PT  - JOURNAL ARTICLE
AU  - S. Hofmann-Thiel
AU  - J. van Ingen
AU  - K. Feldmann
AU  - L. Turaev
AU  - G. T. Uzakova
AU  - G. Murmusaeva
AU  - D. van Soolingen
AU  - H. Hoffmann
TI  - Mechanisms of heteroresistance to isoniazid and rifampin of <em>Mycobacterium tuberculosis</em> in Tashkent, Uzbekistan
AID  - 10.1183/09031936.00089808
DP  - 2009 Feb 01
TA  - European Respiratory Journal
PG  - 368--374
VI  - 33
IP  - 2
4099  - http://erj.ersjournals.com/content/33/2/368.short
4100  - http://erj.ersjournals.com/content/33/2/368.full
SO  - Eur Respir J2009 Feb 01; 33
AB  - Heteroresistance of Mycobacterium tuberculosis (MTB) is defined as the coexistence of susceptible and resistant organisms to anti-tuberculosis (TB) drugs in the same patient. Heteroresistance of MTB is considered a preliminary stage to full resistance. To date, no mechanism causing heteroresistance of MTB has been proven. Clinical specimens and cultures from 35 TB patients from Tashkent, Uzbekistan, were analysed using the Genotype MTBDR assay (Hain Lifescience, Nehren, Germany), which is designed to detect genetic mutations associated with resistance to rifampin and isoniazid. Cases of heteroresistance were further subjected to genotyping using mycobacterial interspersed repetitive unit-variable-number tandem repeat typing, spoligotyping and IS6110 fingerprinting. Heteroresistance to rifampin and/or isoniazid was found in seven cases (20%). In five of them, heteroresistance was caused by two different strains and in two by a single strain of the Beijing genotype. The latter cases had a history of relapse of their TB. For the first time, two different mechanisms of heteroresistance in tuberculosis have been proven using a stepwise molecular-biological approach: 1) superinfection with two different strains, which is of interest for clinical infection control practitioners; and 2) splitting of a single strain into susceptible and resistant organisms. The latter mechanism is most likely to be related to poor treatment quality and could serve as a quality marker for tuberculosis therapy programmes in the future.