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Challenges in microbiological identification of aerobic bacteria isolated from the skin of reptiles.
oleh: Maria Brockmann, Heike Aupperle-Lellbach, Michaela Gentil, Anton Heusinger, Elisabeth Müller, Rachel E Marschang, Michael Pees
| Format: | Article |
|---|---|
| Diterbitkan: | Public Library of Science (PLoS) 2020-01-01 |
Deskripsi
<h4>Introduction</h4>Bacterial pathogens are often involved in dermatitis in reptiles. Exact identification of reptile-specific but otherwise uncommon bacterial species may be challenging. However, identification is crucial to evaluate the importance of the detected bacterial species.<h4>Objective</h4>The aim of this study was to assess the number of aerobic bacterial isolates cultured from skin-derived samples of reptiles which were not reliably identified by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS), and to determine their identity.<h4>Material and methods</h4>Routine bacterial diagnostics were performed on 235 skin samples, and 417 bacterial isolates were analysed by MALDI-TOF MS. The isolates were grouped into categories based on their first score: category I (≥ 2.00), category II (≥ 1.70 and < 2.00), and category III (< 1.70). Isolates from category III were further investigated by 16S rRNA gene sequencing and the following criteria were applied: query cover 100%, e-value rounded to 0.0 and sequence identity (%) > 98.00% for genus identification, and > 99.00% for species identification.<h4>Results</h4>The majority of bacterial isolates were in category I (85.1%) or category II (8.4%). In category III (6.5%) results achieved at first by MALDI-TOF MS corresponded to the results of the molecular analysis in 8.0% of isolates at the species level and in 24.0% at the genus level. Bacterial isolates classified as category III were heterogenic in genus (e.g. Chryseobacterium, Devriesea, Pseudomonas, Staphylococcus, Uruburuella), and some have only been described in reptiles so far.<h4>Conclusions</h4>Most of the aerobic bacterial isolates cultured from reptile skin achieved high scores by MALDI-TOF MS. However, in the majority of category III isolates MALDI-TOF MS results were different from those of the molecular analysis. This strengthens the need to carefully examine low-scored results for plausibility and to be familiar with the occurrence and morphology of relevant reptile-specific bacterial species (e.g. Devriesea agamarum) as well as with the limits of the database used.