Multidrug-resistant Tuberculosis in a Tertiary Hospital in North Sumatera, Indonesia : Clinical Predictors and Molecular Investigation

Abstract

Background: Multidrug-resistant tuberculosis (MDR-TB) is defined as a strain of Mycobacterium tuberculosis with resistance to at least the two major drugs used as first-line anti-tuberculosis drugs, namely rifampicin and isoniazid. The emergence of MDR-TB is a rapidly growing worldwide problem and it has become a crucial threat to tuberculosis (TB) control as well as the most important public health concern in many countries. MDR-TB causes socio-economic consequences to both individuals and society. MDR-TB treatment has become more complicated, more toxic, more expensive, and less effective than the medication of patients infected by susceptible strains. Indonesia, with an estimated population of 254 million in 2014, is listed as a high TB burden, high HIV burden and high MDR-TB burden country by the World Health Organization. In 2014 Indonesia was ranked as eighth among 27 "high burden" countries with MDR-TB cases worldwide, with an estimated 6,800 cases. This study aimed to determine the predictors of multi-drug resistance and analyse the genetic mutations pattern of the three major hot spots (codons 516, 526 and 531) of the rpoB gene, codon 315 of the katG gene, and the regulatory region of inhA by Multiplex-allele specific (MAS)-PCR and GenoType MTBDRplus assay from clinical isolates of pulmonary tuberculosis patients in a tertiary hospital in North Sumatera, Indonesia. Methods: This retrospective study was conducted in a tertiary referral teaching hospital in Medan, North Sumatera Province, Indonesia. Laboratory data and medical histories of all pulmonary tuberculosis patients attending the hospital were reviewed. Patients with culture positive for Mycobacterium tuberculosis and processed for drug-susceptibility testing (DST) to first-line anti-tuberculosis drugs between January 2010 and December 2013 were included. A total of 140 M. tuberculosis stored clinical isolates (54 MDR-TB and 86 Non MDR-TB) through routine clinical diagnosis were blindly tested to detect mutations using MAS-PCR assays and GenoType MTBDRplus. The genes involved were katG, inhA promoter and rpoB. Logistic regression was used to determine significant predictors of MDR- TB based on odds ratios (OR) and 95% confidence intervals (CI). The mutations of the three major hot spots (codons 516, 526 and 531) of the rpoB gene, codon 315 of the kate gene, were assessed by Multiplex-allele specific (MAS)-PCR and GenoType MTBDRplus assay using results of culture-based phenotypic drug susceptibility testing as the reference standard and DNA sequencing. Results: Of 6,174 patients with suspected pulmonary tuberculosis, 842 were confirmed positive by culture, of which DST results were reported for 765. Of these, 115 (15%) had diabetes mellitus, 73 (9.5%) were HIV-infected, and 98 (12.8%) were MDR-TB. Multivariate analysis indicated that patients with a history of previous tuberculosis treatment (OR = 3.75; 95% C.I. = 2.40 - 5.86 and aged 25 to 45 years (OR = 2.37; 95% C.I. = 1.07 - 5.27) were significant predictors of MDR-TB. Among 140 stored clinical isolates tested by MAS-PCR, mutation in rpoB gene was found at codons 531 (55.9%), 526 (36.8%) and 516 (4.4%) respectively. Compared with the drug susceptibility test, the sensitivity and specificity of MAS-PCR assay for rpoB gene mutation were 97.1% and 98.6%, respectively. Sixty-four (64) isolates tested by GenoType MTBDRplus assay showed mutation in the rpoB gene (73.4%), the katG gene (46.9%) and the promoter region of the inhA gene (7.8%). Conclusion: Previous tuberculosis treatment and age 25-45 years were significant predictors of MDR-TB. Treating patients with previous tuberculosis treatment based on DST results should therefore be considered. The profile of the MDR-TB isolates showed high frequency of mutations at codon 531 and 526 of rpoB gene and codon 315 of the katG gene.