Serotype distribution and antimicrobial resistance of Salmonella isolates from retail chicken carcasses in six provinces of China / 中华预防医学杂志

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.

Molecular typing characterization of food-borne methicillin-resistant Staphylococcus aureus in China / 中华预防医学杂志

Objective@#To analyses the antimicrobial resistance and molecular characterization of 21 MRSA isolates cultured from retail foods from different provinces in China, and evaluate the molecular typing methods.@*Methods@#Twenty-one MRSA isolates were obtained from national foodborne pathogen surveillance network in 2012 (Chinese salad, n=3; milk, n=1; cake, n=2; rice, n=1; cold noodle, n=1; spiced beef, n=1; dumpling, n=1; packed meal, n=1; salad, n=1; raw pork, n=9). The antimicrobial resistance of 21 strains to 12 antimicrobial agents was tested by broth dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to obtain the genetic types of MLST (ST) and spa typing. The clonal complex (CC) was assigned by eBURST soft and the MLVA type (MT) and MLVA complex (MC) were identified via the database of the MLVA website (http://www.mlva.net). SmaI pulsed-field gel electrophoresis (SmaⅠ-PFGE) was also carried out to obtain the PFGE patterns of 21 strains. The genetic diversity and discriminatory power of typing were calculated by the Simpson's index of diversity (diversity index, DI) to find out the best genotyping method for MRSA.@*Results@#All MRSA isolates showed multi-drug resistance(MDR), and were resistant to oxacillin, benzylpenicillin, clindamycin and erythromycin, and 71.4% (15/21), 47.6% (10/21), 42.9% (9/21) and 28.6% (6/21) of the MRSA isolates were resistant to tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole and gentamicin, respectively. Moreover, one strain was found to be resistant to all three antimicrobials of levofloxacin, moxifloxacin and rifampicin. Great diversity was found in these food-associated MRSA (6 STs, 7 spa types, and 9 MTs). PFGE patterns were more diverse than those of other three molecular typing methods (19 pulse types). The index of diversity (DI) of PFGE, MLVA, spa typing and MLST was 0.99, 0.80, 0.73, and 0.61, respectively. Among the MRSA isolates, CC9-ST9-t899-MT929-MC2236 (PFGE Cluster Ⅴ) was the most prevalent clone, which were all cultured from raw pork (9 isolates). Besides, two MRSA were identified as CC59-ST338-t437-MT621-MC621 (PFGE Cluster Ⅳ). Different clone had their own resistance spectrum profiles.@*Conclusion@#The food-borne MRSA isolates were all MDR in this study. Different clones had their own resistance spectrum profiles. MLVA represented a promising tool for molecular epidemiology tracing of MRSA in foodborne disease events.

Antimicrobial susceptibility and drug-resistance genes of Yersinia spp. of retailed poultry in 4 provinces of China / 中华预防医学杂志

Objective@#To monitor the antimicrobial resistance and drug-resistance genes of Yersinia enterocolitis, Y. intermedia and Y. frederiksenii recovered from retailed fresh poultry of 4 provinces of China.@*Methods@#The susceptibility of 25 isolated Yersinia spp. to 14 classes and 25 kinds of antibiotics was determined by broth microdilution method according to CLSI (Clinical and Laboratory Standards Institute). The antibiotic resistance genes were predicted with antibiotic resistance genes database (ARDB) using whole genome sequences of Yersinia spp.@*Results@#In all 22 Y. enterocolitis tested, 63.7% (14 isolates), 22.8% (5 isolates), 4.6% and 4.6% of 1 isolates exhibited the resistance to cefoxitin, ampicillin-sulbactam, nitrofurantoin and trimethoprim-sulfamethoxazole, respectively. All the 25 isolates were multi-drug resistant to more than 3 antibiotics, while 64.0% of isolates were resistant to more than 4 antibiotics. A few Y. enterocolitis isolates of this study were intermediate to ceftriaxone and ciprofloxacin. Most Yersinia spp. isolates contained antibiotic resistance genes mdtG, ksgA, bacA, blaA, rosAB and acrB, and 5 isolates recovered from fresh chicken also contained dfrA1, catB2 and ant3ia.@*Conclusion@#The multi-drug resistant Yersinia spp. isolated from retailed fresh poultry is very serious in the 4 provinces of China, and their contained many kinds of drug-resistance genes.

The structure characteristics of prophages of foodborne Enterococcus hirae R17 and their interaction relationships with host bacterium / 中国食品卫生杂志

Objective This study was to understand the structure characteristics of prophages in the genome of Enterococcus hirae R17,and also to analyze their interaction relationships with the host bacterium.Methods The gene distribution and gene encoding characteristics of prophages in the genome of Enterococcus hirae R17 were identified using the PHAST software.The virulence gene,antimicrobial resistance genes,and environmental resistance genes in the prophages were also analyzed.Results Three prophages were found on the chromosome of Enterococcus hirae,including two incomplete prophage elements (Prophage-1 and Prophage-2) and one complete prophage (Prophage-3).Some function genes of bacteria were found in the sequence of three prophages,including nucleotide transportation and metabolism related genes.One incomplete prophage carrying erythromycin-and bacitracin-resistance genes was identified in the plasmid,which suggested that prophage induced gene horizontal transfer caused erythromycin-and bacitracin-resistance of Enterococcus hirae R17.Conclusion This study laid a solid foundation for the diversity analysis of prophages of Enterococcus hirae.Prophages played an important role in promotion of antimicrobial resistance of enterococci.Scientists should pay more attention to the spread of antimicrobial resistance and pathogenicity induced by prophages.

Diversified Functions and Regulation of Adipokine Visfatin / 生物化学与生物物理进展

Visfatin is a highly conserved protein expressed by visceral fat tissues that previously identified as pre B cell colony-enchancing factor (PBEF). Visfatin is a 52 ku cytokine and has been shown to exert multiple distinct biological activities. By interacting with insulin receptors, visfatin exhibits insulin mimicking or antagonizing effects under different circumstances. In addition, it possesses an nicotinamide phosphoribosyl transferase (Nampt) activity inside the cells, which functions at the rate-limiting step along the pathway of nicotinamide adenine dinucleotide (NAD) biosyntheses. And finally, as an extracellular cytokine, visfatin is able to induce the expression of inflammatory cytokines, such as TNF?, IL-1? and IL-6. Visfatin has drawn increasing attentions to researchers for its close association with a variety of human metabolic and acute/chronic inflammatory diseases or disorders, including diabetes, obesity, acute lung injury, rheumatoid arthritis, sepsis, myocardial infarction and inflammatory bowel disease. Recently, the SNP (single nucleotide polymorphism) analyses of visfatin and its promoter regions have provided more in-depth understandings of its roles in disease pathogenesis. A discussion in the current knowledge of the structure and diversified functions of visfatin, as well as its connections with a variety of common diseases was given.