Genotypic and phenotypic drug resistance of mycobacterium tuberculosis origins research methods

Aim and hypotesis: Tuberculosis is still one of the most common and deadly infectious diseases in the world. Early detection of bacillus in the sputum and treatment of the patients with appropriate drugs before contamination of others are the most important factors to control dissemination of tuberculosis. In the present study, tuberculosis cases admitted to our hospital and Aydın Tuberculosis Dispensary are included and demographic data, as well as rates of resistance to antituberculosis drugs and detection of mutations leading to resistance were studied to obtain data to guide the management of patients with tuberculosis in our region.Method: This study was done at Mycobacteria Laboratory of Department of Medical Microbiology, Adnan Menderes University Research Hospital, between 1th January 2009 and 1th June 2010. Sixty three (100,0 %) M. tuberculosis strains were isolated from 63 tuberculosis patients. NAP, IS6110 PCR, PCR-RFLP were used for identification of strains included in the study; BACTEC 460 TB (Becton Dickinson, USA) system was used for detection of antituberculosis drug resistance and Tuberculosis Resistance Kit (Autoimmun Diagnostika GmbH, Germany) was used for detection of resistance genes.Results: Among 63 (26,8%) patients included to present study 48 (76,2%) were male and 15 (23,8%) were female. The ages of patients were from 13 to 85 (mean 46,4 ± 18,5). The AFP results of patients showed that 45 patients (71,4 %) were AFB positive, and 18 (28,6 %) patients were AFP negative. Among 63 M. tuberculosis isolates 61 (96,8 %) were susceptible to antituberculosis drugs (isoniazid, rifampicin, ethambutol, streptomycin) with BACTEC 460 TB and in two isolates (3,2 %), resistance to antituberculosis drugs were detected: one isolate was resistant to isoniasid and one other strain was resistant to streptomycin (% 1,6). Multidrug-resistant tuberculosis was not detected with the BACTEC 460 TB. Presence of mutations that cause antituberculosis drug resistance was investigated with Tuberculosis Resistance Kit, and no mutation was detected in 47 (74,6 %) isolates. A total of 25 mutations were detected in the remaining 16 (25,4 %) isolates. A total of four isolates had mutation for only isoniazid resistance, two strains had mutations for only rifampicin resistance, two isolates had only quinolone resistance mutation, two isolates had both isoniazid and rifampicin resistance mutations two isolates had both isoniazid and quinolone resistance mutations, two strains had rifampicin and quinolone resistance mutations, one isolate carried both streptomycin and quinolone resistance mutations , and one strain had isoniazid, rifampicin and streptomycin resistance mutations. Of nine isolate with isoniasid resistance mutation, five had katG 315 mutation and, four had inhA 16,15,8 mutation. Of seven strains with rifampicin resistance mutation, two had rpoB 526 mutations, one had rpoB 513-516 mutation, one had rpoB 522-526 mutation, and one had rpoB 529-533 mutation. Of two strains with streptomycin resistance mutation, both had rpsL 43 mutations, and one had rpsL 88 mutation in addition. Of seven strains quinolon resistance mutations all had gyrA 90-94 mutations.Conclusion: Increasing drug resistance of Mycobacterium tuberculosis to antituberculosis drugs, the treatment can be made effective in preventing and makes it necessary to carry out sensitivity tests. In the treatment of tuberculosis is an important problem multidrug-resistant tuberculosis. Increase in cases of multidrug-resistant tuberculosis, difficult struggle with tuberculosis. Therefore, early detection of multidrug-resistant tuberculosis and the prevention of the spread of classical culture methods of susceptibility testing methods instead of a quick conclusion to be made in less time. Genotypic methods may be useful in epidemiological studies. However, phenotypic and genotypic methods should be used together for the mutation is not always reflected to phenotypic resistance.Keywords: Mycobacterium tuberculosis, Tuberculosis, Multidrug-resistant tuberculosis, BACTEC 460 TB, Tuberculosis Resistance Kit