Salmonella typing in New South Wales: current methods and application of improved epidemiological tools.
ABSTRACT Salmonellosis caused by enteropathogens of the genus Salmonella is a major public health concern in Australia. Serotyping is usually performed in enteric reference laboratories for the initial characterisation and differentiation of Salmonella species. Further strain identification within serovars may be achieved by phage typing and this is used as an epidemiological tool for outbreak investigations. Phage typing has limited discriminatory ability and the necessity of sending specimens interstate from NSW for this test causes delays in recognising outbreaks and reduces the likelihood of identifying the source. Multilocus variable-number tandem-repeat analysis has a high discriminatory power and faster turnaround time, and is the method of choice for outbreak investigation. Additionally, a newly developed multiplex PCR-based reverse line blot hybridisation system is able to identify most of the phage types prevalent in NSW. Combining these last two molecular methods will significantly enhance outbreak investigations and surveillance of Salmonella infections in NSW.
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- "There are many methods for genotyping of Salmonella, and polymerase chain reaction (PCR)-based typing methods are very prevalent. A multiplex PCR-based reverse line blot hybridization system can enhance outbreak investigations and surveillance of Salmonella infections (5). Recently, real-time PCR-based single nucleotide polymorphism typing method has been used for global epidemiological analysis of S. Typhi (6). "
ABSTRACT: To determine the genotype of Salmonella enterica serovar Typhi (S. Typhi) strains in China and analyze their genetic diversity. We collected S. Typhi strains from 1959 to 2006 in five highly endemic Chinese provinces and chose 40 representative strains. Multilocus sequence typing was used to determine the genotypes or sequence types (ST) and microarray-based comparative genomic hybridization (M-CGH) to investigate the differences in gene content among these strains. Forty representative S. Typhi strains belonged to 4 sequence types (ST1, ST2, ST890, and ST892). The predominant S. Typhi genotype (31/40) was ST2 and it had a diverse geographic distribution. We discovered two novel STs - ST890 and ST892. M-CGH showed that 69 genes in these two novel STs were divergent from S. Typhi Ty2, which belongs to ST1. In addition, 5 representative Typhi strains of ST2 isolated from Guizhou province showed differences in divergent genes. We determined two novel sequence types, ST890 and ST892, and found that ST2 was the most prevalent genotype of S. Typhi in China. Genetic diversity was present even within a highly clonal bacterial population.Croatian Medical Journal 12/2011; 52(6):688-93. DOI:10.3325/cmj.2011.52.688 · 1.31 Impact Factor
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- "Phage typing is done by using an internationally recognized set of phages to identify the bacteria. According to Wang et al. (2008), Salmonella Typhimurium with a set of 34 phages allows the identification of 207 phage types. Deoxyribonucleic acid fingerprinting techniques for distinguishing bacterial isolates have been shown to be fast, sensitive, specific, highly reproducible, and less labor-intensive than conventional methodologies (Whyte et al., 2002; Oliveira et al., 2003). "
ABSTRACT: The current study was conducted to determine the usefulness of 2 molecular techniques, automated repetitive extragenic palindromic-PCR (REP-PCR) and denaturing gradient gel electrophoresis (DGGE), to identify Salmonella serotypes of poultry origin. Salmonella continues to be a foodborne pathogen of principal concern in the United States. The interspersed conserved repetitive sequence of the bacterial genome and the 16-23S rDNA intergenic spacer region were amplified for REP-PCR and DGGE, respectively. Fifty-four Salmonella isolates from 2 turkey processing plants (A and B) were used for this comparison. Serotypes consisted of Brandenburg, Derby, Hadar, and Typhimurium, with n=6, 21, 12, and 15, respectively. The REP-PCR was fully automated, whereas DGGE was run on an acrylamide gel and the image was captured digitally. Both dendrograms were created using the unweighted pair group method with arithmetic average. There were more variations in percentage similarity in DGGE when compared with REP-PCR. The banding patterns were more distinct and uniform in the REP-PCR group than with DGGE. The results from the REP-PCR were generated within 1 h, whereas the DGGE required approximately 1 d to run. These data suggest that DGGE and REP-PCR are useful tools for identifying Salmonella serotypes isolated from poultry production or processing environments. In addition, REP-PCR is more rapid, may have a higher discriminatory power, but may be less cost-effective than DGGE. However, more research may be needed to validate this argument. Both DGGE and REP-PCR displayed high sensitivity in discriminating among Salmonella serotypes and either method could be considered as an alternative to more expensive and time-consuming conventional antibody-based serotyping methodologies.Poultry Science 06/2010; 89(6):1293-300. DOI:10.3382/ps.2009-00390 · 1.67 Impact Factor
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ABSTRACT: form only given. We establish the feasibility of using incoherent inelastic neutron scattering from stretch-oriented conjugated polymers films to obtain both polarization and energy information about the low-frequency modes: interchain phonons and librons, intrachain torsional motions, ring-librations. The polarized densities of states of low-frequency modes of polyacetylene [cis- and trans-(CH)/sub x/,, and Na-doped (CH)/sub x/] have been obtained. To assign the different features of the density of states and the changes upon doping, the neutron investigation is combined with molecular dynamics simulations. For instance, in polyacetylene, the out-of-phase translation of the two chains of the primitive cell (longitudinal optical phonon mode) has been identified at 12 cm/sup -1/ in cis-(CH)/sub x/, and 32 cm/sup -1/ in trans (CH)/sub x/, and the dorninent features of the density of states, at 120 cm/sup -1/ in cis-(CH)/sub x/ and 170 cm/sup -1/l in trans-(CH)/sub x/, are assigned to intramolecular torsional motions (transverse modes). Upon doping, marked changes in the density of states are observed, a broad minimum appearing at 130 cm/sup -1/, in the spectral region dominated by intramolecular torsional displacements. Incoherent neutron scattering experiments in polyanifine and poly(p-phenylenevinylene) provide, for the first time, important insight into the dynamics of phenyl-ring librations. These modes are identified and their temperature dependencies are studied.