Antibiotic-resistant shigella strain cases soar in Australia

By Angela Betsaida B. Laguipo, BSNDec 19 2019

A drug-resistant strain of a highly contagious sexually-transmitted bowel infection spreads in Victoria, Australia, with a vast majority of cases happening in men who have sex with men.

A team of researchers has reported a Shigella strain circulating that’s resistant to all types of antibiotics. Their findings, which were published in the New England Journal of Medicine, show that from early 2018 to mid-2019, there were about 171 cases of the drug-resistant bacterial infection, compared to just a few cases from the previous year.

Rod-shaped bacteria Shigella which cause food-borne infection shigellosis or dysentery, 3D illustration Credit: Kateryna Kon / Shutterstock

Shigella is a gram-negative bacterium that causes an infection called shigellosis. Shigellosis causes bloody diarrhea or dysentery and can be passed through direct contact with the bacteria in the stool. In the new cases, the bacteria have been passed through sexual contact in gay or bisexual men. Shigellosis is highly contagious, causing about 190 million cases of diarrhea each year across the globe.

In the past, shigella infection is easily treated with oral antibiotics at home. However, the new strain identified by the Doherty Institute scientists in Melbourne is resistant to all oral antibiotics, prompting hospitalization and administration of antibiotics intravenously.

Shigellosis is common in children in low and middle-income countries due to the scarcity of clean water. The usual cause of the spread of the pathogen is due to poor sanitation and contaminated water or food. But in other countries, particularly first world countries, shigellosis is more common in travelers and in men who have sex with men, as it is also known as a sexually-transmitted disease.

"Just two or three bacteria can make you really sick, which is why it's so easily transmitted, particularly in men who have sex with men," Prof. Deborah Williamson, a professor at the University of Melbourne and the Deputy Director of the Microbiological Unit Public Health Laboratory at the Doherty Institute, said.

"In this study, we used whole-genome sequencing to show that all of the cases from the past year and a half are highly related to each other, which strongly suggests person-to-person transmission within specific sexual networks,” she added.

The researchers are unsure what’s behind the outbreak, but they suspect it may be tied to the increase of casual sex through online dating apps and the decreased fear of getting HIV due to the increasing number of people taking pre-exposure prophylaxis, PrEp. They also linked the increase in global travel to the surge of Shigellosis cases.

The best way to control the spread of the infection is to trace recent contacts. This way, doctors can treat all contacts of an infected person, especially if they had sexual intercourse. Further, improved surveillance and messaging can help trace all contacts and prevent the spread of the pathogen.

Since the new infection can’t be treated by oral antibiotics, the researchers recommend that patients be hospitalized to receive the right drug and route, so the bacteria won’t spread to other people. Also, doctors are concerned about the misuse of antibiotics, which leads to antibiotic resistance.

Antibiotic treatment should be given only in priority cases, such as those who have a severe illness, those who have weak immune systems, and those who work in high-risk settings. The researchers also urge the public to perform regular handwashing, observe proper hygiene and safe sex to reduce the risk of acquiring the infection. Employees who are infected should be excluded from work until symptoms are relieved.

What is Shigellosis?

Shigellosis is an infectious illness that’s caused by the bacteria Shigella, which causes a wide range of signs and symptoms, including stomach cramps, diarrhea, and fever after one to two days of exposure to the bacteria. Normally, the infection resolves within five to seven days.

Shigella infection is often contracted when a person visits a developing country, but it can also be transmitted when people come in contact with microscopic amounts of feces from an ill person. It can be spread through close personal contact, touching contaminated surfaces, nappies, and toys, and in some cases, it can spread through oral-anal sex.