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Molecular Characterization of Cronobacter sakazakii Strains Isolated from Powdered Milk

Ondrej Holý1, Julio Parra-Flores2, Sarah Lepuschitz3

  • 1Department of Public Health, Palacký University Olomouc, 77515 Olomouc, Czech Republic.

Foods (Basel, Switzerland)
|December 30, 2020
PubMed

Insights

Cronobacter sakazakii strains from powdered milk possess virulence factors and antibiotic resistance genes, including mcr-9.1. These findings highlight the need for robust molecular methods to ensure public health and food safety.

Area of Science:

  • Food Microbiology and Safety
  • Bacterial Pathogenesis
  • Genomics and Bioinformatics

Background:

  • Cronobacter spp. are opportunistic pathogens within the Enterobacteriaceae family, posing significant risks, particularly to neonates through meningitis and necrotizing enterocolitis.
  • Powdered milk has been identified as a potential vehicle for Cronobacter contamination, necessitating thorough investigation of strains isolated from this source.

Purpose of the Study:

  • To determine the in silico and in vitro putative virulence factors of six Cronobacter sakazakii strains isolated from powdered milk in the Czech Republic.
  • To identify genetic determinants of virulence and antibiotic resistance, including the presence of CRISPR-Cas systems.

Main Methods:

  • Strain identification using MALDI-TOF MS and whole-genome sequencing (WGS).
  • Detection of virulence and resistance genes via Ridom SeqSphere+ and the Comprehensive Antibiotic Resistance Database (CARD).
  • In vitro adherence and invasion assays using mouse neuroblastoma cells; CRISPR-Cas system analysis using CRISPRCasFinder.

Main Results:

  • Four sequence types (ST1, ST145, ST245, ST297) were identified among the six Cronobacter sakazakii isolates.
  • Strains 13755-1B and 1847 demonstrated adherence capabilities, with strain 1847 also showing invasion potential.
  • Genes associated with flagellar and outer membrane proteins, chemotaxis, hemolysins, invasion, and survival were detected. Notably, the colistin resistance gene mcr-9.1 and cephalothin resistance gene bla were identified, along with specific plasmids and CRISPR matrices.

Conclusions:

  • The study identified significant virulence and antibiotic resistance genes in Cronobacter sakazakii strains from powdered milk, underscoring potential public health risks.
  • Combined molecular methodologies, including WGS and bioinformatics analysis, are crucial for effective risk assessment and decision-making by health authorities to protect the population.

Keywords:
CRISPR-CasCronobacter sakazakiiantibiotic resistance genespowdered milkvirulencewhole-genome sequencing

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