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1.
Microb Pathog ; 194: 106801, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39025378

ABSTRACT

Listeria monocytogenes (L. monocytogenes) is a prevalent foodborne pathogen with a remarkable capacity to form biofilms on utensil surfaces. The Listeriolysin O (LLO) exhibits hemolytic activity, which is responsible for causing human infections. In this study, we investigated the inhibitory effect and mechanism of oregano essential oil (OEO) on L. monocytogenes, evaluated the effects on its biofilm removal and hemolytic activity. The minimum inhibitory concentration (MIC) of OEO against L. monocytogenes was 0.03 % (v/v). L. monocytogenes was treated with OEO at 3/2 MIC for 30 min the bacteria was decreased below the detection limit (10 CFU/mL) in PBS and TSB (the initial bacterial load was about 6.5 log CFU/mL). The level of L. monocytogenes in minced pork co-cultured with OEO (15 MIC) about 2.5 log CFU/g lower than that in the untreated group. The inhibitory mechanisms of OEO against planktonic L. monocytogenes encompassed perturbation of cellular morphology, elevation in reactive oxygen species levels, augmentation of lipid oxidation extent, hyperpolarization of membrane potential, and reduction in intracellular ATP concentration. In addition, OEO reduced biofilm coverage on the surface of glass slides by 62.03 % compared with the untreated group. Meanwhile, OEO (1/8 MIC) treatment reduced the hemolytic activity of L. monocytogenes to 24.6 % compared with the positive control. Molecular docking suggested carvacrol and thymol might reduce the hemolytic activity of L. monocytogenes. The results of this study demonstrate that OEO exhibits inhibitory effects against L. monocytogenes, biofilms and LLO, which had potential as natural antimicrobial for the inhibition of L. monocytogenes.


Subject(s)
Anti-Bacterial Agents , Bacterial Toxins , Biofilms , Hemolysin Proteins , Listeria monocytogenes , Microbial Sensitivity Tests , Oils, Volatile , Origanum , Reactive Oxygen Species , Listeria monocytogenes/drug effects , Biofilms/drug effects , Biofilms/growth & development , Oils, Volatile/pharmacology , Oils, Volatile/chemistry , Origanum/chemistry , Hemolysin Proteins/metabolism , Hemolysin Proteins/antagonists & inhibitors , Hemolysin Proteins/pharmacology , Bacterial Toxins/metabolism , Bacterial Toxins/antagonists & inhibitors , Reactive Oxygen Species/metabolism , Anti-Bacterial Agents/pharmacology , Animals , Heat-Shock Proteins/metabolism , Hemolysis/drug effects , Swine , Adenosine Triphosphate/metabolism , Membrane Potentials/drug effects , Molecular Docking Simulation , Cymenes
2.
Compr Rev Food Sci Food Saf ; 23(4): e13407, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39030802

ABSTRACT

This research presents a comprehensive review of Salmonella presence in retail fresh fruits and vegetables from 2010 to 2023, utilizing data from recognized sources such as PubMed, Scopus, and Web of Science. The study incorporates a meta-analysis of prevalence, serovar distribution, antimicrobial susceptibility, and antimicrobial resistance genes (ARGs). Additionally, it scrutinizes the heterogeneous sources across various food categories and geographical regions The findings show a pooled prevalence of 2.90% (95% CI: 0.0180-0.0430), with an increase from 4.63% in 2010 to 5.32% in 2022. Dominant serovars include S. Typhimurium (29.14%, 95% CI: 0.0202-0.6571) and S. Enteritidis (21.06%, 95% CI: 0.0181-0.4872). High resistance rates were noted for antimicrobials like erythromycin (60.70%, 95% CI: 0.0000-1.0000) and amoxicillin (39.92%, 95% CI: 0.0589-0.8020). The most prevalent ARGs were blaTEM (80.23%, 95% CI: 0.5736-0.9692) and parC mutation (66.67%, 95% CI: 0.3213-0.9429). Factors such as pH, water activity, and nutrient content, along with external factors like the quality of irrigation water and prevailing climatic conditions, have significant implications on Salmonella contamination. Nonthermal sterilization technologies, encompassing chlorine dioxide, ozone, and ultraviolet light, are emphasized as efficacious measures to control Salmonella. This review stresses the imperative need to bolster prevention strategies and control measures against Salmonella in retail fresh fruits and vegetables to alleviate related food safety risks.


Subject(s)
Fruit , Salmonella , Serogroup , Vegetables , Vegetables/microbiology , Fruit/microbiology , Salmonella/drug effects , Salmonella/isolation & purification , Salmonella/genetics , Prevalence , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Food Contamination/analysis , Food Microbiology
3.
J Dairy Sci ; 104(2): 1524-1530, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33246627

ABSTRACT

Effects of chemical structure, concentration, and pH on antimicrobial activity of conjugated bile acids were investigated in 4 strains of lactobacilli. Considerable differences were observed in the antimicrobial activity between the 6 human conjugated bile acids, including glycocholic acid, taurocholic acid, glycodeoxycholic acid, taurodeoxycholic acid, glycochenodeoxycholic acid, and taurochenodeoxycholic acid. Glycodeoxycholic acid and glycochenodeoxycholic acid generally showed significantly higher antimicrobial activity against the lactobacilli, but glycocholic acid and taurocholic acid exhibited the significantly lower antimicrobial activity. Glycochenodeoxycholic acid was selected for further analysis, and the results showed its antimicrobial activity was concentration-dependent, and there was a significantly negative linear correlation (R2 > 0.98) between bile-antimicrobial index and logarithmic concentration of the bile acid for each strain of lactobacilli. Additionally, the antimicrobial activity of glycochenodeoxycholic acid was also observed to be pH-dependent, and it was significantly enhanced with the decreasing pH, with the result that all the strains of lactobacilli were unable to grow at pH 5.0. In conclusion, chemical structure, concentration, and pH are key factors influencing antimicrobial activity of conjugated bile acids against lactobacilli. This study provides theoretical guidance and technology support for developing a scientific method for evaluating the bile tolerance ability of potentially probiotic strains of lactobacilli.


Subject(s)
Anti-Infective Agents/pharmacology , Bile Acids and Salts/pharmacology , Lactobacillus/drug effects , Animals , Anti-Infective Agents/chemistry , Bile Acids and Salts/chemistry , Glycochenodeoxycholic Acid/chemistry , Glycochenodeoxycholic Acid/pharmacology , Glycocholic Acid/chemistry , Glycocholic Acid/pharmacology , Glycodeoxycholic Acid/pharmacology , Humans , Hydrogen-Ion Concentration , Probiotics , Taurochenodeoxycholic Acid/chemistry , Taurochenodeoxycholic Acid/pharmacology , Taurocholic Acid/chemistry , Taurocholic Acid/pharmacology , Taurodeoxycholic Acid/chemistry , Taurodeoxycholic Acid/pharmacology
4.
Foodborne Pathog Dis ; 17(4): 243-252, 2020 04.
Article in English | MEDLINE | ID: mdl-31702399

ABSTRACT

Necrotizing enterocolitis (NEC) is a serious inflammatory intestinal disorder with a high mortality rate, which occurs most commonly in newborn infants. Cronobacter sakazakii, a common contaminant in infant formula, is associated with NEC. However, its role in NEC pathogenesis is unknown, and there are still no effective treatments for NEC. Currently, natural bioactive products have been investigated for their beneficial effects in preventing microbial infection. In this study, a neonatal mouse intestinal inflammation model was used to examine the protective effects of citral (a natural bioactive product) on C. sakazakii-induced intestinal inflammation and damages. It was shown that citral reduced the number of C. sakazakii cells in ileal tissues, and mice treated with citral had a significantly higher body weight than C. sakazakii-infected mice. Citral treatment also ameliorated serious ileal tissue damages, including epithelial sloughing, villous rupture, and enterocyte apoptosis. C. sakazakii infection upregulated the messenger RNA transcription levels of several inflammation-associated genes, increased production of IL-6 and TNF-α, and activated the NF-κB and MAPK signaling pathways in ileal tissues. Citral treatment mitigated these inflammatory responses. The apoptotic index and activities of caspase 3, 8, and 9 increased in murine ileum after C. sakazakii infection, but citral inhibited both enterocyte apoptosis and activations of these caspase. These findings suggest that citral has protective effects on C. sakazakii-induced intestinal inflammation in newborn mice, and it may play a future role in the management of C. sakazakii-associated infections and diseases.


Subject(s)
Acyclic Monoterpenes/administration & dosage , Cronobacter sakazakii/drug effects , Enterobacteriaceae Infections/prevention & control , Enterocolitis, Necrotizing/prevention & control , Protective Agents/administration & dosage , Animals , Animals, Newborn , Disease Models, Animal , Enterobacteriaceae Infections/microbiology , Enterocolitis, Necrotizing/microbiology , Intestines/microbiology , Mice
5.
Foodborne Pathog Dis ; 15(8): 481-488, 2018 08.
Article in English | MEDLINE | ID: mdl-29741928

ABSTRACT

We characterized antibiotic resistance profiles, antibiotic resistance-associated genes, and pulsed-field gel electrophoresis (PFGE) patterns of 145 Salmonella enterica serotype Typhimurium isolates from human infections and retail foods that were possibly responsible for salmonellosis outbreaks from 2008 to 2012 in Shanghai, China. Resistance to at least three antibiotics was found in 66.7% of chicken isolates, 76.5% of duck isolates, 77.8% of pork isolates, and 80.5% of human isolates. Seven antibiotic resistance phenotypes were detected in chicken isolates, 16 in pork isolates, 17 in duck isolates, and 50 in human isolates. No significant difference (p > 0.05) was found between Salmonella isolates derived from human salmonellosis and from retail foods in terms of the percent resistance of ampicillin, amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, nalidixic acid, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, sulfisoxazole, and sulfamethoxazole/trimethoprim. PFGE using XbaI and BlnI showed that some Salmonella isolates recovered from human infections and retail foods had same or highly similar genetic profile. Same or similar antibiotic resistance profiles, antibiotic resistance associated genes (i.e., qnrA, qnrB, qnrS, aac(6')-Ib, and oqxAB), gene cassettes (i.e., aadA2, dfrA12-aadA2, and aadA1), and mutations were detected in those isolates that exhibited high genetic similarities. These findings highlighted the frequent presence of Salmonella Typhimurium in retail chicken, pork, duck, and humans.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial/genetics , Food Contamination , Salmonella typhimurium/isolation & purification , Animals , Bacteriophage Typing , China/epidemiology , DNA, Bacterial/genetics , Electrophoresis, Gel, Pulsed-Field , Food Microbiology , Humans , Meat Products/microbiology , Microbial Sensitivity Tests , Poultry/microbiology , Salmonella Food Poisoning/epidemiology , Salmonella Infections/microbiology , Salmonella typhimurium/classification , Serotyping
6.
Nanotechnology ; 28(22): 225101, 2017 May 08.
Article in English | MEDLINE | ID: mdl-28480869

ABSTRACT

The emergence of antibiotic resistance has resulted in increasing difficulty in treating clinical infections associated with biofilm formation, one of the key processes in turn contributing to enhanced antibiotic resistance. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance has opened up. Based on the many and diverse properties of MoS2 nanosheets that have attracted wide attention, in particular their antibacterial potential, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of the CM-TH nanocomposites showed the synergetic effect that the combination of nanomaterials and antibiotics was more efficient than either working alone. In particularly, the minimum inhibitory concentration values generally decreased by a factor of dozens, suggesting that CM-TH may become a possible alternative to traditional antibiotics in disrupting biofilms and overcoming antibiotic resistance in treating medical diseases.

7.
Nanotechnology ; 2017 Apr 11.
Article in English | MEDLINE | ID: mdl-28398220

ABSTRACT

The emergence of antibiotic resistance has resulted in an increasing difficulty treating clinical infections associated with biofilms formation, one of the key processes contributed to enhance antibiotic resistance in return. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance was opened up. Based on multiple properties especially antibacterial potential of MoS2 nanosheets that have aroused wide attention, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus (S. aureus) and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of CM-TH nanocomposites expressed a synergy effect that the combination of nanomaterials and antibiotics were more efficient than both alone did. Particularly, the MIC values were generally decreased by a factor of dozens, suggesting CM-TH may become a possible alternative to traditional antibiotics in disrupting the biofilms and further to overcome antibiotic resistance in treating medical diseases.

8.
Foodborne Pathog Dis ; 14(7): 393-399, 2017 07.
Article in English | MEDLINE | ID: mdl-28375673

ABSTRACT

One thousand four hundred ninety-one Salmonella isolates recovered from retail foods including chicken, beef, fish, pork, dumplings, and cold dishes in China in 2007, 2008, 2010, 2011, and 2012 were analyzed for distribution of serotype and antimicrobial susceptibility. A total of 129 Salmonella serotypes were detected among 1491 isolates. Salmonella Enteritidis (21.5%), Typhimurium (11.0%), Indiana (10.8%), Thompson (5.4%), Derby (5.1%), Agona (3.8%), and Shubra (3.0%) were the seven most important serotypes in 1491 isolates. For antibiotic susceptibility, except 16 (1.1%) isolates were susceptible to all tested antibiotics, 131 (8.8%) resisted 1-2 and 1344 (90.1%) resisted three or more antibiotics. One thousand forty-six (70.2%) of 1491 Salmonella isolates were identified as multidrug-resistant (MDR) isolates, which could resist three or more categories of antibiotics. Resistance to sulfisoxazole (78.1%) was most common among the tested Salmonella, followed by tetracycline (70.6%), trimethoprim/sulfamethoxazole (68.0%), and nalidixic acid (63.4%). Resistances to amikacin (20.0%), levofloxacin (18.7%), gatifloxacin (17.9%), ceftriaxone (17.7%), and cefoxitin (13.2%) were less frequently detected. Resistance to fluoroquinolones was most common among Salmonella Shubra and Indiana isolates, while resistance to cephalosporins was frequently detected among Salmonella Thompson isolates. The results highlighted the diversity of Salmonella serotypes and the high prevalence of Salmonella MDR isolates in China. Compared with Salmonella Enteritidis and Typhimurium isolates, the higher fluoroquinolones and cephalosporins resistance rates of some individual serotypes (Salmonella Shubra, Indiana, and Thompson) also provided more information for further study related to fluoroquinolones or cephalosporin-resistant Salmonella.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial , Salmonella/drug effects , Cephalosporin Resistance , Cephalosporins/pharmacology , China , Fluoroquinolones/pharmacology , Food Contamination/prevention & control , Food Microbiology , Meat/microbiology , Salmonella/isolation & purification
9.
Foodborne Pathog Dis ; 14(12): 728-734, 2017 12.
Article in English | MEDLINE | ID: mdl-28926285

ABSTRACT

The involvement of AcrAB-TolC efflux pump in regulating fluoroquinolone resistance of naturally occurring Salmonella isolates is insufficiently investigated. In this study, the regulatory genes, acrR, ramR, marRAB, and soxRS of AcrAB-TolC efflux pump, of 27 naturally occurring fluoroquinolone-resistant Salmonella isolates collected in China were sequenced. The expression levels of acrB, ramA, marA, and soxS were also examined using quantitative real-time polymerase chain reaction. Gene alterations were mainly observed for acrR (three mutation types) and ramR (four mutation types), not for marRAB (no mutation) or soxRS (one mutaton type). Overexpressions were also mainly observed for acrB and ramA, not for marA or soxS. Some mutations/deletions in ramR caused highly elevated expression of ramA. Complementation with wild-type ramR gene reduced mRNA levels of acrB and ramA by 1.7- to 2.2-fold and 10.5- to 30.1-fold, respectively, and lowered fluoroquinolones (FQ) minimum inhibitory concentrations by 2- to 8-fold. Neither MarA nor SoxS was found to be associated with increased FQ resistance. This study shows that the AcrAB efflux pump is playing a role in mediating fluoroquinolone resistance, and RamA may be the major global regulator of AcrAB-TolC-mediated fluoroquinolone resistance in Salmonella.


Subject(s)
Bacterial Proteins/genetics , Drug Resistance, Multiple, Bacterial/genetics , Fluoroquinolones/pharmacology , Salmonella/genetics , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , China , DNA, Bacterial/genetics , Genetic Complementation Test , Microbial Sensitivity Tests , Real-Time Polymerase Chain Reaction , Salmonella/classification , Salmonella/drug effects , Sequence Analysis, DNA
10.
Foodborne Pathog Dis ; 13(4): 221-7, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26886843

ABSTRACT

Cronobacter sakazakii (formerly Enterobacter sakazakii) is an opportunistic pathogen that causes meningitis, sepsis, and necrotizing enterocolitis in neonates and infants through consumption of contaminated milk-based foods. In this study, the prevalence of C. sakazakii in 705 retail milk-based infant and baby food samples was investigated in 12 cities in Shaanxi, China, in 2010 and 2012. One hundred and nineteen samples (16.9%) were C. sakazakii positive. The isolates were further characterized for antimicrobial susceptibility to 14 antibiotics, pulsed-field gel electrophoresis profiles, and presence of the virulence genes. Samples of brand W, Y, A, and G in 2010 and 2012 were C. sakazakii positive. All isolates recovered in 2010 and 2012 were susceptible to levofloxacin and cefoperazone. In 2012, no isolate was resistant to gentamicin, cefoxitin, chloramphenicol, gatifloxacin, ciprofloxacin, and ceftriaxone. Antibiotic resistance of the isolates was most commonly found to rifampicin, amoxicillin-clavulanic acid, streptomycin, tetracycline, and ampicillin in both 2010 and 2012, except to trimethoprim/sulfamethoxazole in 2012. Pulsed-field gel electrophoresis profiles indicated that C. sakazakii isolates were genotypically diverse, although these isolates were prevalent in infant and baby foods with the same brand. A total of 34 virulence gene profiles of the C. sakazakii isolates in 2010 and 2012 were detected. Isolates that co-carried hly-ompX-eitCBAD-iucABCD/iutA genes in 2012 were significantly (p < 0.05) more prevalent than those in 2010. The results added new epidemiological evidence for the widespread occurrence of C. sakazakii in retail milk-based infant and baby foods and this should be an indicator of potential health risk for consumers.


Subject(s)
Cronobacter sakazakii/isolation & purification , Food, Preserved/microbiology , Infant Food/microbiology , Infant Formula/microbiology , Milk Substitutes , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , China , Cronobacter sakazakii/classification , Cronobacter sakazakii/drug effects , Cronobacter sakazakii/genetics , Drug Resistance, Bacterial , Drug Resistance, Multiple, Bacterial , Electrophoresis, Gel, Pulsed-Field , Food Inspection , Food, Preserved/economics , Genes, Bacterial , Humans , Infant , Infant Food/economics , Infant Formula/economics , Microbial Sensitivity Tests , Milk Substitutes/economics , Molecular Typing , Phylogeny , Spatio-Temporal Analysis , Virulence Factors/genetics , Virulence Factors/metabolism
11.
Org Biomol Chem ; 13(15): 4551-61, 2015 Apr 21.
Article in English | MEDLINE | ID: mdl-25778708

ABSTRACT

Three series of Momordica charantia (MC)2 analogues were designed, synthesized and evaluated for their anti-hyperglycaemic effects. Alanine scanning focusing on the peptide MC2 indicated the importance of the residues proline (Pro)(3), serine (Ser)(6), isoleucine (Ile)(7) and Ser(10) for anti-hyperglycaemic effects. Among the first series of MC2 analogues, peptide I-4 exhibited a better anti-hyperglycaemic effect and was chosen for further modification. A further two series of conformationally constrained analogues were designed by scanning the residues Pro(3), Ser(6), Ile(7), and Ser(10) with an i - (i + 2) lactam bridge consisting of a glutamic acid-Xaa-lysine (Glu-Xaa-Lys) scaffold and a diproline fragment. By screening in normal mice and mice with diabetes mellitus, peptides II-1, II-2 and III-3 showed a significant improvement in anti-hyperglycaemic and anti-oxidative activities compared with I-4. These data suggest that II-1, II-2 and III-3 could be candidates for future treatment of diabetes mellitus.


Subject(s)
Diabetes Mellitus, Experimental/drug therapy , Hypoglycemic Agents/chemistry , Hypoglycemic Agents/therapeutic use , Interferon-gamma/chemistry , Interferon-gamma/therapeutic use , Momordica charantia/chemistry , Pancreas/drug effects , Peptide Fragments/chemistry , Peptide Fragments/therapeutic use , Amino Acid Sequence , Animals , Blood Glucose/analysis , Cytokines/blood , Diabetes Mellitus, Experimental/blood , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/pathology , Male , Mice , Oxidative Stress/drug effects , Pancreas/metabolism , Pancreas/pathology , Weight Gain/drug effects
12.
Bioorg Med Chem ; 23(1): 132-40, 2015 Jan 01.
Article in English | MEDLINE | ID: mdl-25481394

ABSTRACT

Free fatty acid receptor 1 (FFA1) is a new potential drug target for the treatment of type 2 diabetes because of its role in amplifying glucose-stimulated insulin secretion in pancreatic ß-cell. In the present studies, we identified phenoxyacetic acid derivative (18b) as a potent FFA1 agonist (EC50=62.3 nM) based on the structure of phenylpropanoic acid derivative 4p. Moreover, compound 18b could significantly improve oral glucose tolerance in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice without observation of hypoglycemic side effect. Additionally, compound 18b exhibited acceptable PK profiles. In summary, compound 18b with ideal PK profiles exhibited good activity in vitro and in vivo, and might be a promising drug candidate for the treatment of diabetes mellitus.


Subject(s)
Acetates/chemical synthesis , Acetates/pharmacology , Receptors, G-Protein-Coupled/agonists , Acetates/chemistry , Acetates/pharmacokinetics , Animals , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , Models, Molecular , Rats , Receptors, G-Protein-Coupled/chemistry , Structure-Activity Relationship
13.
Food Microbiol ; 46: 74-80, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25475269

ABSTRACT

One hundred and twenty six Salmonella Enteritidis isolates recovered from 1152 retail raw poultries were characterized by antimicrobial susceptibility test, pulsed-field gel electrophoresis (PFGE), presence of quinolone resistance (Qnr) associated genes, Class I integron, extended spectrum beta-lactamases (ESBLs) encoding genes, and mutations in quinolone resistance-determining region (QRDR) of GyrA and ParC. Resistance was most frequently found to nalidixic acid (88.1%), followed by to tetracycline (65.9%), sulfisoxazole (65.1%), and ampicillin (61.9%), and a less extent to cefoxitin (8.7%), gatifloxacin (8.7%), levofloxacin (7.9%), ceftriaxone (7.1%), and ceftiofur (6.3%). One hundred and twenty three (98.4%) isolates were resistant to at least one antibiotic, and 93 (74.4%) to at least four antibiotics. aac(6')-Ib-cr, qnrB, qnrA and qnrS genes were detected in 15 (11.9%), 11 (8.7%), 6 (4.8%) and 1 (0.8%) isolates, respectively. Amino acid substitutions of Ser83Tyr, Asp87Asn, Asp87Tyr, Asp87Gly and Ser83Phe/Asp87Asn were detected in QRDR of GyrA, Arg80Ser was the unique mutation in ParC. Eight isolates were detected with amino acid substitution both in GyrA and ParC. Three isolates carried Class I integron that harboring dfrA17-aadA5, dhfR1-aadA1, and dfrA1, respectively. Five isolates were detected carrying bla(TEM)-bla(ACC) (n = 1), bla(TEM) (n = 1), bla(TEM)-bla(OxA) (n = 3), respectively. Genetic diversities (D = 0.9255) were found among isolates based on PFGE analysis.


Subject(s)
Meat/microbiology , Salmonella enteritidis/genetics , Salmonella enteritidis/isolation & purification , Animals , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Chickens , China , Drug Resistance, Multiple, Bacterial , Food Contamination/analysis , Food Contamination/economics , Meat/economics , Microbial Sensitivity Tests , Salmonella enteritidis/classification , Salmonella enteritidis/drug effects
14.
J Dairy Sci ; 98(11): 7552-9, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26387017

ABSTRACT

Cronobacter spp. are opportunistic pathogens that can cause serious diseases in neonates and infants via consumption of contaminated milk powder. To determine Cronobacter spp. contamination status, 632 samples, including 15 evaporated milk, 45 intermediate powder, 150 finished products, and 422 manufacturing environment samples, were collected from 3 goat milk powder factories in Shaanxi province, China, from July 2013 to April 2014. The recovered Cronobacter isolates were subtyped using pulsed-field gel electrophoresis to trace the potential dissemination routes during the whole production processing. Sixty-seven Cronobacter spp. isolates were recovered. The prevalence rates in manufacturing environment, intermediate powder, and finished products were 92.5, 6.0, and 1.5%, respectively. The predominant species were Cronobacter sakazakii (88.1%); no Cronobacter turicensis, Cronobacter condimenti, or Cronobacter dublinensis were detected. Sixty-seven Cronobacter isolates were grouped in 26 clusters by pulsed-field gel electrophoresis, and substantial genetic similarity was observed among isolates from different sampling sites in the same factory. Isolates in the main clusters were commonly recovered from intermediate powder, floor powder, and shoes. These data indicated that air, powder, and personnel movement were potential routes for Cronobacter dissemination, and manufacturing environment is the key control point for Cronobacter contamination.


Subject(s)
Cronobacter/classification , Cronobacter/isolation & purification , Food Contamination/analysis , Milk/microbiology , Animals , China , Cronobacter/growth & development , Electrophoresis, Gel, Pulsed-Field , Food Microbiology , Goats
15.
Foodborne Pathog Dis ; 12(3): 228-34, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25658910

ABSTRACT

ß-Lactamases and extended-spectrum ß-lactamases (ESBLs) producing pathogenic bacteria were widely studied previously in China, but were seldom focused on foodborne Salmonella. In this study, an investigation concerning ß-lactamases and ESBLs producing Salmonella recovered from retail raw chickens was performed. Sixty of 699 foodborne Salmonella isolates were detected as ß-lactamases and ESBLs-producing ones that covered 12 Salmonella serotypes and exhibited different pulsed-field gel electrophoresis genotypes. Forty-four of 60 ß-lactamases and ESBLs-producing strains were simultaneously resistant to ampicillin, amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, and cefoxitin. The most commonly detected ß-lactamases and ESBLs-encoding gene was bla(TEM-1) (n = 44), followed by bla(OXA-1) (n = 38), bla(CMY-2) (n = 29), bla(PSE-1-like) (n = 1), bla(CTX-M-3) (n = 16), and bla(CTX-M-15) (n = 1), respectively. Fourteen, 24, 21, and 1 isolates were detected simultaneously positive for 1, 2, 3, and 4 of the detected ß-lactamases and ESBLs-encoding genes, respectively. A Salmonella strain simultaneously co-carrying bla(TEM-1), bla(OXA-1), bla(CMY-2), and bla(CTX-M-3) was first reported in the present study. Amino acid substitution of Trp244Cys/His247Leu was detected in PSE-1, Val218Asp in CMY-2, and Asp242Gly in CTX-M-15 enzymes, respectively. A difference was found among the amino acid sequences of the detected OXA-1, CMY-2, CTX-M, PSE-1, and TEM-1. The results demonstrated that ß-lactamases and ESBLs were emerging and prevalent in foodborne Salmonella.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial/genetics , Meat/microbiology , Salmonella/isolation & purification , beta-Lactamases/genetics , Animals , Chickens , China , Electrophoresis, Gel, Pulsed-Field , Microbial Sensitivity Tests , Salmonella/genetics , Serogroup
16.
Zhonghua Yu Fang Yi Xue Za Zhi ; 49(8): 716-21, 2015 Aug.
Article in Zh | MEDLINE | ID: mdl-26733031

ABSTRACT

OBJECTIVE: To elucidate the epidemic condition and molecular subtyping of ciprofloxacin and cefotaxime co-resistant Salmonella Indiana (S. Indiana) isolated from retail chicken carcasses in six provinces of China. METHODS: A total of 2 647 Salmonella strains isolated from retail chicken carcasses collected from six provinces of China were subjected to antimicrobial susceptibility testing. All Salmonella isolates co-resistant to ciprofloxacin and cefotaxime were further characterized by serotyping, extended-spectrum beta-lactamases (ESBLs) producing strains screening and pulsed field gel electrophoresis (PFGE) typing. RESULTS: Among 2 629 Salmonella isolates tested, 227 (8.52%) isolates were co-resistant to ciprofloxacin and ceftazidime/cefotaxime (Beijing: 11.67% (99/874), Jilin: 8.20% (60/726), Guangdong: 1.39% (7/502), Jiangsu: 15.61% (42/260), Shaanxi: 8.56% (16/186), Inner Mongolia: 0 (0/81)), and 224 of them were identified as S. Indiana. 213 (95.10%) isolates of S. Indiana were ESBLs producing strains. All ciprofloxacin and cefotaxime co-resistant S. Indiana isolates developed a multi-drug resistant profile and 17.86% (40/224) of them were resistant to all antibiotics tested except carbapenems, and 50.89% (114/224) of them resistant to 9 antibiotics, additionally, 25.45% (57/224) of them showed multi-drug resistance to 8 antibiotics. All ciprofloxacin and cefotaxime co-resistant S. Indiana isolates were divided into 32 PFGE clusters and 150 PFGE patterns. Strains of S. Indiana from same or different sampling site and time seemed to either share the same PFGE patterns or be differential to each other in different regions. CONCLUSION: The results indicated that chicken carcasses collected from parts of China were heavily contaminated by ciprofloxacin and cefotaxime co-resistant S. Indiana and could serve as an important reservoir of ciprofloxacin and cefotaxime co-resistant Salmonella. Molecular subtyping results indicated that cross contamination or common pollution source might be in these strains.


Subject(s)
Food Contamination , Meat/microbiology , Salmonella/classification , Salmonella/isolation & purification , Animals , Anti-Bacterial Agents/pharmacology , Cefotaxime/pharmacology , Chickens/microbiology , China , Ciprofloxacin/pharmacology , Drug Resistance, Multiple, Bacterial , Electrophoresis, Gel, Pulsed-Field , Food Microbiology , Serotyping , beta-Lactamases
17.
Appl Environ Microbiol ; 80(19): 6204-11, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25085489

ABSTRACT

Punicalagin, an essential component of pomegranate rind, has been demonstrated to possess antimicrobial activity against several food-borne pathogens, but its activity on the virulence of pathogens and its anti-quorum-sensing (anti-QS) potential have been rarely reported. This study investigated the efficacy of subinhibitory concentrations of punicalagin on Salmonella virulence factors and QS systems. A broth microdilution method was used to determine the MICs of punicalagin for 10 Salmonella strains. Motility assay and quantitative reverse transcription (RT)-PCR were performed to evaluate the effects of punicalagin on the virulence attributes and QS-related genes of Salmonella. The MICs of punicalagin for several Salmonella strains ranged from 250 to 1,000 µg/ml. Motility assays showed that punicalagin, at 1/16× MIC and 1/32× MIC, significantly decreased bacterial swimming and swarming motility, which corresponded to downregulation of the motility-related genes (fliA, fliY, fljB, flhC, and fimD) in RT-PCR assays. RT-PCR also revealed that punicalagin downregulated the expression of most of the selected genes involved in Salmonella virulence. Moreover, a QS inhibition assay indicated that punicalagin dose dependently inhibited the production of violacein by Chromobacterium violaceum and repressed the expression of QS-related genes (sdiA and srgE) in Salmonella. In addition, punicalagin significantly reduced Salmonella invasion of colonic cells (P<0.01) with no impact on adhesion. These findings suggest that punicalagin has the potential to be developed as an alternative or supplemental agent for prevention of Salmonella infection.


Subject(s)
Anti-Bacterial Agents/pharmacology , Gene Expression Regulation, Bacterial/drug effects , Hydrolyzable Tannins/pharmacology , Quorum Sensing/drug effects , Salmonella typhimurium/drug effects , Bacterial Adhesion/drug effects , Bacterial Proteins/antagonists & inhibitors , Chromobacterium/drug effects , Chromobacterium/metabolism , Dose-Response Relationship, Drug , Down-Regulation , Indoles/metabolism , Microbial Sensitivity Tests , Salmonella typhimurium/pathogenicity , Salmonella typhimurium/physiology , Virulence/drug effects , Virulence Factors/antagonists & inhibitors
18.
Food Microbiol ; 42: 14-8, 2014 Sep.
Article in English | MEDLINE | ID: mdl-24929711

ABSTRACT

Extended-spectrum beta-lactamases (ESBL)-producing Salmonella enterica have been reported worldwide. However, research on foodborne ESBL-producing Salmonella has been rarely conducted. One hundred and thirty eight ceftriaxone or/and cefoperazone-resistant Salmonella strains recovered from retail foods in Shaanxi and Henan Province, China, were screened for ESBL. The ESBL-producing strains were further characterized for antimicrobial resistance, pulse field gel electrophoresis (PFGE) profiles, and the presence of blaTEM, blaSHV, blaOXA, blaCTX-M, and blaPSE. The transferability of ESBL encoding genes to a susceptible Escherichia coli strain was also investigated. Thirty (21.7%) isolates were identified as ESBL positive and belonged to S. enterica serovars Indiana, Shubra, Typhimurium, and Enteritidis. S. Indiana and S. Shubra isolates were firstly identified in ESBL-producing strains. Great genetic diversity was seen among these ESBL-producing strains. Nucleotide sequence analysis revealed that blaTEM-1B was the only ESBL-encoding gene among the genes tested and was detected in 26 of 30 strains and was carried in the conjugative plasmids. The blaTEM-1B gene was transferable through conjugation at rates ranging from 4.71 × 10(-7) to 7.55 × 10(-6) transconjugant per recipient cell. This study provides the evidence of foodborne ESBL-producing Salmonella, and the transferability of plasmid harboring ESBL-encoding genes could possibly contribute to the dissemination of ESBL.


Subject(s)
Bacterial Proteins/metabolism , Meat/microbiology , Salmonella/enzymology , Salmonella/isolation & purification , beta-Lactamases/metabolism , Animals , Bacterial Proteins/genetics , Cattle , Chickens , China , Conjugation, Genetic , Electrophoresis, Gel, Pulsed-Field , Fishes , Food Contamination/analysis , Gene Transfer, Horizontal , Microbial Sensitivity Tests , Molecular Sequence Data , Phylogeny , Plasmids/genetics , Plasmids/metabolism , Salmonella/classification , Salmonella/genetics , Swine , beta-Lactamases/genetics
19.
Foodborne Pathog Dis ; 11(4): 281-6, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24404781

ABSTRACT

The aims of this study were to evaluate the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in retail foods in Shaanxi, China and to investigate antimicrobial resistance and molecular characteristics of these strains. A total of 1979 retail food samples were randomly collected during 2008-2012 from supermarkets and farmers markets and screened for S. aureus, and then S. aureus isolates were further examined to determine whether they were MRSA. MRSA isolates were further characterized by antimicrobial susceptibility test, pulsed-field gel electrophoresis, spa typing, multilocus sequence typing, and SCCmec typing, and were examined for genes encoding enterotoxins, exfoliative toxins, Panton-Valentine leukocidin (pvl), and toxic shock syndrome toxin 1. Among all the samples examined, four (1.4%) raw milk samples, six (2.3%) chicken samples, one (0.6%) pork sample, three (0.6%) ready-to-eat food samples, and three (2.5%) dumpling samples were positive for MRSA. No MRSA isolates were recovered from infant foods. A total of 23 MRSA isolates were recovered from the 17 MRSA-positive samples. Antimicrobial susceptibility tests showed that, among these MRSA isolates, resistance was most frequently observed to penicillin, ampicillin, oxacillin, cefoxitin, and clindamycin (each 100%), followed by erythromycin (95.7%) and clarithromycin (87.0%). The commonly detected toxin genes were pvl, seg, seb, sed, followed by see, sec, and sei. Seven spa types (t189, t377, t437, t899, t10793, t5762, and a new spa type) and three SCCmec types (II, IVb, and V) were identified. More than half (52.2%) of the MRSA isolates belonged to ST9, followed by ST88, ST59, ST188, ST72, and ST630. Our findings indicate that MRSA in food could be from both animal and human origin. Although the prevalence is low, the presence of multidrug resistant and enterotoxigenic MRSA strains in foods poses a potential threat to consumers and emphasizes the need for better control of sources of contamination.


Subject(s)
Food Microbiology , Foodborne Diseases/microbiology , Meat/microbiology , Methicillin Resistance , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Staphylococcal Infections/microbiology , Animals , Anti-Bacterial Agents/pharmacology , Chickens , China/epidemiology , Electrophoresis, Gel, Pulsed-Field , Foodborne Diseases/epidemiology , Humans , Methicillin/pharmacology , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/genetics , Microbial Sensitivity Tests , Molecular Typing , Prevalence , Staphylococcal Infections/epidemiology , Swine
20.
Foodborne Pathog Dis ; 11(9): 698-705, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25188409

ABSTRACT

Four hundred sixty-two nalidixic acid- and/or ciprofloxacin-resistant Salmonella isolates were examined for presence of quinolone-resistance mechanisms. A total of 339 amino acid substitutions were identified in GyrA (204) and ParC (135). Ser83Phe/Asp87Gly (29.4%) were most commonly detected in GyrA in 136 isolates, and to a lesser extent of Asp87Asn (22.8%), Asp87Gly (19.1%), Ser83Phe/Asp87Asn (19.1%), and Ser83Tyr (5.1%). Ser80Arg (97.0%) was detected in ParC in 132 isolates. Simultaneous mutations in GyrA and ParC (n=109) were commonly detected to be Ser83Phe/Asp87Gly(GyrA)-Ser80Arg(ParC) (35.8%), Asp87Asn(GyrA)-Ser80Arg(ParC) (22.9%), and Ser83Phe/Asp87Asn(GyrA)-Ser80Arg(ParC) (21.1%). qnrA, qnrB, qnrS, aac(6')-Ib, qepA, and oqxAB were detected in 52 (11.3%), 64 (13.9%), 11(2.4%), 107 (23.2%), 6 (1.3%), and 194 (42.0%) of 462 isolates, respectively. Isolates carried more qnr, aac(6')-Ib, qepA, and oqxAB genes, and amino acid substitution in GyrA and ParC was more resistant to nalidixic acid and fluoroquinolones.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Poultry/microbiology , Salmonella Food Poisoning/microbiology , Salmonella/enzymology , Amino Acid Substitution , Animals , Chickens/microbiology , DNA Gyrase/genetics , DNA Topoisomerases/genetics , Drug Resistance, Bacterial , Electrophoresis, Gel, Pulsed-Field , Fluoroquinolones/pharmacology , Humans , Microbial Sensitivity Tests , Mutation , Nalidixic Acid/pharmacology , Quinolones/pharmacology , Salmonella/drug effects , Salmonella/genetics , Salmonella/isolation & purification
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