Objective: To analyze the drug resistance and genomic characteristics of Salmonella enterica serovar London isolated from clinical and food sources in Hangzhou City from 2017 to 2021. Methods: A total of 91 Salmonella enterica serovar London strains isolated from Hangzhou City from 2017 to 2021 were analyzed for drug susceptibility, pulsed field gel electrophoresis (PFGE) typing and whole genome sequencing. Multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST) and detection of drug resistance genes were performed by using the sequencing data. Phylogenetic analysis was conducted to compare the 91 genomes from Hangzhou City with 347 genomes from public databases. Results: No significant difference in the drug resistance rate was observed between clinical strains and food strains to 18 drugs in Hangzhou City(all P>0.05), and the multidrug resistance (MDR) rate was 75.8% (69/91). Most strains were resistant to 7 drug classes simultaneously. One strain was resistant to Polymyxin E as well as positive for mcr-1.1, and 50.5% (46/91) of the strains were resistant to Azithromycin and were positive for mph(A). All 91 Salmonella enterica serovar London strains were ST155, which were subdivided into 44 molecular types by PFGE and 82 types by cgMLST. Phylogenetic analysis showed that most strains from Hangzhou City (83/91) were clustered together, and a small number of human isolates from Europe, North America and pork isolates from Hubei and Shenzhen were mixed in the cluster. Other strains from Hangzhou City (8/91) were closely related to strains from Europe, America and Southeast Asia. Strains isolated from pork were the most closely related to clinical strains. Conclusion: The epidemic of Salmonella enterica serovar London in Hangzhou City is mainly caused by the spread of ST155 strains, which is mainly transmitted locally. At the same time, cross-region transmission to Europe, North America, Southeast Asia, and other provinces and cities in China may also occur. There is no significant difference in the drug resistance rate between clinical strains and food strains, and a high level of MDR is found in the strains. Clinical infection of Salmonella enterica serovar London may be closely related to pork consumption in Hangzhou City.
Humans ; Salmonella enterica/genetics* ; Serogroup ; Anti-Bacterial Agents/pharmacology* ; Multilocus Sequence Typing ; Cities ; London ; Clonidine ; Phylogeny ; Genomics ; Drug Resistance ; Electrophoresis, Gel, Pulsed-Field ; Microbial Sensitivity Tests

Outbreaks caused by highly industrialized food companies are characterized by cross-border, trans-regional, rapid and unpredictable, related to serious disease and economic burden. A cluster of cases with monophasic salmonella enterica serovar Typhimurium ST34 infection suspected to be associated with consumption of contaminated chocolate products have been reported in several Europe countries since December 2021. After retrospective investigations, the buttermilk circuit in the Belgian factory was suspected to be the point of origin of the contamination. This outbreak could provide a reference for the risk management of foodborne pathogens contamination in China. The objective of this paper was to summarize the process and characteristics of the outbreak of monophasic S. Typhimurium caused by contaminated chocolate products, analyze the characteristics of ST34 monophasic S. Typhimurium and the microbial management measures in the process of chocolate products, and systematically discuss the suggestions for the risk management of foodborne pathogens contamination and countermeasures for the rapid development of industrialization of food enterprises in China, in order to provide scientific and technological support for the prevention and control, prediction and early warning of sudden cases in China.
Humans ; Salmonella typhimurium ; Serogroup ; Salmonella Infections/prevention & control* ; Chocolate ; Retrospective Studies ; Salmonella enterica ; Disease Outbreaks/prevention & control* ; Risk Management

Objective: To investigate the molecular characteristics of ciprofloxacin-cefotaxime-azithromycin co-resistant Salmonella enterica serovar Thompson (S. Thompson) isolates from sporadic cases of foodborne diseases and aquatic foods in Hunan province. Methods: Ciprofloxacin-cefotaxime-azithromycin co-resistant S. Thompson isolates were selected from samples, and broth microdilution method was used to determine the resistance to 11 antibiotics of these isolates in vitro. Whole genome sequencing was used for investigating antimicrobial resistance gene patterns and phylogenetic relationships of strains. Results: Nine ciprofloxacin-cefotaxime-azithromycin co-resistant isolates were recovered from 19 S. Thompson isolates. Among nine ciprofloxacin-cefotaxime-azithromycin co-resistant isolates, eight of them harbored IncC plasmids, simultaneously carrying plasmid-mediated quinolone resistance (PMQR) genes qepA and qnrS1, β-lactamase resistance gene bla_CMY-2, azithromycin resistance gene mph(A), and one isolate harbored IncR plasmid, and carried PMQR genes qnrB4 and aac(6')-Ib-cr, bla_OXA-10 and mph(A). Genetic environment analysis showed that qnrS1, qepA, mph(A) and bla_CMY-2 genes might be integrated on genomes of strains by ISKra4, IS91, IS6100 and ISEcp1, respectively. Phylogenetic core genome comparisons demonstrated that ciprofloxacin-cefotaxime-azithromycin co-resistant isolates from patients and aquatic foods were genetically similar and clustered together. Conclusion: Ciprofloxacin-cefotaxime-azithromycin co-resistant S. Thompson isolates have been isolated from both human and aquatic food samples, suggesting that the spread of multidrug resistant Salmonella between human and aquatic animals.
Animals ; Humans ; Ciprofloxacin ; Cefotaxime ; Azithromycin ; Serogroup ; Phylogeny ; Drug Resistance, Multiple, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Salmonella ; Quinolones ; Foodborne Diseases ; Plasmids ; Salmonella enterica ; Microbial Sensitivity Tests

OBJECTIVES: This study aimed to reveal the epidemiologic characteristics of the outbreak of gastroenteritis caused by Salmonella enterica serovar Thompson in Busan Metropolitan City and to identify points for improvement to prevent of food-borne disease outbreak.METHODS: This was a case-control study. The control group comprised asymptomatic students in the same classes of the cases. The presence or absence of symptoms, ingestion of each food provided by school meal service, and commonly ingested foods in addition to those foods in meal service were investigated. Moreover, specimens collected from rectal swab, preserved foods, and environmental surface were tested.RESULTS: Of the 6,092 subjects, 1,111 (1,083 students, 22 school personnel, and 6 foodservice employees) were included in the case group; this corresponded to an 18.4% attack rate. Symptoms included diarrhea (n=1,051, 94.6%), abdominal pain (n=931, 83.8%), febrile sensation (n=502, 45.2%), and vomiting (n=275, 24.8%). The epidemic curves of each 10 schools were unimodal. Investigation of food intake showed a significantly high odds ratio for chocolate cake in 5 out of the 10 schools. Laboratory test detected Salmonella enterica serovar Thompson both in rectal swab specimens of 9 schools and in collected preserved chocolate cakes of 9 schools. Pulsed-field gel electrophoresis test result showed that Salmonella enterica seorvar Thompson isolated from human and foods were the same.CONCLUSIONS: The source of infection for the Salmonella enterica serovar Thompson outbreak in the 10 schools of Busan Metropolitan City is chocolate cake. Traceback investigation for origin of contaminated food in food-borne disease outbreak and safety control during food production should be more enhanced.
Abdominal Pain ; Busan ; Cacao ; Case-Control Studies ; Diarrhea ; Eating ; Electrophoresis, Gel, Pulsed-Field ; Food, Preserved ; Foodborne Diseases ; Gastroenteritis ; Humans ; Korea ; Meals ; Odds Ratio ; Salmonella enterica ; Salmonella Infections ; Salmonella ; Sensation ; Serogroup ; Vomiting

It is crucial to optimize the dose of fluoroquinolones to avoid antibiotic resistance and to attain clinical success. We undertook this study to optimize the dose of enrofloxacin against Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) in chicken by assessing its pharmacokinetic/pharmacodynamic (PK/PD) indices. The antibacterial activities of enrofloxacin against S. Enteritidis were evaluated. After administering 10 mg/kg body weight (b.w.) of enrofloxacin to broiler chickens of both sexes by intravenous (IV) and peroral (PO) routes, blood samples were drawn at different intervals and enrofloxacin concentrations in plasma were determined. PK/PD indices were calculated by integrating the PK and PD data. The elimination half-lives (T(1/2)), time required to reach peak concentration (T(max)), peak concentration (C(max)), and area under curve (AUC) after administering enrofloxacin by PO and IV routes were 25.84 ± 1.40 h, 0.65 ± 0.12 h, 3.82 ± 0.59 µg/mL, and 20.84 ± 5.0 µg·h/mL, and 12.84 ± 1.4 h, 0.22 ± 0.1 h, 6.74 ± 0.03 µg/mL, and 21.13 ± 0.9 µg.h/mL, respectively. The bioavailability of enrofloxacin was 98.6% ± 8.9% after PO administration. The MICs of enrofloxacin were 0.0625–1 µg/mL against S. Enteritidis strains, and the MIC₅₀ was 0.50 µg/mL. The C(max)/MIC₅₀ were 7.64 ± 0.2 and 13.48 ± 0.7 and the 24 h AUC/MIC₅₀ were 41.68 ± 0.1 and 42.26 ± 0.3 after administering the drug through PO and IV routes, respectively. The data in this study indicate that the application of 50 mg/kg b.w. of enrofloxacin to chicken through PO and IV routes with a dosing interval of 24 h can effectively cure S. Enteritidis infection, indicating the need for a 5-fold increase in the recommended dosage of enrofloxacin in chicken.
Area Under Curve ; Biological Availability ; Body Weight ; Chickens ; Drug Resistance, Microbial ; Fluoroquinolones ; Pharmacokinetics ; Plasma ; Salmonella enterica ; Salmonella enteritidis ; Salmonella ; Serogroup

OBJECTIVES: This study aimed to reveal the epidemiologic characteristics of the outbreak of gastroenteritis caused by Salmonella enterica serovar Thompson in Busan Metropolitan City and to identify points for improvement to prevent of food-borne disease outbreak. METHODS: This was a case-control study. The control group comprised asymptomatic students in the same classes of the cases. The presence or absence of symptoms, ingestion of each food provided by school meal service, and commonly ingested foods in addition to those foods in meal service were investigated. Moreover, specimens collected from rectal swab, preserved foods, and environmental surface were tested. RESULTS: Of the 6,092 subjects, 1,111 (1,083 students, 22 school personnel, and 6 foodservice employees) were included in the case group; this corresponded to an 18.4% attack rate. Symptoms included diarrhea (n=1,051, 94.6%), abdominal pain (n=931, 83.8%), febrile sensation (n=502, 45.2%), and vomiting (n=275, 24.8%). The epidemic curves of each 10 schools were unimodal. Investigation of food intake showed a significantly high odds ratio for chocolate cake in 5 out of the 10 schools. Laboratory test detected Salmonella enterica serovar Thompson both in rectal swab specimens of 9 schools and in collected preserved chocolate cakes of 9 schools. Pulsed-field gel electrophoresis test result showed that Salmonella enterica seorvar Thompson isolated from human and foods were the same. CONCLUSIONS: The source of infection for the Salmonella enterica serovar Thompson outbreak in the 10 schools of Busan Metropolitan City is chocolate cake. Traceback investigation for origin of contaminated food in food-borne disease outbreak and safety control during food production should be more enhanced.
Abdominal Pain ; Busan ; Cacao ; Case-Control Studies ; Diarrhea ; Eating ; Electrophoresis, Gel, Pulsed-Field ; Food, Preserved ; Foodborne Diseases ; Gastroenteritis ; Humans ; Korea ; Meals ; Odds Ratio ; Salmonella enterica ; Salmonella Infections ; Salmonella ; Sensation ; Serogroup ; Vomiting

Salmonella enterica serovar Typhimurium is one of the most important bacterial pathogens causing diarrhea. The resistance of S. typhimurium to antimicrobial agents, which has recently been isolated from patients, is causing serious problems. We investigated the effects of salicylic acid (Sal) and acetyl salicylate (AcSal) on the susceptibility of S. typhimurium to cephalosporin antibiotics, which are known to increase resistance to cephalosporin and quinolone antibiotics. The MIC of cephalosporin antibiotics was higher than that of the media without Sal. The rate of accumulation of ethidium bromide (EtBr) in the bacteria by the outer membrane protein (Omp) was not different from that of the bacteria cultured in the medium containing Sal. However, Carbonyl cyanide-m-chlorophenylhydrazone (CCCP), an inhibitor of bacterial efflux pumps, significantly reduced the rate of accumulation of EtBr in bacteria cultured on Sal containing medium. In the medium containing CCCP, the MIC of the antimicrobial agent tended to decrease as compared with the control. In addition, the MIC of the bacteria treated with CCCP and Sal was higher than that of the antimicrobial agent against the CCCP treated experimental bacteria. These results suggest that Sal decreases the expression of OmpF in the Omp of S. typhimurium and reduces the permeability of cephalosporin antibiotics to bacteria, which may induce tolerance to cephalosporin antibiotics.
Anti-Bacterial Agents ; Anti-Infective Agents ; Bacteria ; Carbonyl Cyanide m-Chlorophenyl Hydrazone ; Cephalosporin Resistance ; Cephalosporins ; Diarrhea ; Ethidium ; Humans ; Membrane Proteins ; Permeability ; Salicylic Acid ; Salmonella enterica ; Salmonella typhimurium ; Salmonella ; Serogroup

Bovine abortion, diarrhea, and respiratory disease complexes, caused by infectious agents, result in high and significant economic losses for the cattle industry. These pathogens are likely transmitted by various vectors and reservoirs including insects, birds, and rodents. However, experimental data supporting this possibility are scarce. We collected 117 samples and screened them for 44 bovine abortive, diarrheal, and respiratory disease complex pathogens by using Dembo polymerase chain reaction (PCR), which is based on TaqMan real-time PCR. Fifty-seven samples were positive for at least one pathogen, including bovine viral diarrhea virus, bovine enterovirus, Salmonella enterica ser. Dublin, Salmonella enterica ser. Typhimurium, and Neospora caninum; some samples were positive for multiple pathogens. Bovine viral diarrhea virus and bovine enterovirus were the most frequently detected pathogens, especially in flies, suggesting an important role of flies in the transmission of these viruses. Additionally, we detected the N. caninum genome from a cockroach sample for the first time. Our data suggest that insects (particularly flies), birds, and rodents are potential vectors and reservoirs of abortion, diarrhea, and respiratory infectious agents, and that they may transmit more than one pathogen at the same time.
Animals ; Birds ; Cattle ; Cockroaches ; Diarrhea Viruses, Bovine Viral ; Diarrhea ; Diptera ; Disease Reservoirs ; Disease Vectors ; Enterovirus ; Enterovirus, Bovine ; Genome ; Insects ; Neospora ; Polymerase Chain Reaction ; Real-Time Polymerase Chain Reaction ; Rodentia ; Salmonella enterica ; Virulence Factors

Objective: To understand the circulation, drug resistance and molecular characteristics of Salmonella1, 4, [5], 12: i:- in human in Guangdong province. Methods:Salmonella1, 4, [5], 12: i:- isolated from diarrhea patients in Guangdong during 2007-2016 were detected for drug resistance, genes and PFGE characteristics. Results: A total of 2 960 strains Salmonella1, 4, [5], 12: i: - were isolated from human diarrhea cases during this period. The positive rates of the isolation increased year by year. The male to female ratio of the infection cases was 1.58∶1, and the infection mainly occurred in infants and young children. Except imipenem, Salmonella1, 4, [5], 12: i: - was resistant to other 17 antibiotics to some extent. The drug resistant rates to ceftazidime, cefotaxime and ciprofloxacin increased from 2011 to 2016. Multi-drug resistance was serious, for example, the multi-drug resistant strains with ASSuT accounted for 70.62% (435/616) and the multi-drug resistant strains with ACSuGSTTm accounted for 27.11% (167/616). The lack of fljA, fljB and hin genes, as well as the retaining of iroB, STM2740, STM2757 genes, resulted in the unable expression of FljBenx gene with 8 different defection profiles. There were 934 different PFGE patterns observed in 2 347 strains, which displayed a relatively large fingerprint polymorphism. The major PFGE pattern was JPXX01. GD0226, which was found in 97 strains, accounting for 4.13% (97/2 347). The PFGE patterns in 168 Salmonella1, 4, [5], 12: i: - strains were consistent with that of Salmonella typhimurium. Conclusions:Salmonella1,4,[5], 12: i: - strains has become the major serotype of Salmonella that cause diarrhea in human in Guangdong. The multi-drug resistance of Salmonella1,4, [5], 12: i: - was serious, and since the defection of fljA, fljB and hin genes, the expression of FljBenx protein failed. The PFGE results were diverse, which displayed polymorphism in inheritance.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents/pharmacology* ; Child ; Child, Preschool ; China/epidemiology* ; Diarrhea/microbiology* ; Drug Resistance, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Female ; Humans ; Infant ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Salmonella Infections/prevention & control* ; Salmonella enterica/isolation & purification* ; Salmonella typhimurium ; Serogroup ; Serotyping ; Young Adult

Pet turtles are well-known to harbor an array of bacterial pathogens which can cause zoonotic infections in humans as well as opportunistic infections in the turtles itself. Essential oils are the natural plant extracts which have been traditionally used for disease treatment. In the present study, the essential oil of lavender (EOL) was examined for its antibacterial activity against thirty-eight strains of turtle-borne pathogenic bacteria belonging to seven species; Aeromonas hydrophila, A. caviae, A. dhakensis, Citrobacter freundii, Proteus mirabilis, Salmonella enterica and Pseudomonas aeruginosa. Antibacterial activity of EOL was tested by means of disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests. In addition, the antimicrobial susceptibility pattern of 11 commonly used antimicrobials was examined and the multiple antibiotic resistance (MAR) index was calculated. The results revealed that EOL was active against all tested turtle-borne pathogenic bacteria except P. aeruginosa. The range of MIC and MBC values of EOL against isolates except P. aeruginosa were recorded as 0.5-1% (V/V) and 0.5-2% (V/V), respectively. The MBC/MIC ratio was detected as <4, revealing that the tested EOL was bactericidal. Besides, most of the isolates were resistant to different antimicrobials in antimicrobial disk diffusion test. MAR index values of the tested strains were ranging from 0.27 to 0.91. The outcomes indicate that EOL has a potential to be used as an antibacterial agent against pathogenic bacteria isolated from pet turtles.
Aeromonas hydrophila ; Animals ; Bacteria* ; Citrobacter freundii ; Diffusion ; Drug Resistance, Microbial ; Guinea Pigs ; Humans ; Lavandula* ; Microbial Sensitivity Tests ; Oils, Volatile ; Opportunistic Infections ; Plant Extracts ; Proteus mirabilis ; Pseudomonas aeruginosa ; Salmonella enterica ; Turtles ; Zoonoses