Drug Susceptibility Testing of Nontuberculous Mycobacteria Utilizing GenoType NTM DR Assay, in Zambia

Background: Nontuberculous mycobacteria (NTM) present a growing challenge as opportunistic pathogens, particularly in regions with complex interactions between humans and their shared environments. Drug susceptibility testing (DST) is crucial in guiding and optimizing treatment for severe NTM infections despite discrepancies between in vitro susceptibility results and actual treatment outcomes. This study was set out to determine drug susceptibility testing of NTMs isolated from humans and water in Zambia's Eastern and Southern provinces. Methods: Eight isolates (4 Mycobacterium avium complex (MAC) and four (4) Mycobacterium abscessus complex (MABC)) were subjected to DST for macrolides and aminoglycosides using GenoType NTM-DR assay. Among the four MABC isolates, two (2) were from humans and two (2) from water. The GenoType NTM-DR assay identifies species and predicts antibiotic resistance based on genetic markers. Results: All the MAC (M. intracellulare and M. avium) isolates were susceptible to macrolides and aminoglycosides, while MABC, specifically M. abscessus subsp. Abscessus and M. abscessus subsp. bolleti showed resistance to macrolides arising from mutations in the erm (41) gene while demonstrating susceptibility to aminoglycosides. Conclusion: We conclude that macrolides and aminoglycosides can be used to treat infections caused by M. avium. Additionally, the detection of drug-resistant MABC strains in water highlights the urgency for enhanced preventive measures such as water treatment and filtration, alongside public awareness efforts regarding water safety and antibiotic resistance risks.