Abstract
Over the past few decades, there has been a significant increase in the number of mycobacterial species described. Currently, the genus Mycobacterium consists of 170 species. Most species are called nontuberculous mycobacteria (NTM) and are potentially or rarely pathogenic and ubiquitous. One of the main challenges in mycobacteriology is the rapid and precise identification of these microorganisms. In this work, we compared two protein extraction protocols for the identification of 38 reference strains and clinical isolates, representing 27 species, by mass spectrometry (MALDI-TOF MS) to subsequently use the best method for identifying environmental mycobacteria. The results obtained with reference strains and clinical isolates showed that protocol A was effective in identifying 92.1% of mycobacterial specimens at the species level and protocol B, 50%. Therefore, protocol A was evaluated for the rapid identification of 27 environmental mycobacterial isolates. These isolates were subjected to PCR-restriction enzyme analysis (PRA-hsp65). Two isolates were misidentified by PRA-hsp65, whereas MALDI-TOF MS was able to identify them correctly. The results were confirmed by hsp65 and 16S rRNA gene sequencing. Mass spectrometry has the advantage of being a simpler and faster technique than PRA-hsp65, and our results showed that MALDI-TOF MS is a valuable tool for the identification of environmental mycobacterial isolates.
Highlights
The genus Mycobacterium consists of 170 species and 13 subspecies
We evaluated the application of MALDI-TOF MS for the identification of environmental mycobacteria and compared it with the results obtained with PCR-restriction enzyme analysis (PRA)-hsp65
Twenty reference strains from Instituto Adolfo Lutz (IAL Collection) and Universidade Federal do Rio de Janeiro (UFRJ Collection) and 18 clinical isolates previously identified by PRA-hsp65 at IAL were used in the present study (Table 1)
Summary
The genus Mycobacterium consists of 170 species and 13 subspecies (www.bacterio.net/mycobacterium.html). Most species are considered potentially or rarely pathogenic and are called nontuberculous mycobacteria (NTM). This group is widely found in environments shared by humans and animals [1]-[4]. NTM has demonstrated a potential for the degradation of xenobiotic substances [5]-[8]. They have gained interest due to the increased number of infections associated with invasive procedures, such as anesthetic treatments and surgeries, as well as numerous reports of infections associated with pulmonary diseases such as cystic fibrosis [9]-[13]. NTM infections are characterized by scarce treatment options related to multidrug resistance
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