Evidenziazione molecolare di resistenza di Mycobacterium tuberculosis complex a rifampicina e isoniazide

From June 2004 to June 2005, a total of 58 mycobacterial isolates were recovered from inpatients admitted to the “Ospedale Maggiore” in Novara, Italy. Most of the above strains were from respiratory secretions. Among the 32 isolates identified as Mycobacterium tuberculosis complex (MTC), susceptibility testing to streptomycin, isoniazid, rifampin, ethambutol and pyrazinamide was subsequently performed by using the MGIT 960 system. Starting from positive cultures, the Genotype MTBDR “Arnika” test, based on target amplification and stripbased reverse hybridization was also carried out. In addition to the MTC identification, the test can investigate the resistance to both rifampin (by molecular analysis of the rpoB region) and isoniazid (by detecting mutations at the resistance domain of katG gene). The results were compared with those obtained by conventional liquid medium susceptibility testing. Full agreement with both drugs was obtained on all the tested isolates. In conclusion, the GenoType MTBDR assay was found to enable a very rapid resistance detection of the most important anti-tubercular drugs.These data are important to set up an effective therapy and consequent disease control.