Abstract
BackgroundPyrazinamide (PZA) is an important component of first-line drugs because of its distinctive capability to kill subpopulations of persistent Mycobacterium tuberculosis (MTB). The prodrug (PZA) is converted to its active form, pyrazinoic acid (POA) by MTB pncA-encoded pyrazinamidase (PZase). Mutation in pncA is the most common and primary cause of PZA resistance. The aim of the present study was to explore the molecular characterization of PZA resistance in a Pashtun-dominated region of Khyber Pakhtunkhwa, Pakistan.MethodsWe performed drug susceptibility testing (DST) on 753 culture-positive isolates collected from the Provincial Tuberculosis Control Program Khyber Pakhtunkhwa using the BACTEC MGIT 960 PZA method. In addition, the pncA gene was sequenced in PZA-resistant isolates, and PZA susceptibility testing results were used to determine the sensitivity and specificity of pncA gene mutations.ResultsA total of 69 isolates were PZA resistant (14.8%). Mutations were investigated in 69 resistant, 26 susceptible and one H37Rv isolates by sequencing. Thirty-six different mutations were identified in PZA-resistant isolates, with fifteen mutations, including 194_203delCCTCGTCGTG and 317_318delTC, that have not been reported in TBDRM and GMTV Databases and previous studies. Mutations Lys96Thr and Ser179Gly were found in the maximum number of isolates (n = 4 each). We did not detect mutations in sensitive isolates, except for the synonymous mutation 195C > T (Ser65Ser). The sensitivity and specificity of the pncA sequencing method were 79.31% (95% CI, 69.29 to 87.25%) and 86.67% (95% CI, 69.28 to 96.24%).ConclusionMutations in the pncA gene in circulating isolates of geographically distinct regions, especially in high-burden countries, should be investigated for better control and management of drug-resistant TB. Molecular methods for the investigation of PZA resistance are better than DST.
Highlights
Pyrazinamide (PZA) is an important component of first-line drugs because of its distinctive capability to kill subpopulations of persistent Mycobacterium tuberculosis (MTB)
The supernatant was transferred to a fresh tube containing 5% phenol, while the pellet was mixed with phosphate buffer and cultured on Lowenstein–Jensen medium (LJ) in MGIT tubes containing 7H9 media
Socio-demographic characteristics A total of 4518 samples were collected from TB subjects from all districts of Khyber Pakhtunkhwa (KPK)
Summary
Pyrazinamide (PZA) is an important component of first-line drugs because of its distinctive capability to kill subpopulations of persistent Mycobacterium tuberculosis (MTB). Mutation in pncA is the most common and primary cause of PZA resistance. Tuberculosis (TB) is a common life-threatening infectious disease caused by Mycobacterium tuberculosis (MTB) [1]. The misuse of these antibiotics has led to the emergence of multidrug-resistant (MDR) strains of MTB [3]. The incidence of drug resistance (MDR/RR-TB) is twenty-six thousand (16–36) with 14 (8.5–19) per hundred thousand individuals in a population. This situation leaves a high challenge to the TB control program in the country
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