Naturally Occurring Motility-Defective Mutants of Salmonella enterica Serovar Enteritidis Isolated Preferentially from Nonhuman Rather than Human Sources

Yim, Lucía; Betancor, Laura; Martinez, Arací; Bryant, Clare E.; Maskell, Duncan J.; Chabalgoity, José A.

doi:10.1128/aem.05318-11

Cited by 20 publications

(19 citation statements)

References 46 publications

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“…The internalization of Salmonella in nonphagocytic cells is a highly coordinated event, mediated by flagella, fimbriae, and the SPI-1-encoded type III secretion system (34). Nonmotile mutant salmonellae have been reported to display reduced invasiveness in epithelial cells (35). In this sense, the reduction in the motility of VIM-2-producing S. Typhimurium might also account for the aforementioned loss of invasiveness.…”

Section: Discussionmentioning

confidence: 99%

Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

Cordeiro

Chabalgoity

Yim

et al. 2014

Antimicrob Agents Chemother

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Antibiotic resistance, especially due to ␤-lactamases, has become one of the main obstacles in the correct treatment of Salmonella infections; furthermore, antibiotic resistance determines a gain of function that may encompass a biological cost, or fitness reduction, to the resistant bacteria. The aim of this work was to determine in vitro if the production of the class B ␤-lactamase VIM-2 determined a fitness cost for Salmonella enterica serovar Typhimurium. To that end the gene bla VIM-2 was cloned into the virulent strain S. Typhimurium SL1344, using both the tightly regulated pBAD22 vector and the natural plasmid pST12, for inducible and constitutive expression, respectively. Fitness studies were performed by means of motility, growth rate, invasiveness in epithelial cells, and plasmid stability. The expression of bla VIM-2 was accompanied by alterations in micro-and macroscopic morphology and reduced growth rate and motility, as well as diminished invasiveness in epithelial cells. These results suggest that VIM-2 production entails a substantial fitness cost for S. Typhimurium, which in turn may account for the extremely low number of reports of metallo-␤-lactamase-producing Salmonella spp.

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Section: Discussionmentioning

confidence: 99%

Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

Cordeiro

Chabalgoity

Yim

et al. 2014

Antimicrob Agents Chemother

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“…For detection of flagella in live cells, we performed a previously described method using Alexa Fluor 594-carboxylic acid succinimidyl ester (Molecular Probes), an amino-specific fluorescent dye (37). Briefly, overnight cultures of bacteria grown in LB broth at 37°C and 200 rpm were diluted 1/100 in fresh medium and grown under the same conditions to mid-log phase (OD 600 ϭ 0.4 to 0.6).…”

Section: Methodsmentioning

confidence: 99%

“…Motility tests were performed as described by Yim et al (37). Briefly, 2 l of overnight culture grown in LB broth was spotted onto the surface of an LB plate containing 0.3% agar (semisolid agar) and incubated for 6 h at 37°C.…”

Section: Methodsmentioning

confidence: 99%

“…Briefly, overnight cultures of bacteria grown in LB broth at 37°C and 200 rpm were diluted 1/100 in fresh medium and grown under the same conditions to mid-log phase (OD 600 ϭ 0.4 to 0.6). The protocol was then followed exactly as described previously (37). The samples were visualized on an Olympus FV300 confocal laser scanning microscope with Fluoview software 4.3, a 100ϫ oil immersion objective (numerical aperture [NA] ϭ 1.35), and 543/610-nm excitation/emission wavelengths.…”

Section: Methodsmentioning

confidence: 99%

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Repression of Flagella Is a Common Trait in Field Isolates of Salmonella enterica Serovar Dublin and Is Associated with Invasive Human Infections

et al. 2014

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eThe nontyphoidal Salmonella enterica serovar Dublin is adapted to cattle but infrequently infects humans, very often resulting in invasive infections with high levels of morbidity and mortality. A Salmonella-induced intestinal acute inflammatory response is postulated as a mechanism to prevent bacterial dissemination to systemic sites. In S. enterica serovar Typhimurium, flagella contribute to this response by providing motility and FliC-mediated activation of pattern recognition receptors. In this study, we found 4 Salmonella enterica isolates, with the antigenic formula 9,12:؊:؊, that, based on fliC sequence and multilocus sequence type (MLST) analyses, are aflagellate S. Dublin isolates. Interestingly, all were obtained from human bloodstream infections. Thus, we investigated the potential role of flagella in the unusual invasiveness exhibited by S. Dublin in humans by analyzing flagellation and proinflammatory properties of a collection of 10 S. Dublin human clinical isolates. We found that 4 of 7 blood isolates were aflagellate due to significantly reduced levels of fliC expression, whereas all 3 isolates from other sources were flagellated. Lack of flagella correlated with a reduced ability of triggering interleukin-8 (IL-8) and CCL20 chemokine expression in human intestinal Caco-2 cells and with reduced early inflammation in the ceca of streptomycin-pretreated C57/BL6 mice. These results indicate that flagella contribute to the host intestinal inflammatory response to Salmonella serovar Dublin and suggest that their absence may contribute to its systemic dissemination through dampening of the gut immune response. Analysis of FliC production in a collection of cattle isolates indicated that the aflagellate phenotype is widely distributed in field isolates of S. Dublin.

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“…Mutation of the fliC gene together with motA mutation in S. Enteritidis impaired bacterial invasion severely but not adhesion (11). A comparison of several naturally occurring motA mutants of S. Enteritidis with nonflagellated mutant strains (fliC mutants) determined that they exhibit less invasiveness to Caco-2 cells (24). It was concluded that a strain with paralyzed flagella induced a higher proinflammatory response than a nonflagellated strain, suggesting that presence of paralyzed flagella is more effective than the absence of flagella (24).…”

Section: Figmentioning

confidence: 99%

Salmonella enterica Serovar Kentucky Flagella Are Required for Broiler Skin Adhesion and Caco-2 Cell Invasion

Salehi

Howe

Lawrence

et al. 2017

Appl Environ Microbiol

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Nontyphoidal Salmonella strains are the main source of pathogenic bacterial contamination in the poultry industry. Recently, Salmonella enterica serovar Kentucky has been recognized as the most prominent serovar on carcasses in poultry-processing plants. Previous studies showed that flagella are one of the main factors that contribute to bacterial attachment to broiler skin. However, the precise role of flagella and the mechanism of attachment are unknown. There are two different flagellar subunits (fliC and fljB) expressed alternatively in Salmonella enterica serovars using phase variation. Here, by making deletions in genes encoding flagellar structural subunits (flgK, fliC, and fljB), and flagellar motor (motA), we were able to differentiate the role of flagella and their rotary motion in the colonization of broiler skin and cellular attachment. Utilizing a broiler skin assay, we demonstrated that the presence of FliC is necessary for attachment to broiler skin. Expression of the alternative flagellar subunit FljB enables Salmonella motility, but this subunit is unable to mediate tight attachment. Deletion of the flgK gene prevents proper flagellar assembly, making Salmonella significantly less adherent to broiler skin than the wild type. S. Kentucky with deletions in all three structural genes, fliC, fljB, and flgK, as well as a flagellar motor mutant (motA), exhibited less adhesion and invasion of Caco-2 cells, while an fljB mutant was as adherent and invasive as the wild-type strain.IMPORTANCE In this work, we answered clearly the role of flagella in S. Kentucky attachment to the chicken skin and Caco-2 cells. We demonstrated that the presence of FliC is necessary for attachment to broiler skin. Expression of the alternative flagellar subunit FljB enables Salmonella motility, but this subunit is unable to mediate strong attachment. Deletion of the flgK gene prevents proper flagellar assembly, making Salmonella significantly less adherent to broiler skin than the wild type. S. Kentucky with deletions in all three structural genes, fliC, fljB, and flgK, as well as a flagellar motor mutant (motA), exhibited less adhesion and invasion of Caco-2 cells, while an fljB mutant was as adherent and invasive as the wild-type strain. We expect these results will contribute to the understanding of the mechanisms of Salmonella attachment to food products.

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Naturally Occurring Motility-Defective Mutants of Salmonella enterica Serovar Enteritidis Isolated Preferentially from Nonhuman Rather than Human Sources

Cited by 20 publications

References 46 publications

Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

Repression of Flagella Is a Common Trait in Field Isolates of Salmonella enterica Serovar Dublin and Is Associated with Invasive Human Infections

Salmonella enterica Serovar Kentucky Flagella Are Required for Broiler Skin Adhesion and Caco-2 Cell Invasion

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