Retail Chicken Carcasses Research Articles

Isolation and Characterization of Cefotaxime and Ciprofloxacin Co-Resistant Escherichia coli in Retail Chicken Carcasses

Transmission of antimicrobial-resistant bacteria to humans through the food chain is of great importance for public health. In this study, it was aimed to isolate and characterize the cefotaxime and ciprofloxacin-resistant Escherichia coli in retail chicken meat samples sold in Hatay. The isolates were subjected to phylogenetic group typing and antimicrobial susceptibility testing. The genetic relatedness of the isolates was determined using Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) technique. The isolates were also screened for the presence of both antimicrobial and plasmid-mediated quinolone resistance (PMQR) genes by PCR. Cefotaxime and ciprofloxacin co-resistant E. coli isolates with diverse genetic origins were recovered in 42.3% (22/52) of retail chicken carcasses. The E. coli isolates belonged to the phylogenetic group D2 were dominant (40.9%, 9/22), followed by B1 (27.3%, 6/22), B23 (18.2%, 4/22), and A1 (13.6%, 3/22), respectively. Based on dendrogram analysis, the ERIC-PCR method differentiated the isolates into 10 clusters (I-X). The multidrug resistance (MDR) was observed in 81.8% (18/22) of the isolates. PMQR determinants were not identified in any isolates tested. Molecular analysis revealed one or more β-lactamase-encoding genes in all isolates as a single or in combination: blaCTX-M-blaTEM (n=5), blaCMY-2 (n=5), blaCTX-M (n=5), blaCMY-2-blaSHV (n=3), blaCMY-2-blaTEM (n=3), and blaCTX-M-blaCMY-2 (n=1). This study highlights that retail chicken meat is an important reservoir of cefotaxime and ciprofloxacin co-resistant E. coli isolates. It is necessary to evaluate their contribution to the community and hospital infections.

Comparative resistome, mobilome, and microbial composition of retail chicken originated from conventional, organic, and antibiotic-free production systems

The aim of this study was to investigate the microbial composition, and the profiles of antimicrobial resistance genes (ARGs, resistome) and mobile genetic elements (mobilome) of retail chicken carcasses originated from conventional intensive production systems (CO), certified antimicrobial-free intensive production systems (AF), and certified organic production systems with restricted antimicrobial use (OR). DNA samples were collected from 72 chicken carcasses according to a cross-sectional study design. Shot-gun metagenomics was performed by means of Illumina high throughput DNA sequencing followed by downstream bioinformatic analyses. Gammaproteobacteria was the most abundant bacterial class in all groups. Although CO, AF, and OR did not differ in terms of alpha- and beta-microbial diversity, the abundance of some taxa differed significantly across the groups, including spoilage-associated organisms such as Pseudomonas and Acinetobacter. The co-resistome comprised 29 ARGs shared by CO, AF and OR, including genes conferring resistance to beta-lactams (blaACT-8, 10, 13, 29; blaOXA-212;blaOXA-275 and ompA), aminoglycosides (aph(3')-IIIa, VI, VIa and spd), tetracyclines (tet KL (W/N/W and M), lincosamides (inu A,C) and fosfomycin (fosA). ARGs were significantly less abundant (P < 0.05) in chicken carcasses from AF and OR compared with CO. Regarding mobile genetic elements (MGEs), transposases accounted for 97.2% of the mapped genes. A higher abundance (P=0.037) of MGEs was found in CO compared to OR. There were no significant differences in ARGs or MGEs diversity among groups according to the Simpson´s index. In summary, retail frozen chicken carcasses from AF and OR systems show similar ARGs, MGEs and microbiota profiles compared with CO, even though the abundance of ARGs and MGEs was higher in chicken carcasses from CO, probably due to a higher selective pressure.

Molecular surveillance of non-O157 Shiga toxigenic Escherichia coli in selected chicken abattoirs and retail outlets in Osogbo, Osun State, Nigeria

Three selected chicken abattoirs and two retail locations were studied to determine the frequency of occurrence and profile for Shiga toxin-producing Escherichia coli (STEC) strains present in abattoirs and retail (frozen) chicken carcasses in Osun state, Nigeria. Samples were plated on Eosin Methylene Blue agar for the presence of E. coli. Furthermore, the isolates were confirmed serologically as non-O157 STEC using latex agglutination serotyping kit. Multiplex PCR was used to check for specific virulence factors in the isolated E. coli strains. The mean colony count results showed that effluent water samples from the Ikirun slaughter slab type abattoir were the highest at 25 cfu/ml. A post hoc comparison showed that this value was significantly higher than that of the slaughtering table at Oluode-1 (P = 0.04) and retail chicken meat samples at Igbona (P = 0.01). The results show that chicken abattoirs are poor reservoirs of STEC. Moreover, the results from this study showing that the stx2-producing strains that are more prone to cause hemolytic uremic syndrome is the predominant strain in the study area is worrisome. These results underscore the improper hygiene practices of the abattoir workers combined with inadequate waste management and biological waste disposal systems. It is recommended that regulatory bodies in this locality should focus on ensuring the upgrade of biological waste disposal from these abattoirs in order to limit spread of potentially virulent pathogens into the runoff and ground water.

Enumeration, Antimicrobial Resistance, and Virulence Genes Screening of Enterococcus spp. Isolated from Retail Chicken Carcasses in the United Arab Emirates.

Enterococci have recently emerged as nosocomial pathogens worldwide. Their ubiquitous nature determines their frequent finding in foods as contaminants. In this study, we aimed to determine the counts, species diversity, antimicrobial resistance profile, and to screen for a set of virulence genes among enterococci. Enterococcus were identified from 75.7% (125/165) of chilled chicken carcasses, belonging to seven companies, sampled from retail markets in Abu Dhabi Emirate, United Arab Emirates (U.A.E.). Overall, the samples, with a mean Enterococcus count of 2.58 log10 colony-forming unit (CFU)/g with a standard deviation of ±1.17 log10 CFU/g. Among the characterized Enterococcus isolates (n = 90), Enterococcus faecalis was the predominant species (51.1%), followed by Enterococcus faecium (37.8%). Using Vitek2 automated antimicrobial sensitivity panel, we found none of the E. faecalis nor E. faecium to be resistant to ampicillin, teicoplanin, vancomycin, or tigecycline. A third of the E. faecalis (28.3%) and E. faecium (35.3%) were resistant to high-level gentamicin. Over half of E. faecalis (54.3%) were resistant to ciprofloxacin, and the same was in about a third of E. faecium isolates (29.4%). Linezolid resistance was identified in 10 E. faecalis and 7 E. faecium isolates belonging to samples from three companies. All of the linezolid-resistant isolates harbored oxazolidinone resistance optrA gene. Virulence-associated genes (asa1 and gelE) were significantly (p < 0.05) more detected among E. faecalis compared to E. faecium isolates recovered in this study. Over half of the E. faecalis (25/46) and E. faecium (20/34) isolates were identified as multidrug-resistant. This study provides further insight into virulence genes and their association with the dissemination of multidrug-resistant E. faecalis and E. faecium in supermarket chicken meat in the U.A.E. This is probably the first description of the optrA gene in enterococci from supermarket chicken meat in the U.A.E. and from Arab countries. This study adds to the regional and global understanding of antimicrobial resistance spread in foods of animal origin.

Genomic Features of MCR-1 and Extended-Spectrum β-Lactamase-Producing Enterobacterales from Retail Raw Chicken in Egypt.

Colistin is considered as a last resort agent for treatment of severe infections caused by carbapenem-resistant Enterobacterales (CRE). Recently, plasmid-mediated colistin resistance genes (mcr type) have been reported, mainly corresponding to mcr-1 producers. Those mcr-1-positive Enterobacterales have been identified not only from human isolates, but also from food samples, from animal specimens and from environmental samples in various parts of the world. Our study focused on the occurrence and characterization of mcr-1-positive Enterobacterales recovered from retail raw chicken in Egypt. From the 345 retail chicken carcasses collected, a total of 20 samples allowed to recover mcr-1-positive isolates (Escherichia coli, n = 19; Citrobacter freundii, n = 1). No mcr-2- to mcr-10-positive isolate was identified from those samples. The colistin resistance trait was confirmed for all those 20 isolates with a positivity of the Rapid Polymyxin NP (Nordmann-Poirel) test. Minimum inhibitory concentrations (MICs) of colistin for all MCR-1-producing isolates ranged between 4 and 16 μg/mL. Noticeably, 9 out of the 20 mcr-1-positive isolates produced an extended-spectrum β-lactamase (ESBL), respectively producing CTX-M-9 (n = 2), CTX-M-14 (n = 4), CTX-M-15 (n = 2), and SHV-12 (n = 1). Noteworthy, the fosA4 gene encoding resistance to fosfomycin was found in a single mcr-1-positive E. coli isolate, in which both genes were located on different conjugative plasmids. The pulsed-field gel electrophoresis (PFGE) patterns were identified, corresponding to 10 different sequence types (STs), highlighting the genetic diversity of those different E. coli. Whole-genome sequencing revealed three major types of mcr-1-bearing plasmids, corresponding to IncI2, IncX4, and IncHI2 scaffolds. The occurrence of MCR-1-producing multidrug-resistant Enterobacterales in retail raw chicken is of great concern, considering the possibility of transmission to humans through the food chain.

Prevalence of Antibiotic-Resistant Escherichia coli Isolates from Local and Imported Retail Chicken Carcasses

The spread of antibiotic resistance among bacterial strains has been associated with consumption of food contaminated with both pathogenic and nonpathogenic bacteria. The objective of this study was to determine the prevalence of antibiotic resistant Escherichia coli isolates in local and imported retail raw chicken meat in Qatar. A total of 270 locally produced (chilled) and imported (chilled or frozen) whole chicken carcasses were obtained from three Hypermarket stores in Qatar. The 216 E. coli isolates recovered from the chicken samples were subjected to antibiotic susceptibility testing with the disk diffusion method. Extended-spectrum β-lactamase (ESBL) production was evaluated with the double disk synergy test. Isolates harboring colistin resistance were identified with a multiplex PCR assay and DNA sequencing. Nearly 89% (192) of the 216 isolates were resistant to at least one of the 18 antibiotics tested. Isolates from local and imported chicken carcasses had relatively higher resistance to sulfamethoxazole (62% of isolates), tetracycline (59.7%), ampicillin and trimethoprim (52.3% each), ciprofloxacin (47.7%), cephalothin (45.4%), and colistin (31.9%). Less resistance was found to amoxicillin-clavulanic acid (6%), ceftriaxone (5.1%), nitrofurantoin (4.2%), piperacillin-tazobactam (4.2%), cefepime (2.3%), meropenem (1.4%), ertapenem (0.9%), and amikacin (0.9%). Nine isolates (4.2%) were ESBL producers, and 137 (63.4%) were multidrug resistant. The percentages of multidrug-resistant, ESBL-producing, and colistin resistant isolates were significantly higher among isolates from local chilled than from imported chilled and frozen chicken samples. Our findings indicate the high prevalence of antibiotic-resistant E. coli in chicken meat sold at retail in Qatar.

Antimicrobial Resistance, Genetic Diversity and Multilocus Sequence Typing of Escherichia coli from Humans, Retail Chicken and Ground Beef in Egypt.

Contamination of retail foods with foodborne pathogens, particularly the antimicrobial resistant ones, poses a persistent threat to human health. There is a dearth of information about the overlapping Escherichia coli (E. coli) lineages circulating among retail foods and humans in Egypt. This study aimed to determine the clonal diversity of 120 E. coli isolates from diarrheic patients (n = 32), retail chicken carcasses (n = 61) and ground beef (n = 27) from Mansoura, Egypt using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Simpson’s index of diversity was calculated to compare the results of both typing methods. Antimicrobial resistance phenotypes, genotypes and phylogrouping of the isolates were also determined. Higher frequencies of antimicrobial resistance were found among chicken isolates compared to beef and human isolates; regardless of isolate source, the predominant antimicrobial resistances were found against ampicillin (87/120, 72.5%), tetracycline and sulfisoxazole (82/120, 68.3%, each), and streptomycin (79/120, 65.8%). None of the isolates displayed resistance to meropenem. The prevalent genes detected were tetA (64.2%), blaTEM (62.5%), sul1 (56.7%), floR (53.3%), sul2 (50%), strB (48.3%) and strA (47.5%) corresponding with resistance phenotypes. Alarmingly, blaCTX was detected in 63.9% (39/61) of chicken isolates. The majority of E. coli isolates from humans (90.6%), beef (81.5%) and chicken (70.5%) belonged to commensal phylogroups (A, B1, C). Using PFGE analysis, 16 out of 24 clusters (66.7%) contained isolates from different sources at a similarity level ≥75%. MLST results assigned E. coli isolates into 25, 19 and 13 sequence types (STs) from chicken, human and beef isolates, respectively. Six shared STs were identified including ST1011, ST156, ST48, ST224 (chicken and beef), ST10 (human and chicken) and ST226 (human and beef). Simpson’s index of diversity was higher for MLST (0.98) than PFGE (0.94). In conclusion, the existence of common genetic determinants among isolates from retail foods and humans in Egypt as well as the circulation of shared STs indicates a possible epidemiological link with potential zoonotic hazards.

DETERMINATION OF in vitro BIOFILM FORMATION ABILITIES OF FOOD BORNE Salmonella enterica ISOLATES

Salmonellosis caused by non-typhodial Salmonella enterica serotypes is one of the most important food-borne diseases worldwide and biofilm structure formed by these pathogens provide a reservoir for food contamination and a source for infections. This study was performed in order to determine biofilm formation abilities of food borne Salmonella isolates on polystyrene and on air liquid interphase and their colony morphologies when grown on Congo Red Agar plates. 32 food-borne Salmonella strains isolated from retail chicken carcasses in Edirne province of Turkey and belonging to the Infantis, Enteritidis, Kentucky and Telaviv serotypes were used. The microtiter plate technique was used to determine biofilm formation abilities of the isolates on polystyrene surfaces by measuring the optical density (OD) values of the stained bacterial biofilms. The results showed that the strongest biofilm formation capacities of the isolates were observed at 22°C for 3 days of incubation. Although all isolates formed pellicle on the liquid-air interface at 22°C, only 13% of the isolates belonging to the Infantis, Kentucky and Enteritidis serovars formed pellicle at liquid-air interface at 37°C. Three different colony morphotypes (saw; smooth and white, bdar; brown, dry and rough, rdar; red, dry and rough) were determined on Congo Red Agar among the isolates. High biofilm formation abilities of the tested Salmonella isolates can lead to widespread of virulence and resistance properties, especially to medically important antibiotics such as ciprofloxacin, via food chain. This situation constitutes an important concern for public health.

Draft genome sequences of two ciprofloxacin-resistant Salmonella enterica subsp. enterica serotype Kentucky ST198 isolated from retail chicken carcasses in Egypt.

Salmonella enterica serotypes, particularly antimicrobial-resistant strains, pose a major threat to public health worldwide. This study describes the draft genome sequences of two ciprofloxacin-resistant Salmonella enterica subsp. enterica serotype Kentucky isolates (H5 and H18) recovered from chicken carcass rinsates in Mansoura, Egypt. Antimicrobial susceptibility phenotypes were determined for the two Salmonella Kentucky isolates by broth microdilution using a Sensititre™ system. Genomic DNA from both isolates was sequenced using an Illumina MiSeq system. Antimicrobial resistance genes were identified using ARG-ANNOT, and multilocus sequence typing (MLST) was performed using MLST 1.8. The draft genome for Salmonella Kentucky H5 contained 4.84Mbp in 54 contigs, and that for Salmonella Kentucky isolate H18 contained 4.94Mbp in 64 contigs. Sequence analysis using ARG-ANNOT identified the presence of the resistance genes blaTEM-57, aadA1, aadA2, cmlA1, sul3 and tetA in both isolates, whereas dfrA, sul2, floR, and aph(3)-Ia were found in isolate H18 only. The amino acid substitutions Ser83Phe and Asp87Gly in GyrA and Thr57Ser and Ser80Ile in ParC were detected in both isolates. Both isolates belonged to ST198. The draft genome sequences allowed identification of a ciprofloxacin-resistant Salmonella Kentucky ST198 epidemic clone with multidrug resistance in poultry products produced for human consumption in Egypt. These data indicate that poultry continues to be a reservoir for this persistent clone.

Serotype distribution and antimicrobial resistance of Salmonella isolates from retail chicken carcasses in six provinces of China

Objective: To obtain the serotype diversity and antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses for sale in six regions of China. Methods: From August 2010 to March 2012, each month 20 retail chicken carcasses including freshly slaughtered, chilled and frozen samples were collected from supermarkets and farmer's markets in 7 monitoring sites in Beijing, Jilin province, Inner Mongolia Autonomous, Shanxi province, Jiangsu province and Guangdong province, respectively. Samples were routinely collected for 12 months for each site. 1 680 chicken carcasses were collected in total and 2 629 Salmonella strains were isolated by PCR and biochemical method. Luminex xMAP method and classical slide agglutination method were carried out to determine isolates' serotypes. Minimal inhibitory concentrations (MICs) of 10 classes of antimicrobials including 14 agents were determined using broth micro-dilution method. Mocular methods were used to determine antimicrobial resistance genes of CIP-CTX-CT co-resistant isolates. Results: In all, 2 629 Salmonella isolates, there were 17 seorgroups and 58 serotypes, B and D1 were the dominant serogroups with rates of 34.7% (n=913) and 31.0% (n=815), Enteritidis (30.8%, n=810), Indiana (17.6%, n=463), Infantis (10.6%, n=278) were the top three serovars. We found 224 CIP-CTX co-resistant S. Indiana containing 3 colistin resistant strains, one of them carrying mcr-1 gene and being ESBLs positive, which demonstrated a nine multi drug resistance against 11 antimicrobials tested. Conclusion: These data began to describe the complicated serovar diversity and heavy antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses in six regions of China. The findings highlight the emergence of ciprofloxacin and cefotaxime co-resistant S. Indiana and also a mcr-1 positive S. Indiana with heavy multi drug resistance.

Serovar diversity and antimicrobial resistance of non-typhoidal Salmonella enterica recovered from retail chicken carcasses for sale in different regions of China

Non-typhoidal Salmonella enterica (NTS), the etiological agents in foodborne salmonellosis, is a major public health concern. This study describes the serovar diversity and antimicrobial resistance phenotypes identified in NTS isolates from retail whole chicken carcasses across six provinces of China. From food samples tested, a total of 2210 Salmonella isolates were recovered and these were serotyped by conventional and molecular serotyping methods and tested for their susceptibility to a panel of antimicrobial compounds. Sixteen serogroups and 52 serovars were identified, with serogroups B, D1 and C1 common among Enteritidis, Indiana and Infantis isolates. The serovar distribution varied both geographically and seasonally. Most (80.18%) of these isolates were found to be resistant to at least one antimicrobial compound and 54.6% were multi-drug resistant (MDR). Resistance to nalidixic acid (NAL) was common (70.6%) among the 11 tested compounds and no isolate was found to be resistant to carbapenems. There were 119 antimicrobial resistance profiles identified in the study collection. Two-hundred eighty-four isolates, including 99 Salmonella enterica serovar Indiana (S. Indiana), were resistant to seven or eight classes of antimicrobial compound. One-hundred eighty-three S. Indiana isolates were found to be co-resistant to ciprofloxacin and cefotaxime and 179 of these were confirmed as extended-spectrum β-lactamase producers. These data begin to describe the serovar diversity and antimicrobial resistance of NTS isolates recovered from retail chicken carcasses in parts of China. The findings highlight the emergence of ciprofloxacin and cefotaxime co-resistant S. Indiana, a feature displaying serious antimicrobial resistance but not commonly reported in human infections of Salmonella until recently. The food safety implications of these findings are discussed.

Characterization of extended-spectrum β-lactamases (ESBLs)-producing Salmonella in retail raw chicken carcasses

Extended-spectrum β-lactamases (ESBLs)-producing Salmonella is considered a serious concern to public health worldwide. However, limited information is available on ESBLs-producing Salmonella in retail chicken products in China. The objective of this study was to characterize ESBLs-producing Salmonella isolates from retail chickens in China. A total of 890 Salmonella isolates from retail chicken carcasses collected from 4 provinces were firstly screened for ESBLs-production phenotype via the double-disk synergy test method. A total of 96 (10.8%, n=890) ESBLs-producing Salmonella were identified and subjected to PFGE analysis, characterization for the presence of ESBLs encoding genes, transposons, carbapenemase and virulence genes. A total of 59 PFGE profiles were detected in these 96 isolates, among which 57.3% were found to harbor blaTEM-1, whereas 30.2%, 24.0%, 18.8% and 7.3% were carrying blaOXA-1, blaCTX-M-15, blaCTX-M-3 and blaPSE-1 genes, respectively. Moreover, 42 (43.8%) isolates co-carried 2 ESBLs-producing genes, and two (2.1%) isolates co-carried 3 genes. Furthermore, 24 (25.0%) ESBLs-producing isolates carried VIM and 10 (10.4%) carried KPC encoding genes that closely associated with carbapenems resistance. Eighty-eight isolates harbored transposons ranging from 4.2% for Tn903 to 76.0% for Tn21. Out of the 88 Salmonella that harbored transposons, 25%, 22.7%, 23.9%, 10.2% and 1.1% of isolates were found to carry 2, 3, 4, 5 and 6 transposons, respectively. The minimum inhibitory concentration (MIC) values for cephalosporins (ceftriaxone, cefoperazone and cefoxitin) to ESBLs-producing isolates were from 4 to 1024μg/mL, for nalidixic acid were from 64 to 512μg/mL, for fluoroquinolones (ciprofloxacin, levofloxacin and gatifloxacin) were from 4 to 256μg/mL. Twenty-nine virulence genes were detected in the 96 ESBLs-producing isolates with 2.1% harbored spvR (lowest) and 90.6% harbored marT and steB (highest). All isolates carried at least one virulence gene, 83.3% of the isolates co-carried ≥10, 17.7% co-carried ≥15, and 1.0% co-carried 23 virulence genes. Interestingly, 16.7% of the isolates resistant to >12 antibiotics tested and shown to carry >4 transposons and 10 virulence genes. Our findings indicated that ESBLs-producing Salmonella isolated from retail chicken meat in China were highly resistant to antibiotics, frequently harbored transposons, virulence genes, carbapenems hydrolysis enzymes and ESBLs encoding genes. These isolates can pose a significant public health risk.

Bacterial Contamination Associated with Retail Chicken Carcasses in Osogbo, Nigeria

Abstract Background: Worldwide, food borne illness is often associated with consumption of meat and poultry products sold at retail markets. A study on the bacteriological status of chicken carcass in Osogbo, Nigeria, was carried out to determine the prevalence of Arcobacter species, Escherichia coli and Staphylococcus aureus in chicken carcasses. Methodology: A total of 100 samples of chicken carcasses were collected from two major processing points in Osogbo, Nigeria. The samples were analysed for the presence of bacterial contaminants using standard microbiological isolation and identification procedures, with antimicrobial susceptibility test performed using the disk diffusion method. Result: Of hundred chicken carcasses sampled, 38% were positive for Arcobacter species and E. coli while 60% accounted for S. aureus isolates. Ninety percent of Arcobacter spp isolates were susceptible to ciprofloxacin, 85% to gentamicin, and pefloxacin, 70% to chloramphenicol and 90% were resistant to amoxicillin, 85% to augumentin and 80% to streptomycin. Hundred percent of E. coli isolates were susceptible to ciprofloxacin, pefloxacin, 95% to gentamicin and 100% were resistant to streptomycin, 85 % resistant to amoxicillin, augumentin, while 100% of S. aureus isolates were susceptible to trimethoprim sulphamethoxazole, 90% susceptible to gentamicin, 80% to streptomycin and 100% of the S.aureus isolates were resistant to ampliclox. Conclusion: The bacteriological status of chicken carcass revealed high contamination with Arcobacter, E coli and S. aureus with varying degree of antibiotic resistance therefore, improvement in meat processing procedures and strict hygiene measures towards reduction of these pathogens in food products should be encouraged.

Enumeration and antimicrobial resistance of Campylobacter species from retail chicken carcasses

To determine Campylobacter contamination level and antimicrobial resistance patterns from chicken carcasses in supermarkets and farmer's markets of 9 districts in Beijing. From August 2012 to July 2013, whole chicken carcasses (n = 240) were collected from 27 supermarkets and 18 farmer's markets of nine districts in Beijing. The level of Campylobacter contamination was enumerated by plate counting method using the modified Karmali and modified Preston agar. Presumptive Campylobacter isolates were identified and characterized by gram stain, agglumination test and a multiplex PCR method. The level of Campylobacter contamination was calculated following the USDA/FSIS Campylobacter enumeration method. Selected 151 Campylobacter isolates were further characterized by minimal inhibitory concentrations(MICs) of eight antimicrobials. A total of 26.3% (63/240) of the retail whole chicken carcasses were contaminated by Campylobacter and 151 Campylobacter isolates were recovered, including 85 Campylobacter jejuni isolates and 66 Campylobacter coli isolates. The P25, P50, P75 of Campylobacter contamination concentration were 7.5, 45.0 and 350.0 CFU/g, respectively. The antimicrobial resistance rate of C. jejuni and C. coli were as the following: azithromycin(AZI, 13% (11/85), 82% (54/85)), chloramphenicol (CHL, 33% (28/85), 42% (28/85)), ciprofloxacin (CIP, 95% (81/85), 100% (85/85)), doxycycline (DOX, 38% (32/85), 80% (53/85)), erythromycin (ERY, 12% (10/85), 82% (54/85)), gentamicin (GEN, 25% (21/85), 68% (45/85)), tetracycline (TET, 67% (57/85), 73% (62/85)), all isolates were susceptible to meropenem (MEP). The multi-drug resistance ratio of C. jejuni (55% (47/85) )was significantly lower than that (86% (57/66) )of C. coli (χ(2) = 16.70, P < 0.01). Among 151 Campylobacter isolates, 21 antimicrobial resistance patterns were identified, including 20 patterns among C. jejuni isolates and 10 patterns among C.coli isolates. Among C.jejuni isolates, CIP-DOX-TET was dominant (22% (19/85)), followed by CIP-TET (14% (12/85)), CHL-CIP-TET(9% (8/85)) and CHL-CIP-GEN (7% (6/85)). Among C.coli isolates,AZI-CHL-CIP-DOX-ERY-GEN-TET (35% (23/66)) was the dominant, followed by AZI-CIP-DOX-ERY-GEN-TET (21% (14/66) )and AZI-CIP-DOX-ERY-TET(15% (10/66)). Our findings showed a high prevalence and concentration of Campylobacter contamination in retail chicken carcasses of nine districts in Beijing, especially the on-site slaughtered chicken from the farmer's markets. The resistance levels of these recovered Campylobacter isolates were serious.

Enumeration and characterization of campylobacter species from retail chicken carcasses in Beijing, China.

Epidemiological data have implicated contaminated raw or undercooked chicken as primary vehicles of Campylobacter transmission to humans. Risk assessment relating to Campylobacter contamination of poultry products in China is frequently hampered by the lack of quantitative data. In this study, whole chicken carcasses (n=240) were collected from the retail markets of Beijing. The level of Campylobacter contamination was enumerated by the plate-counting method. The representative Campylobacter isolates were characterized for antimicrobial resistance. Selected representative isolates were further analyzed by the multilocus sequencing typing method for genetic relatedness. Overall, 26.3% (63/240) of the retail whole chicken carcasses were contaminated by Campylobacter, and the values ranged from 2.5 to 7050 colony-forming units (CFU)/g. The 50th percentile of Campylobacter value was 45 CFU/g in chicken carcass. Multidrug-resistant profiles were observed in 33 (39.2%) C. jejuni isolates (from 27 chicken carcasses) and 57 (86.4%) C. coli isolates (from 30 chicken carcasses). One dominant ST (ST6322) and one dominant clonal complex (CC828) consisting of multidrug-resistant C. coli isolates were identified. Our findings showed a high prevalence of Campylobacter contamination in retail chicken carcasses, which could be a source of exposure to multidrug-resistant isolates for consumers. This study provided baseline enumeration data for the quantitative risk assessment and evaluation of new control measures of Campylobacter contamination in retail chicken products in China.

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

Epidemiological reports have implicated contaminated raw or undercooked chicken as primary vehicles of Salmonella transmission to human beings. Risk assessments relating to Salmonella contamination of poultry products in China are frequently hampered by the lack of quantitative data. In this study, whole chicken carcasses (n=395) were collected from the retail markets of Beijing, and the level of Salmonella contamination was enumerated by most probable number (MPN) analysis and all Salmonella isolates were further characterized for their serotypes and antimicrobial resistance. Overall, 49.9% (197/395) of the retail whole chicken carcasses were contaminated by Salmonella and the MPN values ranged from 1.5 to >550 MPN/100 g. The 50% percentile of Salmonella MPN value was 7.5 MPN/100 g in chicken carcass. The predominant serotypes isolated were Salmonella Enteritidis (n=309, 94 samples), Salmonella Indiana (n=205, 54 samples) and Salmonella Infantis (n=89, 23 samples). Multidrug-resistant Salmonella isolates were recovered from 100 chicken carcass samples; 102 isolates (from 41 chicken carcasses) even showed resistance to both ciprofloxacin and cefotaxime. Our findings showed a high prevalence of Salmonella contamination in retail chicken carcasses, which could be a source of exposure for consumers to multidrug-resistant isolates. This study provided baseline enumeration data for the risk assessment and evaluation of new control measures of Salmonella contamination in retail chicken products.

Identification of Multiple Subtypes of Campylobacter jejuni in Chicken Meat and the Impact on Source Attribution

Most source attribution studies for Campylobacter use subtyping data based on single isolates from foods and environmental sources in an attempt to draw epidemiological inferences. It has been suggested that subtyping only one Campylobacter isolate per chicken carcass incurs a risk of failing to recognise the presence of clinically relevant, but numerically infrequent, subtypes. To investigate this, between 21 and 25 Campylobacter jejuni isolates from each of ten retail chicken carcasses were subtyped by pulsed-field gel electrophoresis (PFGE) using the two restriction enzymes SmaI and KpnI. Among the 227 isolates, thirteen subtypes were identified, the most frequently occurring subtype being isolated from three carcasses. Six carcasses carried a single subtype, three carcasses carried two subtypes each and one carcass carried three subtypes. Some subtypes carried by an individual carcass were shown to be potentially clonally related. Comparison of C. jejuni subtypes from chickens with isolate subtypes from human clinical cases (n = 1248) revealed seven of the thirteen chicken subtypes were indistinguishable from human cases. None of the numerically minor chicken subtypes were identified in the human data. Therefore, typing only one Campylobacter isolate from individual chicken carcasses may be adequate to inform Campylobacter source attribution.

Characterization of Staphylococcus aureus Isolates from Retail Chicken Carcasses and Pet Workers in Northwest Arkansas

Staphylococcus aureus can be carried on the skin and nasal passages of humans and animals as a commensal. A case of human methicillin-resistant S. aureus infection resulting from contact with pork has been reported. Poultry carcasses are sold at retail with the skin intact, but pork and beef typically are not. Thus, the risk of methicillin-resistant S. aureus human infection from whole raw poultry carcasses may be greater than that of exposure from pork or beef. The objective of this study was to isolate and characterize S. aureus from whole retail poultry carcasses and compare the isolates to S. aureus isolates from humans. A total of 25 S. aureus isolates were collected from 222 whole poultry carcasses. The isolates were characterized phenotypically with antibiotic resistance disc diffusion assays and genotypically using multilocus sequence typing. A total of 17 S. aureus isolates obtained from healthy humans were included and characterized in the same way as the poultry isolates. Staphylococcus spp. were recovered from all poultry carcasses. Only 25 poultry carcasses (11.2%) were contaminated with S. aureus. Of these 25 isolates, 36% were resistant to at least one of the antibiotics tested and 20% were resistant to two or more antibiotics tested. However, 100% of the human isolates were resistant to at least one of the antibiotics and 94% were resistant to two or more antibiotics. The results of the multilocus sequence typing indicate that most of the isolates grouped according to source. These results indicate a low prevalence of S. aureus present in poultry, and the isolates were not phenotypically similar to human isolates. The low number of S. aureus isolates from this study indicates that chicken carcasses would appear to not be a significant source of this bacterium.

Comparison of Destructive and Nondestructive Sampling Techniques of Retail Chicken Carcasses for Enumeration of Hygiene Indicator Microorganisms

The type of sampling technique used to obtain food samples is fundamental to the success of microbiological analysis. Destructive and nondestructive techniques, such as tissue excision and rinsing, respectively, are widely employed in obtaining samples from chicken carcasses. In this study, four sampling techniques used for chicken carcasses were compared to evaluate their performances in the enumeration of hygiene indicator microorganisms. Sixty fresh chicken carcasses were sampled by rinsing, tissue excision, superficial swabbing, and skin excision. All samples were submitted for enumeration of mesophilic aerobes, Enterobacteriaceae, coliforms, and Escherichia coli. The results were compared to determine the statistical significance of differences and correlation (P < 0.05). Tissue excision provided the highest microbial counts compared with the other procedures, with significant differences obtained only for coliforms and E. coli (P < 0.05). Significant correlations (P < 0.05) were observed for all the sampling techniques evaluated for most of the hygiene indicators. Despite presenting a higher recovery ability, tissue excision did not present significant differences for microorganism enumeration compared with other nondestructive techniques, such as rinsing, indicating its adequacy for microbiological analysis of chicken carcasses.

POLYMERASE CHAIN REACTION‐BASED ASSAYS FOR THE DETECTION AND DIFFERENTIATION OF POULTRY SIGNIFICANT PSEUDOMONADS

ABSTRACTPseudomonas genus‐specific primers targeting the 16s rRNA gene were used in a real‐time polymerase chain reaction (PCR) assay for rapid analysis of Pseudomonas isolated from retail chicken carcasses. A multiplex PCR assay was also designed using specific primers targeting the gyrase B sub‐unit gene to rapidly distinguish between several species of poultry significant Pseudomonads. The assays were used to evaluate the species and level of spoilage Pseudomonads on raw chicken carcasses over an 8‐day storage period. No Pseudomonas were detected on the chicken carcasses until 4 days after storage using culturing and plating techniques, but the PCR‐based assays developed in this research were more sensitive and detected Pseudomonas in carcass rinses performed immediately after processing. With the multiplex PCR assay, it was determined that most of the Pseudomonas spoilage was because of Pseudomonas fluorescens and Pseudomonas fragi.PRACTICAL APPLICATIONSEconomic losses as a result of spoilage are estimated between 5 and 17 billion dollars annually. In the poultry industry, the Pseudomonads not only cause the majority of this spoilage, but are also primary biofilm formers which may harbor and spread pathogens. Currently, only biochemical assays are available in the food industry for detection and differentiation of Pseudomonads. However, biochemical assays require 5 days for results, are limited to detection of a few species, and often produce erroneous results. The PCR assays developed in this work can reduce detection time to a few hours. Furthermore, these nucleic acid‐based assays have the potential to simplify the identification process, reduce food spoilage and foodborne illness, and speed the diagnosis of ill birds.