Dear Editor;
Dr. Walayat et al recently published their report on Mycobacterium neoaurum line-related bacteremia with pulmonary involvement: Case report and review of literature [1].
Non-tuberculosis mycobacteria (NTM) or Mycobacterium other than tuberculosis (MOTT) are ubiquitous in the environmental resources such as water, soil, sand, dust, milk and animal. These group of bacteria can contaminated the hospital equipment such as catheter, ventilator, abdominal shunts or other sterile instrument which can cause of opportunistic infection in and cause of immune-compromised patients and even healthy individuals [2,3]. According to the American Thoracic Society (ATS) guideline, identification and differentiation of clinically isolates of Non-tuberculosis mycobacterium is essential for identification of emerging NTM species, final diagnosis, patient management, appropriate identification and epidemiological investigations [4].
Identification of NTM using conventional test including acid-fast staining, growth rate, pigment production, biochemical features and metabolization of carbohydrates are time-consuming, labor-intensive, require a skillful microbiologist and unable to discriminate between species of mycobacteria [4]; but molecular methods such as direct sequence analysis of the housekeeping genes including 16S rRNA, rpoB, hsp65, 16S–23S rRNA internal transcribed spacer (ITS) and gyrB is inexpensive, rapid, reliable method for accurate identification and differentiation of Mycobacterium spp. [4,5].
Mycobacterium neoaurum is rapidly growing scotochromogenic mycobacterium species which was introduced by Tsukamura and Mizuno in 1972 [6]. M. neoaurum was classified as one of the members of Mycobacterium parafortuitium group; usually, Mycobacterium neoaurum infection has associated with immunodeficiency patients [1,6].
16S rRNA is best option for identification of emerging species of Non-tuberculosis mycobacteria. Based on the 16S rRNA sequence, Mycobacterium spp. should have nucleotide signature at positions 70–98 (A–T), 293–304 (G–T), 307 (C), 328 (T), 614–626), 661–744 (G–C), (A–T), 631 (G), 824–876 (T–A), 825–875 (A–T) and 843 (C). Moreover, rapidly growing mycobacteria (RGM) has short helix 18 at positions 451–482 [4,7]. Mycobacterium neoaurum has unique 16S rRNA sequence signature and 16S rRNA can applied in order to accure identification of M. neoaurum from clinical and environmental samples [6].
I’m request the authors attend to the following questions.
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1
Please explain the mycobacterial isolation method, which was not mentioned in the report.
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2
According to the reports, mycobacterial species can able cause of disseminated infection; Therefore, Please explain Mycobacterium neoaurum how was identified to the species level, which was not mentioned or any evidence of the GenBank/EMBL/DDBJ accession number in the report.
Conflict of interest
Nil.
References
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