Tuberculosis Becoming More Drug-Resistant Worldwide

Scientists are discovering an alarming number of drug-resistant tuberculosis cases in Africa, Asia, Europe, and Latin America. The new TB strains are resistant to up to four powerful antibiotic drugs.

The large international study was published on Thursday in the Lancet medical journal, and shows that both multi drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) were higher than previously thought, threatening global efforts to curb the spread of the deadly disease, reports Reuters.

Sven Hoffner of the Swedish Institute for Communicable Disease Control, said of the study that:

“Most international recommendations for TB control have been developed for MDR-TB prevalence of up to around 5 percent. Yet now we face prevalence up to 10 times higher in some places, where almost half of the patients … are transmitting MDR strains.”

Tuberculosis has already been named a worldwide pandemic. It infected 8.8 million people in 2010, killing 1.4 million. Drug-resistant TB is more difficult and also more costly to treat than normal TB. It is also more fatal.

Treating normal tuberculosis is a long process already, and treating MDR-TB and SDR-TB takes even longer. Normal TB treatment requires patients to take a cocktail of powerful antibiotics for six months. Several patients fail to complete their treatment correct, which has fueled the rise of drug-resistant forms.

MDR-TB is resistant to at least two first-line drugs, called isoniazid and rifampicin , while SDR-TB is resistant to both drugs, plus a powerful antibiotic called fluoroquinolone, as well as a second-line injectable antibiotic.

ABC News notes that the study, called the Preserving Effective TB Treatment Study (PETTS), involved 1,278 MDR-TB patients from eight countries. The researchers discovered that 44 percent had already developed a resistance to the two first-line drugs, as well as at least one second-line drug. They also discovered that 6.7 percent had a resistance to at least two second-line drugs, making them classified as XDR-TB.

The strongest risk factor for developing a drug-resistant strain were previous treatment with second-line drugs (meaning that prior treatments were not effective and exacerbated the disease’s resistance), as well as unemployment, a history of imprisonment, alcohol abuse, and smoking.

The PETTS study was launched by the International Working Group on MDR tuberculosis. It was coordinated through health departments in Estonia, Latvia, Peru, Philippines, Russia, South Africa, South Korea and Thailand, and the drug-susceptibility testing was performed at the US Centers for Disease Control and Prevention.

Lead author Tracy Dalton of the Centers for Disease Control wrote in the report that, “The global emergency of extensively drug-resistant tuberculosis heralds the advent of widespread, virtually untreatable tuberculosis.”