Antibiotic Resistant Typhoid Spreads Even After Drug Control Regime: Study

Just curbing use of antibiotics is not enough to control the spread of drug resistant typhoid fever, claims a new study.

The study, conducted by researchers at the Oxford University Clinical Research Unit and colleagues, found that antibiotic-resistant strains of Salmonella Typhi can defeat drug-sensitive strains, even in the absence of the drugs.

Usually, developing resistance to a drug comes at a huge price for the bacterial strains. In the absence of the antibiotics, these drug-resistant strains are weaker than the sensitive strains and so can be defeated easily.

For this study the researchers developed 12 laboratory strains of Salmonella typhi bacteria that had one or more genetic mutations. These changes helped the strains develop resistance to the antibiotic therapy for typhoid fever-fluoroquinolone.

"When we grew different strains of Salmonella Typhi in the lab, we found that half of the antibiotic resistant strains had a growth advantage over their parent strain, even in the absence of antibiotic, enabling them to predominate in the population," Dr Maciej Boni, a Sir Henry Dale Fellow funded jointly by the Wellcome Trust and Royal Society at the Oxford University Clinical Research Unit in Vietnam, who co-led the study, said in a news release.

Typhoid fever is associated with bad sanitation and is transmitted through food and water contaminated with Salmonella typhi. The disease can be treated, but there is a widespread resistance to the drug. Typhoid infects the gut and bloodstream and leads to fever that touch temperatures of 39 degree to 40 degree C. It can also cause constipation and diarrhea along with spots on chest, confusion and perforation of the gut.

Each year, nearly 21 million cases of typhoid fever are reported worldwide and when untreated, one in five people die. Those who survive are most likely to suffer from physical or mental disabilities. According to the World Health Organization, 90 percent of the typhoid deaths occur in Asia and the disease is mainly seen in children below age of five.

Dr Jimmy Whitworth, Head of International Activities at the Wellcome Trust concluded saying, "These important findings from researchers in Vietnam are very worrying. If confirmed, one of our main strategies for controlling drug-resistance in typhoid will be ineffective. We will need to concentrate on developing more effective and affordable vaccines, and improving water supplies and sanitation, a Herculean task for low and middle income countries."