New data from the UK Health Protection Agency (HPA) shows that the number of patients with drug-resistant Tuberculosis (TB) grew by 26% to 431 in 2011, up from 342 cases in the previous year.

Drug-resistant TB, when a patient fails to respond to one of the four main antibiotics used to treat the infection, accounted for 8.4% of the laboratory-confirmed cases in 2011.

Overall, 8963 cases of TB were reported to the HPA in 2011, up from 8,410 cases in 2010.

Professor Ibrahim Abubakar, HPA head of TB surveillance, insisted that cases of TB have been stabilising since 2005, but expressed concern over the increase in drug-resistant cases.

"The threat of multi-drug-resistant tuberculosis is spreading worldwide."

Patients usually acquire the drug-resistant disease either as a result of spread of a drug-resistant strain from another person or as a result of inappropriate or incomplete treatment.

Treatment outcome data revealed that 84% of patients completed their treatment in 2010.

Abubakar added: "TB continues to disproportionately affect those in hard to reach and vulnerable groups, particularly migrants. In order to reduce TB cases in the future, it’s very important that health commissioners, especially in parts of the country with the highest rates of TB, prioritise the delivery of appropriate clinical and public health TB services."

The threat of multi-drug-resistant tuberculosis is spreading worldwide. In June 2012, experts from the Johns Hopkins University School of Medicine in the US state of Maryland called for increased screening and more rapid testing of the 9 million people estimated to be infected with TB each year.

The call follows results of a survey, published in the New England Journal of Medicine, showing that the harder-to-treat TB variants are much more widespread than previously thought.

The survey of 4000 patients in China who were either newly diagnosed or recently treated for TB showed that one in ten was infected with drug-resistant strains of the lung disease.