Prevalence, seasonal occurrence and antimicrobial resistance of Salmonella in poultry retail products in Greece

Prevalence of Campylobacter spp., Salmonella spp., and Listeria monocytogenes, and Population Levels of Food Safety Indicator Microorganisms in Retail Raw Chicken Meat and Ready-To-Eat Fresh Leafy Greens Salads Sold in Greece

The presence of microbial pathogens in foods compromises their safety resulting in foodborne illnesses, public health disorders, product recalls, and economic losses. In this work, 60 samples of chilled raw chicken meat and 40 samples of packaged ready-to-eat (RTE) fresh leafy greens salads, sold in Greek retail stores (butchers and supermarkets), were analyzed for the presence of three important foodborne pathogenic bacteria, i.e., Campylobacter spp., Salmonella spp., and Listeria monocytogenes, following the detection protocols of the International Organization for Standardization (ISO). In parallel, the total aerobic plate count (APC), Enterobacteriaceae, total coliforms, Escherichia coli, and staphylococci were also enumerated as hygiene (safety) indicator organisms. When present, representative typical colonies for each pathogen were biochemically verified, following the ISO guidelines. At the same time, all the Campylobacter isolates from chicken (n = 120) were identified to the species level and further phylogenetically discriminated through multiplex and repetitive sequence-based (rep) polymerase chain reaction (PCR) methods, respectively. Concerning raw chicken, Campylobacter spp. were recovered from 54 samples (90.0%) and Salmonella spp. were recovered from 9 samples (15.0%), while L. monocytogenes was present in 35 samples (58.3%). No Campylobacter was recovered from salads, and Salmonella was present in only one sample (2.5%), while three salads were found to be contaminated with L. monocytogenes (7.5%). The 65% of the Campylobacter chicken isolates belonged to C. jejuni, whereas the rest, 35%, belonged to C. coli. Alarmingly, APC was equal to or above 106 CFU/g in 53.3% and 95.0% of chicken and salad samples, respectively, while the populations of some of the other safety indicators were in some cases also high. In sum, this study unravels high occurrence percentages for some pathogenic and food safety indicator microorganisms in raw chicken meat and RTE fresh leafy greens salads sold in Greek retail, highlighting the need for more extensive microbiological control throughout the food production chain (from the farm/field to the market).

Prevalence of Salmonella species and factors associated with contamination of mechanically recovered poultry meat imported into South Africa, 2016-2017

Background and Aim

Mechanically recovered meat (MRM) products have been linked to outbreaks of human salmonellosis. However, no studies have investigated the prevalence of Salmonella species in MRM products in South Africa despite the products being imported. Therefore, this study aimed to estimate the prevalence and factors associated with Salmonella spp. contamination of mechanically recovered poultry meat (MRPM) imported into South Africa.

Materials and Methods

This study used secondary data of MRPM consignments imported through a port entry into South Africa from May 2016 to December 2017. Crude and factor-specific proportions of Salmonella positive MRPM and their 95% confidence intervals were calculated. A logistic regression model was used to assess the association among country, season, importer, year, and MRPM Salmonella status.

Results

A total of 8127 MRPM consignments were imported. Seventeen percentages (17.18%, 985/5733) of consignments tested positive for Salmonella species and only 364 isolates were serotyped. Salmonella Heidelberg (73.90%, 269/364) was the most common serotype followed by Salmonella Infantis (6.59%, 24/364), Salmonella Salamae (4.67%, 17/364), and Salmonella Schwarzengrund (3.57%, 13/364). The odds of a consignment testing positive for Salmonella spp. was higher among consignments from country-B (Odds Ratio [OR]: 3.958, p < 0.0001) compared to "All others." The odds of testing positive for Salmonella were also higher among consignments imported in autumn (OR: 1.488, p < 0.0001) but lower among those imported in spring (OR: 0.767, p = 0.0004) and summer (OR: 0.843, p < 0.0001) when compared to the winter season. Consignments imported in 2016 compared to 2017 were 1.563 times (p < 0.0001) as likely to test positive for a Salmonella species.

Conclusion

Salmonella species were reported in MRPM consignments in this study with Salmonella Heidelberg being the most common serotype. Furthermore, some Salmonella serotypes reported in this study have been implicated in foodborne disease outbreaks. Country of origin, season, and year of importation were significantly associated with the odds of a consignment testing positive for Salmonella species.

Comparison of Antibiotic Resistance Profiles of Salmonella Isolates from Retail Meats in Nanchang, China, in Two Periods

Salmonella is one of the most important foodborne pathogens. In this article, a total of 160 Salmonella isolates recovered from retail meats in June-July 2018 (before COVID-19 outbreak) and December 2020-April 2021 (after COVID-19 outbreak) in Nanchang, China, were characterized for serotyping, antimicrobial susceptibility, and specific resistance gene screening. The prevalence of Salmonella Typhimurium increased from 5.4% in 2018 to 19.1% in 2021, and Salmonella Enteritidis increased from 3.3% in 2018 to 8.8% in 2021. Compared with those in June-July 2018, Salmonella isolates in December 2020-April 2021 demonstrated a significant increase in resistance to 13 tested antibiotics except for doxycycline and nitrofurantoin (p < 0.05). The Salmonella isolates in December 2020-April 2021 showed a higher presence of plasmid-mediated quinolone resistance genes (qnrA, qnrB, and qnrS), and mutations in the quinolone resistance-determining region (gyrA Asp87Asn, gyrA Asp87Tyr, parC Thr57Ser, and parC Ser80Ile). Whole-genome sequencing was used to analyze four polymyxin B-resistant strains. Some common mutation sites in eptC and micA were found in the four strains. Based on the data in this article, it indicated that antibiotic resistance was facilitated and more gene mutations related to quinolone resistance were developed.

Salmonella spp. in Chicken: Prevalence, Antimicrobial Resistance, and Detection Methods

Multidrug-resistant Salmonella spp. is one of the leading causes of worldwide foodborne disease outbreaks. Animal-derived foods, particularly chicken and poultry products, are the most likely source of Salmonella transmission to humans. The increasing demand for chicken meat has raised a global food safety issue. This review aims to determine the prevalence and antimicrobial resistance of Salmonella spp. in chickens from various countries in Asia. The methods for detecting Salmonella will also be discussed in this review. The prevalence of Salmonella spp. in chicken and poultry products is lower in developed countries than in developing countries. In addition, the incidence of Salmonella spp. in chicken and poultry products from fresh markets is higher than those from supermarkets. Furthermore, this review also reported the presence of multidrug-resistant Salmonella strains in various Asian countries. Rapid Salmonella detection based on immunological assays, molecular-based assays, and biosensors can provide more accurate results with high sensitivity and specificity. These methods also require a shorter time than the cultural-based Salmonella detection method. The use of suitable detection methods to determine the presence of Salmonella spp. in chicken and poultry products is important to ensure food safety.

Use of Phages to Treat Antimicrobial-Resistant Salmonella Infections in Poultry

Simple Summary

Salmonellosis, an infection in humans and animals caused by Salmonella spp., poses a major concern to public health and food safety worldwide. Antibiotics are mostly prescribed to treat salmonellosis. Unfortunately, indiscriminate use of antibiotics leads to the emergence and transmission of multidrug-resistant Salmonella spp. As antibiotics are becoming increasingly ineffective, infections caused by MDR strains will be difficult to manage. The search for an alternative to antibiotics has led scientists to give renewed attention on phage therapy. Though commercial use of phages for controlling Salmonella in poultry is still in its early stage, the use of lytic phages is considered an environmentally friendly, cost-effective, and sustainable antimicrobial approach. Moreover, it provides advantages over antibiotics in terms of specificity, cost of development, resistance, and genetic amenability. Studies on laboratory and field scale use show promise on the effectiveness of phages against MDR Salmonella spp. However, inadequate data on safety of phage use, phage stability, and lack of regulatory framework remain major obstacles in the commercial application of phages. Our article provides a comprehensive overview on global prevalence and antimicrobial resistance of Salmonella in poultry, the efforts to control Salmonella using phage therapy, and challenges as well as future prospects of phage therapy.

Abstract

Salmonellosis is one of the most common bacterial infections that impacts both human health and poultry production. Although antibiotics are usually recommended for treating Salmonella infections, their misuse results in the evolution and spread of multidrug-resistant (MDR) bacteria. To minimize the health and economic burdens associated with antimicrobial resistance, a novel antibacterial strategy that can obliterate pathogens without any adverse effects on humans and animals is urgently required. Therefore, therapeutic supplementation of phages has gained renewed attention because of their unique ability to lyse specific hosts, cost-effective production, environmentally-friendly properties, and other potential advantages over antibiotics. In addition, the safety and efficacy of phage therapy for controlling poultry-associated Salmonella have already been proven through experimental studies. Phages can be applied at every stage of poultry production, processing, and distribution through different modes of application. Despite having a few limitations, the optimized and regulated use of phage cocktails may prove to be an effective option to combat infections caused by MDR pathogens in the post-antibiotic era. This article mainly focuses on the occurrence of salmonellosis in poultry and its reduction with the aid of bacteriophages. We particularly discuss the prevalence of Salmonella infections in poultry and poultry products; review the trends in antibiotic resistance; and summarize the application, challenges, and prospects of phage therapy in the poultry industry.

Retail Chicken Carcasses as a Reservoir of Multidrug-Resistant Salmonella

is a major cause of foodborne disease outbreaks worldwide, mainly through poultry. Recently, there has been an increase in multidrug-resistant (MDR) Salmonella infections globally. The increased drug resistance results in increased costs and poorer health outcomes due to unavailability or delayed treatment. This study aims to determine the prevalence of Salmonella in retail raw chicken meat and identify their antimicrobial resistance profiles. A total of 270 retail raw chicken carcasses (local and imported) were collected from three hypermarket chains in Qatar between November 2017 and April 2018. Thirty carcasses were contaminated with Salmonella (11.11%). The prevalence of Salmonella in locally produced chicken was higher than in imported chicken (OR = 2.56, 95% CI: 1.18–5.53, p = 0.016). No significant differences were found between the prevalence and storage temperature or hypermarket chain. The highest resistance rates in the isolates were reported to tetracycline (73.7%) followed by nitrofurantoin (53.3%), ampicillin (50%), amoxicillin-clavulanic acid, ceftriaxone (26.7%), and ciprofloxacin (23.3%). Eight isolates were potential extended-spectrum β-lactamase-producers, all in imported frozen chicken (p < 0.0001). Additionally, 43.3% of the isolates were MDR and associated with frozen chicken (OR = 16.88, 95% CI: 2.55–111.47, p = 0.002). The findings indicate that while the prevalence of Salmonella in retail chicken in Qatar is moderate, a large proportion of them are MDR.

Antimicrobial Resistance Profiles of Non-typhoidal Salmonella From Retail Meat Products in California, 2018

Non-typhoidal Salmonella remains a leading cause of foodborne illness in the United States, with food animal products serving as a key conduit for transmission. The emergence of antimicrobial resistance (AMR) poses an additional public health concern warranting better understanding of its epidemiology. In this study, 958 retail meat samples collected from January to December 2018 in California were tested for Salmonella. From multivariable logistic regression, there was a 6.47 (90% CI 2.29–18.27), 3.81 (90% CI 1.29–11.27), and 3.12 (90% CI 1.03–9.45) higher odds of contamination in samples purchased in the fall, spring, and summer than in winter months, respectively, and a 3.70 (90% CI 1.05–13.07) higher odds in ground turkey compared to pork samples. Fourteen distinct serotypes and 17 multilocus sequence types were identified among the 43 isolates recovered, with S. Kentucky (25.58%), S. Reading (18.60%), S. Infantis (11.63%), and S. Typhimurium (9.30%) comprising the top serotypes. High prevalence of resistance was observed in retail chicken isolates for streptomycin (12/23, 52.17%) and tetracycline (12/23, 52.17%), in ground turkey isolates for ampicillin (8/15, 53.34%), and in ground beef isolates for nalidixic acid (2/3, 66.67%). Fourteen (32.56%) were susceptible to all antimicrobials tested, 11 (25.58%) were resistant to one drug, and 12 (27.91%) were resistant to two drugs. The remaining six isolates (13.95%) were multidrug-resistant (MDR, ≥3 drug classes) S. Infantis (n = 4), S. Reading (n = 1), and S. Kentucky (n = 1). Whole-genome sequencing (WGS) identified 16 AMR genes and 17 plasmid replicons, including bla_CTX–M–65 encoding ceftriaxone resistance and a D87Y mutation in gyrA conferring resistance to nalidixic acid and reduced susceptibility to ciprofloxacin. The IncFIB(pN55391) replicon previously identified in connection to the worldwide dissemination of pESI-like mega plasmid carriage in an emerged S. Infantis clone was detected in four of the six MDR isolates. Genotypes from WGS showed high concordance with phenotype with overall sensitivity and specificity of 95.31% and 100%, respectively. This study provides insight into the AMR profiles of a diversity of Salmonella serotypes isolated from retail meat products in California and highlights the value of routine retail food surveillance for the detection and characterization of AMR in foodborne pathogens.

Assessing antimicrobial resistance occurrence in the Portuguese food system: Poultry, pigs and derived food, 2014-2018

Antimicrobial resistance (AMR) spread in the food system is a major threat to public and animal health. We describe AMR trends in zoonotic bacteria and identify risk factors associated with AMR occurrence in animals and derived food in Portugal. Data from the Portuguese AMR surveillance programme on food-producing animals, 2014-2018, were used. AMR frequencies were calculated for Escherichia coli, Campylobacter and Salmonella in broilers, turkeys, pig populations and their derived food products. AMR-associated factors were studied for Salmonella isolates: population, sampling stage (farm, slaughterhouse and processing plant), sample type (environmental, carcase and food), sampler (HACCP, industry, official and official and industry), sample context (control and eradication programmes and monitoring), year (2014-2018) and season. Logistic regression was applied to estimate crude odds ratio and adjusted odds ratio (aOR) with 95% confidence intervals (95% CI). The final models were obtained using a backward stepwise method. This study included 2,157 Escherichia coli, 561 Campylobacter and 1,071 Salmonella isolates. The highest prevalence estimates amongst tested antimicrobials for each bacterial species in 2014-2018 had the following ranges: (i) (fluoro)quinolones: E. coli: 84%-93%, Campylobacter: 94%-98%; (ii) tetracyclines: E. coli: 68%-91%, Campylobacter: 87%-91%, Salmonella: 72%; (iii) penicillins: E. coli: 82%-100%; (iv) sulphonamides: E. coli: 68%-82%. Compared with the reference categories for host (broiler), year (2014), season (winter) and sampler (HACCP own checks), resistance to at least one antimicrobial in Salmonella was significantly less likely in laying hens (aOR 0.28; 95% CI: 0.18-0.42), 2016 (aOR 0.56; 95% CI: 0.33-0.93), 2017 (aOR 0.29; 95% CI: 0.17-0.51) and 2018 (aOR 0.35; 95% CI: 0.20-0.61), autumn (aOR 0.63; 95% CI: 0.40-0.97) and more likely to occur in broiler products (aOR 5.14; 95% CI: 2.61-10.54), pork products (aOR 6.84; 95% CI: 3.74-12.98) and official and industry combined sampling (aOR 2.16; 95% CI: 1.06-4.47). This study reveals a high prevalence of Salmonella resistance, especially during the summer and in post-farm stages of the Portuguese food system to nearly all antimicrobials and in the summer in farms to (fluoro)quinolones. Measures to tackle resistance are required.

Monte Carlo Simulation Model for Predicting Salmonella Contamination of Chicken Liver as a Function of Serving Size for Use in Quantitative Microbial Risk Assessment

ABSTRACT

The first step in quantitative microbial risk assessment (QMRA) is to determine the distribution of pathogen contamination among servings of the food in question at some point in the farm-to-table chain. In the present study, the distribution of Salmonella contamination among servings of chicken liver for use in the QMRA was determined at meal preparation. Salmonella prevalence (P), most probable number (MPN, N), and serotype for different serving sizes were determined by use of a combination of five methods: (i) whole sample enrichment; (ii) quantitative PCR; (iii) culture isolation; (iv) serotyping; and (v) Monte Carlo simulation. Epidemiological data also were used to convert serotype data to virulence (V) values for use in the QMRA. A Monte Carlo simulation model based in Excel and simulated with @Risk predicted Salmonella P, N, serotype, and V as a function of a serving size of one (58 g) to eight (464 g) chicken livers. Salmonella P of chicken livers was 72.5% (58 of 80) per 58 g. Four Salmonella serotypes were isolated from chicken livers: (i) Infantis (P = 28%, V = 4.5); (ii) Enteritidis (P = 15%, V = 5); (iii) Typhimurium (P = 15%, V = 4.8); and (iv) Kentucky (P = 15%, V = 0.8). Salmonella N was 1.76 log MPN/58 g (median) with a range of 0 to 4.67 log MPN/58 g, and the median Salmonella N was not affected (P > 0.05) by serotype. The model predicted a nonlinear increase (P ≤ 0.05) of Salmonella P from 72.5%/58 g to 100%/464 g, a minimum N of 0 log MPN/58 g to 1.28 log MPN/464 g, and a median N from 1.76 log MPN/58 g to 3.22 log MPN/464 g. Regardless of serving size, predicted maximum N was 4.74 log MPN per serving, mean V was 3.9 per serving, and total N was 6.65 log MPN per lot (10,000 chicken livers). The data acquired and modeled in this study address an important data gap in the QMRA for Salmonella and whole chicken liver.

HIGHLIGHTS

Prevalence and risk factors for Salmonella spp. contamination of slaughtered chickens in Taiwan

The present study was designed to estimate the prevalence of Salmonella contamination in Taiwanese broilers at slaughter and to identify risk factors associated with the presence of Salmonella in processed batches of broilers. Carcass rinse samples from 362 batches of broilers were collected from 45 chicken abattoirs in Taiwan between February 2013 and November 2014. Univariate analyses and multivariable logistic regression analyses were conducted to identify putative risk factors for contamination. Salmonella was detected in 32.6 % (95 % CI: 30.4-34.8) of individual broilers and 56.4 % (95 % CI: 51.1-61.5) of the sampled batches. The multivariable logistic regression model identified season (July to November) (OR = 1.95; 95 % CI: 1.2-3.2) as increasing the risk of infection. Abattoirs in the southern region (Taichung and Kaohsiung) (OR = 0.45; 95 % CI: 0.3-0.8); batches scalded for > 90 s (OR = 0.2; 95 % CI: 0.1-0.3) and batches of commercial white broilers (BR) (OR = 0.21; 95 % CI: 0.1-0.4) all had a decreased risk of contamination compared to abattoirs from the northern region, scalding < 90 s and Taiwan native chickens (TNC), respectively. This study highlights the influence of environmental conditions and poultry breed on the risk of Salmonella contamination of chickens during slaughter.

Analysis of the assessment of antimicrobial susceptibility. Non-typhoid Salmonella in meat and meat products as model (systematic review)

BACKGROUND

The scientific publications of antimicrobial susceptibilities and resistance must be precise, with interpretations adjusted to the standard. In this frame, knowledge of antimicrobial resistance is fundamental in pathogenic microorganisms such as Salmonella spp., known for many annual deaths worldwide. The objective of this work was to compare the interpretation of standards, the concentrations, and the breakpoints, to study antimicrobial resistance in Non-Typhoidal Salmonella (NTS) isolated from beef, pork, and chicken meat, meat products, and propose additional considerations that improve the use and usefulness of published results.

RESULTS

After refining the search based on meeting the inclusion and exclusion criteria, 48 papers were selected. In 33 (68.8%) of them, the disc diffusion method was used, in 11 (22.9%) the MIC determination method, and in 4 (8.33%) were used both. In 24 (50%) of the articles, the selection of a different (correct) standard could have had an impact on the interpretation of antimicrobial susceptibility, which observed when considering three scenarios, i) comparison between the year of the isolation versus the implemented standard, ii) comparison between the year of submission versus implemented standard and iii) comparison between the year of publication versus implemented standard.

CONCLUSIONS

The most frequent scenario was the inadequate selection of standards, indicating that some studies had not ensured that applied standards kept in line with the date of isolation, date of publication and interpretation of susceptibilities. We proposed 2 years for standards use for resistance and multi-resistance interpretations. On the other hand, we invite researchers to publish their results in the shortest possible time, and editors and reviewers of scientific journals to prioritise these types of studies and verify the correspondence between the standard cited and the one used and the one to be taken into account.

Antimicrobial Resistance of Non-Typhoid Salmonella in Meat and Meat Products

Salmonella enterica serovars are associated with numerous annual deaths worldwide and are responsible for a large number of foodborne diseases. Within this frame of reference, knowledge of antimicrobial susceptibility represents the fundamental approach of most Salmonella treatments. Therefore, scientific publications of antimicrobial susceptibilities and resistance must be precise, with interpretations adjusted to a particular standard. Hence, the three objectives in this study were: (i) to describe the frequency of antimicrobial-resistant isolates of Non-Typhoidal Salmonella (NTS) isolated from beef, pork, chicken meat, and other meat products; (ii) to describe the distribution of serovars and their multi-resistance to antibiotics for clinical use (veterinary and human) between 1996 and 2019; and (iii) to propose additional considerations that could improve the use and usefulness of the published results. Our results determined that the predominant isolates came from poultry. Enteritidis and Typhimurium were the most reported serovars by MIC (with both having the highest resistance to TET) while the lowest resistance was to CIP and CRO for Enteritidis and Typhimurium, respectively. The multi-resistance pattern AMP AMC CEP GEN KAN STR TET was the most frequently observed pattern by MIC in Montevideo and Seftenberg, while, for disc diffusion, the pattern AMP STR TET was the most frequent in the Bredeney serotype. In conclusion, researchers should carry out homogeneous sampling procedures, identify the types of the samples, use standard identification methods, and employ appropriate standards for antimicrobial susceptibility interpretation. Additionally, there is also a need for all WHO members to comply with the WHA 73.5 resolution. Our final recommendation is for all producers to reduce antibiotic prophylactic use.

Factors associated with Salmonella enterica and Escherichia coli during downtime in commercial broiler chicken barns in Ontario

Salmonella enterica and Escherichia coli are bacteria of concern to veterinary public health and poultry health. Our research aimed to determine the factors associated with S. enterica and E. coli in commercial broiler chicken barns during the rest period between flocks to identify the best methods of sanitation for bacterial load reduction. This involved collecting samples from September 2015 to July 2016 from the floors of 36 barns before sanitation (baseline) and at 2 time intervals after sanitation, followed by microbiological and molecular analysis. A priori variables of interest included sanitation procedure (dry cleaning, wet cleaning, disinfection), sampling point (baseline, 2 d after sanitation, 6 d after sanitation), and flooring type (concrete, wood). The odds of detecting S. enterica were higher on wooden floors that were wet-cleaned than on concrete floors that were dry-cleaned, lower in the winter and spring than in the fall, and lower when samples were collected 2 d and 6 d after sanitation than at baseline. For E. coli, the concentration was higher on wooden floors than on concrete floors and in the summer than in the fall, and it was lower in postsanitation samples from disinfected barns than in presanitation samples from dry-cleaned barns and in the winter than in the fall. Among E. coli isolates, factors associated with the presence of qacEΔ1, a gene associated with resistance to quaternary ammonium compounds, included sanitation procedure, flooring type, cycle length, and the number of times per yr the barn is disinfected. Our findings highlight the importance of cleaning after litter removal, although the sanitation procedure chosen might differ depending on which pathogen is present and causing disease issues; dry cleaning appears to be preferable for S. enterica control, especially in barns with wooden floors, whereas disinfection appears to be preferable for E. coli reduction.

Rapid Microbial Quality Assessment of Chicken Liver Inoculated or Not With Salmonella Using FTIR Spectroscopy and Machine Learning

Chicken liver is a highly perishable meat product with a relatively short shelf-life and that can get easily contaminated with pathogenic microorganisms. This study was conducted to evaluate the behavior of spoilage microbiota and of inoculated Salmonella enterica on chicken liver. The feasibility of Fourier-transform infrared spectroscopy (FTIR) to assess chicken liver microbiological quality through the development of a machine learning workflow was also explored. Chicken liver samples [non-inoculated and inoculated with a four-strain cocktail of ca. 10³ colony-forming units (CFU)/g Salmonella] were stored aerobically under isothermal (0, 4, and 8°C) and dynamic temperature conditions. The samples were subjected to microbiological analysis with concomitant FTIR measurements. The developed FTIR spectral analysis workflow for the quantitative estimation of the different spoilage microbial groups consisted of robust data normalization, feature selection based on extra-trees algorithm and support vector machine (SVM) regression analysis. The performance of the developed models was evaluated in terms of the root mean square error (RMSE), the square of the correlation coefficient (R²), and the bias (B_f) and accuracy (A_f) factors. Spoilage was mainly driven by Pseudomonas spp., followed closely by Brochothrix thermosphacta, while lactic acid bacteria (LAB), Enterobacteriaceae, and yeast/molds remained at lower levels. Salmonella managed to survive at 0°C and dynamic conditions and increased by ca. 1.4 and 1.9 log CFU/g at 4 and 8°C, respectively, at the end of storage. The proposed models exhibited A_f and B_f between observed and predicted counts within the range of 1.071 to 1.145 and 0.995 to 1.029, respectively, while the R² and RMSE values ranged from 0.708 to 0.828 and 0.664 to 0.949 log CFU/g, respectively, depending on the microorganism and chicken liver samples. Overall, the results highlighted the ability of Salmonella not only to survive but also to grow at refrigeration temperatures and demonstrated the significant potential of FTIR technology in tandem with the proposed spectral analysis workflow for the estimation of total viable count, Pseudomonas spp., B. thermosphacta, LAB, Enterobacteriaceae, and Salmonella on chicken liver.

Antibiotic resistance in Salmonella spp. isolated from poultry: A global overview

Salmonella enterica is the most important foodborne pathogen, and it is often associated with the contamination of poultry products. Annually, Salmonella causes around 93 million cases of gastroenteritis and 155,000 deaths worldwide. Antimicrobial therapy is the first choice of treatment for this bacterial infection; however, antimicrobial resistance has become a problem due to the misuse of antibiotics both in human medicine and animal production. It has been predicted that by 2050, antibiotic-resistant pathogens will cause around 10 million deaths worldwide, and the WHO has suggested the need to usher in the post-antibiotic era. The purpose of this review is to discuss and update the status of Salmonella antibiotic resistance, in particular, its prevalence, serotypes, and antibiotic resistance patterns in response to critical antimicrobials used in human medicine and the poultry industry. Based on our review, the median prevalence values of Salmonella in broiler chickens, raw chicken meat, and in eggs and egg-laying hens were 40.5% ( interquartile range [IQR] 11.5-58.2%), 30% (IQR 20-43.5%), and 40% (IQR 14.2-51.5%), respectively. The most common serotype was Salmonella Enteritidis, followed by Salmonella Typhimurium. The highest antibiotic resistance levels within the poultry production chain were found for nalidixic acid and ampicillin. These findings highlight the need for government entities, poultry researchers, and producers to find ways to reduce the impact of antibiotic use in poultry, focusing especially on active surveillance and finding alternatives to antibiotics.

Highly clonal relationship among Salmonella Enteritidis isolates in a commercial chicken production chain, Brazil

In this study, we described the comparison among pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), ribotyping, and PCR-ribotyping methods for subtyping Salmonella Enteritidis isolated from an industrial chicken production chain. One hundred and eight S. Enteritidis were isolated at all stages of poultry meat processing plant. These isolates were pheno- and genotypically characterized by using antimicrobial susceptibility test, phage typing, RAPD, PFGE, ribotyping, and PCR-ribotyping. The highest antibiotic resistance rates were observed for enrofloxacin (18.5%) followed by furazolidone (15.7%), cefoxitin (1.8%), ciprofloxacin, and ampicillin with 0.9% each one, while seven isolates (6.4%) were pan-susceptible. Most strains belonged to the globally disseminated phage type PT4 (n = 74; 69.2%). Additionally, we identified strains belonging to phage types PT1 (n = 19; 17.8%) and PT7a (n = 14; 13.1%). Moreover, our results showed that these four molecular methods indicate similar results showing high similarity (≥ 90%) among S. Enteritidis strains, suggesting that these isolates appear to be from a common ancestor being spread at all stages of the poultry production chain. In summary, the combined molecular approaches of these methods remain a suitable alternative to efficiently subtyping S. Enteritidis in the absence of high-resolution genotyping methods and these results may serve as a baseline study for development of mitigation strategies.

Regulating appetite in broilers for improving body and muscle development - A review

Appetite is the desire for feed and water and the voluntary intake of feed and is an important regulator of livestock productivity and animal health. Economic traits such as growth rate and muscle development (meat deposition) in broilers are directly correlated to appetite. Factors that may influence appetite include environmental factors, such as stress and temperature variation, and animal‐specific factors, such as learning period, eating capacity and preferences. Feed preferences have been reported to be determined in early life, and this period is important in broilers due to their fast growth and relatively short growth trajectories. This may be of importance when contemplating the use of more circular and sustainable feeds and the optimization of appetite for these feeds. The objective of this review was to review the biological mechanisms underlying appetite using data from human, animal and bird models and to consider the option for modulating appetite particularly as it relates to broiler chickens.

CTX-M-55-type ESBL-producing Salmonella enterica are emerging among retail meats in Phnom Penh, Cambodia

Background

Salmonella enterica is a leading cause of human gastroenteritis. S. enterica strains that produce ESBLs (ESBL-Salm) remain rare in Europe and North America, but less is known about their prevalence among animal-derived foods in countries with weaker food safety practices and unregulated veterinary antibiotic use.

Objectives

To examine the prevalence and characteristics of ESBL-Salm from retail meats in Phnom Penh, Cambodia.

Methods

We tested fish, pork and chicken from two markets for ESBL- and carbapenemase-producing Salmonella from September-December 2016, using cefotaxime- and ertapenem-supplemented media, respectively. ESBL-Salm were sequenced and their genomes characterized. We performed plasmid conjugation experiments to assess the co-transferability of ESBL-encoding genes and MDR phenotypes.

Results

Twenty-six of 150 fish and meat samples (17%) were positive for ESBL-Salm, including 10/60 fish (17%), 15/60 pork (25%) and 1/30 chicken (3%). Carbapenemase-producing Salmonella strains were not detected. Pork-origin ESBL-Salm were primarily serotypes Rissen (10/15) or a monophasic variant of Typhimurium 4,5,12:i:- (3/15), whereas Saintpaul (3/10) and Newport (4/10) were more common among fish. Most ESBL enzymes were encoded by blaCTX-M-55 genes (24/26) harboured on conjugative IncA/C2 (n = 14) or IncHI2 (n = 10) plasmids. Resistance to up to six additional drug classes was co-transferred by each plasmid type. ESBL-Salm were resistant to almost every antibiotic recommended for severe salmonellosis treatment.

Conclusions

CTX-M-55-type S. enterica are highly prevalent among pork and fish from Phnom Penh markets and their spread appears to be mediated by MDR IncA/C2 and IncHI2 plasmids. Food safety must be improved and veterinary antibiotic use should be regulated to protect public health.

Prevalence, abundance, serovars and antimicrobial resistance of Salmonella isolated from retail raw poultry meat in China

This study investigated the prevalence and levels of Salmonella contamination of retail raw poultry meat in China, and examined serovar distribution and antimicrobial susceptibility profiles of the recovered isolates. In total, 664 poultry meat samples were collected from retail markets in 39 cities across China. Salmonella was isolated from 249 (37.5%) samples, including 190 (36.7%) chicken, 48 (40.7%) duck and 11 (39.2%) pigeon samples. The most probable number (MPN) values of 36.1% of the positive samples ranged from 0.3 to 10 MPN/g, with three samples exceeding 110 MPN/g. Among the 667 Salmonella isolates, 35 serovars and 42 multilocus sequence typing patterns were identified. Predominant serovars included Salmonella enterica serovar Enteritidis (32.7%), Salmonella enterica serovar Indiana (14.2%) and Salmonella enterica serovar Typhimurium (11.9%), while two novel STs were identified (ST7352 and ST7612). Except for one unnamed strain (4,12:d:-), all of the identified serovars have previously been linked to human infections. Antimicrobial susceptibility testing of the 318 non-duplicate isolates revealed that only 5 (1.6%) were susceptible to all 22 tested antimicrobials, while 191 (60.1%) exhibited resistance to at least three classes of antimicrobials. The highest levels of resistance were observed for nalidixic acid (72.3%), followed by ampicillin (55.3%) and streptomycin (48.7%). Of particular concern was the detection of highly multidrug-resistant Salmonella enterica serovar Indiana isolates, most (84.1%) of which showed co-resistance to ciprofloxacin and ceftriaxone. Overall, our findings showed a high prevalence of Salmonella contamination of retail raw poultry meat, which could expose consumers to multidrug-resistant isolates. This study provides comprehensive data for evaluation of new control measures for Salmonella contamination of poultry.

Prevalence, Serovars, and Antimicrobial Resistance of Salmonella in Cecal Samples of Chickens Slaughtered in Pluck Shops in Trinidad

The aim of the study was to determine the prevalence and zonal distribution of Salmonella serotypes in poultry and to determine the antimicrobial resistance profile of Salmonella isolates. A total of 1,503 cecal samples of poultry were randomly collected from 33 pluck shops across Trinidad. Isolation and identification of Salmonella followed standard methods, and the disk diffusion method was used to determine resistance of isolates to 14 antimicrobial agents. Ninety-one (6.1%) of the 1,503 samples collected from four zones were positive for Salmonella. The frequency of isolation of Salmonella from chicken ceca (6.5%) was higher than that detected in duck ceca (5.1%), but the difference was not statistically significant (P > 0.05). Ten serotypes were detected, with Salmonella Molade, Salmonella enterica subsp. enterica I, and Salmonella Typhimurium the most prevalent at 56.0, 11.0, and 8.8%, respectively. The highest frequency of isolation of Salmonella was recorded in the northeast zone (59.3%). All 91 isolates exhibited resistance to at least 1 of the 14 antimicrobial agents. The highest frequency of resistance was exhibited to ampicillin (51.0%), kanamycin (49.5%), and streptomycin (37.4%). A total of 22 resistance patterns were exhibited by the 91 isolates of Salmonella, and 13 isolates (14.3%) exhibited multiple drug resistance. The results emphasize the need to implement hygienic practices to reduce the levels of contamination at poultry pluck shops and the need for prudent use of antimicrobial agents in the poultry production system in Trinidad.

Thermal Inactivation of Salmonella in Pâté Made from Chicken Liver

HIGHLIGHTS

Cooking may reduce the potential risk of salmonellosis associated with liver pâté. A 5-log reduction was achieved when inoculated pâté was cooked to an internal temperature of ≥73.8°C. A 5-log reduction was achieved when pâté was made with inoculated liver fried for >8 min at 140°C. Findings of this study may be useful for establishing cooking guidelines for liver and pâté.

Salmonella Typhimurium in Iran: Contribution of molecular and IS200 PCR methods in variants detection

Salmonella Typhimurium, a zoonotic pathogen, is regarded as a major health and economic concern worldwide. Recently, monophasic variants of this serovar have been significantly associated with human gastroenteritis outbreaks globally, making its accurate identification essential for epidemiological and control purposes. We have identified and analyzed 150 S. Typhimurium from 884 Salmonella genus isolated from humans, domestic animals, poultry, food items and abattoirs origins. The Salmonella isolates were obtained from Iranian National Veterinary Reference Laboratories of 9 provinces during 2007–2016, and from five hospitals in Tehran in 2015. The isolates were evaluated biochemically, serologically, and by PCR amplification of invA, mdh, STM4492, fliC, fljA, fljB, hin genes, IS200 and DT104. invA and mdh genes were used to confirm the S. Typhimurium serotype, fliC and fljB genes for determination of monophasic variants and amplification of IS200 to discriminate the monophasic variants from the closely related serotypes. We identified 78.6% (118/150) as classical S. Typhimurium (fliC, fljB and IS200 positive), 12.6% (19/150) were IS200 negative from all isolates. DT104 is another marker for S.Typhimurium serovar typing. Contrary to EFSA guidelines 20.6% (19/29) of human isolates that lacked IS200 insertion sequence, were confirmed as S.Typhimurium. Compared to the North American/European isolates the low prevalence of fljB negative 6% (9/150) and the high abundance of fliC negative 23.3% (35/150) isolates also were indicative of a different regional atypical population. Studies have shown that the prevalence of monophasic (fljB^-) S. Typhimurium worldwide is promoted by the Swine industry. Thus, one reason for this high number of different atypical strains could be inhibition of swine breeding system (house hold and industry) in Iran. These results demonstrate a need for a modified identifying protocol to overcome the regional differences.

Chicken Liver-Associated Outbreaks of Campylobacteriosis and Salmonellosis, United States, 2000-2016: Identifying Opportunities for Prevention

Chicken liver has been implicated in several reported U.S. illness outbreaks, probably caused by inadequate cooking and pathogen contamination. To identify commonalities among these outbreaks that could represent targets for prevention, we describe chicken liver–associated U.S. outbreaks during 2000–2016 reported to the Food Safety and Inspection Service, to the Centers for Disease Control and Prevention, and in published literature. We identified 28 outbreaks (23 [82.1%] were campylobacteriosis only, 3 [10.7%] were salmonellosis only, and 2 [7.1%] were caused by both pathogens), with 18 (64.3%) occurring during 2014–2016. Common outbreak features included blended chicken liver dishes (e.g., pâté; 24 [85.7%]), inadequate cooking (26 [92.8%]), and preparation in foodservice settings (e.g., sit-down restaurants; 25 [89.3%]). The increasing frequency of reported outbreaks highlights chicken liver as an important food safety problem. Public health partners should collaborate on prevention measures, including education on proper foodservice preparation of blended chicken liver dishes.

Salmonella Contamination in Layer Farms in China: Detection and Genetic Analysis

Salmonella is the most common cause of foodborne illnesses worldwide. Poultry eggs are a major contamination source of Salmonella. The prevalence of Salmonella has been effectively reduced since a series of measures were taken to reduce contamination in egg-laying houses. In the present study, 1,512 environmental samples obtained from layer farms of different production scales were screened in a voluntary Salmonella survey study. Contaminations were detected using a PCR method. Genetic relationships among Salmonella samples were specified using molecular typing by enterobacterial repetitive intergenic consensus (ERIC)-PCR. The survey results showed that two layer farms, located in the Shandong and Hebei provinces, were contaminated with Salmonella. Thirty-one samples from these two farms, including feed, drinking nipples, egg collection belt, air inlets and outlets, air, overshoes, and eggshells, were identified as Salmonella-positive. It was observed that certain samples within the henhouses as well as in the egg collecting areas showed relatively high genetic similarities. The survey conclusively revealed minor Salmonella contamination in northern China. Moreover, various areas within the layer farms were identified as part of the propagation chain of Salmonella. Furthermore, evidence of cross-contamination of Salmonella was found in the laying houses and egg collection areas, even between these two regions. Therefore, it is necessary to establish routine Salmonella detection and subsequent environmental control measures in order to decrease the prevalence of Salmonella.

Salmonella in raw chicken meat from the Romanian seaside: frequency of isolation and antibiotic resistance

The purpose of this study was to investigate the occurrence of Salmonella in raw chicken meat samples collected at the Romanian seaside and to evaluate the antimicrobial susceptibility of the isolates. In 2012, 317 chicken meat samples from slaughterhouses (n = 289) and retail markets (n = 28) were evaluated. Overall, 13.2% (42) of the samples contained Salmonella; 12.8% (37) and 17.8% (5) from the chicken carcasses at slaughterhouses and the fresh meat from retail markets, respectively. Eight serotypes of Salmonella enterica subsp. enterica were identified: Infantis (18 isolates), Bredeney (7), Virchow (6), Djugu (4), Grampian (4), Brandenburg (1), Derby (1), and Ruzizi (1). The isolates were resistant to tetracycline (66.6% of isolates), nalidixic acid (64.3%), sulfamethoxazole (64.3%), ciprofloxacin (61.9%), streptomycin (59.5%), trimethoprim (33.3%), ampicillin (9.5%), chloramphenicol (7.1%), and gentamicin (2.4%). No resistance was found to cefotaxime and ceftazidime. Thirty (71.4%) of the 42 tested isolates had multidrug resistance patterns to at least two antimicrobials. This survey highlighted a multidrug-resistant Salmonella contamination rate in raw chicken meat in this area of Romania, which can seriously threaten human health.

Effects of climate change on the persistence and dispersal of foodborne bacterial pathogens in the outdoor environment: A review

According to the Intergovernmental Panel on Climate Change (IPCC), warming of the climate system is unequivocal. Over the coming century, warming trends such as increased duration and frequency of heat waves and hot extremes are expected in some areas, as well as increased intensity of some storm systems. Climate-induced trends will impact the persistence and dispersal of foodborne pathogens in myriad ways, especially for environmentally ubiquitous and/or zoonotic microorganisms. Animal hosts of foodborne pathogens are also expected to be impacted by climate change through the introduction of increased physiological stress and, in some cases, altered geographic ranges and seasonality. This review article examines the effects of climatic factors, such as temperature, rainfall, drought and wind, on the environmental dispersal and persistence of bacterial foodborne pathogens, namely, Bacillus cereus, Brucella, Campylobacter, Clostridium, Escherichia coli, Listeria monocytogenes, Salmonella, Staphylococcus aureus, Vibrio and Yersinia enterocolitica. These relationships are then used to predict how future climatic changes will impact the activity of these microorganisms in the outdoor environment and associated food safety issues. The development of predictive models that quantify these complex relationships will also be discussed, as well as the potential impacts of climate change on transmission of foodborne disease from animal hosts.

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.

Emergence and maintenance of multidrug-resistant Escherichia coli of canine origin harbouring a blaCMY-2-IncI1/ST65 plasmid and topoisomerase mutations

OBJECTIVES

To characterize the mechanisms implicated in fluoroquinolone (FQ) and expanded-spectrum cephalosporin (ESC) resistance in three clinical and seven faecal multidrug-resistant (MDR; resistant to at least three antimicrobial classes) Escherichia coli isolates from a dog with atopic dermatitis, also suffering from recurrent otitis, that had already been exposed to prolonged antimicrobial treatment and colonized for a long period.

METHODS

MICs of FQs, ESCs and other antimicrobials were determined by the broth microdilution method. Phenotypic tests (efflux pump inhibition and combination disc tests) and isoelectric focusing were combined with genotypic analyses [PCRs, sequencing, conjugation, S1 nuclease PFGE, PCR-based replicon typing, plasmid multilocus sequence typing (pMLST) and PCR mapping] to characterize the molecular basis of FQ and ESC resistance. Isolates were further characterized by MLST and PFGE.

RESULTS

Three otitis and five faecal isolates with enrofloxacin MICs of 32 to >128 mg/L displayed the GyrA:S83L+D87N/ParC:E62K/ParE:G545D pattern harbouring novel ParC and ParE substitutions, whereas the two remaining faecal isolates were susceptible or borderline resistant single-step mutants (GyrA:S83L pattern) and carried qnrS1. Efflux pump overexpression also contributed to FQ resistance and the MDR phenotype. The three otitis and five faecal isolates also exhibited cefoxitin/ceftazidime MICs of 32-64 mg/L and harboured blaCMY-2, adjusted to ISEcp1, on an IncI1/ST65 conjugative plasmid, previously described in Salmonella Heidelberg from poultry. Interestingly, all isolates shared an identical MLST type (ST212), with the otitis isolates showing indistinguishable patterns with the high-level resistant faecal E. coli isolates.

CONCLUSIONS

The long-term maintenance of FQ- and ESC-resistant clones harbouring topoisomerase mutations and a blaCMY-2-IncI1/ST65 plasmid in canine commensal flora after prolonged antimicrobial use may contribute to the dissemination of multidrug resistance.

Prevalence and quantitative detection of Salmonella in retail raw chicken in Shaanxi, China

Quantitative Salmonella concentrations and prevalence of Salmonella in raw chicken at the retail level in Shaanxi province, China, was determined in this study. Two hundred forty samples were collected in Yangling and the surrounding cities, in Shaanxi Province, China, for data collection over 12 successive months from April 2011 to March 2012. During the whole surveillance year, the overall Salmonella contamination rate of retail raw chicken was identified as 43.3%, the most-probable-number (MPN) values ranged from 0.0036 to 0.8596 MPN per g, and the average value was 0.1655 MPN per g, except in 11 of the samples, which had MPN values of more than 11 MPN per g. In April 2011, the highest prevalence rate, which was 80.0%, was observed, and the corresponding MPN value was 0.8596 MPN per g. Observed in November 2011, the lowest prevalence rate and the corresponding MPN value were 5.0% and 0.0036 MPN per g, respectively. Prevalence of Salmonella in chicken collected from the supermarket (49.2%) was higher but not significantly different from that in the wet markets (37.5%), although the MPN value of samples in the wet market (0.1912 MPN per g) was higher than that in the supermarket (0.1396 MPN per g). Prevalence of Salmonella was the highest in the frozen chicken (53.3%) compared with chilled chicken (45.0%) and freshly slaughtered chicken (37.5%); however, the MPN value of the freshly slaughtered chicken (0.1912 MPN per g) was higher than those of either frozen chicken (0.1804 MPN per g) or the chilled chicken (0.0988 MPN per g).

Impact of Heat Stress on Poultry Production

Simple Summary

Due to the common occurrence of environmental stressors worldwide, many studies have investigated the detrimental effects of heat stress on poultry production. It has been shown that heat stress negatively affects the welfare and productivity of broilers and laying hens. However, further research is still needed to improve the knowledge of basic mechanisms associated to the negative effects of heat stress in poultry, as well as to develop effective interventions.

Abstract

Understanding and controlling environmental conditions is crucial to successful poultry production and welfare. Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth and egg production to decreased poultry and egg quality and safety. Moreover, the negative impact of heat stress on poultry welfare has recently attracted increasing public awareness and concern. Much information has been published on the effects of heat stress on productivity and immune response in poultry. However, our knowledge of basic mechanisms associated to the reported effects, as well as related to poultry behavior and welfare under heat stress conditions is in fact scarce. Intervention strategies to deal with heat stress conditions have been the focus of many published studies. Nevertheless, effectiveness of most of the interventions has been variable or inconsistent. This review focuses on the scientific evidence available on the importance and impact of heat stress in poultry production, with emphasis on broilers and laying hens.