Abstract

In Nigeria, one of the highest tuberculosis (TB) burdened nations, sputum smear microscopy is routinely employed for TB diagnosis at Directly Observed Treatment Short-Course (DOTS) Centers. This diagnostic algorithm does not differentiate Mycobacterium tuberculosis complex (MTC) from nontuberculous mycobacteria (NTM). Between December 2008 and January 2009, consecutive patients diagnosed with TB were screened for inclusion at 10 DOTS centers in Ibadan, Nigeria. To verify Mycobacterium species in patients diagnosed, we cultured and identified mycobacterial isolates using PCR, line probe assay, and spoligotyping techniques. From 48 patients screened, 23 met the inclusion criteria for the study. All the 23 study patients had a positive culture. Overall, we identified 11/23 patients (48%) with MTC only, 9/23 (39%) with NTM only, and 3/23 (13%) with evidence of both MTC and NTM. Strains of MTC identified were Latin American Mediterranean (LAM) genotype (n = 12), M. africanum (n = 1), and the genotype family T (n = 1). Four M. avium-intracellulare-M. scrofulaceum complexes, one M. chelonae complex, one M. abscessus, and one M. intracellulare were identified. Our findings underscore the need to incorporate molecular techniques for more precise diagnosis of TB at DOTS centers to improve clinical outcomes and safe guard public health, particularly in TB endemic countries.

Highlights

  • For several years, Nigeria has remained in the league of the highest TB burdened nations of the world and is currently ranked 4th globally [1]

  • To explore whether misdiagnosis is a problem in Nigeria, we cultured sputum and conducted molecular characterization of acid fast isolates in patients already diagnosed with TB based on the local diagnostic algorithm at Directly Observed Treatment Short-Course (DOTS) centers in Ibadan, Southwestern Nigeria

  • Based on morphological growths on Middlebrook 7H11 agar culture plates and the molecular analyses, we identified 11/23 patients (48%) with Mycobacterium tuberculosis complex (MTC) only, 9/23 (39%) with nontuberculous mycobacteria (NTM) only, and 3/23 (13%) with evidence of both MTC and NTM bacteria present (Table 1)

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Summary

Introduction

Nigeria has remained in the league of the highest TB burdened nations of the world and is currently ranked 4th globally [1]. Treatment Short-Course (DOTS) Centers in Nigeria [2]. The diagnostic algorithm entails interpreting presence of acid fast bacilli in sputum smear microscopy as TB. This algorithm does not differentiate Mycobacterium tuberculosis complex (MTC) from nontuberculous mycobacteria (NTM) [3], which are ubiquitous environmental mycobacteria [4,5,6], Journal of Pathogens. ∗ refers to patient with negative sputum smear but positive X-ray; +/− positive or negative; NR: not required; ND: not determined. To explore whether misdiagnosis is a problem in Nigeria, we cultured sputum and conducted molecular characterization of acid fast isolates in patients already diagnosed with TB based on the local diagnostic algorithm at DOTS centers in Ibadan, Southwestern Nigeria

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