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Objective In this study, milk from a cow with mastitis was analyzed to determine the presence of mycobacterial infection. Milk quality and security problems pertaining to the safe consumption of dairy products were also discussed in this study. Methods Milk was preprocessed with 4% Na OH. Then, mycobacteria were isolated from the milk sample on L-J medium. The isolate was identified using multiple loci Polymerase Chain Reaction(PCR) and multi-locus sequence analysis with 16 S r RNA, sod A, hsp65, and ITS genes. The drug sensitivity of the isolate to 27 antibiotics was tested through alamar blue assay. Results Smooth, moist, pale yellow colonies appeared on the L-J medium within a week after inoculation. Based on the results of multiple loci PCR analysis, the isolate was preliminarily identified as non-tuberculous mycobacteria. The 16 S r RNA, Sod A, hsp65, and ITS gene sequences of the isolate exhibited 99%, 99%, 99%, and 100% similarities, respectively, with those of the published reference strains of Mycobacterium elephantis(M. elephantis). The drug sensitivity results showed that the strain is resistant to isoniazid, p-aminosalicylic acid, and trimesulf but is sensitive to ofloxacin, rifampicin, amikacin, capreomycin, moxifloxacin, kanamycin, levofloxacin, cycloserine, ethambutol, streptomycin, tobramycin, rifabutin, ciprofloxacin, linezolid, cefoxitin, clarithromycin, and minocycline. Conclusion To the best of our knowledge, this study is initially to report the isolation of M. elephantis from the milk of a cow with mastitis in China.
Objective In this study, milk from a cow with mastitis was analyzed to determine the presence of mycobacterial infection. Milk quality and security problems pertaining to the safe consumption of dairy products were also discussed in this study. Milk was preprocessed with 4% Na OH The mycobacteria were isolated from the milk sample on LJ medium. The isolate was identified using multiple loci Polymerase Chain Reaction (PCR) and multi-locus sequence analysis with 16 S r RNA, sod A, hsp65, and ITS genes. The drug sensitivity of the isolate to 27 antibiotics was tested through alamar blue assay. Results Smooth, moist, pale yellow colonies appeared on the LJ medium within a week after inoculation. Based on the results of multiple loci PCR analysis, the isolate was preliminarily identified as non -tuberculous mycobacteria. The 16S rRNA, Sod A, hsp65, and ITS gene sequences of the isolated extract 99%, 99%, 99%, and 100% similarities, respectively, with those of the published ref erence strains of Mycobacterium elephantis (M. elephantis). The drug sensitivity results showed that the strain is resistant to isoniazid, p-aminosalicylic acid, and trimesulf but is sensitive to ofloxacin, rifampicin, amikacin, capreomycin, moxifloxacin, kanamycin, levofloxacin, cycloserine , ethambutol, streptomycin, tobramycin, rifabutin, ciprofloxacin, linezolid, cefoxitin, clarithromycin, and minocycline. Conclusion To the best of our knowledge, this study is initially to report the isolation of M. elephantis from the milk of a cow with mastitis in China .