Molecular Identification of Nontuberculous Mycobacteria in Humans in Zimbabwe Using 16S Ribosequencing

Nyasha Chin’ombe1, *, Boniface Muzividzi2, Ellen Munemo2, Pasipanodya Nziramasanga1
1 Molecular Microbiology Laboratory, Department of Medical Microbiology, University of Zimbabwe, P O Box A178, Avondale, Harare, Zimbabwe
2 National Microbiology Reference Laboratory, P.O. Box ST 749, Southerton, Harare, Zimbabwe

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© Chin’ombe et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (, which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Molecular Microbiology Laboratory, Department of Medical Microbiology, University of Zimbabwe, P.O. Box A178, Avondale, Harare, Zimbabwe; Tel: +263-4-791631; E-mail:



Several nontuberculous mycobacteria (NTM) were previously isolated from diverse environments such as water, soil, sewage, food and animals. Some of these NTM are now known to be opportunistic pathogens of humans.


The main purpose of the study was to identify NTM isolates stored at the National Microbiology Reference Laboratory (NMRL) and were previously isolated from humans during a national tuberculosis (TB) survey.


Pure NTM cultures already isolated from human sputum samples during the national TB survey were retrieved from the NMRL and used for this study. DNA was extracted from the samples and 16S ribosomal RNA gene amplified by polymerase chain reaction. The amplicons were sequenced and bioinformatics tools were used to identify the NTM species.


Out of total of 963 NTM isolates stored at the NMRL, 81 were retrieved for speciation. Forty isolates (49.4%) were found to belong to Mycobacterium avium-intracellulare complex (MAC) species. The other 41 isolates (50.6%) were identified as M. lentiflavum (6.2%), M. terrae complex (4.9%), M. paraense (4.9%), M. kansasii (3.7%), M. moriokaense (3.7%), M. asiaticum (2.5%), M. novocastrense (2.5%), M. brasiliensis (2.5%), M. elephantis (2.5%), M. paraffinicum (1.2%), M. bohemicum (1.2%), M. manitobense (1.2%), M. intermedium (1.2%), M. tuberculosis complex (1.2%), M. parakoreense (1.2%), M. florentinum (1.2%), M. litorale (1.2%), M. fluoranthenivorans (1.2%), M. sherrisii (1.2%), M. fortuitum (1.2%) and M septicum (1.2%). Two isolates (2.5%) could not be identified, but were closely related to M. montefiorense and M. phlei respectively. Interestingly, the MAC species were the commonest NTM during the survey.


The study emphasizes the importance of identifying species of NTM in Zimbabwe. Future studies need to ascertain their true diversity and clinical relevance.

Keywords: Identification, Mycobacteria, Nontuberculous, rRNA gene, Sequencing, 16S.