More evidence, better diagnostics needed before redefining severe forms of drug-resistant TB

Reports of tuberculosis (TB) cases with severe patterns of drug resistance are increasing, said experts who attended a World Health Organization (WHO) meeting in Geneva March 21-22, 2012. Participants stressed that the emergence of drug resistance should be a wake-up call for Ministries of Health. The group urged the global TB community to make greater efforts to prevent drug resistance and scale up provision of appropriate care and management to avoid a scenario where TB becomes incurable. The meeting’s participants concluded that there is currently insufficient evidence to adopt new case definitions for drug-resistant TB. Drug susceptibility testing (DST), which is key to defining new levels of drug resistance, lacks accuracy for several of the drugs that are used to treat multi drug-resistant (MDR) and extensively drug resistant (XDR)-TB. Secondly, there is insufficient correlation of DST results with clinical response to treatment for several drugs currently used to treat XDR-TB. Thirdly,...