Cronobacter spp. Isolated from Quick-Frozen Foods in China: Incidence, Genetic Characteristics, and Antibiotic Resistance

Abstract

Cronobacter spp. are emerging foodborne pathogens that cause severe diseases. However, information on Cronobacter contamination in quick-frozen foods in China is limited. Therefore, we studied the prevalence, molecular characterization, and antimicrobial susceptibility of Cronobacter in 576 quick-frozen food samples collected from 39 cities in China. Cronobacter spp. were found in 18.75% (108/576) of the samples, and the contamination degree of the total positive samples was 5.82 MPN/g. The contamination level of frozen flour product samples was high (44.34%). Among 154 isolates, 109 were C. sakazakii, and the main serotype was C. sakazakii O1 (44/154). Additionally, 11 serotypes existed among four species. Eighty-five sequence types (STs), including 22 novel ones, were assigned, indicating a relatively high genetic diversity of the Cronobacter in this food type. Pathogenic ST148, ST7, and ST1 were the main STs in this study. ST4, epidemiologically related to neonatal meningitis, was also identified. All strains were sensitive to cefepime, tobramycin, ciprofloxacin, and imipenem, in which the resistance to cephalothin was the highest (64.94%).Two isolates exhibited multidrug resistance to five and seven antimicrobial agents, respectively. In conclusion, these findings suggest that the comparatively high contamination level of Cronobacter spp. in quick-frozen foods is a potential risk warranting public attention.

Microbiological survey and genomic analysis of Cronobacter sakazakii strains isolated from US households and retail foods

“…With respect to foods, Cronobacter spp. have been most frequently recovered from plant-based foods, such as vegetables, legumes, fruits, sprouts, cereal products, flour-based confections, herbs, nuts, teas, and spices ( 29 , 30 , 58 – 71 ). This current survey of US retail foods similarly identified substantial contamination of plant-based products.…”

Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in Cronobacter sakazakii

“…C. sakazakii is not thermotolerant (survives between 6 and 45 °C) but can proliferate in dry stress, even at a low water activity level of 0.3 [ 5 ]. It was reported that 18.75% of quick-frozen food collected from 39 cities in china were contaminated with C. sakazakii in 576 samples, wherein the contamination of frozen flour products was up to 44.34% [ 6 ]. In addition, opened powdered formula and breast pump parts were highly susceptible to contamination with C. sakazakii [ 7 ].…”