The spectrum of primary drug resistance of Mycobacterium tuberculosis in patients with tuberculosis in relation to human immunodeficiency virus status
Aim. To estimate the detection rate and spectrum of primary drug resistance of Mycobacterium tuberculosis (MBT) in patients with tuberculosis (TB) in relation to their human immunodeficiency virus (HIV) status in a region with high HIV infection rates (the Perm Territory) and to compare of drug-resistant MBT (DR-MBT) in patients with HIV/TB co-infection, by using phenotypic and molecular genetic testing (MGT) methods. Subjects and methods. The results of sputum bacteriological examination were analyzed in 178 HIV-infected patients and 354 non-HIV-infected individuals with a TB diagnosis made in the period July 1, 2014 to August 1, 2015. The diagnostic algorithm for all patients involved a duplicate sputum test for MBT by two techniques: fluorescence microscopy (FM) and inoculation into the Levenstein-Jensen dense culture medium. In patients with HIV/TB, the bacteriological examination was complemented with two more methods: detection of MBT DNA by a real-time polymerase chain reaction assay using the AmpliTube-RV system (Synthol, Russia); and inoculation into the Middlebrook liquid nutrient medium, by applying the automated BACTEC MGIT 960 system. Results. In patients with HIV/TB, the sensitivity of FM proved to be lower than in those with TB (24.2 and 32.8%, respectively; p<0.05) and that of inoculations into the dense culture medium was comparable regardless of HIV status (60.7 and 57.1%, respectively; p>0.05). The primary drug resistance of MBT in patients with HIV-TB was higher than that in HIV-negative individuals (60.2 and 41.6%, respectively; p<0.05). The phenotypic method (inoculation into the Levenstein-Jensen culture medium) and MGT revealed their agreement for the resistance of MBT to rifampicin (the most clinically significant drug in the choice of treatment policy) in 88.5% of the patients with HIV/TB. Conclusion. In patients with HIV/TB, the sensitivity of FM for detecting acid-resistant mycobacteria was lower than in those with TB and that of inoculations into the dense medium was comparable regardless of HIV status.