New vaccine for deadly gut infection being tested

SINGAPORE — Potentially life-threatening infections caused by a gut bug that has plagued hospitals worldwide could soon be a thing of the past. A vaccine is currently being tested in a Phase III clinical trial in 17 countries, including Singapore.

A study conducted at National University Hospital (NUH) in 2012 found that an average of one Clostridium difficile (C. difficile) case occurs in every 1,000 patients in a hospital every day.

There are currently no formal statistics on C. difficile infections in Singapore.

In the United States, almost half a million people are infected with C. difficile each year, according to a Centres for Disease Control and Prevention (CDC) study released in February. The infection can cause diarrhoea and inflammation of the colon.

The majority of the infections occur when patients receive medical care in hospitals or nursing homes.

The C. difficile bacteria, found in infected patients’ faeces, is notoriously hardy. It produces spores that can survive outside the body and on all kinds of surfaces for long periods of time, and is passed through contact with contaminated surfaces.

This means it can easily spread from patient to patient in hospitals and nursing homes, said Professor Leo Yee Sin, director of Institute of Infectious Diseases and Epidemiology at Tan Tock Seng Hospital.

“Eliminating the spores is extremely difficult as they can survive routine cleaning using soap and water, as well as hand sanitisation using alcohol-based gels,” said Prof Leo.

An infected person may suffer symptoms ranging from mild watery stools to severe diarrhoea with dehydration, which may then spark off a host of other life-threatening complications, including organ damage.

“In cases where the gut is severely inflamed, it becomes fragile. Bleeding can occur and the gut can perforate or break, and the patient may die from sepsis,” said Prof Leo.

Recurrent infections are also a “huge problem”, and this is another reason for an effective vaccine, said Professor Paul Anantharajah Tambyah, a senior consultant at Division of Infectious Diseases at NUH.

The vaccine was developed by pharmaceutical company Sanofi Pasteur. Researchers are in the midst of recruiting up to 15,000 adults, aged 50 years or older (see box), who are at risk of C. difficile infections.

“The vaccine is designed to produce an immune response that targets the toxins generated by the C. difficile bacteria. Ultimately, it may help prevent a future infection from occurring,” said Prof Tambyah, one of Singapore’s principal investigators for the trial.

The vaccine is targeted at the elderly who are undergoing planned surgery, as well as adults with multiple diseases that require frequent and/or prolonged antibiotic use and recurrent hospital admissions — factors that would place them at risk of contracting the infection, said Prof Tambyah.

OLDER PATIENTS hit HARD

Older patients generally have a higher risk of getting C. difficile infections, as well as dying from complications, said Prof Tambyah. Other at-risk groups include those who are staying in hospitals or nursing homes for long periods of time.

“The risk of infection increases the longer the patient stays in the hospital because there is a higher likelihood of being exposed to C. difficile spores,” said Dr Leo.

Although younger adults can get C. difficile infections too, more than 80 per cent of deaths occur in those aged 65 years and older, according to the CDC. Especially at risk are those on antibiotics, which can disrupt a gut’s normal flora.

Prof Leo explained: “C. difficile bacteria in the gut are usually controlled by the presence of other harmless bacteria. When those ‘good’ bacteria are wiped out by antibiotics, C. difficile may start to increase and produce toxins that cause disease.”

Antibiotic misuse may be one of the main driving forces for the increase in resistant forms of C. difficile. A 2014 Vital Signs report from the CDC found that a 30 per cent decrease in the use of antibiotics linked to C. difficile infections in hospitals could reduce the incidence of deadly infections by more than 25 per cent.

The infection can be treated with a course of antibiotics, albeit a different one from which the patient was previously exposed to.

Faecal transplants, where the patient receives healthy gut bacteria from a donor, have also been used as a form of treatment for severe cases of infections. Rarely do doctors have to resort to surgery to remove the whole colon, said Prof Tambyah.

Correction: In an earlier version of this story, we had wrongly attributed a quote. We have corrected it and are sorry for the error.