Molecular fingerprinting of multidrug-resistant mycobacterium tuberculosis strains in Beirut reveals genetic diversity and father to daughter transmission

ABSTRACT

The typing of six consecutive multidrug-resistant Mycobacterium tuberculosis strains isolated from patients with tuberculosis [TB] at the American University of Beirut Medical Center, was performed by touchdown double-repetitive-element [DRE]-PCR. The isolates exhibited four distinct patterns in DRE-PCR with three isolates exhibiting unique patterns and three isolates yielded similar DNA fragment patterns [cluster pattern]. Only two of the three cluster isolates exhibited identical patterns as revealed by restriction fragment length polymorphism [RFLP] targeting specific mutations in the rpoB and katG genes that confer resistance to rifampin and isoniazid, respectively. A direct epidemiological linkage for the two isolates exhibiting genotypic relatedness was also established as the isolates were recovered from a 33-year-old man and his 8-year-old daughter. The data show that transmission of multidrug-resistant M. tuberculosis strains is contributing to the emergence of drug-resistant TB in Beirut. Combining DRE-PCR with RFLP at the rpo B and katG genes could provide a powerful means for investigating the spread of multidrug-resistant M. tuberculosis strains in Lebanon