The World Health Organization's guidelines for treating multidrug-resistant tuberculosis include the use of at least five potentially effective drugs. However, a new PLOS Medicine prospective cohort study suggests adding a sixth drug to that cocktail was associated with a 36 percent greater likelihood of the bacteria responding to treatment.
Using information from more than 1,100 MDR-TB cases across nine countries, a CDC researcher also found that doing baseline drug susceptibility testing on a patient beforehand improved results. This type of testing helps to determine which treatments might help fight the infection, and selecting a regimen based on those results increased the likelihood of effectiveness by 65 percent. Adding drugs to the regimen that had not gone through susceptibility testing only benefited the patient if they were already receiving at least three drugs known to be effective.
Although the study was observational and based on patient data across many cases that didn't account for shared characteristics that could affect disease outcome or relapse information, the authors conclude that a change to the current MDR-TB WHO treatment guidelines could be beneficial. In general, more widespread use of rapid, high-quality drug susceptibility testing would likely help clinicians to design more effective regimens for individual patients, they wrote in a news release.