Two Treponema pallidum strains account for the majority of syphilis infections, including among females, in Queensland, Australia.

Abstract: An ongoing outbreak of syphilis in Australia, first reported in the state of Queensland in 2011, has led to increasing cases of congenital syphilis, including several deaths. Here, we applied multi-locus sequence typing (MLST) on available Treponema pallidum PCR-positive samples from the state of Queensland from the beginning of the outbreak to July 2020. In total, 393 samples from 337 males and 56 females were genotyped. Of 36 different Treponema pallidum sequence types (ST) observed, the two most common STs, ST 1 (also reported to be a dominant strain in various other countries) and ST 100 (the latter differing from ST 1 by only one single nucleotide polymorphism (SNP) based on the MLST scheme), together comprised 69% (271/393) of all samples, including the majority of samples in females (79%; 44/56). ST 1 was prevalent throughout the entire study period. Both strains remained the most common STs during the year 2020 where social distancing and other measures were implemented due to the COVID-19 pandemic. Both STs had high male-to-female ratios and included male rectal infections, therefore suggestive of occurrence primarily among men-who-have-sex-with-men (MSM). Hence, bridging from MSM to heterosexual networks may potentially contribute to infections among females, but further studies are needed to confirm this. Overall, there was considerable diversity of Treponema pallidum genotypes observed throughout the study period, but the fact that two key strains accounted for the majority of infections, including among females, stresses the need for further investigations into the transmission of these strains, and potentially a need for targeted public health interventions to better control the spread of syphilis in Queensland.

Addressing the crisis of congenital syphilis: Key findings from an evaluation of the management of syphilis in pregnancy and the newborn in South-East Queensland.

BACKGROUND: Syphilis in pregnancy and congenital syphilis (CS) are increasing in Australia. Prevention of adverse outcomes requires adherence to management guidelines. AIMS: The aim is to evaluate the management of syphilis in pregnant women and their newborns. MATERIALS AND METHODS: A retrospective study of public health notifications, clinical records and testing results of women with positive syphilis serology in pregnancy requiring treatment from 2016 to 2018 inclusive across South-East Queensland was conducted. Management was described and compared with contemporary guidelines from the Australasian Society of Infectious Diseases, the Communicable Diseases Network Australia and the United States Centers for Disease Control and Prevention. RESULTS: Of 30 women identified, 22 (73%) had management consistent with the guidelines (stage-appropriate penicillin regimen, appropriate dosing interval and treatment completed greater than 30 days before delivery). Only 14 (47%) women had documentation of partner testing and/or treatment. Of 26 mother-infant pairs with complete data, 16 (62%) had investigations at delivery consistent with recommendations (parallel maternal-infant rapid plasma reagin, infant syphilis immunoglobulin M, placental histopathology +/- syphilis polymerase chain reaction and infant clinical examination). One infant met the criteria for confirmed CS. Five infants received penicillin therapy. Only seven (27%) infants had serological monitoring after discharge. CONCLUSIONS: Management can be optimised with timely maternal testing and treatment, comprehensive partner screening and treatment, strict adherence to seven-day penicillin dosing for late latent syphilis and thorough maternal and infant testing after treatment and delivery. If maternal treatment was inadequate in pregnancy, consideration needs to be given to close evaluation and empiric treatment of the infant.