Avaliação da eficácia de métodos alternativos baseados em MALDI-TOF MS para a detecção de Salmonella sp. em linguiça de frango tipo frescal

Abstract

Salmonella sp. is widely distributed in nature and can be sourced from a variety of sources, being contracted mainly due to the ingestion of contaminated animal foods such as eggs, meat, poultry and milk. Of these, chicken meat plays an important role in the epidemiology of human salmonellosis. The present work proposed alternative methodologies, using MALDI-TOF MS to identify Salmonella sp. recovered from food and compared this technique the reference method (BAM/FDA, 2018). Twelve samples of fresh-type chicken sausage commercialized in the municipality of Sete Lagoas - MG, during the period from 01/22/2018 to 06/26/2018 were used. They were divided in 3 portions and two of them were intentionally contaminated with Salmonella enterica subsp. enterica sorovar Typhimurium ATCC 14028 in two concentrations (10 and 1000 CFU/g), respectively. The third portion was considered negative control. The portions were subjected to methods: Method 1: (BAM/FDA, 2018), Method 2: where the step of biochemical and serological identification was replaced by MALDI-TOF MS identification, Method 3: suppression of the selective enrichment step and biochemical and serological identification. Method 4: suppression of the selective enrichment step and identification by MALDI-TOF MS. In the samples contaminated intentionally with Salmonella in the concentrations (C1 and C2), the microorganism was recovered in 100% of the samples when submitted to the methodology M2, M3 and M4. These results were equivalent to those obtained by the reference methodology. However, the M3 and M4 methodologies failed to detect the presence of Salmonella sp. in the control sample, which was positive according to the M1 and M2 methodologies, since they were probably present in reduced concentrations (<10 CFU/g). At the concentrations tested (C1 and C2), 82% and 88% of Salmonella sp. by the methodology MALDI-TOF MS (M2) and (M1) respectively. The methodologies M3 and M4 recovered 94% of Salmonella sp. The use of the MALDI-TOF MS technique conferred precision and rapidity in the identification of the pathogen, reduced the time of analysis, and identified other species possibly present in the food.