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Abstract: It is well recognized that Salmonella can survive long-term starvation and desiccation stresses and contaminate foods that have intermediate to low water activities; however, little is known about the specific molecular mechanisms underlying its survival and persistence in low water activity foods. In this study, we used the RNA-seq approach to compare the transcriptomes (27–33 million 36-bp reads per sample) of a Salmonella enterica subsp. enteric serovar Enteritidis strain ATCC BAA-1045 after inoculation in peanut oil (water activity 0.30) for 72 h, 216 h and 528 h to those grown in Luria-Bertani (LB) broth for 12 h and 312 h. Our results showed that desiccated Salmonella cells in peanut oil were in a physiologically dormant state with <5% of its genome being transcribed compared to 78% in LB broth. Among the few detected transcripts in peanut oil, genes involved in heat and cold shock response, DNA protection and regulatory functions likely play roles in cross protecting Salmonella from desiccation and starvation stresses. In addition, non-coding RNAs may also play roles in Salmonella desiccation stress response. This is the first report of using RNA-seq technology in characterizing bacterial transcriptomes in a food matrix. [Copyright &y& Elsevier]

Cronobacter was positive in cereals at a relatively high rate. In the present study, we investigated the occurrence and characteristics of this pathogen systematically in diverse cereals. All sampled food (N = 467) contained Cronobacter with a high positive rate of 54.0%. The enumeration experiment showed the concentration ranged from 0.3 to more than 110 MPN/100 g, and 87.9% of 127 samples were less than 10 MPN/100 g. There were significant differences (p < 0.05) in positive rates for Cronobacter among cereal kernels (40.2%), cereal flour (66.7%), cereal products made from raw cereal flour (87.6%), and cereal products made from flour (ready-to-eat) (17.4%). The dominant Cronobacter species was C. sakazakii and C. dublinensis , followed by C. malonaticus and C. turicensis. Two interesting clusters with more than 90% similarities were identified by pulsed-field gel electrophoresis (PFGE). The C1 cluster (four isolates) indicated these strains were derived from a common source and persisted in the food production environment for an extended time. The C2 cluster (six isolates) indicated the pathogen could be transmitted via cereal processing. Our research provided baseline data for Cronobacter in diverse cereals and was helpful for understanding Cronobacter transmission. The results also indicate that additional control measures should be developed to reduce the risk of infection by these opportunistic pathogenic bacteria. • A high positive rate (54.0%) of Cronobacter was found in diverse cereals. • Cereal flour might pose a risk of Cronobacter infection. • The dominant species are C. sakazakii , C. dublinensis , and C. Malonaticus. • The pathogen could be transmitted via cereal processing. [ABSTRACT FROM AUTHOR]

Abstract Cronobacter are opportunistic bacterial pathogens of both infants and adults. We investigated the incidence and distribution of Cronobacter in 1245 samples of cereal and related environments. 39.1% (101/258) rice-related and 46.9% (98/209) wheat-related samples tested positive for Cronobacter , and the positive rate differed notably according to processing method. Cronobacter was found in rice and wheat plants at the tillering, filling and mature stages. Soil, water and swab samples from nearby milling plants were assayed, and results revealed that 6.3% (7/122) of water from paddy fields, 49.1% (28/57) and 62.1% (41/67) of swab samples from rice and wheat flour milling plants were Cronobacter positive. Pulsed-field gel electrophoresis (PFGE) subtyping indicated that some strains had a common profile, which suggested their persistence in the environment, potential transmission routes and cross-contamination in processing. Finally, we surveyed 18 families to evaluate potential risks. None of the families who primarily ate rice cooked with water tested positive for Cronobacter , though of 66.7% families (6/9) whose food staples were produced from wheat flour tested positive. Taken together, our results are important for understanding Cronobacter transmission and will aid in the development of additional control measures to reduce the risk of infection by these opportunistic pathogenic bacteria. Highlights • Cronobacter detection rates notably changed with different processing methods. • Cronobacter was present in different growth stages of rice and wheat. • The presence of Cronobacter in the domestic environment was related to primary staple foods. • Consumption of cereal flour may pose a high risk for Cronobacter infection. [ABSTRACT FROM AUTHOR]

The common use of gloves in retail practices represents a potential route for cross contamination of foodborne pathogens in fresh-cut produce. Using fresh-cut cantaloupe as a food model, we investigated factors that may influence glove-mediated cross contamination by Listeria monocytogenes and developed mathematical models to illustrate the patterns of transfer during fresh-cutting practices. Contact time (2, 5, 10 s), contact pressure (0.05, 0.18, 0.37 psi), and glove type (nitrile, polyvinyl chloride, polyethylene) did not have a significant effect on transfer of L. monocytogenes from cantaloupe rind to flesh, or from flesh to flesh. However, glove type appeared to affect L. monocytogenes transfer from the stem scar tissue to cantaloupe flesh (P = 0.0371). Transfer from rind pieces that had been washed with water was significantly higher than transfer from pieces that had not been washed (P = 0.0006). Predictive modeling and experimental validation suggested that transfer of L. monocytogenes on cantaloupe flesh persists over 85 pieces through consecutive contacts with a gloved hand. Findings of the study provide new scientific data to aid researchers, retailers, and caterers in safety risk assessments of fresh-cut practices used to prepare cantaloupes and other produce items. • Single-use gloves for preparation of fresh-cut cantaloupes were possible vehicles for sustained transfer of L. monocytogenes. • Multiple factors were investigated for their impact on glove-mediated cross contamination of fresh-cut cantaloupe by L. monocytogenes. • Residue surface moisture significantly facilitated the transfer of L. monocytogenes from cantaloupe rind to flesh via gloves. • Mathematical models were developed to illustrate L. monocytogenes transfer on fresh-cut cantaloupe through gloved hands. [ABSTRACT FROM AUTHOR]