Worldwide Emergence of Extensively Drug-resistant Tuberculosis

Abstract

Mycobacterium tuberculosis strains that are resistant to an increasing number of second-line drugs used to treat multidrug-resistant tuberculosis (MDR TB) are becoming a threat to public health worldwide. We surveyed the Network of Supranational Reference Laboratories for M. tuberculosis isolates that were resistant to second-line anti-TB drugs during 2000-2004. We defined extensively drug-resistant TB (XDR TB) as MDR TB with further resistance to >3 of the 6 classes of second-line drugs. Of 23 eligible laboratories, 14 (61%) contributed data on 17,690 isolates, which reflected drug susceptibility results from 48 countries. Of 3,520 (19.9%) MDR TB isolates, 347 (9.9%) met criteria for XDR TB. Further investigation of population-based trends and expanded efforts to prevent drug resistance and effectively treat patients with MDR TB are crucial for protection of public health and control of TB. These drugs are more costly, toxic, and less effective than first-line drugs used for routine treatment of TB (3-6). As with other diseases, resistance to TB drugs results primarily from nonadherence by patients, incorrect drug prescribing by providers, poor quality drugs, or erratic supply of drugs (7).To facilitate treatment of MDR TB in resource-limited countries, where most TB cases occur (1,2), the World Health Organization (WHO) and its partners developed the Green Light Committee, which helps ensure proper use of second-line drugs, to prevent further drug resistance (8). Nonetheless, the Green Light Committee encountered numerous anecdotal reports of MDR TB cases with resistance to most second-line drugs. Once a strain has developed resistance to second-line drugs, these new TB strains are even more difficult to treat with existing drugs. Untreated or inadequately treated patients are at increased risk of spreading their disease in the community, which could lead to outbreaks in vulnerable populations and widespread emergence of a lethal, costly epidemic of drugresistant TB, reminiscent of the MDR TB outbreaks in the early 1990s (9-13). Therefore, to determine whether these anecdotal reports were isolated events, early evidence of an emerging epidemic, or the occurrence of virtually

Protein denaturation and protein:drugs interactions from intrinsic protein fluorescence measurements at the nanolitre scale

“…1 The need is increasingly pressing because previously containable pathogenic organisms such as Mycobacterium tuberculosis, the seventh leading cause of death worldwide, 2 Clostridium difficiles, and Streptococcus aureus continue to develop multidrug resistance. At the same time, new targets are being identified through genome sequencing and proteomics at an increasing pace.…”

First Insight Into the Fluoroquinolone and Aminoglycoside Resistance of Multidrug-Resistant Mycobacterium tuberculosis in Saudi Arabia

“…The drug resistance pattern showed a higher rate of panresistant isolates (50.6%) which is very high compared with previous large-scale studies and an indicative factor of XDR-TB emergence. [28][29][30] Mutation analysis of RIF resistance showed a domination of rpoB codon 531 (77.1%) followed by codon 526 (13.2%). This finding distinctly reflects the conclusions of one of our recent nationwide study and other reports which showed high rate of mutation in codon 531 as the main cause of RIF resistance in Saudi Arabia.…”

Prevalence of Multi-Drug Resistant (MDR) pulmonary tuberculosis in a tertiary care hospital of Narshingdi, Bangladesh

“…Tuberculosis is a common and in many cases lethal infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis 1 . Tuberculosis usually attacks the lungs but can also affect other parts of the body 2 .…”