RESUMEN
Objective::To explore the feasibility of the rapid identification system(MALDI-Biotyper System) of microorganisms for rapid identification of Pseudomonas aeruginosa and clinical isolation of Staphylococcus aureus. Method::Identification quality control and clinical isolation were conducted for drug resistance of S. aureus by microbial rapid identification system and broth dilution method. The scores of microbial rapid identification system were compared with the MIC value of broth dilution method. The drug resistance of P. aeruginosa was simultaneously identified to determine the accuracy and applicability of the rapid identification system of microorganisms. Result::The scores of the microbial rapid identification system showed that the score of sensitive quality control strain S. aureus was higher than 2.000, and the that of resistant strain of methicillin-resistant S. aureus(methicillin-resistant S. aureus, MRSA)was between 1.700 and 2.000.The score of clinically isolated S. aureus was between 1.700 and 2.000, which suggested the drug resistance and was consistent with the MIC value of the broth dilution method. At the same time, the systemic identification value of the P. aeruginosa, which is independent of the quality control sensitive strain, was greater than 2.000, showing sensitivity and it was a sensitive strain itself, which was consistent with the results. Conclusion::The microbial rapid identification system scoring method can be used for the rapid identification of the drug resistance of S. aureus and P. aeruginosa.
RESUMEN
Legionella spp. are widespread bacteria in aquatic environments with a growing impact on human health. Between the 61 species, Legionella pneumophila is the most prevalent in human diseases; on the contrary, Legionella non-pneumophila species are less detected in clinical diagnosis or during environmental surveillance due to their slow growth in culture and the absence of specific and rapid diagnostic/analytical tools. Reliable and rapid isolate identification is essential to estimate the source of infection, to undertake containment measures, and to determine clinical treatment. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), since its introduction into the routine diagnostics of laboratories, represents a widely accepted method for the identification of different bacteria species, described in a few studies on the Legionella clinical and environmental surveillance. The focus of this study was the improvement of MALDI-TOF MS on Legionella non-pneumophila species collected during Legionella nosocomial and community surveillance. Comparative analysis with cultural and mip-gene sequencing results was performed. Moreover, a phylogenetic analysis was carried out to estimate the correlations amongst isolates. MALDI-TOF MS achieved correct species-level identification for 45.0% of the isolates belonging to the Legionella anisa, Legionella rubrilucens, Legionella feeleii, and Legionella jordanis species, displaying a high concordance with the mip-gene sequencing results. In contrast, less reliable identification was found for the remaining 55.0% of the isolates, corresponding to the samples belonging to species not yet included in the database. The phylogenetic analysis showed relevant differences inside the species, regruped in three main clades; among the Legionella anisa clade, a subclade with a divergence of 3.3% from the main clade was observed. Moreover, one isolate, identified as Legionella quinlivanii, displayed a divergence of 3.8% from the corresponding reference strain. However, these findings require supplementary investigation. The results encourage the implementation of MALDI-TOF MS in routine diagnostics and environmental Legionella surveillance, as it displays a reliable and faster identification at the species level, as well as the potential to identify species that are not yet included in the database. Moreover, phylogenetic analysis is a relevant approach to correlate the isolates and to track their spread, especially in unconventional reservoirs, where Legionella prevention is still underestimated.