Australian sexually transmitted infection (STI) management guidelines for use in primary care 2022 update

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.

Unnecessary antibiotic use in men who have sex with men (MSM) with anogenital symptoms attending a sexual health clinic: a retrospective analysis

OBJECTIVES

To quantify the amount of unnecessary antibiotics, in particular ceftriaxone, given to men who have sex with men (MSM) with anogenital symptoms as part of presumptive management in an urban sexual health clinic and examine factors associated with unnecessary ceftriaxone.

METHODS

This is a retrospective cross-sectional analysis of electronic records from all visits involving MSM reporting symptoms of bacterial sexually transmitted infection (STI) and who received presumptive antibiotics at Sydney Sexual Health Centre. The following variables were extracted: demographic and sexual behaviour data, presenting symptoms, prior STI diagnoses, use of anoscopy, use of point-of-care microscopy, prescriptions of antibiotics and subsequent nucleic acid amplification testing (NAAT) results for chlamydia and gonorrhoea in all anatomical sites (urethra, pharynx and rectum). We defined unnecessary antibiotic as an agent prescribed to treat an STI organism that was subsequently not detected.

RESULTS

Among 1061 visits in this analysis, 41.8% yielded negative NAAT results for both chlamydia and gonorrhoea in all anatomical sites. There were 44.3% of visits which had positive gonorrhoea NAAT result in at least one anatomical site. There were 187 courses of ceftriaxone prescribed in patients who tested negative for gonorrhoea in all anatomical sites and therefore were unnecessary. Unnecessary ceftriaxone prescribing occurred in 50.2% of visits with anorectal symptoms, 19.6% of scrotal symptoms and 7.3% of urethral symptoms. Microscopy was associated with significantly less unnecessary ceftriaxone in urethral but not anorectal or scrotal presentations. In multivariable analysis, the following factors were associated with a higher likelihood of unnecessary ceftriaxone use: anorectal symptoms, scrotal symptoms, gonorrhoea in the preceding year, contact of a bacterial STI and living with HIV.

CONCLUSIONS

This study highlights the significant amount of unnecessary ceftriaxone used for STI symptoms in MSM. A new pathway incorporating rapid point-of-care molecular testing in symptomatic patients may improve the precision of antibiotic prescribing and reduce unnecessary use.

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.

Mycoplasma genitalium in pregnancy, including specific co-infections, is associated with lower birthweight: A prospective cohort study

BACKGROUND

Mycoplasma genitalium infection in pregnancy is increasingly reported at similar frequencies to other sexually transmitted infections (STIs). Knowledge on its contribution to adverse pregnancy outcomes is very limited, especially relative to other STIs or bacterial vaginosis (BV). Whether M. genitalium influences birthweight remains unanswered.

METHODS

Associations between birthweight and M. genitalium and other STIs (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) and BV in pregnancy were examined in 416 maternal-newborn pairs from a prospective cohort study in Papua New Guinea.

FINDINGS

Compared to uninfected women, M. genitalium (-166.9 g, 95% confidence interval [CI]: -324.2 to -9.7 g, p = 0.038) and N. gonorrhoeae (-274.7 g, 95% CI: -561.9 to 12.5 g, p = 0.061) infections were associated with lower birthweight in an adjusted analysis. The association for C. trachomatis was less clear, and T. vaginalis and BV were not associated with lower birthweight. STI prevalence was high for M. genitalium (13.9%), N. gonorrhoeae (5.0%), and C. trachomatis (20.0%); co-infections were frequent. Larger effect sizes on birthweight occurred with co-infections of M. genitalium, N. gonorrhoeae, and/or C. trachomatis.

CONCLUSION

M. genitalium is a potential contributor to lower birthweight, and co-infections appear to have a greater negative impact on birthweight. Trials examining the impact of early diagnosis and treatment of M. genitalium and other STIs in pregnancy and preconception are urgently needed.

FUNDING

Funding was received from philanthropic grants, the National Health and Medical Research Council, and the Burnet Institute. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Australian consensus statement on doxycycline post-exposure prophylaxis (doxy-PEP) for the prevention of syphilis, chlamydia and gonorrhoea among gay, bisexual and other men who have sex with men

INTRODUCTION

Doxycycline post-exposure prophylaxis (doxy-PEP) involves consuming 200 mg of doxycycline up to 72 hours after a condomless sex act to reduce the risk of bacterial sexually transmitted infections (STIs). Recent clinical trials of doxy-PEP have demonstrated significant reductions in syphilis, chlamydia and, to a lesser degree, gonorrhoea among gay, bisexual and other men who have sex with men (GBMSM). There is a high level of interest in doxy-PEP in the GBMSM community and, in response, the Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine (ASHM) held a national consensus conference with the aim of creating preliminary guidance for clinicians, community, researchers and policy makers.

MAIN RECOMMENDATIONS

There was broad agreement that doxy-PEP should be considered primarily for the prevention of syphilis in GBMSM who are at risk of this STI, with a secondary benefit of reductions in other bacterial STIs. At the end of the consensus process, there remained some disagreement, as some stakeholders felt strongly that doxy-PEP should be considered only for the prevention of syphilis in GBMSM, and that the risk of increasing antimicrobial resistance outweighed any potential benefit from reductions in other bacterial STIs in the target population. The national roundtable made several other recommendations for clinicians, community, researchers and policy makers, as detailed in this article. ASHM will support the development of detailed clinical guidelines and education materials on doxy-PEP (www.ashm.org.au/doxy-pep).

CHANGES IN MANAGEMENT AS A RESULT OF THIS CONSENSUS STATEMENT

For GBMSM at high risk of syphilis, and perhaps other bacterial STIs, clinicians may consider prescribing doxy-PEP for a limited period of time, followed by a review of ongoing need. Unlike human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP), doxy-PEP may not be suitable as a population-level intervention and should instead be used more selectively.

Serological follow-up after syphilis diagnosis in Israel

The global incidence of syphilis is increasing. Continuity of care challenges the control of sexually transmitted diseases. In this study, we assessed the follow-up and serological decline differences between community- and hospital-diagnosed patients in Israel. A historical cohort study was conducted using the Israel National Syphilis Center (NSC) repository. Patients with a positive non-specific Venereal Disease Research Laboratory (VDRL) test between 2011 and 2020 were included. Rates of serological follow-up and serological titre decreases were compared between hospital- and community-diagnosed patients. The study included 4,445 patients, 2,596 (58.4%) were diagnosed in community clinics and 1,849 (41.6%) in hospitals. Of community-diagnosed patients, 1,957 (75.4%) performed follow-up testing, compared with 834 (51.2%) hospital-diagnosed patients (p < 0.001). On multivariate analysis, the odds ratio of serology follow-up among community-diagnosed patients was 2.8 (95 per cent confidence interval (95% CI): 2.2-3.5) that of hospital-diagnosed patients. There were 1,397 (71.4%) community-diagnosed patients with serological titre decrease, compared with 626 (74.9%) hospital-diagnosed patients (p = 0.03). On multivariate analysis, this difference diminished. Serological follow-up testing is suboptimal and was performed more often among patients initially diagnosed in the community compared to hospitals. Continuity of care should be improved to promote successful patient care and prevent disease spread.

Men after the sexual assault: The journey from medical service to court

BACKGROUND

There may be significant physical and psychological consequences and impacts for males who experience sexual assault as adults, however, published literature in this context is sparse, specifically for the investigative outcomes in the criminal legal process.

METHOD

This clinical audit tracked 138 adult males who presented for forensic and medical sexual assault care from initial presentation to ACT Police investigation and court outcome from 2004 to 2022.

RESULTS

There were 103/138 (74.6%) males who attended for medical and forensic care within 72 h of the reported assault. Pre-existing mental health conditions were self-reported in 59/138 (42.7%) males. Nearly half of males 67/138 (48.5%) had a medical evidence kit collected. Males presenting for medical care 44/138 (31.2%) went on to report to ACT Policing, 36/44 (81.2%) of cases did not proceed to court. The most common clearance type was inadequate evidence to proceed (17/44, 38.6%). In 8/44 (18.2%) of adult male cases who subsequently reported to ACT Police, the investigation resulted in entry to the judicial process with a suspect charged with a sexual offence. Five of those cases resulting in a conviction.

CONCLUSIONS

Many adult male patients presented within timeframes that enabled the provision of time critical medical care and provided an opportunity for forensic medical evidence collection. Many adult males 59 (42.7%) self-reported pre-existing mental health conditions upon initial presentation. Attrition occurred throughout the patient journey with many males not reporting to police and thus not presenting in the legal process. This further emphasises the need for independent sexual violence patient advisors to support adult male victims through the medical and criminal justice process.

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.

Near-to-patient-testing to inform targeted antibiotic use for sexually transmitted infections in a public sexual health clinic: the NEPTUNE cohort study

Background

Empiric treatment of sexually transmitted infections can cause unnecessary antibiotic use. We determined if near-to-patient-testing (NPT) for Neisseria gonorrhoeae, Chlamydia trachomatis and Mycoplasma genitalium (MG) improved antibiotic-use for a range of clinical presentations.

Methods

Clients attending with non-gonococcal urethritis (NGU), proctitis, as STI-contacts, or for an MG-test-of-cure (MG-TOC) between March and December 2021 were recruited. Participants received near-to-patient-testing (NPT-group) for the three STIs using the GeneXpert® System (Cepheid), and concurrent routine-testing by transcription-mediated-amplification (TMA; Aptima, Hologic). Antibiotic-use among NGU or proctitis cases in the NPT-group was compared to clinic-controls undergoing routine-testing only. The proportion in the NPT-group who notified partners <24 hrs of their STI-specific result was calculated.

Findings

Among 904 consults by 808 NPT-participants, ≥1 STI was detected in 63/252 (25.0%) with NGU, 22/51 (43.1%) with proctitis, and 167/527 (31.7%) STI-contacts. MG was detected among 35/157 (22.3%) MG-TOC consults. Among NGU and proctitis cases, fewer in the NPT-group received empiric treatment compared to clinic-controls (29.4% [95% CI: 24.3-34.9%] vs 83.8% [95% CI: 79.2-87.8%], p < 0.001), resulting in more NPT-group cases appropriately treated (STI-specific drug/no drug appropriately; 80.9% [95% CI: 76.0-85.1%] vs 33.0% [95% CI: 27.7-38.6%], p < 0.001) and fewer mistreated (incorrect drug/treated but pathogen-negative; 17.8% [13.7-22.6%] vs 61.4% [55.6-66.9%], p < 0.001). Of 167/264 in the NPT-group with an STI who responded regarding partner-notification, 95.2% notified all/some partners; 85.9% notified them <24 hrs of the STI-specific result.

Interpretation

Near-to-patient-testing significantly improved antibiotic use and a high proportion of individuals rapidly notified partners of STI-specific results, highlighting the broad benefits of timely diagnostic strategies for STIs in clinical decision making and partner notification.

Funding

ARC ITRP Hub-grant; NHMRC.

Mycoplasma genitalium: Key Information for the Primary Care Clinician

Mycoplasma genitalium (MG) is an emerging sexually transmitted infection, which appears to be a cause of urethritis and cervicitis and has been associated with pelvic inflammatory disease (PID), epididymitis, proctitis, infertility, complications during pregnancy, and human immunodeficiency virus (HIV) transmission. Three Food and Drug Administration (FDA) approved tests are available. Testing should be focused to avoid inappropriate antibiotic use. The Center of Disease Control and Prevention (CDC) guidelines recommend testing for persistent male urethritis, cervicitis, and proctitis and state that testing should be considered in cases of PID. Testing is also recommended for sexual contacts of patients with MG. Testing is not recommended in asymptomatic patients, including pregnant patients, who do not have a history of MG exposure. Although resistance-guided therapy is recommended, there are currently no FDA approved tests for MG macrolide resistance, and tests are not widely available in the United States. The CDC recommends 2-step treatment with doxycycline followed by azithromycin or moxifloxacin. Moxifloxacin is recommended if resistance testing is unavailable or testing demonstrates macrolide resistance..

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.

Sexually transmitted infections diagnosed in individuals presenting for forensic and medical care following sexual assault

BACKGROUND

People who report sexual assault express concerns regarding contracting sexually transmitted infection (STI); however, published literature regarding the risk of STI transmission in this context is sparse.

METHOD

We audited STI and blood-borne virus (BBV) testing at a forensic and medical sexual assault care service in the Australian Capital Territory between 2004 and 2022. Eligibility for testing among 1928 presentations was defined based on risk (eg, reported penetration). Testing at presentation included chlamydia and gonorrhoea 1850, syphilis and BBV 1472, and after 2-6 weeks, 890 out of 1928 (46.2%) and after 3 months 881 out of 1928 (45.7%), respectively.

RESULTS

At presentation, 100 out of 1928 (5.2%) individuals were diagnosed with chlamydia, of those, 95 out of 1799 (5.3%) were female, and 5 out of 121 (4.1%) were male. Gonorrhoea was diagnosed in 7 out of 1920 (0.4%), 5 out of 95 female and 2 out of 5 male. Hepatitis B, which was all pre-existing, was diagnosed in 5 out of 1799 (0.3%). Overall, chlamydia prophylaxis was given to 203 out of 1928 (10.5%) and HIV post-exposure prophylaxis to 141 out of 1928 (7.3%).At 2-6 weeks of follow-up, 10 out of 890 (1.1%) individuals were diagnosed with chlamydia, with no gonorrhoea diagnosed. There were no cases of syphilis, hepatitis B or HIV diagnosed at 3-month serology testing in 881 individuals. Chlamydia detection at follow-up was more common in the group aged 15-29 years. Of those provided with chlamydia prophylaxis, 203 out of 1928, only 16 out of 203 (7.9%) were diagnosed with chlamydia.

CONCLUSIONS

The offer of STI testing is almost universally accepted by individuals presenting for post-sexual assault care. There were no identifiable factors to justify the routine use of chlamydia prophylaxis. STI testing provided an opportunity for screening and should remain part of the clinical care of people who report sexual assault.

Australian Sexual Health Service Users' Perspectives on Reducing the Oral Transmission of Bacterial STIs: A Qualitative Study

Growing rates of bacterial sexually transmitted infections (STIs) demand new approaches to STI prevention. Sexual practices involving saliva or direct contact with the mouth increase the risk of STI transmission, but community awareness remains largely unexplored in the literature. The Community Awareness and Surveillance of STI Transmission study sought to explore sexual health clinic attendees' awareness of oral STIs; experiences when seeking testing and treatment; and acceptable educational and clinical interventions. Twenty-one semi-structured interviews were conducted with a diverse group of Melbourne Sexual Health Center attendees'. Reflective thematic analysis was undertaken, revealing key themes across people of different genders, sexual identities, ages, and nationalities. All participants emphasized the importance of understanding how their sexual practices might put them at risk of an oral STI. They also sought care from specialist sexual health services with the expectation that health-care providers (HCPs) in these settings had more understanding of diverse sexual practices. Participants' decisions to protect themselves against oral STIs were primarily driven by the effect the decision had on pleasure and intimacy. Comfort during the health-care encounter and trust in HCPs facilitated better understanding of individual STI risk. Differences in awareness and risk reduction strategies were noted based on past experience with oral testing and STIs. These findings highlight the importance of HCPs and public health interventions providing solutions that recognize the central role of pleasure and intimacy in our sexual lives.

Safety Aspects and Rational Use of Single Intramuscular Dose Ceftriaxone: Clinical Insights on the Management of Uncomplicated Gonococcal Infections

Gonorrhea, a sexually transmitted infection caused by Neisseria gonorrhoeae, is a grave public health concern. Gonorrhea is the second most reported sexually transmitted infection worldwide. The treatment of uncomplicated gonococcal infections has evolved dramatically in response to the emergence of antimicrobial resistance. Multiple resistance mechanisms (for example, beta-lactamase production, antimicrobial efflux, and target site modification) exist, some of which may cause multidrug-resistance. Ceftriaxone was first recommended as an option for uncomplicated gonococcal infections in 1985, and it is now a mainstay of therapy in all clinical practice guidelines. Ceftriaxone has consistently shown high microbiologic cure rates in clinical trials, and it has demonstrated an excellent safety profile. Although its use may be limited in patients with hypersensitivity to penicillins, the risk of using ceftriaxone in such patients is overestimated. The emergence of reduced ceftriaxone susceptibility in N. gonorrhoeae, coupled with a lack of diverse treatment alternatives and the limited pipeline of new antimicrobials, is a significant threat to the treatment of gonorrhea.

People living with HIV who inject or have injected non-prescription drugs: Evidence of substantial differences in health inequalities and experiences of clinical care

INTRODUCTION

This study investigates differences in health and well-being associated with current, past or no injecting drug use (IDU) among people living with HIV (PLHIV) in Australia, identifying key health care considerations between injecting experiences.

METHODS

Data were extracted from the HIV Futures 9 study; a survey of PLHIV conducted in 2018-2019. Chi-square and analysis of variance analyses compared clinical and treatment characteristics, major physical and mental comorbidities, sexually transmitted infection diagnoses, and quality of life for those who reported current (last 12 months), past (12+ months ago) or no IDU.

RESULTS

Current IDU (n = 106) was associated with higher rates of sexually transmitted infection testing and diagnoses, higher frequency of self-reported antiretroviral therapy non-adherence due to drug use and greater social quality of life than past (n = 126) or no IDU (n = 508; total N = 740). Past and current IDUs were associated with more mental illness diagnoses and self-reported concern about drug use. Past IDU was associated with more physical comorbidities, lower satisfaction with clinical care and greater difficulty in affording health care than current or no IDU.

DISCUSSION AND CONCLUSIONS

Past and current IDUs are associated with unique health concerns. However, past IDU appears to be related to greater dissatisfaction in navigating health care than individuals with current IDU experience. Higher social connection and the types of services being accessed by individuals who currently inject may play a role in shaping service satisfaction. Peer-based interventions to help support individuals in accessing services that are affirming of their needs is an ongoing priority.

Cost-effectiveness of testing for Mycoplasma genitalium among men who have sex with men in Australia

OBJECTIVES

Mycoplasma genitalium (MG) disproportionately affects men who have sex with men (MSM). We determined the cost-effectiveness of different testing strategies for MG in MSM, taking a healthcare provider perspective.

METHODS

We used inputs from a dynamic transmission model of MG among MSM living in Australia in a decision tree model to evaluate the impact of four testing scenarios on MG incidence: (1) no one tested; (2) symptomatic MSM; (3) symptomatic and high-risk asymptomatic MSM; (4) all MSM. We calculated the incremental cost-effectiveness ratios (ICERs) using a willingness-to-pay threshold of $A30 000 per quality-adjusted life year (QALY) gained. We explored the impact of adding an antimicrobial resistance (AMR) tax (ie, additional cost per antibiotic consumed) to identify the threshold, whereby any testing for MG is no longer cost-effective.

RESULTS

Testing only symptomatic MSM is the most cost-effective (ICER $3677 per QALY gained) approach. Offering testing to all MSM is dominated (ie, higher costs and lower QALYs gained compared with other strategies). When the AMR tax per antibiotic given was above $150, any testing for MG was no longer cost-effective.

CONCLUSION

Testing only symptomatic MSM is the most cost-effective option, even when the potential costs associated with AMR are accounted for (up to $150 additional cost per antibiotic given). For pathogens like MG, where there are anticipated future costs related to AMR, we recommend models that test the impact of incorporating an AMR tax as they can change the results and conclusions of cost-effectiveness studies.

Syphilis in pregnancy: a qualitative investigation of healthcare provider perspectives on barriers to syphilis screening during pregnancy in south-east Queensland

BACKGROUND

Increasing rates of syphilis in pregnancy (SiP) in Australia and other high-income countries, has led to the resurgence of congenital syphilis. Suboptimal syphilis screening during pregnancy has been identified as a key contributing factor.

METHODS

This study aimed to explore, from the perspective of multidisciplinary healthcare providers (HCPs), the barriers to optimal screening during the antenatal care (ANC) pathway. Semi-structured interviews conducted with 34 HCPs across multiple disciplines practising in south-east Queensland (SEQ) were analysed through a process of reflexive thematic analysis.

RESULTS

Barriers were found to occur at the system level of ANC, through difficulties in patient engagement in care, limitations in the current model of health care delivery and limitations in the communication pathways across health care disciplines; and at the individual HCP level, through HCP knowledge and awareness of epidemiological changes in syphilis in SEQ, and adequately assessing patient risk.

CONCLUSION

It is imperative that the healthcare systems and HCPs involved in ANC address these barriers to improve screening in order to optimise management of women and prevent congenital syphilis cases in SEQ.

Antimicrobial susceptibility assays for Neisseria gonorrhoeae: a proof-of-principle population-based retrospective analysis

BACKGROUND

Neisseria gonorrhoeae treatment guided by molecular antimicrobial susceptibility assays could improve treatment options and antimicrobial stewardship; however, few commercial assays are available. We aimed to investigate antimicrobial susceptibility of N gonorrhoeae isolates in New South Wales, Australia, and estimate the potential usefulness of hypothetical combinations of rapid molecular antimicrobial susceptibility assays.

METHODS

In this proof-of-principle, population-based, retrospective analysis, we assessed N gonorrhoeae susceptibility data for ceftriaxone, azithromycin, ciprofloxacin, and penicillin. Isolates were previously collected as part of the Australian Gonococcal Surveillance Programme between Jan 1, 2008, and Dec 31, 2019. All cultured N gonorrhoeae isolates with susceptibility data to all four antimicrobials were included. However, only one isolate was included if several isolates originated from the same individual within 13 days of the previous isolate originating from that individual, and there were less than two standard double-dilution minimum inhibitory concentrations between the isolates. We assessed the use of different combinations of hypothetical antimicrobial susceptibility assays and treatment combinations in terms of their ability to minimise overall ceftriaxone use, and use specifically in isolates with decreased susceptibility to ceftriaxone, compared with standard non-assay-guided empirical ceftriaxone treatment.

FINDINGS

We included 23 089 N gonorrhoeae isolates. The prevalence of antimicrobial sensitivity fluctuated significantly during the study. Isolates with decreased susceptibility to ceftriaxone were more likely to be resistant to one or more antimicrobials than isolates without decreased susceptibility (782 [98·6%] of 793 vs 10 661 [47·8%] of 22 296), particularly ciprofloxacin (p<0·0001) and penicillin (p<0·0001). Compared with empirical ceftriaxone treatment, we estimated that strategies based on the use of hypothetical antimicrobial susceptibility would reduce ceftriaxone use (p<0·0001). However, because of co-resistance, most assay-directed treatment strategies, including those involving use of assays for two antibiotics, would result in only moderate reductions in ceftriaxone use among isolates with decreased susceptibility to ceftriaxone.

INTERPRETATION

Individualised treatment guided by molecular antimicrobial susceptibility diagnostics could help to reduce overall ceftriaxone use in gonorrhoea. However, the use of these assays needs to be informed by the non-random nature of co-resistance among circulating N gonorrhoeae strains.

FUNDING

Australian Government and Queensland Government.

Determinants and prediction of Chlamydia trachomatis re-testing and re-infection within 1 year among heterosexuals with chlamydia attending a sexual health clinic

Background

Chlamydia trachomatis (chlamydia) is one of the most common sexually transmitted infections (STI) globally, and re-infections are common. Current Australian guidelines recommend re-testing for chlamydia 3 months after treatment to identify possible re-infection. Patient-delivered partner therapy (PDPT) has been proposed to control chlamydia re-infection among heterosexuals. We aimed to identify determinants and the prediction of chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia to identify potential PDPT candidates.

Methods

Our baseline data included 5,806 heterosexuals with chlamydia aged ≥18 years and 2,070 re-tested for chlamydia within 1 year of their chlamydia diagnosis at the Melbourne Sexual Health Center from January 2, 2015, to May 15, 2020. We used routinely collected electronic health record (EHR) variables and machine-learning models to predict chlamydia re-testing and re-infection events. We also used logistic regression to investigate factors associated with chlamydia re-testing and re-infection.

Results

About 2,070 (36%) of 5,806 heterosexuals with chlamydia were re-tested for chlamydia within 1 year. Among those retested, 307 (15%) were re-infected. Multivariable logistic regression analysis showed that older age (≥35 years old), female, living with HIV, being a current sex worker, patient-delivered partner therapy users, and higher numbers of sex partners were associated with an increased chlamydia re-testing within 1 year. Multivariable logistic regression analysis also showed that younger age (18-24 years), male gender, and living with HIV were associated with an increased chlamydia re-infection within 1 year. The XGBoost model was the best model for predicting chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia; however, machine learning approaches and these self-reported answers from clients did not provide a good predictive value (AUC < 60.0%).

Conclusion

The low rate of chlamydia re-testing and high rate of chlamydia re-infection among heterosexuals with chlamydia highlights the need for further interventions. Better targeting of individuals more likely to be re-infected is needed to optimize the provision of PDPT and encourage the test of re-infection at 3 months.