Public health authorities in the UK have issued a warning about a highly drug-resistant strain of a serious bacterial gut infection that can be contracted through sex.
Between March and November last year, 17 cases of Shigella dysentery with resistance to several first-line antibiotics were detected.
It appears that transmission is clustered among gay and other men who have sex with men (MSM). Fourteen of the 17 UK cases involve men and nine further cases have been identified in the United States, all involving MSM.
Standard treatment with first line antibiotics such as azithromycin and ceftriaxone may not be effective, though other oral antibiotics will still work.
Shigella causes severe, prolonged diarrhoea and stomach cramps. It transmitted by contact with very small amounts of human faeces and can be passed on during certain sexual activities. Rimming, fingering, fisting, anal sex, handling sex toys after use in the anus, and occasionally oral sex can all carry a risk. The bacteria may pass from fingers to the mouth.
Symptoms typically occur within three days of exposure and include:
- Frequent diarrhoea lasting more than 48 hours.
- Stomach cramps.
- Fever.
- Vomiting.
- General weakness and tiredness.
Shigella can be especially serious in HIV-positive individuals who have a low CD4 count.
Individuals who have these symptoms should see their GP or a sexual health clinic, mentioning Shigella. The doctor should request a stool sample for appropriate tests (faecal PCR and culture).
The multi-drug resistant cases were identified between March and November last year. Eight of the cases were in London, but smaller numbers have also been diagnosed in all other UK regions.
Doctors treating patients with severe diarrhoea need to be aware of this predominately male cluster of multi-drug-resistant cases, and ask patients about their sexual activity and recent travel. If appropriate, samples should be obtained for laboratory testing to check for resistance. Enhanced public health surveillance has also been activated.
Symptoms of this strain of multi-drug-resistant Shigella typically include diarrhoea lasting for more than a week, despite treatment with antibiotics. Although resistant to several antibiotics, the strain remains susceptible to other drugs including chloramphenicol, ertapenem, temocillin, mecillinam and fosfomycin.
The risk of sexual transmission can be reduced by avoiding oral-faecal contact and by washing hands and showering after sex. Using protection for fingering, rimming and fisting, including gloves and changing condoms between anal and oral sex also help reduce the risk of transmission.
Public Health England have yet to assemble full information about the risk factors associated with contracting the drug-resistant strain. However, several behavioural characteristics were associated with a serious outbreak of Shigella among MSM in the UK in 2014, including:
- High numbers of sexual partners met online or at sex parties.
- Chemsex, especially the use of mephedrone, methamphetamine, ketamine and GBL.
- Injecting drug use.