Objective: To investigate the antimicrobial resistance status and pulsed field gel electrophoresis (PFGE) patterns of Salmonella enteritidis (S.enteritidis) in Shanxi Province in order to provide references for the treatment of Salmonella infection and for tracing the source of outbreaks of foodborne diseases. Methods: Sixty-four S. enteritidis strains were collected by monitoring sites for foodborne diseases from April 2015 to March 2018. Biochemical identification system and serotyping analysis were used for bacterial identification. Drug susceptibility patterns were analyzed with micro-broth dilution method. PFGE was used for molecular typing. Results: The antimicrobial resistance rate of 64 S. enteritidis strains to nalidixic acid (95.31%) was the highest, followed by that to ampicillin (90.63%) and to ampicillin/sulbactam (81.25%). They had lower resistance rates to cefazolin, cefotaxime, tetracycline, ceftazidime, trimethoprim/sulfamethoxzole and ciprofloxacin (3.13%-23.44%) and were all sensitive to chloramphenicol, cefotaxime, azithromycin, imipenem and gentamicin. No statistically significant difference in drug resistance rates was found between the sporadic strains and the outbreak strains (P>0.05). All 64 S. enteritidis strains digested with XbaⅠwere divided into 33 molecular patterns by PFGE. The numbers of bacteria contained in each pattern ranged from 1 to 10 strains. The similarity among patterns was between 54.6% and 100%. Conclusion More attention should be paid to the drug resistance status of S. enteritidis in Shanxi Province. It is necessary to strengthen the standardized administration of antibiotics. The PFGE patterns of S. enteritidis reveal the presence of significant genetic polymorphism. PFGE is of great significance in analyzing the genetic relationship among S. enteritidis strains and in identifying and tracing the source of outbreaks of foodborne diseases.

Objective: To investigate the contamination status of Salmonella, Vibrio parahaemolyticus and Staphylococcus aureus and bacterial resistance in retail meat products in Taiyuan, Shanxi Province. Methods: In the epidemic season of diarrhea in 2017, poultry and meat product specimens were randomly collected from the farmer′s markets and supermarkets of 10 districts and counties of Taiyuan. Salmonella, Vibrio parahaemolyticus and Staphylococcus aureus were isolated form these specimens. Serotypes of Salmonella strains were analyzed. ELSIA was used to detect Staphylococcus aureus enterotoxin (A-E). Vibrio parahaemolyticus isolates were tested for the virulence genes encoding direct hemolysin (tdh) and indirect hemolysin (trh). Antibiotic resistance of the three food-borne pathogens were analyzed using microdilution methods. Results: A total of 38 food-borne pathogens were isolated from 123 poultry and livestock meat product specimens with a positive rate of 30.9%, of which mainly were Salmonella (26 strains, 21.1%), followed by Vibrio parahaemolyticus (8 strains, 6.5%) and Staphylococcus aureus (4 strains, 3.3%). The 26 strains of Salmonella belonged to 10 serotypes. The Salmonella strains isolated from pork specimens had diverse serotypes. Salmonella serovar Derby, Salmonella serovar Gold-coast and Salmonella serovar Liverpool were isolated from raw and cooked pork food for the first time in Taiyuan. All Salmonella strains isolated form chicken products were Salmonella enteritis. The enterotoxin types of the four Staphylococcus aureus strains were three E-type and one complex type (A/E). All Vibrio parahaemolyticus isolates were negative for tdh or trh gene. Ampicillin, chloramphenicol, streptomycin, sulphonamides and tetracyclines (ACSSuT) resistance was prevalent in multi-drug resistant (MDR) Salmonella strains, but there was high sensitivity to fluoroquinolones and cephalosporins. MDR Staphylococcus aureus accounted for 75%. No third-generation cephalosporin- or fluoroquinolone-resistant or MDR Vibrio parahaemolyticus strains were isolated. Conclusions There were food-borne multi-pathogenic bacteria contamination in retail raw and cooked meat products in Taiyuan. Salmonella strains had diverse serotypes and high MDR rate. It was suggested that the regulatory authorities should strengthen the management of antibiotic use in aquaculture and specialized laboratory-based monitoring of meat supply chain.