Multi-locus sequence typing and antimicrobial susceptibility profile of Cronobacter sakazakii and Cronobacter malonaticus isolated from corn-based farinaceous foods commercialized in Brazil.

Abstract

The aim of this study was to evaluate the microbiological quality of 45 samples of corn-based farinaceous foods commercialized in Brazil. The bacteriological analysis performed were: detection of Salmonella and Cronobacter, and enumeration of faecal coliforms and Bacillus cereus. The Cronobacter isolates were phenotypically characterized by Vitek 2.0 and the antibiotic susceptibility profile. Molecular characterization was accomplished by real-time PCR targeting dnaG gene and MLST. No sample presented contamination by Salmonella or B. cereus (<102 UFC/g). Faecal coliforms were detected in two (4.4%) samples but in low concentration (≤23.0 MPN/g), and 20 samples (44.4%) contained Cronobacter. Twenty-nine unique Cronobacter isolates were identified as C. sakazakii (n=18), C. malonaticus (n=2); that presented 11 different fusA alleles, including new fusA 183. MLST analysis revealed 17 sequence types (STs), six of which were newly identified (ST687-690, 693, and 694). Resistance or intermediary resistance were found to ceftazidime (15.0%), aztreonam (15.0%), nalidixic acid (15.0%), nitrofurantoin (15.0%), cefepime (10.0%), gentamicin (5.0%), and tetracycline (5.0%). The presence of Cronobacter in corn-based farinaceous foods could be a significant risk to infants as these products are used as alternatives to commercially available infant formula. Strategies to manage the risk of Cronobacter infections due to the consumption of these alternative feeds need to be developed by the regulatory agencies.