Practical in-storage interventions to control foodborne pathogens on fresh produce

Although tremendous efforts have been made to ensure fresh produce safety, various foodborne outbreaks and recalls occur annually. Most of the current intervention strategies are evaluated within a short timeframe (less than 1 h), leaving the behavior of the remaining pathogens unknown during subsequent storages. This review summarized outbreak and recall surveillance data from 2009 to 2018 obtained from government agencies in the United States to identify major safety concerns associated with fresh produce, discussed the postharvest handling of fresh produce and the limitations of current antimicrobial interventions, and reviewed the intervention strategies that have the potential to be applied in each storage stage at the commercial scale. One long-term (up to 12 months) prepacking storage (apples, pears, citrus among others) and three short-term (up to 3 months) postpacking storages were identified. During the prepacking storage, continuous application of gaseous ozone at low doses (≤1 ppm) is a feasible option. Proper concentration, adequate circulation, as well as excess gas destruction and ventilation systems are essential to commercial application. At the postpacking storage stages, continuous inhibition can be achieved through controlled release of gaseous chlorine dioxide in packaging, antimicrobial edible coatings, and biocontrol agents. During commercialization, factors that need to be taken into consideration include physicochemical properties of antimicrobials, impacts on fresh produce quality and sensory attributes, recontamination and cross-contamination, cost, and feasibility of large-scale production. To improve fresh produce safety and quality during storage, the collaboration between researchers and the fresh produce industry needs to be improved.     

Effect of processing on the microbiological quality and safety of chicken carcasses at slaughterhouse

Microbiological contamination of chicken meat depends on the conditions under which the animals are reared, slaughtered and processed. The aim of this study was to determine the influence of farm origin and processing stages at slaughterhouse on the microbial safety and quality of chicken. Samples of chicken carcasses from three different farms were taken from a slaughterhouse. Mesophiles, Escherichia coli, coagulase positive Staphylococcci counts, presence of Listeria monocytogenes,Campylobacter and Salmonella were determined at five sampling points: after defeathering, after evisceration, after washing, after chilling and after cutting. Chilling reduced log numbers of mesophiles, coagulase positive Staphylococci and E. coli by 0.85, 1.52 and 2.2 log units, respectively. Salmonella was not detected after chilling. High prevalence of Campylobacter spp was observed at all the stages ranging between 84% and 100%. L. monocytogenes was not detected in chicken carcasses after defeathering. However, it was detected after evisceration and after washing and chilling. The most critical stage for L. monocytogenes contamination was the portioning operation, the prevalence in breast and legs being 88% and 84%, respectively.     

肾脏内科住院患者感染病原菌分布及耐药性分析

目的:调查肾脏内科住院患者感染病原菌分布和耐药性，为临床治疗细菌感染的抗菌药物选择提供依据。方法:收集2016年1月至2019年6月期间入住皖南医学院弋矶山医院肾脏内科患者送检标本培养阳性病原菌数据。结果:共培养出286株细菌，以呼吸道感染和泌尿道感染为主。革兰阴性菌占比89.51%，革兰阳性菌占比10.49%。革兰阴性菌中，肠杆菌科细菌检出前三位细菌分别是大肠埃希菌、肺炎克雷伯菌和阴沟肠杆菌，非发酵阴性菌检出前二位细菌分别是铜绿假单胞菌、鲍曼不动杆菌；其中产超广谱β内酰胺酶细菌（ESBLs）检出率为32.87%，以大肠埃希菌和肺炎克雷伯菌为主，对氨曲南和头孢曲松耐药率分别为83.8%和100%；碳青霉烯类耐药菌检出率为6.29%。在革兰阳性菌中金黄色葡萄球菌最常见，其中耐甲氧西林金黄色葡萄球菌（MRSA）检出率为4.89%。结论:在本院肾脏内科住院患者细菌感染中，产ESBLs大肠埃希菌和肺炎克雷伯菌检出率高。     

Nonhydrolyzable Heptose Bis- and Monophosphate Analogues Modulate Pro-inflammatory TIFA-NF-κB Signaling

d -Glycero-d -manno-heptose-1β,7-bisphosphate (HBP) and d -glycero-d -manno-heptose-1β-phosphate (H1P) are bacterial metabolites that were recently shown to stimulate inflammatory responses in host cells through the activation of the TIFA-dependent NF-κB pathway. To better understand structure-based activity in relation to this process, a family of nonhydrolyzable phosphonate analogues of HBP and H1P was synthesized. The inflammation modulation by which these molecules induce the TIFA-NF-κB signal axis was evaluated in vivo at a low-nanomolar concentration (6 nM) and compared to that of the natural metabolites. Our data showed that three phosphonate analogues had similar stimulatory activity to HBP, whereas two phosphonates antagonized HBP-induced TIFA-NF-κB signaling. These results open new horizons for the design of pro-inflammatory and innate immune modulators that could be used as vaccine adjuvant.     

Biological Meat Safety: Challenges Today and the Day After Tomorrow

The paper overviews the present status and challenges, as well as new and emerging longer-term issues, in the area of biological meat safety. It includes outlines of both prioritization process for biological meatborne hazards and global strategies for control of the priority hazards. It is concluded that modern meat safety assurance is meat chain- and risk-based, whilst the monitoring system should enable warning about any new and emerging meat safety issues.     

Inactivation of foodborne pathogens on the surfaces of different packaging materials using low-pressure air plasma

In the present study, low-pressure glow discharge plasma was used for surface decontamination of the common food packaging materials, namely glass, polyethylene, polypropylene, nylon, and paper foil. Low-pressure air plasma was generated over a vacuum pressure range of 0.5–5.0 Torr, and at a power density range of 12.4–54.1 mW/cm³. Compared to plasma-unexposed surfaces, no significant changes in optical properties, color characteristics, surface temperatures, tensile strengths, and deformation strains were observed with plasma-exposed surfaces. On plasma exposure of food pathogens-loaded packaging materials surfaces, as high as 4-log reduction (99.99%) in viable cell counts of tested food pathogens, especially Escherichia coli O157:H7 and Staphylococcus aureus, was observed within 5 min. And, the pathogens inactivation pattern can be better explained by Singh-Heldman model. Therefore, low-pressure air plasma was shown to be effective for inactivation of major foodborne pathogens, and different food packaging materials can be decontaminated using the plasma without adversely affecting their physical properties.     

ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN

A review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready-to-eat crops.     

Relationships between Bacteroides 16S rRNA genetic markers and presence of bacterial enteric pathogens and conventional fecal indicators

Occurrence and prevalence of different bacterial enteric pathogens as well as their relationships with conventional (total and fecal coliforms) and alternative fecal indicators (host-specific Bacteroides 16S rRNA genetic markers) were investigated for various water samples taken from different sites with different degrees of fecal contamination. The results showed that a wide range of bacterial pathogens could be detected in both municipal wastewater treatment plant samples and in surface water samples. Logistic regression analysis revealed that total and human-specific Bacteroides 16S rRNA genetic markers showed significant predictive values for the presence of Escheriachia coli O-157, Salmonella, heat-labile enterotoxin (LT) of enterotoxigenic E. coli (ETEC), and heat-stable enterotoxin for human (STh) of ETEC. The probability of occurrence of these pathogenic bacteria became significantly high when the concentrations of human-specific and total Bacteroides 16S rRNA genetic markers exceeded 10(3) and 10(4) copies/100 mL. In contrast, Clostridium perfringens was detected at high frequency regardless of sampling sites and levels of Bacteroides 16S rRNA genetic markers. No genes related to Shigella spp., Staphylococcus aureus and Vibrio cholerae were detected in any samples analyzed in this study. Conventional indicator microorganisms had low levels of correlation with the presence of pathogens as compared with the alternative fecal indicators. These results suggested that real-time PCR-based measurement of alternative Bacteroides 16S rRNA genetic markers was a rapid and sensitive tool to identify host-specific fecal pollution and probably associated bacterial pathogens. However, since one fecal indicator might not represent the relative abundance of all pathogenic bacteria, viruses and protozoa, combined application of alternative indicators with conventional ones could provide more comprehensive pictures of fecal contamination, its source and association with pathogenic microorganisms.     

Essential oil nanoemulsions: antibacterial activity in contaminated fruit juices

Many human acid tolerant bacterial and fungal pathogens can be transmitted through the consumption of the contaminated fruit juices. We aim to formulate essential oil nanoemulsions (basil, black seed, turmeric, clove & cinnamon), determine their ability to clear contamination by food borne bacterial pathogens from fruit juices. The antibacterial activity of the optimised formulations was tested in the fruit juices against bacterial pathogens causing gastrointestinal tract infections. The minimum bactericidal concentration (MBC) of clove emulsions ranged from 15.6 to 25 μL mL⁻¹. Cinnamon oil emulsion had an MBC ranging between 15 and 31 μL mL⁻¹. At MBC, cinnamon oil emulsions caused a 6log₁₀ decrease in viable counts by 8 h and maintained the sterility of fruit juices for 7 days at ambient temperature. Thus, clove and cinnamon microemulsions can be used as juice additives to control food borne bacterial pathogens and maintain the bacterial sterility of fruit juices.