Transmission of Listeria monocytogenes from raw chicken meat to cooked chicken meat through cutting boards

Effect of plasma-activated water on planktonic and biofilm cells of Vibrio parahaemolyticus strains isolated from cutting board surfaces in retail seafood markets

AIMS

This research aimed to analyze cutting board surfaces in seafood markets to find Vibrio parahaemolyticus, assess the isolates' ability to form biofilms, generate and evaluate characteristics of plasma-activated water (PAW), and compare the effect of PAW on planktonic and biofilm cells of the isolated V. parahaemolyticus strains.

METHODS AND RESULTS

A total of 11 V. parahaemolyticus strains were isolated from 8.87% of the examined cutting boards. Biofilm-forming ability was evaluated for these isolates at temperatures of 10°C, 20°C, and 30°C using crystal violet staining. Four strains with the highest biofilm potential were selected for further analysis. The pH of the PAW used in the study was 3.41 ± 0.04, and the initial concentrations of hydrogen peroxide, nitrate, and nitrite were 108 ± 9.6, 742 ± 61, and 36.3 ± 2.9 µM, respectively. However, these concentrations decreased significantly within 3-4 days during storage at room temperature. PAW exhibited significant antimicrobial effects on V. parahaemolyticus planktonic cells, reducing viable bacteria up to 4.54 log CFU/ml within 20 min. PAW also reduced the number of biofilm cells on stainless steel (up to 3.55 log CFU/cm2) and high-density polyethylene (up to 3.06 log CFU/cm2) surfaces, although to a lesser extent than planktonic cells.

CONCLUSIONS

PAW exhibited significant antibacterial activity against V. parahaemolyticus cells, although its antibacterial properties diminished over time. Furthermore, the antibacterial activity of PAW against biofilm cells of V. parahaemolyticus was less pronounced compared to the planktonic cells. Therefore, the actual effectiveness of PAW in seafood processing environments can be affected by biofilms that may form on various surfaces such as cutting boards if they are not cleaned properly.

Cross-contamination in the kitchen: A model for quantitative microbiological risk assessment

A quantitative microbiological risk assessment model for the cross-contamination transmission route in the kitchen (KCC) is presented. Bacteria are transmitted from contaminated (chicken) meat to hands, kitchen utensils, and other surfaces, subsequently contaminating a salad. The model aims to estimate the fraction of bacteria on the meat that is ingested due to cross-contamination, determine the importance of the different transmission routes, and assess the effect of scenarios (interventions) on the fraction ingested. The cross-contamination routes defined, bacterial source-to-recipient transfer fractions as available and derived from literature, and important characteristics (e.g., washing in cold water vs. hot water with soap) shaped the KCC model. With this model, 32 scenarios of an eight-step preparation of a "meat and salad" meal in a domestic kitchen were stochastically simulated. The "cutting board-salad" route proved dominant and the salad plays a major role in the final exposure. A realistic scenario (washing hands, cutting board, and knife with cold water after cutting the meat) estimates that a mean fraction of 3.2E - 3 of the bacteria on the meat is ingested. In the case of "hand washing with hot water and soap" and "cutting board and knife replacement," the mean fraction ingested is 3.6E - 6. For a subsequent meal, where the contaminated sources were kitchen fomites, the estimated mean fraction is 4.3E - 4. In case of hamburger, part of the bacteria is unavailable for cross-contamination, resulting in a mean fraction ingested of about 5.4E - 5. The role of the dishcloth in cross-contamination transmission proved to be minor.

Distribution and Antimicrobial Resistance Characterization of Listeria monocytogenes in Poultry Meat in Jiading District, Shanghai

To investigate the distribution, contamination status, and antibiotic resistance of Listeria monocytogenes in four types of retail poultry meat, including chicken, duck, goose, and pigeon, sold in Jiading District, Shanghai, a total of 236 retail poultry meat samples were collected, and L. monocytogenes isolates were obtained for identification and antibiotic susceptibility testing against 14 common antibiotics. Forty-one L. monocytogenes isolates were detected from the 236 retail poultry meat samples, with detection rates of 24.47%, 19.44%, 14.75%, and 4.44% in chicken, goose, duck, and pigeon meat, respectively. Among refrigerated, frozen, and room temperature samples, refrigerated poultry had the highest detection rate at 25.40%, while frozen poultry had the lowest at 13.33%. The detection rate of L. monocytogenes in chicken meat differed significantly between the storage temperatures, while no significant differences were found for other poultry types. No significant differences in detection rates were observed between different retail locations or packaging methods. Isolates exhibited complete resistance to cefoxitin (FOX) and increasing resistance over time to tetracycline (TET) and clindamycin (CLI), while low levels of resistance were found for penicillin (PEN), oxacillin (OXA), and erythromycin (ERY). Resistance to ERY and TET suggests the potential for multidrug resistance. Significant differences in antibiotic resistance profiles were observed among L. monocytogenes from the various poultry types. In summary, contamination status and antibiotic resistance profiles differed among retail chicken, duck, goose, and pigeon meat sold and the resistance rate of strains continues to increase in Jiading District, Shanghai. Targeted control measures should be implemented to reduce the emergence of resistant strains, as retail conditions had minimal impact on L. monocytogenes prevalence in poultry meat.

Tracking the contamination sources of microbial population and characterizing Listeria monocytogenes in a chicken slaughterhouse by using culture-dependent and -independent methods

Listeria monocytogenes is the etiologic agent of listeriosis, a foodborne disease that poses a threat to public health globally. Chicken meat exhibits heightened susceptibility to L. monocytogenes contamination during butchery. The persistence of this pathogen in the slaughterhouse environment enables recurring contamination of meat products. This study aimed at identifying the sources and transmission routes of L. monocytogenes contamination within an abattoir where it was consistently detected for three consecutive years (2019-2021). Furthermore, the environmental factors aiding contamination along chicken processing lines were determined by surveying the microbiome within the facility. Samples collected in 2019 to 2021 were subjected to culture-dependent analysis to assess the prevalence, serotypes, and multi-locus sequence typing (MLST) of L. monocytogenes. Additionally, the specimens collected in 2021 underwent culture-independent analysis via real-time quantitative polymerase chain reaction (qPCR) and 16S rRNA gene amplicon sequencing to identify the contamination sources and characterize the entire microbial community within the slaughterhouse. L. monocytogenes was isolated only from the clean zone, where the final slaughtering stage occurs. Most strains isolated from the final carcasses showed the same genetic cluster as the isolate in the chilling water and were assigned to MLST profile ST3. Culture-independent qPCR confirmed L. monocytogenes contamination in all samples, excluding post-scalding carcasses, prewashed post-evisceration carcasses, and the bleeding areas. Consequently, qPCR enabled more comprehensive identification of L. monocytogenes contamination points than culture-dependent approaches. Moreover, 16S rRNA gene amplicon sequencing demonstrated that psychro-tolerant and spoilage-related bacteria with L. monocytogenes-like attributes exhibited enhanced viability in the clean zone and immersion-chilling water. Metagenomics-based source tracking analysis further revealed that the shackles and chilling waters represent predominant sources of cross-contamination between different slaughterhouse zones, whereas the grading and packaging workstations and chilling water in the clean zone were deemed crucial sources affecting final carcass contamination. Collectively, these findings demonstrate through culture-dependent and -independent methods that L. monocytogenes spreads along the slaughter line, contaminating the slaughterhouse. Moreover, by investigating changes in microbial community and bacterial flow along the slaughter line within the facility, the sources influencing carcass contamination can be effectively traced.

Survival strategies of Listeria monocytogenes to environmental hostile stress: biofilm formation and stress responses

Listeria monocytogenes is a critical foodborne pathogen that causes listeriosis and threatens public health. This pathogenic microorganism forms a transmission cycle in nature, food industry, and humans, expanding the areas of contamination among them and influencing food safety. L. monocytogenes forms biofilms to protect itself and promotes survival through stress responses to the various stresses (e.g., temperature, pH, and antimicrobial agents) that may be inflicted during food processing. Biofilms and mechanisms of resistance to hostile external or general stresses allow L. monocytogenes to survive despite a variety of efforts to ensure food safety. The current review article focuses on biofilm formation, resistance mechanisms through biofilms, and external specific or general stress responses of L. monocytogenes to help understand the unexpected survival rates of this bacterium; it also proposes the use of obstacle technology to effectively cope with it in the food industry.

Isolation of Listeria monocytogenes from poultry red mite (Dermanyssus gallinae) infesting a backyard chicken farm in Greece

The poultry red mite (PRM), Dermanyssus gallinae, is arguably the most harmful, ubiquitous haematophagous ectoparasite infesting egg-laying hens. PRM is a vector of various microorganisms, with some being important for food microbiology and public health. The present study aimed to investigate the presence of specific pathogens, including Escherichia coli, Salmonella spp. and Listeria spp., carried by PRM infesting a chicken farm in Greece. Mites were caught using cardboard traps (Avivet), and 100 unwashed PRM were homogenized and used for microbiological cultures. Microbiological cultures were carried out on general and selective substrates to detect the above-mentioned bacteria. Specifically for Listeria spp., DNA was extracted from bacteria grown in Tryptone Soya Yeast Extract Agar using a commercial kit. The hly gene encoding the Listeriolysin O protein was amplified by PCR. Mites were identified as D. gallinae using morphological keys as well as by COI DNA barcoding. Microbiological cultures and PCR assays were positive for Listeria monocytogenes. No other bacteria were detected. The current study constitutes the first molecular isolation of L. monocytogenes from D. gallinae, confirming that PRM can carry this food-borne pathogen. PRM control measures and hygiene practices should be applied to minimize any possible contamination risk of poultry products with L. monocytogenes and safeguard public health.

Deterministic Approach and Monte Carlo Simulation to Predict Listeria monocytogenes Time to Grow on Refrigerated Ham: A Study Supporting Risk-based Decisions for Consumers' Health

This study assessed the growth of Listeria monocytogenes in ready-to-eat (RTE) ham during storage under conditions simulating domestic practices with the intention to offer support in the elaboration of food safety policies that should better protect consumers against food poisoning at home. RTE ham, artificially contaminated at either medium (10²-10³ CFU/g) or high (10⁴-10⁵ CFU/g) concentration, was stored at both isothermal (4℃ in a refrigerator able to maintain a relatively constant temperature and 5℃ and 7℃ in a refrigerator with fluctuating temperature) and dynamic (5℃ and 7℃ with intermittent exposure to ambient temperature, e.g. 25℃) conditions. Under isothermal conditions, the increasing storage temperature determined a significantly increased (p < 0.05) capacity of L. monocytogenes to grow. The kinetic growth parameters were derived by fitting the Baranyi and Roberts model to the experimental data and, based on the maximum specific growth rates, it was estimated the temperature dependence of L. monocytogenes growth in RTE ham. At medium contamination level, sanitary risk time calculation revealed that, unlike storage at 5℃ and 7℃, storage at 4℃ of the RTE ham extends the time period during which the product is safe for consumption by ∼40 and 52%, respectively. However, the real temperature fluctuations included in the Monte Carlo simulations at low L. monocytogenes counts (1, 5 and 10 CFU/g) have shortened the safety margins. Stochastic models also proved to be useful tools for describing the pathogen's behavior when refrigeration of the RTE ham alternates with periods of ham being kept at room temperature, considered dynamic conditions of growth.

Human health risk assessment of bisphenol A (BPA) through meat products

Meat and meat products are often consumed in our daily diet, providing essential nutrients. Contamination by chemical hazards, including bisphenol A (BPA) in meat products, is a concern and is continuously monitored. BPA is well-known for its endocrine-disrupting properties, which may cause potential toxicological effects on reproductive, nervous, and immune systems. Dietary consumption is the main route of BPA exposure, and meat products are a major contributor. BPA exposure from meat consumption is the focus of this review. This review found that BPA has been widely detected in canned and non-canned meat products. BPA in canned meat is assumed to be predominantly from migration from can coatings. Relatively low levels are observed in non-canned products, and the source of contamination in these products has yet to be definitively identified. A recent European Food Safety Authority (EFSA) draft opinion has proposed to lower the tolerable daily intake of BPA from 4 μg kg body weight (bw)^-1 day^-1 to 0.04 ng kg body weight (bw)^-1 day^-1, therefore potential health risks need to be addressed. This review has investigated potential contamination at the farm, industrial processes, and retail levels. Data gaps in the literature are also identified to improve future food safety in the meat industry. Also, a unified risk assessment strategy has been proposed. Further understanding of BPA migration in meat products is needed as a part of the exposure assessment to reduce potential risk, and more data on the dose-response relationship will help comprehend potential adverse health effects of BPA on humans. This research will inform the public, meat producers and processing industry, and policymakers on potential exposure to BPA and risk reduction measures, thus, ensuring food safety.

From chicken to salad: Cooking salt as a potential vehicle of Salmonella spp. and Listeria monocytogenes cross-contamination

Epidemiological studies show that improper food handling practices at home account for a significant portion of foodborne illness cases. Mishandling of raw meat during meal preparation is one of the most frequent hazardous behaviours reported in observational research studies that potentially contributes to illness occurrence, particularly through the transfer of microbial pathogens from the raw meat to ready-to-eat (RTE) foods. This study evaluated the transfer of two major foodborne pathogens, Salmonella enterica and Listeria monocytogenes, from artificially contaminated chicken meat to lettuce via cooking salt (used for seasoning) during simulated domestic handling practices. Pieces of chicken breast fillets were spiked with five different loads (from ca. 1 to 5 Log CFU/g) of a multi-strain cocktail of either S. enterica or L. monocytogenes. Hands of volunteers (gloved) contaminated by handling the chicken, stirred the cooking salt that was further used to season lettuce leaves. A total of 15 events of cross-contamination (three volunteers and five bacterial loads) were tested for each pathogen. Immediately after the events, S. enterica was isolated from all the cooking salt samples (n = 15) and from 12 samples of seasoned lettuce; whereas L. monocytogenes was isolated from 13 salt samples and from all the seasoned lettuce samples (n = 15). In addition, S. enterica and L. monocytogenes were able to survive in artificially contaminated salt (with a water activity of 0.49) for, at least, 146 days and 126 days, respectively. The ability of these foodborne pathogens to survive for a long time in cooking salt, make it a good vehicle for transmission and cross-contamination if consumers do not adopt good hygiene practices when preparing meals.

Extended-spectrum-beta-lactamases and carbapenemase-producing Klebsiella pneumoniae isolated from fresh produce farms in different governorates of Egypt

Background and Aim: Fresh produce farms represents a major source of concern since they are becoming increasingly antibiotic resistant. This study aimed to investigate t he occurrence of carbapenemase and extended-spectrum-beta-lactamases (ESBL) - producing genes in Klebsiella pneumoniae isolated from fresh produce farms in Egypt, irrigation water, and people working in these fields. Materials and Methods: One hundred tomatoes from typical farms were collected in plastic bags. The study also included 20 surface-water samples from different irrigation watersheds in fresh produce farms, as well as 50 feces samples from farmworkers. Suspected K. pneumoniae was grown on Eosin Methylene Blue agar for 24 h before being biochemically identified using the RapID ONE test. PCR was used to detect carbapenemase (blaKPC, blaOXA-48, and blaNDM) and ESBL (blaSHV, blaTEM, and blaCTX) expressing genes on isolates. Results: K. pneumoniae was identified in 30% of water and 10% of worker samples, while only one isolate was found in tomato samples. One of the six irrigation water isolates tested positive for carbapenem-resistant NDM. In contrast, two isolates tested positive for ESBL determinants, one of which was blaSHV and the other having both blaSHV and blaTEM genes. Two of the five K. pneumoniae isolates from farmworkers were positive for blaNDM, with one isolate also testing positive for blaSHV and blaTEM. The blaOXA-48 gene was also discovered in the carbapenem-resistant K. pneumoniae tomato isolate used in this study. Conclusion: Carbapenemase- and ESBL-producing K. pneumoniae were found in fresh produce farms, implying that these resistance genes were being passed down to Egyptian consumers.

Presence of Listeria monocytogenes in Ready-to-Eat Meat Products Sold at Retail Stores in Costa Rica and Analysis of Contributing Factors

ABSTRACT

Listeria monocytogenes is a pathogenic bacterium associated with ready-to-eat (RTE) meat products sold at the retail level. The objective of this research was to determine the prevalence of L. monocytogenes in RTE meat products sold at retail in Costa Rica and to study the factors associated with the levels of contamination; analyzed factors include hygienic practices within stores (cutting techniques and microbial contamination of products) and the behavior of the isolates (persistence against antimicrobials and transfer potential). A total of 190 samples of RTE meat products were collected and analyzed for the presence of coliforms and Listeria spp. Isolates of L. monocytogenes were then evaluated in terms of resistance to disinfectants (quaternary ammonium compound [QAC] and chlorine) and their transfer potential from food contact surfaces (knife and cutting boards). Overall Listeria spp. prevalence was 37.4% (71 of 190); Listeria innocua was present in 32.1% (61 of 190) of the products, and L. monocytogenes was found in just 2.6% (5 of 190) of the samples. Most contaminated samples were cut with a knife at the moment of purchase (44.2%). When analyzing practices within the stores, it was observed that L. monocytogenes transfer from inoculated knife to salchichón was higher for samples cut at the beginning of the experiment. In addition, L. monocytogenes transfer from inoculated cutting boards was independent of the number of slices but contamination from plastic was higher than wood. Regarding L. monocytogenes resistance to disinfectants, average reductions of 2.6 ± 1.1 log CFU/mL were detected after 6 min of exposure to 200 ppm of chlorine; however, chlorine resistance varied among the strains. Prevalence of L. monocytogenes in RTE meat products sold at retail could be associated with handling practices within the stores; further studies are necessary to estimate the impact of these practices on the overall risk for consumers.

HIGHLIGHTS

The antimicrobial effect of thyme and rosemary essential oils against Listeria monocytogenes in sous vide turkey meat during storage

The research was aimed to study the impact of sous vide thermal treatment on the microbiological quality of fresh turkey breast meat after treatment with thyme and rosemary EOs and the survival of Listeria monocytogenes on the turkey meat samples. The samples were vacuum-packed and cooked at 55 °C, 60 °C, and 65 °C for 5, 15, 30 and, 60 min. There was an amount of 5 g (5 ±0.2 g) of the sample placed in PA/PE film bags and inoculated with 100 μL of L. monocytogenes inoculum. The sample was incubated at 37 °C for 18 h after bag sealing. The samples were tested on the 1st and 3rd days of experiments. The microbiological quality of fresh turkey breast meat was assessed by the detection of total microbial counts and meat microbiota was identified by mass spectrometry using MALDI-TOF MS Biotyper (Bruker Daltonics, Germany). Microbial counts differed significantly depending on temperature and time and the microbial counts ranged from 2.21 log cfu.g-1 to 8.26 log cfu.g-1 on the 1st and 3rd day of the experiment. The study shows that the sous vide method with essential oils combination is an effective method and it can be used to protect the microbiota of turkey meat and L. monocytogens survival, however, the quality of raw material is crucial.

Quantification of Cross-Contamination of Campylobacter jejuni during Food Preparation in a Model Kitchen in China

ABSTRACT

Numerous outbreak investigations and case-control studies of campylobacteriosis have provided evidence that handling Campylobacter-contaminated chicken products is a high risk factor for infection and illness. In this study, the cross-contamination and transfer rates of Campylobacter jejuni from chicken to ready-to-eat food were determined in various food handling scenarios. Skinless raw chicken breasts were artificially contaminated with C. jejuni and diced on cutting boards of three different materials. Whether cold water, cold water with detergent, or hot water was used, statistically significant differences were found between the transfer rates of C. jejuni to unwashed and washed cutting boards or hands, respectively. When both kitchen knife and cutting board were reused after dicing the artificially contaminated chicken, the transfer rates of C. jejuni to cucumber cut on bamboo, wooden, and plastic cutting boards were 16.28, 12.82, and 5.32%, respectively. The transfer rates from chicken to bread, a large lift-up water faucet handle, and a small twist faucet handle via unwashed hands were 0.49, 4.64, and 3.14%, respectively. This research provides scientific evidence that various types of contaminated kitchenware and cook's hands are vital potential vehicles for the cross-contamination of Campylobacter from raw chicken to ready-to-eat food and emphasizes the importance of timely and proper cleaning to prevent cross-contamination during food handling; therefore, high-quality consumer education to reduce the risk of foodborne infection is urgent and necessary.

HIGHLIGHTS

Comparative study of microbiological transfer from four materials used in direct contact with apples

Several materials such as plastic, wood, cardboard or stainless steel are used as working surfaces or packaging in direct contact with foodstuffs. In food industries, the hygienic surface status is one of the criteria to product conform packaging as described in the European regulation ECR 1935/2004. Today in European Union, it exists one harmonized regulation specific for Food Contact material made of plastic called EU N°10/2011 (Anonymous 2011a). This regulation specifies that materials intended for safe foodstuff contact must not modify food characteristics in terms of chemical, microbiological and sensorial properties. This study aims to compare the survival and transfer of Penicillium expansum conidia and Escherichia coli cells from several materials to apples. Poplar, cardboards, newly manufactured plastic and reusable plastic specimens were artificially inoculated with both microorganisms, subsequently put in contact with apples and stored under realistic storage conditions. After incubation for up to 1 week, apples and specimens were analysed to assess the survival of the microorganisms and their transfer from materials to apples. While P. expansum survived and did not grow on any of the materials, E. coli mortality was observed after 1 h on wood and cardboard and after 1 week on both plastics. The proportion of microorganisms transferred was different according to the considered material. This transfer was lower than 1% for wood.

Multisite survey of bacterial contamination in ready-to-eat meat products throughout the cooking and selling processes in urban supermarket, Nanjing, China

OBJECTIVE

Ready-to-eat (RTE) meat is a kind of popular instant food easily contaminated by microbes, which is one of the causes of foodborne diseases. This study analyzes the possible sources of RTE food bacterial contamination during processing and subsequent selling.

METHOD

Samples of eight kinds of RTE meat were collected from four supermarkets in Nanjing, China. The knives, chopping boards, trays(containers of food), clamps, air, water, and hands of the sales staff were sampled, and the enumeration of aerobic plate count and total coliforms and pathogenic bacteria was performed.

RESULTS

The survey revealed that poor hygienic levels was the causes that RTE meat products were contaminated by bacteria at different levels. With regard to pathogen, the incidences of Salmonella spp. and Staphylococcus aureus were 4.2% and 2.1%, respectively. These results also revealed that the bacterial contamination of RTE food was caused by the air, as well as clamps, chopping boards, knives, trays, and hands of the operators. The total number of aerobic colonies were positively correlated with the amount of RTE food in one pot (r = .87728, p = .0217), and negatively correlated with the maximum temperature in the center of the meat (r = -.81633, p = .0475).

CONCLUSION

The high number of bacteria in RTE foods indicates potential food safety risks and the need to improve the health of supermarket sales staff. The most important thing is to determine how to raise hygiene awareness of employees through food safety education. Meanwhile, a comprehensive set of regulations on hand cleaning and disinfection should be developed to facilitate public health and reduce foodborne illness caused by the consumption of RTE food.

Testing the Antimicrobial Characteristics of Wood Materials: A Review of Methods

Some wood species have antimicrobial properties, making them a better choice over inert surfaces in certain circumstances. However, the organic and porous nature of wood raises questions regarding the use of this material in hygienically important places. Therefore, it is reasonable to investigate the microbial survival and the antimicrobial potential of wood via a variety of methods. Based on the available literature, this review classifies previously used methods into two broad categories: one category tests wood material by direct bacterial contact, and the other tests the action of molecules previously extracted from wood on bacteria and fungi. This article discusses the suitability of these methods to wood materials and exposes knowledge gaps that can be used to guide future research. This information is intended to help the researchers and field experts to select suitable methods for testing the hygienic safety and antimicrobial properties of wood materials.

Molecular detection of extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolates of chicken origin from East Java, Indonesia

Background and Aim:

Klebsiella pneumoniae is one of the respiratory disease agents in human and chicken. This bacterium is treated by antibiotic, but this treatment may trigger antibiotic resistance. Resistance gene in K. pneumoniae may be transferred to other bacteria. One of the known resistance genes is extended-spectrum β-lactamase (ESBL). This research aimed to study K. pneumoniae isolated from chicken farms in East Java, Indonesia, by observing the antibiotic resistance pattern and detect the presence of ESBL coding gene within the isolates.

Materials and Methods:

A total of 11 K. pneumoniae isolates were collected from 141 chicken cloacal swabs from two regencies in East Java. All isolates were identified using the polymerase chain reaction method. Antimicrobial susceptibility was determined by agar dilution method on identified isolates, which then processed for molecular characterization to detect ESBL coding gene within the K. pneumoniae isolates found.

Results:

The result of antibiotic sensitivity test in 11 isolates showed highest antibiotic resistance level toward ampicillin, amoxicillin, and oxytetracycline (100%, 100%, and 90.9%) and still sensitive to gentamicin. Resistance against colistin, doxycycline, ciprofloxacin, and enrofloxacin is varied by 90.9%, 54.5%, 27.3%, and 18.2%, respectively. All isolates of K. pneumoniae were classified as multidrug resistance (MDR) bacteria. Resistance gene analysis revealed the isolates harbored as bla_SHV (9.1%), bla_TEM (100%), and bla_CTX-M (90.9%).

Conclusion:

All the bacterial isolates were classified as MDR bacteria and harbored two of the transmissible ESBL genes. The presence of antibiotic resistance genes in bacteria has the potential to spread its resistance properties.

Influence of the cleaning system of conveyor belts on microbiological quality of poultry meat

ABSTRACT This study focused on assessing the microbiology of conveyor belts surfaces, cleaned or not with pressurized water, and verification of the influence of this process on the microbiological quality of poultry meat. A reduction on mesophilic, psychrotrophic and Enterobacteriaceae counts (P<0.05) on dry conveyor belts compared to wet ones was observed. For the chicken leg (consisting of drumstick and thigh) samples, no statistically significant differences were detected on counts of indicators of microorganisms on poultry legs (composed by drumstick and thigh). For poultry meat conducted on wet or dry conveyor belts, 99% and 86%, were positive for Listeria spp, respectively. Only one sample of chicken leg was positive for presence of L. monocytogenes. These results demonstrate that there is no need to use water for cleaning conveyor belts during processing, which allows a reduction on the use of potable water in poultry slaughterhouses without jeopardizing food safety and public health.

Behavioral Observation and Microbiological Analysis of Older Adult Consumers' Cross-Contamination Practices in a Model Domestic Kitchen

The incidence of foodborne illness is higher in older adults because of their increased susceptibility; therefore, food safety practices are important. However, inadequate knowledge and negative attitudes toward food safety have been reported, which may increase use of unsafe food handling practices. Data on the actual food safety behaviors of older adults are lacking. In this study, food safety practices of older adults were observed and linked to microbiological analysis of kitchen surfaces to identify suspected routes of contamination. Older adults (≥60 years, n = 100) prepared a set meal in a model domestic kitchen sanitized according to a validated protocol to ensure minimal and consistent microbiological loads. Food safety behaviors were observed using ceiling-mounted cameras and recorded using a predetermined behavioral checklist. Surface microbiological contamination also was determined after food preparation. Overall, older adults frequently implemented unsafe food handling practices; 90% failed to implement adequate hand decontamination immediately after handling raw chicken. For older adults who used a larger number of adequate hand decontamination attempts, microbiological contamination levels in the kitchen following the food preparation session were significantly lower ( P < 0.001). The novel utilization of behavioral observation in conjunction with microbiological analysis facilitated identification of potentially unsafe food handling practices as suspected routes of microbiological cross-contamination in a model domestic kitchen. Findings indicate the potential impact on domestic food safety of unsafe food handling practices used by older adult consumers. This innovative approach revealed that a large proportion of older adults implement behaviors resulting in microbiological cross-contamination that may increase the risk of foodborne illness in the home.

Ready-to-eat meat products as a source of Listeria monocytogenes

In 2015 in the European Union member states listeriosis caused 270 deaths. Food is the route of transmission in 99% of all human infection cases. Several studies from different countries have shown that the presence of Listeria monocytogenes in food can be as high as 58.3%. One of the most important ways to protect food from these microorganisms is to prevent the spread of the bacteria at processing plants at different stages of food production chain. The ability of L. monocytogenes to survive in extreme conditions and to form biofilms on various surfaces is a significant challenge for food safety. Removal of these bacteria from niches in processing plants is difficult and requires the use of sanitisers and precise equipment cleaning. The presence of L. monocytogenes in processing environment at slaughterhouses, deli meat factories or in retail may be a reason of cross-contamination. Proper hygienic systems applied by workers in food preparing places and knowledge about different routes of spreading of these bacteria may effectively decrease the risk of food contamination. Standardised legal regulations and control of meat product manufacture should be a fundamental way to protect food from L. monocytogenes contamination.

Transfer of Campylobacter and Salmonella from Poultry Meat onto Poultry Preparation Surfaces

Thermophilic Campylobacter and Salmonella enterica are major causes of gastrointestinal foodborne infection. Survival of these pathogens on food-associated surfaces is a risk contributing to their spread through the food system. This study examined the transfer of two strains each of C. jejuni, C. coli, Salmonella Enteritidis, and Salmonella Typhimurium from chicken meat to a knife or scissors used on either a plastic or wooden cutting board. Each strain of Campylobacter and Salmonella at ∼108 CFU mL-1 was inoculated (5 mL) onto 25 g of chicken meat with skin and allowed to attach (for 10 min). The meat was then cut (20 times per implement) into 1-cm2 pieces with either a knife or scissors on either a plastic or wooden cutting board. The numbers of pathogens transferred from meat onto cutting implements and cutting board surfaces were enumerated. The surfaces were subsequently either rinsed with water or rinsed with water and wiped with a kitchen towel to mimic commonly used superficial cleaning practices for these implements, and the numbers of pathogens were enumerated again. The bacterial numbers for both pathogens were determined on thin-layer agar. The attachment of the Salmonella strains to chicken meat (∼7.0 to 7.8 log CFU cm-2) was higher than the attachment of the Campylobacter strains (∼4.6 to 6.6 log CFU cm-2). All four Salmonella strains transferred in higher numbers (∼1.9 to 6.3 log CFU cm-2) to all surfaces than did the Campylobacter strains (∼1.1 to 3.9 log CFU cm-2). The transfer rates of both pathogens from the chicken meat to all the surfaces examined varied substantially between ∼0 and 21.1%. The highest rate of transfer (∼21.1%) observed was for C. coli 2875 when transferred from the chicken meat to the scissors. Most cleaning treatments reduced the numbers of both pathogens (∼0.3 to 4.1 log CFU cm-2) transferred to all the surfaces. Our study gives insights into the risks associated with the transfer of Campylobacter and Salmonella from poultry to the surfaces used in poultry preparation.

Comparative Exposure Assessment of ESBL-Producing Escherichia coli through Meat Consumption

The presence of extended-spectrum β-lactamase (ESBL) and plasmidic AmpC (pAmpC) producing Escherichia coli (EEC) in food animals, especially broilers, has become a major public health concern. The aim of the present study was to quantify the EEC exposure of humans in The Netherlands through the consumption of meat from different food animals. Calculations were done with a simplified Quantitative Microbiological Risk Assessment (QMRA) model. The model took the effect of pre-retail processing, storage at the consumers home and preparation in the kitchen (cross-contamination and heating) on EEC numbers on/in the raw meat products into account. The contribution of beef products (78%) to the total EEC exposure of the Dutch population through the consumption of meat was much higher than for chicken (18%), pork (4.5%), veal (0.1%) and lamb (0%). After slaughter, chicken meat accounted for 97% of total EEC load on meat, but chicken meat experienced a relatively large effect of heating during food preparation. Exposure via consumption of filet americain (a minced beef product consumed raw) was predicted to be highest (61% of total EEC exposure), followed by chicken fillet (13%). It was estimated that only 18% of EEC exposure occurred via cross-contamination during preparation in the kitchen, which was the only route by which EEC survived for surface-contaminated products. Sensitivity analysis showed that model output is not sensitive for most parameters. However, EEC concentration on meat other than chicken meat was an important data gap. In conclusion, the model assessed that consumption of beef products led to a higher exposure to EEC than chicken products, although the prevalence of EEC on raw chicken meat was much higher than on beef. The (relative) risk of this exposure for public health is yet unknown given the lack of a modelling framework and of exposure studies for other potential transmission routes.

Comparing listeriosis risks in at-risk populations using a user-friendly quantitative microbial risk assessment tool and epidemiological data

Although infection by the pathogenic bacterium Listeria monocytogenes is relatively rare, consequences can be severe, with a high case-fatality rate in vulnerable populations. A quantitative, probabilistic risk assessment tool was developed to compare estimates of the number of invasive listeriosis cases in vulnerable Canadian subpopulations given consumption of contaminated ready-to-eat delicatessen meats and hot dogs, under various user-defined scenarios. The model incorporates variability and uncertainty through Monte Carlo simulation. Processes considered within the model include cross-contamination, growth, risk factor prevalence, subpopulation susceptibilities, and thermal inactivation. Hypothetical contamination events were simulated. Results demonstrated varying risk depending on the consumer risk factors and implicated product (turkey delicatessen meat without growth inhibitors ranked highest for this scenario). The majority (80%) of listeriosis cases were predicted in at-risk subpopulations comprising only 20% of the total Canadian population, with the greatest number of predicted cases in the subpopulation with dialysis and/or liver disease. This tool can be used to simulate conditions and outcomes under different scenarios, such as a contamination event and/or outbreak, to inform public health interventions.

Putative Cross-Contamination Routes of Listeria monocytogenes in a Meat Processing Facility in Romania

Putative routes of Listeria monocytogenes contamination, based on the workflow of the employees, were studied in a meat processing facility by investigating 226 samples collected from food contact surfaces, non-food contact surfaces, raw materials, and ready-to-eat meat products on four occasions over a 1-year period. In total, 19.7% of non-food contact surfaces, 22.9% of food contact surfaces, 45% of raw materials, and 20% of ready-to-eat meat products were positive for L. monocytogenes (analyzed by the International Organization for Standardization standard method ISO 11290). Pulsed-field gel electrophoresis (PFGE) profiles were determined for a representative subset of these isolates, and 11 distinct pulsotypes were identified, two of which were frequently isolated (T4 and T8) and considered persistent. Strains from the various pulsotypes were screened for the presence of bcrABC and qacH, the genes responsible for tolerance responses to quaternary ammonium compounds. Two strains harbored bcrABC, and these strains had a higher benzalkonium chloride tolerance; however, they were not considered persistent strains. The frequently isolated PFGE pulsotype T8 strains were highly adhesive to abiotic surfaces at 10 and 20°C; however, the pulsotype T6 strain, which was isolated only at the last sampling time, had the highest adhesion ability, and the pulsotype T4 strain (the second most persistent pulsotype) had only modest adhesion. Four putative cross-contamination routes were confirmed by mapping the persistent and other isolates. This information could allow a food safety manager to adjust the work flow to improve the hygienic conditions in a meat processing facility. This study revealed the prevalence and persistence of L. monocytogenes strains in a meat processing facility and established the importance of developing strategies to avoid cross-contamination, recalls, and outbreaks of listeriosis.

A 3-year hygiene and safety monitoring of a meat processing plant which uses raw materials of global origin

A systematic approach in monitoring the hygiene of a meat processing plant using classical microbiological analyses combined with molecular characterization tools may assist in the safety of the final products. This study aimed: (i) to evaluate the total hygiene level and, (ii) to monitor and characterize the occurrence and spread of Salmonella spp. and Listeria monocytogenes in the environment and the final products of a meat industry that processes meat of global origin. In total, 2541 samples from the processing environment, the raw materials, and the final products were collected from a Greek meat industry in the period 2011-2013. All samples were subjected to enumeration of total viable counts (TVC), Escherichia coli (EC) and total coliforms (TCC) and the detection of Salmonella spp., while 709 of these samples were also analyzed for the presence L. monocytogenes. Pathogen isolates were serotyped and further characterized for their antibiotic resistance and subtyped by PFGE. Raw materials were identified as the primary source of contamination, while improper handling might have also favored the proliferation of the initial microbial load. The occurrence of Salmonella spp. and L. monocytogenes reached 5.5% and 26.9%, respectively. Various (apparent) cross-contamination or persistence trends were deduced based on PFGE analysis results. Salmonella isolates showed wide variation in their innate antibiotic resistance, contrary to L. monocytogenes ones, which were found susceptible to all antibiotics except for cefotaxime. The results emphasize the biodiversity of foodborne pathogens in a meat industry and may be used by meat processors to understand the spread of pathogens in the processing environment, as well as to assist the Food Business Operator (FBO) in establishing effective criteria for selection of raw materials and in improving meat safety and quality. This approach can limit the increase of microbial contamination during the processing steps observed in our study as well as the cross contamination of meat products.