated the models' performance with the area under the ROC curve (AUC), accuracy and F1-scores. RESULTS: Our study included 1315 consultations, of which 36.8% (484/1315) were diagnosed with STIs and 63.2% (831/1315) had non-STI conditions. The study population predominantly consisted of heterosexual men (49.5%, 651/1315), followed by gay, bisexual and other men who have sex with men (GBMSM) (25.7%), women (21.6%) and unknown gender (3.2%). The median age was 31 years (intra-quartile range (IQR) 26-39). The top 5 performing models were CatBoost (AUC 0.912), Random Forest (AUC 0.917), LightGBM (AUC 0.907), Gradient Boosting (AUC 0.905) and XGBoost (AUC 0.900). The best model, CatBoost, achieved an accuracy of 0.837, sensitivity of 0.776, specificity of 0.831, precision of 0.782 and F1-score of 0.778. The key important features were lesion duration, type of skin lesions, age, gender, history of skin disorders, number of lesions, dysuria duration, anorectal pain and itchiness. CONCLUSIONS: Our best model demonstrates a reasonable performance in distinguishing STIs from non-STIs. However, to be clinically useful, more detailed information such as clinical images, may be required to reach sufficient accuracy.

Factors associated with HIV pre-exposure prophylaxis use among Asian men who have sex with men in Sydney and Melbourne, Australia: a cross-sectional study.

Background: Asian-born MSM are a priority population as Australia aims to end HIV transmission, but they reported additional barriers to access PrEP and other HIV prevention methods. This study investigates factors associated with PrEP use among Asian MSM in Sydney and Melbourne, Australia, to inform strategies to improve PrEP uptake in this population. Methods: This was a sub-analysis of a community-based cross-sectional survey conducted from March to June 2021. We recruited participants online in Sydney and Melbourne, Australia. Univariable and multivariable logistic regression analyses were performed to identify the factors associated with PrEP use in the last six months and lifetime. Latent class analyses were used to identify subgroups of Asian MSM sharing similar characteristics related to their risk practices for HIV. Findings: Overall, 870 Asian MSM were included: 288 Oceanian-born Asian MSM and 582 Asian-born MSM. Three latent classes were identified: 1) Asian-born MSM who recently arrived in Australia with limited English, were less likely to use PrEP and at higher risk of HIV infection (e.g., had condomless anal sex with a casual sex partner in the last six months) (4.6%); 2) Asian MSM who were at lower risk of HIV infection and less likely to use PrEP (69.3%) and; 3) Asian MSM who were at substantial risk of HIV infection and more likely to use PrEP (26.1%). Compared to Oceanian-born Asian MSM, those who were born in Southeast Asia (adjusted odds ratio (aOR) = 0.5, 95% confidence interval (CI) 0.3-0.7) and South Asia (aOR = 0.4, 95% CI 0.2-0.8) were less likely to ever use PrEP. Compared to Oceanian-born Asian MSM, those who were born in Southeast Asia (aOR = 0.4, 95% CI 0.3-0.7), Northeast Asia (aOR = 0.5, 95% CI 0.3-0.8) and South Asia (aOR = 0.4, 95% CI 0.2-0.7) were less likely to use PrEP in the last six months. Interpretation: To end HIV transmission in Australia, it will be necessary to develop strategies to improve PrEP access for the significant minority of Asian-born MSM who are at substantial risk of HIV infection. Funding: EPFC and JJO are supported by an Australian National Health and Medical Research Council (NHMRC) Emerging Leadership Investigator Grant (EPFC: GNT1172873 and JJO: GNT1193955). CKF is supported by an Australian National Health and Medical Research Council (NHMRC) Leadership Investigator Grant (GNT1172900).

Optimizing health resource allocation for improving timely HIV diagnosis in China.

INTRODUCTION: The Joint United Nations Programme on HIV/AIDS (UNAIDS) updated the 95-95-95 targets for the HIV endgame in 2030. To achieve the first target in a timely manner, we investigate the optimized strategy of resource allocation to maximize timely HIV diagnosis in 14 populations in China. METHODS: We developed a mathematical model by integrating epidemiological, demographical and behavioural data from 12 high-risk and two general populations to evaluate the impact of various resource allocation strategies of HIV testing on HIV incidence in China. We identified the optimized allocation strategy that maximizes the number of HIV diagnoses at an estimated total spending on HIV tests in China and calculated the per-capita cost of new HIV case detection. RESULTS: We estimated that 144,795 new HIV cases may occur annually in 14 populations in China, with a total annual spending of US$2.8 billion on HIV testing. The largest proportion of spending was allocated to general males (44.0%), followed by general females (42.6%) and pregnant women (5.1%). Despite this allocation strategy, only 45.5% (65,867/144,795, timely diagnosis rate) of annual new infections were diagnosed within a year of acquisition, with a cost of $42,852 required for each new HIV case detection. By optimizing the allocation of HIV testing resources within the same spending amount, we found that general females received the highest proportion of spending allocation (45.1%), followed by low-risk men who have sex with men (13.9%) and pregnant women (8.4%). In contrast, the proportion of spending allocation for the general males decreased to 0.2%. With this optimized strategy, we estimated that 120,755 (83.4%) of annual new infections would be diagnosed within a year of acquisition, with the cost required for one HIV case detection reduced to $23,364/case. Further spending increases could allow for significant increases in HIV testing among lower-risk populations. CONCLUSIONS: Optimizing resource allocation for HIV testing in high-risk populations would improve HIV timely diagnosis rate of new infections and reduce cost per HIV case detection.

Sexual health clinic attendees' views on antibiotic post-exposure prophylaxis and vaccinations for sexually transmitted infections prevention: A qualitative study.

Background: The rising prevalence of bacterial sexually transmitted infections (STIs) is cause for concern in the context of antimicrobial resistance and the potential health outcomes of untreated infections. Objective: The Community Awareness and Surveillance of Transmission (CAST) study sought sexual health service users' views on reducing the prevalence of STIs. Methods: Semi-structured interviews were conducted with sexual health clinic attendees who had received a diagnosis of chlamydia, gonorrhea or syphilis in the previous six months. Participant comments relating to antibiotic post-exposure prophylaxis (APEP) and vaccination were inductively coded, then compared using comparative qualitative data analysis methods described by Miles and Huberman. Findings: Twenty-one participants with differing genders, ages, nationalities and sexual orientations, were interviewed. Participants across informant groups expressed concerns about APEP for STI prevention because of potential antimicrobial resistance and personal health impacts. Vaccination against bacterial STIs was more acceptable. Common factors mentioned in relation to both interventions included perception of individual STI risk over time, safety, effectiveness and accessibility. Conclusions: The views of sexual health service users support efforts to find alternatives to more frequent use of antibiotics, such as vaccinations against bacterial STIs, to reduce STI incidence and support antimicrobial stewardship.