STI Testing

Low coverage of prevention, testing, and treatment services for STIs during the pandemic has fueled a resurgence of these infections globally. Over 1 million new sexually transmitted infections are acquired worldwide every day, with the majority being asymptomatic.

The surge in STI cases post-COVID highlights the ongoing importance of stringent measures in the prevention, testing and treatment of STIs.

Below, we provide information for asymptomatic patient testing and highlight four common STIs: chlamydia, gonorrhoea, syphilis and trichomoniasis. We cover symptoms to look for, as well as testing and treatment recommendations. For more information on STIs, please download our brochures. 

Download Doctor STI BrochureDownload Patient STI Brochure

 
Testing guidelines for asymptomatic patients

Who to test

To determine risk, take a sexual history and offer STI screening to all patients who:¹

• Request STI testing
• Are at increased risk of an STI: unprotected sex, new sexual partner(s)
  or those living or travelling to areas of higher prevalence in Australia or other countries
• Have had a known exposure to any STI or a history of an STI within the past 12 months
• Are the partner of any of the above
  
  

Opportunistic testing

Due to the combination of the asymptomatic nature of many common STIs and young adults not presenting to their primary healthcare provider frequently, offering STI screening to patients at risk may need to be opportunistic.

In addition to the previous listing of patients to test, additional opportunities to offer STI screening to patients could include:

• Offering screening to female patients when they attend for their HPV screening from age 25. This is an ideal opportunity as testing for chlamydia and gonorrhoea can be performed on the same ThinPrep vial used to collect the Cervical Screening sample.
• Considering a repeat STI screen for women re-presenting for routine Cervical Screening at 30 years of age.
• Offering screening during contraceptive discussion appointments.
  
  

What to test:

• HIV (if recent exposure, repeat at 6 weeks), syphilis, and Hepatitis B virus (HBV), if immunisation status is not previously documented (blood tests).
• Gonorrhoea and chlamydia (urethral swabs, first-pass urine (FPU), and vaginal/endocervical swabs.
  Note: Vaginal/endocervical swabs are more sensitive than FPU samples in female patients).¹
  
  

Chlamydia

Chlamydial infection, caused by the bacterial pathogen Chlamydia trachomatis, is the most commonly reported communicable disease in Australia, and those under age 30 are most at risk. Frequently asymptomatic, particularly in women, chlamydia is simple to test and treat.

Symptoms

85-90% of individuals with chlamydia have no symptoms. However, if present, symptoms may include dysuria, penile urethral and vaginal discharge, testicular and pelvic pain, intermenstrual and postcoital bleeding, pain during sex and anorectal symptoms. Chlamydia can also cause a wide range of complications, including cervicitis, Pelvic Inflammatory Disease (PID), infertility, pregnancy-related complications (e.g., ectopic pregnancy), epididymo-orchitis, reactive arthritis and conjunctivitis.

Testing recommendations

Urethral swabs, first-pass urine (FPU) and vaginal/endocervical swabs. Note: Vaginal/endocervical swabs are more sensitive than FPU samples in female patients.

Additionally, an anorectal swab for patients with anorectal symptoms and all Men Who Have Sex with Men (MSM), along with pharyngeal swab for MSM. Due to the risk of coinfections, STI guidelines recommend that gonorrhoea testing should accompany chlamydia testing.

Treatment

Recommended first-line treatment for uncomplicated genital or pharyngeal infection for chlamydia is doxycycline 100 mg taken orally twice daily for 7 days. An alternative is a single dose of 1 gram oral azithromycin. To improve antibiotic stewardship, immediate treatment is not recommended for all sexual contacts of chlamydia. Instead, offer testing of exposed anatomical sites and await results.

Test of cure 

Testing for re-infection is recommended at 3 months. Consider testing for other STIs if not undertaken at first presentation.

Gonorrhoea

The bacterium Neisseria gonorrhoeae causes a disease spectrum very similar to that of chlamydia. In up to 3% of patients, bacteraemic (bloodstream) spread can result in disseminated gonorrhoea with presentations of septic arthritis, polyarthralgias or dermatitis. There was a concerning 16% increase in gonococcal infection notifications in Australia in 2023 (40,404) compared to 34,745 in 2019.

Symptoms

Up to 70% of women with genital gonococcal infection are asymptomatic, while approximately 80% of men present with mostly mild symptoms. Symptoms may include dysuria, penile urethral and vaginal discharge, conjunctivitis (purulent, sight-threatening) and dyspareunia with cervicitis. Anorectal symptoms may include discharge, irritation, painful defecation and disturbed bowel function. Gonorrhoea can also cause a wide range of complications such as pelvic inflammatory disease (dyspareunia, intermenstrual bleeding, post-coital bleeding, discharge), Bartholin gland abscess, and epididymoorchitis, although this is rare.

Testing recommendations

Urethral swabs, first-pass urine (FPU) and vaginal/endocervical swabs. Note: Vaginal/endocervical swabs are more sensitive than FPU samples in female patients.

Additionally, for Men Who Have Sex with Men (MSM), collect anorectal and pharyngeal swabs, even if patient is asymptomatic at these sites. Collect an additional penile urethral swab for culture if discharge is present or before antibiotics.

If patient has symptoms, collect a clinician-collected endocervical swab. Swabs should be collected for culture to enable resistance testing prior to treatment.

Due to the risk of co-infections, STI guidelines recommend that chlamydia testing should accompany gonorrhoea testing.

Treatment

Treatment depends on the site of infection. Please refer to the guidelines at sti.guidelines.org.au for treatments regarding uncomplicated genital and anorectal infections, uncomplicated pharyngeal infections and adult gonococcal conjunctivitis.

Test of cure 

Test of cure should be performed 2 weeks after completion of treatment. As re-infection is common, it is recommended that patients are tested again at 3 months.

If test of cure or re-infection testing is positive, please seek specialist advice.

Syphilis

Unfortunately, rates of syphilis are increasing in high income countries across the globe. In 2023, there were 6,451 cases of Syphilis < 2 years of duration in Australia, compared to 5,915 cases in 2019. This 9% increase is of concern, as a baby can contract congenital syphilis through transplacental transmission from its mother. The transmission rate is highest (60% to 90%) during untreated primary and secondary syphilis. There were 20 cases of congenital syphilis in Australia in 2023, compared to 4 in 2019, representing a concerning 400% increase.

Symptoms

Approximately 50% of individuals with syphilis have no symptoms. Often called the “Great Imitator,” syphilis can mimic many other conditions. Consider syphilis testing in all patients with unexplained symptoms.

Primary syphilis – on average 3 weeks post infection

• The presence of one or multiple genital, anal or oral ulcers that occur at the site of entry.

Secondary syphilis – more than 6 weeks post infection

• May include fever, malaise, headache and lymphadenopathy.
• Look for a generalised rash involving the trunk however, it may just affect the palms and soles. A skin rash occurs in over 90% of cases.

Testing recommendations

Syphilis should be excluded in all sexually active patients presenting with a rash. If the patient presents with a genital lesion, a swab for syphilis PCR as well as serology is recommended. If there is a clinical suspicion of primary syphilis but serology is negative, ensure a PCR swab has been completed and repeat serology after 2 weeks following presumptive treatment.

Treatment

For early syphilis, the recommended treatment is Benzathine penicillin 2.4 MU (1.8 g) administered as 2 intramuscular injections, each containing 1.2 MU (0.9 g). For late syphilis or syphilis of unknown duration, the treatment remains the same but is administered weekly for 3 weeks.

Test of cure 

Repeat testing at 3 months, 6 months and 12 months (if necessary) post-treatment.

Pregnancy: Offer routine syphilis testing at the first antenatal visit. Recommend follow-up testing at 28–32 weeks, dependent on local guidelines.

Trichomoniasis

Trichomoniasis is the most common curable, non-viral sexually transmitted infection (STI) worldwide. Caused by a single-celled protozoan parasite, Trichomonas vaginalis (TV), the estimated incidence of trichomoniasis among 15–49 year olds globally is said to be 156 million new cases in 2020 (WHO). However, the accurate incidence remains unknown as it is not a notifiable disease (exception being the Northern Territory), and the screening criteria are undefined. It has also been referred to as “The Neglected STI” due to the limited knowledge of its sequelae and associated costs.

Symptoms

• 70 to 80% have minimal or no genital symptoms
• Men may present with urethritis, epididymitis or prostatitis
• Women present with vaginal discharge, which can be profuse, malodorous or yellow-green
• Trichomoniasis in women with HIV is associated with increased risk of Pelvic Inflammatory Disease (PID)
  
  

Trichomonas vaginalis is associated with significant reproductive morbidity, including a greater likelihood of pre-term birth, premature rupture of membranes and small for gestational age infants. Trichomonas vaginalis infection is also associated with 1.5-fold increase in risk of HIV acquisition.

Testing recommendations

Wet-mount microscopy used to diagnose Trichomonas vaginalis infection, is an inexpensive Point-of-Care (POC) test. However, wet mounts have poor sensitivity (≤ 66%), which rapidly declines to 20% within one hour after collection. NAATs (Nucleic Acid Amplification Tests) provide a rapid and reproducible method to accurately diagnose Trichomonas vaginalis infections with sensitivity and specificity > 95% (95.2 – 100%) compared with wet mount and culture. A recent study from the Melbourne Sexual Health Clinic reported a statistically significant increase of 21% in Trichomonas vaginalis from 2011 to 2019 which was in part attributable to change in diagnostic methods form culture to NAAT. The significant improvement in Trichomonas vaginalis diagnosis utilising molecular methods has been widely recognised.

STI co-infections

Accurate rates of STI co-infections are often difficult to discern as the infections are notified separately. However, it is well recognised that persons at risk of STI acquisition are also at risk of co-infection with more than one STI. Co-infection of Chlamydia trachomatis in individuals diagnosed with Neisseria gonorrhoeae is well recognised.

In patients presenting with urethritis or other symptoms suspicious of a sexually transmitted infection, it is important to consider co-infections with other STIs. Multisite STI screening for multiple pathogens is recommended for sexually active adults at risk, to identify both symptomatic and asymptomatic infections.

 

^References

^{1. Australian STI Management Guidelines for use in Primary Care. https://sti.guidelines.org.au/ (Accessed 07 March 2024).}
 

Our expert pathologists:

Dr Sudha Pottumarthy-Boddu
MBBS FRCPA D(ABMM)

Lab: Osborne Park
Speciality: Clinical Microbiologist, microbiology
Areas of Interest: Antimicrobial susceptibility trends and molecular methods in the diagnosis of infectious diseases
Phone: 1300 134 111
Email: sudha.pottumarthyboddu@clinicallabs.com.au

Dr Sudha Pottumarthy-Boddu comes to us from Houston, Texas, where she was Assistant Professor in the Department of Pathology and Laboratory Medicine at the University of Texas, School of Medicine. She was also the Technical Director of the Clinical Laboratory Services at the Houston Department of Health and Human Services. After graduating from medical school in India, Dr Pottumarthy-Boddu migrated to New Zealand and completed her Pathology/Microbiology Fellowship training with the Royal College of Pathologists of Australasia. She is a recipient of various awards and scholarships, including the Neil Prentice Memorial Prize of RCPA. She is also a Diplomate of the American Board of Medical Microbiology. Over the last 10 years she gained experience in various hospital, research, and public health laboratories in the US, publishing over 30 articles in peer-reviewed journals and presenting at various national and international conferences. Detection of the first USA isolate of Enterobacter spp. with NmcAcarbapenem hydrolyzing enzyme and establishing clinical significance of Nocardia verterana are noteworthy. Dr Pottumarthy-Boddu’s main research interests are antimicrobial susceptibility trends and molecular methods in the diagnosis of infectious diseases.

Dr Stella Pendle
MSc MBBCh DTM&H FRCPA

Lab: Bella Vista
Speciality: Microbiology
Areas of Interest: General bacteriology, infectious serology, VRE and hepatitis
Phone: (02) 8887 9999
Email: stella.pendle@clinicallabs.com.au

Dr Pendle has been working as a Clinical Microbiologist in Australia since 2005, when she obtained her fellowship of the Royal College of Pathologists of Australasia (FRCPA). In 2012, she joined Australian Clinical Labs (formerly Healthscope Pathology) as Supervising Pathologist in charge of the microbiology, infectious serology, and molecular diagnostics departments. Dr Pendle has special interests in general bacteriology, infectious serology, syphilis, and hepatitis. She has published several papers in her fields of interest, including VRE, chlamydial infections, and HIV. She actively participates in hospital infection control and promotes rational antibiotic prescribing. She is a member of the Australasian Society for Infectious Diseases and the Antimicrobial Society of Australia.



Dr Linda Dreyer
MMBChB MMED (Path) (South Africa) FRCPA

Lab: Clayton
Speciality: Infection Control, Microbiology
Areas of Interest: Antimicrobials, infection control, and molecular diagnostic assays in
contemporary clinical microbiology
Phone: (03) 9538 6777
Email: linda.dreyer@clinicallabs.com.au

Dr Linda Dreyer completed her undergraduate studies in 1996, receiving a Bachelor’s degree in Medicine and Surgery (MBChB) from the Faculty of Health Sciences, University of Pretoria, South Africa. Following four years of clinical practice as a Medical Officer in the Department of Family Medicine, she commenced specialisation in 2000. She was appointed as Registrar in Clinical Virology at the University of Pretoria/Gauteng Province, where she worked for two years. In 2003, she was appointed as Senior Registrar in Microbiology. Dr Dreyer received her Master’s degree in Clinical Microbiology (MMed (Path)) from the University of Pretoria in 2006. She worked as a consultant for the National Health Laboratory Services (NHLS) in Pretoria until January 2008. During her time at NHLS, she was involved in teaching medical students and microbiology registrars, and gave lectures to nursing staff, medical students, and specialists. She also sat on the Infection Control Committee and the Antimicrobial Stewardship Committee of the Pretoria Academic Hospital. In 2008, she came to Melbourne and joined Australian Clinical Labs (formerly Healthscope Pathology) as a Senior Registrar, and obtained Fellowship of The Royal College of Pathologists of Australasia (FRCPA) in 2010. Dr Dreyer has special interests in the appropriate use of antimicrobials, infection control, and molecular diagnostic assays in contemporary clinical microbiology.