Salmonella Serovar Identification Using PCR-Based Detection of Gene Presence and Absence

Abstract

There are more than 2,500 known Salmonella serovars, and some of these can be further subclassified into groups of strains that differ profoundly in their gene content. We refer to these groups of strains as "genovars." A compilation of comparative genomic hybridization data on 291 Salmonella isolates, including 250 S. enterica subspecies I strains from 32 serovars (52 genovars), was used to select a panel of 384 genes whose presence and absence among serovars and genovars was of potential taxonomic value. A subset of 146 genes was used for real-time PCR to successfully identify 12 serovars (16 genovars) in 24 S. enterica strains. A further subset of 64 genes was used to identify 8 serovars (9 genovars) in 12 multiplex PCR mixes on 11 S. enterica strains. These gene panels distinguish all tested S. enterica subspecies I serovars and their known genovars, almost all by two or more informative markers. Thus, a typing methodology based on these predictive genes would generally alert users if there is an error, an unexpected polymorphism, or a potential new genovar.

Protection of Salmonella by ampicillin-resistant Escherichia coli in the presence of otherwise lethal drug concentrations

“…In this study, we examined the possibility that ampicillin-resistant E. coli, gram-negative bacteria that were engineered to secrete b-lactamase into their medium (Dugatkin et al 2005a;Clark et al 2009), might benefit ampicillin-sensitive cohorts of other species, especially species that could cause human disease. Salmonella enterica serovar Typhimurium is a causative agent of salmonellosis (Arrach et al 2008). Most persons infected with this organism develop diarrhoea, fever, vomiting and abdominal cramps 12 -72 h after infection.…”

High-Throughput Molecular Determination of Salmonella enterica Serovars by Use of Multiplex PCR and Capillary Electrophoresis Analysis

“…In other cases, some serovars have been shown to be highly similar genetically, which suggests that a "genovar" classification be adopted, based upon genetic relatedness. It is also proposed that genovar classification may be more appropriate than serovar classification (4,39).…”

Development of Microarray and Multiplex Polymerase Chain Reaction Assays for Identification of Serovars and Virulence Genes in Salmonella Enterica of Human or Animal Origin

“…previous multiplex PCR study 2 noted that some target DNA may not be amplified because of intraserovar variation at the primer binding regions, which could lead to the compiling of false-amplicon codes. In the present study, the 95.3% concordance of multiplex PCR and microarray suggests that such mutations may not significantly affect the effectiveness of multiplex PCR to determine the serovar of a Salmonella isolate.…”

“…In the past, multiplex PCR assays were limited to identifying a small number of serovars, and these assays did not attempt to predict the overall pathogenicity of Salmonella isolates. 2,7,26,46 A recent study 27 described a multiplex PCR procedure consisting of 2 multiplex PCR panels for determining 30 clinically relevant serovars of Salmonella. The objective of the present study was to increase the number of serovars identified using the multiplex procedure and to develop an additional multiplex PCR panel called Salmonella Typing Virulence (STV) that determines the presence or absence of the genes spvC, invA, and sseL to allow researchers to predict the overall pathogenicity, invasiveness, and replication ability of the Salmonella isolates, respectively.…”