Post by The Lancet Infectious Diseases

🔥 A new study shows marked differences in growth, spread, and antimicrobial resistance (AMR) between sexually and non-sexually transmitting shigellosis in the UK. 🦠Julie Marshall and colleagues conducted a genetic epidemiological study using UK Health Security Agency national genomic surveillance data from 138 laboratories across 15 health regions (n=3,514 isolates) to examine the transmission pathways of Shigella sonnei between 2004 and 2020. Authors quantified and compared geospatial spread, transmission intensity, and phylogenetic strain and AMR dynamics across different demographic groups [high-risk travel, pMSM (presumptive men who have sex with men), and non-pMSM; the primary outcome]. Authors also evaluated the relative influence of AMR on pathogen dynamics in demographic groups and the emergence of an extensively drug-resistant S sonnei clade collected in England between Jan 1, 2016, and Dec 30, 2021, as a secondary analysis. 📊 Sexually transmitted strains of Shigella spread more than twice as fast across geographical distances as non-sexually transmitted strains- after around 2.5 years, related sexually transmitted cases were on average 117 km apart, compared with 46 km for non-sexually transmitted cases.  In addition, S sonnei transmitted more intensively among pMSM with 100 more transmission chains for a given population than among other S sonnei acquisition pathways (95% CI 41–171, p=0·0020). AMR to at least one clinically relevant antibiotic was highest among sexually transmitted strains at 69%, compared with 40% among non-sexually transmitted strains and 49% among travel cases. The study also found evidence of ‘bystander resistance’, resistance in Shigella driven by antibiotic treatment for other co-occurring sexually transmitted infections such as gonorrhoea. However, this reduced significantly after 2018 when gonorrhoea treatment guidelines changed. 💡 Improved handwashing and food hygiene will have little impact on sexually transmitting shigellosis.  Sexually transmitting shigellosis is an increasing, distinct public health threat which urgently needs exploration of other preventative measures and increased awareness. Despite an active pipeline of Shigella vaccine candidates, no Shigella vaccine is currently available for use. Read the full paper here: https://bit.ly/4gx1vDU #Shigellosis, #sexualtransmission, #AMR, #menwhohavesexwithmen Noémie Lefrancq, Lewis C. E. Mason, Fariha Jawed, Yi Ling Tam, Claire Jenkins, Henrik Salje, Kate Baker