Cronobacter spp.—Opportunistic Foodborne Pathogens: an Update on Evolution, Osmotic Adaptation and Pathogenesis

Cronobacter spp. are opportunistic, foodborne pathogens capable of causing severe illnesses predominantly in premature and low-birth-weight infants. These organisms have evolved features, which aid them to survive under harsh environmental conditions but may also contribute to pathogenesis during infection. In this review, we highlight efforts to study genetic diversity and evolutionary aspects, osmotic adaptation and pathogenesis of these pathogens. Next-generation genome sequencing-based techniques elucidated a species-level bidirectional divergence driven by niche adaptation in Cronobacter spp. Whole genome comparisons and proteomics revealed genes and pathways contributing to the survival and persistence phenotype in low-moisture environments. In silico genome comparisons and application of suitable in vivo models provided answers to pathogenesis-related questions. Development and application of innovative molecular techniques and in vivo infection models have shed light on how Cronobacter spp. adapt to challenges experienced in natural, food processing and host-related environments.