Mycobacterium Genotypes in Pulmonary Tuberculosis Infections and Their Detection by Trained African Giant Pouched Rats
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Tuberculosis (TB) diagnosis in low-income countries is mainly done by microscopy. Hence, little is known about the diversity of Mycobacterium spp. in TB infections. Different genotypes or lineages of Mycobacterium tuberculosis vary in virulence and induce different inflammatory and immune responses. Trained Cricetomys rats show a potential for rapid diagnosis of TB. They detect over 28 % of smear-negative, culture-positive TB. However, it is unknown whether these rats can equally detect sputa from patients infected with different genotypes of M. tuberculosis. A 4-month prospective study on diversity of Mycobacterium spp. was conducted in Dar es Salaam, Tanzania. 252 sputa from 161 subjects were cultured on Lowenstein-Jensen medium and thereafter tested by rats. Mycobacterial isolates were subjected to molecular identification and multispacer sequence typing (MST) to determine species and genotypes. A total of 34 Mycobacterium spp. isolates consisting of 32 M. tuberculosis, 1 M. avium subsp. hominissuis and 1 M. intracellulare were obtained. MST analyses of 26 M. tuberculosis isolates yielded 10 distinct MST genotypes, including 3 new genotypes with two clusters of related patterns not grouped by geographic areas. Genotype MST-67, shared by one-third of M. tuberculosis isolates, was associated with the Mwananyamala clinic. This study shows that diverse M. tuberculosis genotypes (n = 10) occur in Dar es Salaam and trained rats detect 80 % of the genotypes. Sputa with two M. tuberculosis genotypes (20 %), M. avium hominissuis and M. intracellulare were not detected. Therefore, rats detect sputa with different M. tuberculosis genotypes and can be used to detect TB in resource-poor countries.
KeywordsTuberculosis Mycobacterium Sputum Sample Mycobacterial Isolate Genotype Isolate
We wish to thank authorities of the Tanzania’s National Tuberculosis and Leprosy Programme (NTLP) and the collaborating DOTS centres in Dar es Salaam for their excellent support during this project. Support from all staff of the SUA-APOPO TB detection laboratory, and technical support from Jonas Fitwangile (Department of Veterinary Microbiology and Parasitology, Sokoine University of Agriculture) is highly appreciated. We thank Mary Louise Grossman for help preparing the manuscript. Funding by the UBS Optimus Foundation (UBS) to S.H.E.K. and B.J.W. is gratefully acknowledged.
Conflict of interest
The authors declare that they have no conflict of interest regarding this work.
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