Molecular Identification of Mycobacterium Species of Public Health Importance in Cattle in Zimbabwe by 16S rRNA Gene Sequencing

Abstract

Mycobacteriumspecies are naturally found in the environment as well as in domestic animals such as cattle. So far, more than 150 species ofMycobacterium, some of which are pathogenic, have been identified. Laboratory isolation, detection and identification ofMycobacteriumspecies are therefore critical if human and animal infections are to be controlled. The objective of this study was to identifyMycobacteriumspecies isolated in cattle in Zimbabwe using 16S ribosomal RNA gene amplification and sequencing. A total of 134 cow dung samples were collected throughout Zimbabwe and mycobacteria were isolated by culture. Only 49 culture isolates that were found to be acid-fast bacilli positive by Ziehl-Neelsen staining. The 16S rRNA gene was successfully amplified by PCR in 41 (84%) of the samples. There was no amplification in 8 (16%) of the samples. Out of the 41 samples that showed amplification, 26 (63%) had strong PCR bands and were selected for DNA sequencing. Analysis of the DNA sequences showed that 7 (27%) belonged toMycobacterium neoaurum, 6 (23%) belonged toMycobacterium fortuitum, 3 (12%) toMycobacterium goodii, 2 (1%) toMycobacterium arupense, 2 (1%) toMycobacterium peregrinumorM. septicumand 1 isolate (0.04%) toMycobacterium elephantis. There were 5 (19%) isolates that were non-mycobacteria and identified as Gordonia terrae, a close relative ofMycobacterium. The study therefore provided a molecular basis for detection and identification ofMycobacteriumspecies in animals and humans.