Antimicrobial resistance and management of invasive Salmonella disease.

Salmonellosis continues to be a major public health problem worldwide. It also contributes to negative economic impacts due to the cost of surveillance investigation, treatment and prevention of illness. As such, research on Salmonella has gained great interest and concern from scientists. The purpose of this review is to discuss the classification and nomenclature, characteristic, clinical manifestation, epidemiology, transmission vehicles, antibiotic resistance and quorum sensing of Salmonella.

Salmonella: a foodborne pathogen

Prevalence and characterization of Salmonella species isolated from pigs, ducks and chickens in Sichuan Province, China.

Foodborne illnesses continue to have an economic impact on global health care systems. There is a growing concern regarding the increasing frequency of antibiotic resistance in foodborne bacterial pathogens and how such resistance may affect treatment outcomes. In an effort to better understand how to reduce the spread of resistance, many research studies have been conducted regarding the methods by which antibiotic resistance genes are mobilized and spread between bacteria. Transduction by bacteriophages is one of many horizontal gene transfer mechanisms, and recent findings have shown phage-mediated transduction to be a significant contributor to dissemination of antibiotic resistance genes. Here, we review the viability of transduction as a contributing factor to the dissemination of antibiotic resistance genes in foodborne pathogens of the Enterobacteriaceae family, including nontyphoidal Salmonella and Shiga toxin-producing Escherichia coli, as well as environmental factors that increase transduction of antibiotic resistance genes.

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Bacteriophages Contribute to the Spread of Antibiotic Resistance Genes among Foodborne Pathogens of the Enterobacteriaceae Family - A Review.

Role of antigens and virulence factors of Salmonella enterica serovar Typhi in its pathogenesis.

Prevalence and characterization of Salmonella serovars in retail meats of marketplace in Shaanxi, China

Mutations in gyrase and topoisomerase genes associated with fluoroquinolone resistance in Salmonella serovars from retail meats

Objective Salmonella isolates from retail food were examined for antimicrobial susceptibility and further characterized to better understand the development and dissemination of antimicrobial resistance among foodborne Salmonella in China. Methods Antimicrobial susceptibility of 359 Salmonella isolates was determined by using agar dilution methods recommended by the Clinical and Laboratory Standards Institute. Antimicrobial resistance integrons and resistance genes were identified using PCR. Mutations in gyrase and Topoisomerase genes related to fluoroquinolones resistance were also determined using PCR and gene sequencing analysis. Results Among the 359 Salmonellae isolates, 67% were resistant to Sulfamethoxazole, followed by resistant to trimethoprim/Sulfamethoxazole (58%), tetracycline (56%), kanamycin (37%), nalidixic acid (35%), ampicillin (33%), amoxicillin/clavulanic acid (32%), streptomycin (29%), chloramphenicol and gentamicin (26%), ciprofloxacin (21%), ceftriaxone (16%), cefoxitin (9%) and cefoperazone (8%). Among the 284 resistant isolates, 79% were resistant to at least one antimicrobial, 25.9% to 10 or more than 10 antimicrobials, and 2.5% to 14 antibiotic agents. Integrons were detected in some of sulfamethoxazole-ressitant Salmonella, and the most common integron was 1.4 kb, Antimicrobial resistance genes carried by integrons included aadA1, aadA2, aadA5, tetR, blaPSE1, blaDHA1, blaVEB-1, dhfr I, dhfr V, dhfrVl and dhfr17. The blaTEM gene was also detected in 51.6% of 62 ceftriaxone and/or cefoperazone resistant isolates, and blacMY-2 was detected in 56.5% of the isolates. 13.6% of the Salmonella isolates carried Salmonella Gene Island. Sixty-eight point mutations were detected in gyrA, parC and parE of 35 fluoroquinolone-resistant Salmonella isolates. The common mutations in gyrA gene were Ser83Phe, Ser83Tyr, Asp87Gly and Asp87Asn, whereas ser80Arg was detected in parC. Mutations including Lys441 Ile, Lys428Gln, Asp494Asn, Lys428Gln and Gly442Ser were detected in parE, which was first reported in Salmonella. Conclusion Antimicrobial resistance of Salmonella recovered from food in Shaanxi province was common. Several genetic elements including integron, Salmonella Gene Island, beta-lactamase genes and mutations in gyrase and topoisomerase genes played an important role in antimicrobial resistance of Salmonella.

Antimicrobial susceptibility and related genes of Salmonella serovars from retail food in Shaanxi province

The ongoing outbreak of the monkeypox, caused by monkeypox virus (MPXV), has been a public health emergency of international concern, indicating an urgent need for rapid and sensitive MPXV detection. Here, we designed a diagnostic test based on loop-mediated isothermal amplification (LAMP) and nanoparticle-based lateral flow biosensor(LFB)for diagnosis of MPXV infection, termed MPX-LAMP-LFB. A set of six LAMP primers was designed based the ATI gene of MPXV, and LAMP amplification of MPXV templates was performed at 63°C for only 40 min. The results were rapidly and visually decided using the LFB test within 2 min. The MPX-LAMP-LFB assay can specifically detect MPXV strains without cross-reaction with non-MPXV pathogens. The sensitivity of the MPX-LAMP-LFB assay is as low as 5 copies/μl of plasmid template and 12.5 copies/μl of pseudovirus in human blood samples. The whole process of the MPX-LAMP-LFB assay could be completed ~1 h, including rapid template preparation (15 min), LAMP reaction (40 min)and result reporting (<2 min). Collectively, MPX-LAMP-LFB assay developed here is a useful tool for rapid and reliable diagnosis of MPXV infection.

Loop-mediated isothermal amplification combined with lateral flow biosensor for rapid and sensitive detection of monkeypox virus

Sclerotinia sclerotiorum is a serious disease of oil crop. The P5CR gene is the first gene reported to be associated with resistance to Sclerotinia infection in soybeans, and its closest homologs are located on chromosomes A10 and C09 of Brassica napus. We named these BnP5CR1 and BnP5CR2, respectively. The purpose of this study was to examine the single-nucleotide polymorphism (SNP) and haplotype diversity (Hd) of BnP5CR2 among canola cultivars with different levels of resistance to S. sclerotiorum as well as the expression patterns of BnP5CR2 via an association analysis using resistant and susceptible cultivars of B. napus. The results can thus provide information for future research on the mechanisms of disease resistance to S. sclerotiorum and the breeding of resistant canola cultivars. A total of 95 and 12 polymorphic sites were detected in 1870 and 678 SNP sites in 16 BnP5CR2 and their coding DNA sequence (CDS) population, respectively. A total of six different haplotypes (H1–H6) were inferred from the 16 BnP5CR2 gene-CDS that contributed to the high level of polymorphism. Hd was equal to 0.617, and H1 shared by 10 cultivars was the dominant haplotype, suggesting that H1 is an ancient haplotype among the BnP5CR2 genes. H6 and H5 haplotpypes were present in Nan12R and ZhongYou821, respectively. The expression level in vitro of the BnP5CR2 between Nan12R and ZhongYou821 was significantly different. The upregulated expression of BnP5CR2 in resistant cultivars was higher than that of susceptible cultivars under 6 h, 12 h, 24 h, and 36 h treatments of pathogen stress, among which the expression level was significantly increased at 6 h, 12 h and 36 h in resistant cultivars, and the difference reached a highly significant level at 6 h (p < 0.01). The two cultivars with clear differences in expression features possessed different BnP5CR2 gene-CDS-haplotypes, indicating that gene-CDS-haplotype diversity may have greater power than SNPs for the detection of causal genes for quantitative traits.

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SNP and Haplotype Variability in the BnP5CR2 Gene and Association with Resistance and Susceptible Cultivars for Sclerotinia sclerotiorum in Brassica napus

Dong Qu

Papers

Prevalence and characterization of Salmonella serovars in retail meats of marketplace in Shaanxi, China

Mutations in gyrase and topoisomerase genes associated with fluoroquinolone resistance in Salmonella serovars from retail meats

Antimicrobial susceptibility and related genes of Salmonella serovars from retail food in Shaanxi province

Loop-mediated isothermal amplification combined with lateral flow biosensor for rapid and sensitive detection of monkeypox virus

SNP and Haplotype Variability in the BnP5CR2 Gene and Association with Resistance and Susceptible Cultivars for Sclerotinia sclerotiorum in Brassica napus