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Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources.

ABSTRACT: Salmonellosis represents a worldwide health problem because it is one of the major causes of food-borne disease. Although motility is postulated as an important Salmonella virulence attribute, there is little information about variation in motility in natural isolates. Here we report the identification of a point mutation (T551 ? G) in motA, a gene essential for flagellar rotation, in several Salmonella enterica serovar Enteritidis field isolates. This mutation results in bacteria that can biosynthesize structurally normal but paralyzed flagella and are impaired in their capacity to invade human intestinal epithelial cells. Introduction of a wild-type copy of motA into one of these isolates restored both motility and cell invasiveness. The motA mutant triggered higher proinflammatory transcriptional responses than an aflagellate isolate in differentiated Caco-2 cells, suggesting that the paralyzed flagella are able to signal through pattern recognition receptors. A specific PCR was designed to screen for the T551 ? G mutation in a collection of 266 S. Enteritidis field isolates from a nationwide epidemic, comprising 194 from humans and 72 from other sources. We found that 72 of the 266 (27%) isolates were nonmotile, including 24.7% (48/194) of human and 33.3% (24/72) of food isolates. Among nonmotile isolates, 15 carried the T551 ? G mutation and, significantly, 13 were recovered from food, including 7 from eggs, but only 2 were from human sources. These results suggest that the presence of paralyzed flagella may impair the ability of S. Enteritidis to cause disease in the human host but does not prevent its ability to colonize chickens and infect eggs.

SUBMITTER: Yim L

PROVIDER: S-EPMC3209157 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources.

Yim Lucía L Betancor Laura L Martínez Arací A Bryant Clare C Maskell Duncan D Chabalgoity José A JA

Applied and environmental microbiology 20110916 21

Salmonellosis represents a worldwide health problem because it is one of the major causes of food-borne disease. Although motility is postulated as an important Salmonella virulence attribute, there is little information about variation in motility in natural isolates. Here we report the identification of a point mutation (T551 → G) in motA, a gene essential for flagellar rotation, in several Salmonella enterica serovar Enteritidis field isolates. This mutation results in bacteria that can biosy ...[more]

PMID: 21926214

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Project description:Salmonella enterica serovar Enteritidis has emerged as a significant foodborne pathogen throughout the world and is commonly characterized by phage typing. In Canada phage types (PT) 4, 8 and 13 predominate and in 2005 a large foodborne PT13 outbreak occurred in the province of Ontario. The ability to link strains during this outbreak was difficult due to the apparent clonality of PT13 isolates in Canada, as there was a single dominant pulsed-field gel electrophoresis (PFGE) profile amongst epidemiologically linked human and food isolates as well as concurrent sporadic strains. The aim of this study was to perform comparative genomic hybridization (CGH), DNA sequence-based typing (SBT) genomic analyses, plasmid analyses, and automated repetitive sequence-based PCR (rep-PCR) to identify epidemiologically significant traits capable of subtyping S. Enteritidis PT13.CGH using an oligonucleotide array based upon chromosomal coding sequences of S. enterica serovar Typhimurium strain LT2 and the Salmonella genomic island 1 successfully determined major genetic differences between S. Typhimurium and S. Enteritidis PT13, but no significant strain-to-strain differences were observed between S. Enteritidis PT13 isolates. Individual loci (safA and fliC) that were identified as potentially divergent in the CGH data set were sequenced in a panel of S. Enteritidis strains, and no differences were detected between the PT13 strains. Additional sequence-based typing was performed at the fimA, mdh, manB, cyaA, citT, caiC, dmsA, ratA and STM0660 loci. Similarly, no diversity was observed amongst PT13 strains. Variation in plasmid content between PT13 strains was observed, but macrorestriction with BglII did not identify further differences. Automated rep-PCR patterns were variable between serovars, but S. Enteritidis PT13 strains could not be differentiated.None of the methods identified any significant variation between PT13 strains. Greater than 11,300 base pairs of sequence for each of seven S. Enteritidis PT13 strains were analyzed without detecting a single polymorphic site, although diversity between different phage types of S. Enteritidis was observed. These data suggest that Canadian S. Enteritidis PT13 strains are highly related genetically.

Dataset Information

Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources.

Publications

Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources.

Similar Datasets

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