Enumeration and Characterization ofCampylobacterSpecies from Retail Chicken Carcasses in Beijing, China

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).

Subtyping of Campylobacter coli isolated from raw poultry meat in retail markets using amplified intergenic locus polymorphism - A novel rapid subtyping method

In order to provide more phylogenetic information of Campylobacter coli in large-scale epidemiological investigation, this work was undertaken to develop a novel genotyping method based on amplified intergenic locus polymorphism (AILP), by using pulsed-field gel electrophoresis (PFGE; using SmaI enzymes) as control. Eleven pairs of primers were selected to type C. coli strains for this purpose. A total of 68 C. coli isolates recovered from 51 retail raw chicken and 37 retail raw duck were subtyped. The Simpson's index of diversity (SID) of AILP and PFGE, as well as the adjusted Rand index (AR) and the adjusted Wallace coefficient (AW) between AILP and PFGE, were calculated. The new AILP method differentiated 68 C. coli isolates into 55 different subtypes (SID = 0.993), compared with 46 different profiles obtained from PFGE (SID = 0.980). The SID value of the AILP method was improved with the increasing number of primers, and a combination of 7 loci was selected as the optimal combination. The congruent analysis of the AILP method and PFGE showed moderate congruence between the two methods (AR = 0.462). The AW indicated that if AILP data is the available one can confidently predict the PFGE cluster. The results of this study showed that the AILP method had higher discrimination than PFGE and also allowed for significant reduction in time and cost.

Quantitative detection and genetic characterization of thermotolerant Campylobacter spp. in fresh chicken meats at retail in Japan

Campylobacter jejuni and C. coli are one of the leading causes of gastrointestinal illnesses, and which are considered to be transmitted to humans mainly from chicken meats. Considering the less availability of quantitative contamination data in the retail chicken meats in Japan, 510 fresh chicken meats retailed at five distinct regions in Japan between June 2019 and March 2021 were examined. The quantitative testing resulted that 45.7% of the samples (254/510) were positive at mean ± standard deviation of 1.15 ± 1.03 logCFU/g, whereas 43 samples (8.4%) exceeded 3.0 logCFU/g. Seasonal comparison revealed increased bacterial counts in fall compared with spring and summer. As for the chicken slaughter age, those slaughtered at >75 days old were less contaminated than those at <75 days old. Genome sequencing analyses of 111 representative C. jejuni isolates resulted in the detection of three antimicrobial resistance genes (gyrA substitution T86I, tetO and blaOXA-61) at 25.2, 27.9 and 42.3%, respectively. In silico MLST analysis revealed the predominance of sequence types (ST)-21 clonal complex (CC), followed by ST-45CC and ST-464CC. The single nucleotide polymorphism (SNP)-based phylogenetic tree largely classified the sequenced C. jejuni isolates into two clusters (I and II), where all C. jejuni from highly contaminated samples (STs-21CC, -22CC and -45CC) belonged to cluster I, independent of both season and slaughter age. To our knowledge, this is the first example to study the current status of Campylobacter contamination levels in fresh chicken meats retailed in Japan. Our data would be contributable to future quantitative microbial risk assessment, to establish effective control measures for campylobacteriosis.

An Investigation into the Critical Factors Influencing the Spread of Campylobacter during Chicken Handling in Commercial Kitchens in China

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Consumption of chicken meat is considered the main route for human infection with Campylobacter. This study aimed to determine the critical factors for Campylobacter cross-contamination in Chinese commercial kitchens during chicken handling. Five commercial kitchens were visited to detect Campylobacter occurrence from 2019 to 2020. Chicken samples (n = 363) and cotton balls from the kitchen surfaces (n = 479) were collected, and total bacterial counts and Campylobacter spp. were detected. Genotypic characterization of 57 Campylobacter jejuni isolates was performed by multilocus sequence typing (MLST). In total, 77.41% of chicken carcass samples and 37.37% of kitchen surfaces showed Campylobacter spp. contamination. Before chicken preparation, Campylobacter spp. were already present in the kitchen environment; however, chicken handling significantly increased Campylobacter spp. prevalence (p < 0.05). After cleaning, boards, hands, and knives still showed high bacterial loads including Campylobacter spp., which related to poor sanitary conditions and ineffective handling practices. Poor sanitation conditions on kitchen surfaces offer greater opportunities for Campylobacter transmission. Molecular typing by MLST revealed that Campylobacter cross-contamination occurred during chicken preparation. The most prevalent sequence types, ST693 and ST45, showed strong biofilm formation ability. Consequently, sanitary condition of surfaces and biofilm formation ability of isolates were the critical points contributing to spread of Campylobacter in kitchen environment. These results provide insight into potential targeted control strategies along the farm-to-plate chain and highlight the necessity for improvements in sanitary conditions. The implementation of more effective cleaning measures should be considered to decrease the campylobacteriosis risk.

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

Genotypic diversity, antimicrobial resistance and biofilm-forming abilities of Campylobacter isolated from chicken in Central China

Background

Campylobacter is considered to be the leading cause of human bacterial gastroenteritis, of which poultry is the main reservoir. Campylobacter contaminated chicken products are a major cause of human Campylobacter infection. In this study, the prevalence of Campylobacter in chicken in central China was investigated, and the genotypic diversity, antimicrobial resistance and biofilm of these isolates were characterized.

Results

A total of 206 Campylobacter isolates, including 166 C. jejuni and 40 C. coli, were isolated from chicken farms and live poultry markets in central China. Multilocus sequence typing and phylogenetic analysis showed that the Campylobacter isolates had diverse genetic backgrounds, which covered most of the dominant clone complexes (CCs) reported throughout China. The most prevalent CCs were CC-464, CC-1150, CC-353, and CC-828. All the isolates showed resistance to norfloxacin, ciprofloxacin and Cefazolin, and a prevalent resistance to fluoroquinolones, β-lactams and tetracyclines was also observed. Among all the isolates, 133 strains showed the ability to form biofilm, thereinto, the isolates in two genetic branches, mainly including CC-21, CC-48, CC-677 and CC-45, showed a significantly lower ability to form biofilm than other genetic branches (p < 0.05). However, in general, the ability to form biofilm varied among different genetic branches, suggesting a complex genetic background to biofilm formation, but not only the genetic lineages. Compared with the strains unable to form biofilm, biofilm-producing strains possessed a significantly higher resistance to ampicillin, neomycin, sulfamethoxazole, amikacin, clindamycin and erythromycin (p < 0.05).

Conclusions

To the best of our knowledge, this is the first report on the relationship of the genotypic diversity, antimicrobial resistance and biofilm-forming abilities of Campylobacter isolated from chicken in Central China, which showed the potential importance of biofilm in antimicrobial resistance. This study will help us better understand the epidemiology and antimicrobial resistance of Campylobacter.

Prevalence and Characterization of Campylobacter jejuni Isolated from Retail Chicken in Tianjin, China

Campylobacter jejuni is an important foodborne pathogen worldwide; however, there is a lack of information on the prevalence and antibiotic-resistant profile of C. jejuni in the People's Republic of China. We determined the prevalence and characteristics of C. jejuni on the retail level in Tianjin, one of the five national central cities in China. A total of 227 samples of chicken wings, legs, and breasts were collected from supermarkets and wet markets; 42 of these samples were confirmed to be positive for Campylobacter contamination. The contamination rates of C. jejuni and other Campylobacter species were 13.7% (31 of 227 samples) and 5.7% (13 of 227 samples), respectively. A group of 31 C. jejuni isolates was subjected to antimicrobial susceptibility testing. All (100%) the selected isolates were resistant to ciprofloxacin and nalidixic acid; 77.4% were resistant to tetracycline, 67.7% to doxycycline, 35.5% to gentamicin, 25.8% to clindamycin and florfenicol, 19.4% to chloramphenicol, and 12.9% to erythromycin and azithromycin. A remarkably high proportion (41.9%) of multidrug-resistant isolates was identified. Multilocus sequence typing was conducted to study the population structure of the C. jejuni strains and their relationship to human isolates. The correlation between antimicrobial resistance traits and certain sequence types (STs) or clonal complexes was determined as well. A great genetic diversity of poultry isolates was identified, with 11 STs belonging to 6 clonal complexes and 11 singleton STs. The novel STs accounted for 40.9% (n = 9) of the 22 STs. ST-21, ST-353, ST-354, ST-443, ST-607, and ST-828 complexes had been previously identified from human isolates. This study revealed an extensive level of antimicrobial resistance and genetic diversity in C. jejuni isolated from chicken products in Tianjin, highlighting the necessity of performing enforced interventions to reduce Campylobacter prevalence in China.

Occurrence and genotypes of Campylobacter species in broilers during the rearing period

Poultry are the main source of Campylobacter infection worldwide. To obtain information on Campylobacter-infected flocks and create a reference for preventing and controlling Campylobacter at farm level, Campylobacter isolates were recovered from broilers and the environments of nine chicken flocks in two farms during growth. The genetic relationship between the Campylobacter isolates was determined using multilocus sequence typing. Flocks were colonized as early as 3 weeks after introduction to the farm. The highest colonization rate was more than 90% and occurred 4-6 weeks after introduction to the farm. Quantitative data showed that the highest Campylobacter loads appeared at 1-2 weeks after initial colonization. Campylobacter loads in cloacal swabs in four flocks were significantly higher at 5 weeks than at 3 weeks (P < 0.05). Multilocus sequence typing of 171 selected isolates revealed 20 sequence types (STs), which consisted of 12 STs for Campylobacter jejuni and eight for Campylobacter coli isolates. The STs of the Campylobacter isolates recovered from farm 1 were more diversified than those from farm 2. The STs of environmental samples were highly consistent with those of the cloacal swab samples. The consistency between Campylobacter STs in the environmental and cloacal swab samples suggested that the environment might be one of the main sources of infection. Thus, our study highlights the prevalence and contamination load of Campylobacter in broilers during their rearing period and emphasizes the need for control and prevention measures for Campylobacter infection in broilers, which is also important for human health.

Molecular epidemiology, virulence determinants and antimicrobial resistance of Campylobacter spreading in retail chicken meat in Central China

Background

Campylobacter species are the major food-borne pathogens which could cause bacterial gastroenteritis in humans. Contaminated chicken products have been recognized as the primary vehicles of Campylobacter transmission to human beings. In this study, the prevalence of Campylobacter in retail chicken meat in Central China was investigated, and the isolates were further characterized using molecular approaches and tested for antibiotic resistance.

Results

A total of 302 chicken samples purchased from April 2014 to April 2015 were tested. The level of Campylobacter contamination was enumerated by most probable number-PCR (MPN-PCR). The Campylobacter positive rate was 17.2% (52/302), with bacterial count varying from 3.6 to 360 MPN/g in positive samples. A total of 52 Campylobacter strains, including 40 Campylobacter jejuni and 12 Campylobacter coli, were isolated from the positive samples. To examine the genetic diversity of the isolates, multilocus sequence typing (MLST) technology was applied, which identified 23 sequence types (STs) belonging to seven clonal complexes (CCs) and unassigned. Among them, the dominant CCs of C. jejuni included CC-353 and CC-464, and the dominant CCs of C. coli were CC-828 and CC-1150. Antibiotic resistance analysis showed that all of the isolates were resistant to norfloxacin and ciprofloxacin. 23 virulence-associated genes were tested in the isolates, which showed that the number of virulence-associated genes detected in the C. jejuni isolates ranged from 16 to 21, while in most of the C. coli isolates ranged from 12 to 16. Virulence-associated genes, flaA, flgB, flgE2, fliM, fliY and cadF were detected in all isolates. VirB11, however, was not detected in any of the isolates.

Conclusions

To the best of our knowledge, this is the first report on the contamination level and molecular biological features of Campylobacter strains in retail chicken meat in Central China, which showed high genetic diversity and remarkable antibiotic resistance. This study provided scientific data for the risk assessment and evaluation of Campylobacter contamination in retail chicken products.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-016-0132-2) contains supplementary material, which is available to authorized users.

A seventeen-year observation of the antimicrobial susceptibility of clinical Campylobacter jejuni and the molecular mechanisms of erythromycin-resistant isolates in Beijing, China

OBJECTIVES

To investigate the dynamic development of the antimicrobial resistance of Campylobacter jejuni isolated from human diarrhea in Beijing, China, between 1994 and 2010, and to further analyze the molecular mechanisms of erythromycin-resistant strains.

METHODS

Susceptibility tests were performed on 203 non-duplicate clinical C. jejuni strains against eight common antibiotics using the standard agar dilution method. The molecular determinants were further studied in the erythromycin (ERY) non-susceptible strains. The analysis focused on the 23S rRNA gene, the rplD and rplV ribosomal genes, the ermB gene, and the regulatory region of the CmeABC efflux pump.

RESULTS

The rates of resistance of C. jejuni to ciprofloxacin (CIP), nalidixic acid (NAL), doxycycline (DOX), tetracycline (TET), florfenicol (FFC), and chloramphenicol (CHL) increased significantly over the period studied (all p<0.05). Similarly, the proportions of resistant patterns (CIP-NAL-DOX-TET, CIP-NAL-DOX-TET-FFC, and CIP-NAL-DOX-TET-CHL) increased remarkably. In this study, 4.4% (9/203) of C. jejuni strains were ERY non-susceptible. The A2075G mutation in the 23S rRNA was found in all of the resistant strains except cj8091, which harbored the ermB gene. Interestingly, the ermB gene was also detected in intermediately resistant isolates, and the earliest ermB-positive strain cj94473 was derived in 1994. Moreover, none of the ribosomal rplD or rplV genes harbored mutations that have been described to confer resistance to macrolides. Different mutations affecting the regulatory region of the CmeABC efflux pump were also found.

CONCLUSIONS

This is the first comprehensive study on the recent trend in antimicrobial resistance and the molecular mechanisms of macrolide resistance in clinical C. jejuni strains isolated in China. More stringent monitoring and regulation of human and animal antimicrobial use are warranted.