Current problems of drug-resistant tuberculosis and its control.
Drug resistance emerges wherever and whenever the microbial environment favors the selective growth of drug-resistant mutants. The programmatic errors that lead to the development of drug resistance are inappropriate regimens, non-adherence to therapy by the patients, the sale and availability of over-the-counter drugs, an interruption in the drug supply, and the unavailability of free diagnosis and treatment. As a result, drug-resistant organisms are spread in the community, generating secondary cases with primary drug resistance, which in turn can spread and generate further cases. The uninterrupted cycle of creation and spreading is responsible for increases in DR. According to global data on anti-tuberculosis drug resistance appearing in the WHO monographs, drug resistance is so ubiquitous as to be encountered in every country. Anti-TB DR among previously treated cases was found to be very high in some countries, while it remained relatively low in others. The median of at least one drug resistance among four major drugs tested, was 25.2% (ranging from 8.3 to 68.5%), and the median MDR-TB was 8.7% (ranging from 0 to 48.2%) among those previously treated patients. Drug resistance among new cases infected with drug-resistant organisms from patients with acquired or primary drug resistance was found to be higher in some areas than in others. The median of at least one drug resistance was 10.9% (ranging from 1.7 to 40.6%) and MDR-TB of 1.1% (ranging from 0 to 14.1%). Twelve geographic areas had levels of 3% or more of MDR-TB among new cases. The majority of MDR-TB cases end up as incurable and spread these deadly organisms in the community, as indicated by several outbreaks in certain areas. Increased MDR-TB will seriously threaten TB control programs in the future. We must therefore exert our best efforts to prevent the further generation of such cases by improving the cure rate of newly diagnosed cases, and by aggressively intervening to identify and remove MDR-TB cases as soon as possible.
Kim
Sang Jae
SJ
Tuberculosis Strategy & Operations, Stop TB Department, World Health Organization, 20 Avenue Appia, CH-1211 Geneva, Switzerland. Kims@who.int
D024901:Drug Resistance, Multiple, Bacterial; D014943:Global Health; D006801:Humans; D009169:Mycobacterium tuberculosis; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control