ABSTRACT
Data on the genetic variation of isolates of Mycobacterium tuberculosis and spectrum of mutations determining resistance to principal anti-tuberculosis drugs isoniazid (INH) and rifampicin (RIF) have not yet been studied in Saudi Arabia. One hundred and fifty-one clinical isolates of M. tuberculosis from different regions in the country showing resistance to RIF and INH were subjected to drug susceptibility testing, characterization of mutations conferring drug resistance and genotyping. Phenotypically 17 (11.3%) isolates were resistance to RIF, 75 (49.6%) were resistant to INH and 59 (39.1%) were resistant to both RIF and INH, respectively. Sixteen (10.6%), 74 (49%) and 56 (37.1%) were determined as resistant to RIF, INH and to both by line probe assay. High frequency of rpoB 531 mutations (67.1%) in RIF resistant strains and katG 315 mutations (65.2%) in INH resistant strains were found. Mutations responsible for INH resistance, katG 315 (P value<0.001, odds ratio: 1.81, 95% CI [1.51, 2.18]) and inhA-15 (P value - 0.004, odds ratio: 1.48, 95% CI [1.22, 1.8]) were predominant among the newly diagnosed cases. Beijing strains were significantly associated with multi drug resistance and mutations in combination of rpoB531 and katG315 (P value - <0.001, odds ratio: 6.83, 95% CI [2.65, 17.58]). In addition multi drug resistance was significantly associated with treatment history (P value<0.001, odds ratio: 3.16, 95% CI [2.14, 4.67]). Furthermore, a higher rate (39.3%) of clustering among the multidrug resistant strains particularly with Beijing family (52.9%) was observed. Saudi Arabia harbors highly diverse drug resistant M. tuberculosis population with an ongoing transmission which needs to be immediately managed.
Subject(s)
Drug Resistance, Multiple, Bacterial , Isoniazid/pharmacology , Mutation , Mycobacterium tuberculosis/genetics , Rifampin/pharmacology , Adolescent , Adult , Aged , Aged, 80 and over , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Catalase/genetics , Catalase/metabolism , Cluster Analysis , DNA, Bacterial/genetics , DNA, Bacterial/metabolism , DNA-Directed RNA Polymerases , Female , Genetic Variation , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/isolation & purification , Odds Ratio , Saudi Arabia/epidemiology , Tuberculosis/diagnosis , Tuberculosis/epidemiology , Tuberculosis/microbiology , Young AdultABSTRACT
The commercially available line probe assay MTBDRplus 2.0 (Hain Lifescience, Nehren, Germany) was evaluated for its ability to detect Mycobacterium tuberculosis complex (MTBC) and mutations conferring resistance to rifampin (RMP) and isoniazid (INH) directly in smear-negative and smear-positive pulmonary clinical specimens under routine laboratory conditions. A total of 348 samples originating from Moldova, a high-incidence country for tuberculosis (TB), were investigated. Two hundred fifty-seven (73.9%) were smear negative, 12 samples were excluded, and 81 (23.3%) were smear positive. Two DNA extraction methods were applied. Compared to culture and clinical data as the reference standard (adapted from Vadwai V et al., J. Clin. Microbiol. 49:2540-2545, 2011), overall sensitivity and specificity were 87.6 and 99.2%, respectively. One hundred four of the 257 smear-negative samples turned out to be culture positive, and 20 were MTBC culture negative but were positive based on clinical symptoms. The combined sensitivity and specificity in the subgroup of smear-negative samples were calculated to be 79.8 and 99.2%, respectively. MTBDRplus 2.0 detected RMP and INH resistance with sensitivity and specificity of 94.3 and 96.0%, respectively. In conclusion, the MTBDRplus 2.0 assay is a rapid and highly sensitive test for the detection of M. tuberculosis strains from smear-positive and -negative clinical specimens and provides additional information on RMP and INH resistance status, which can easily be included in routine laboratory work flow.
