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Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition.

Zilelidou EA, Rychli K, Manthou E, Ciolacu L, Wagner M, Skandamis PN - PLoS ONE (2015)

Bottom Line: Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell.In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures.Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece.

ABSTRACT
Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential.

No MeSH data available.


Related in: MedlinePlus

Cell-contact dependent growth competition of L. monocytogenes strains.L. monocytogenes strains (A) PL25-RifR and (B) ScottA-StrR were grown alone (single), mixed (contact) and in the presence of the second L. monocytogenes strain separated by a 0.4 μm membrane (no-contact) in TSB-Y for 10 days at 10°C. Data represented as log (CFU/ml) are mean values ± standard deviation of three biological replicates performed in duplicate. Different letters indicate statistically significant differences between single culture, contact and non-contact co-cultivation at the different time points (P<0.05).
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pone.0141617.g005: Cell-contact dependent growth competition of L. monocytogenes strains.L. monocytogenes strains (A) PL25-RifR and (B) ScottA-StrR were grown alone (single), mixed (contact) and in the presence of the second L. monocytogenes strain separated by a 0.4 μm membrane (no-contact) in TSB-Y for 10 days at 10°C. Data represented as log (CFU/ml) are mean values ± standard deviation of three biological replicates performed in duplicate. Different letters indicate statistically significant differences between single culture, contact and non-contact co-cultivation at the different time points (P<0.05).

Mentions: Growth of strain ScottA was significantly reduced in the presence of strain PL25 separated by a membrane at day 5, 7 and 10 compared to the single strain (Fig 5B). However, growth reduction was significantly higher when cell contact between the two strains was possible (log CFU/ml reduction of 2–2.7 versus 0.8–1.1).


Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition.

Zilelidou EA, Rychli K, Manthou E, Ciolacu L, Wagner M, Skandamis PN - PLoS ONE (2015)

Cell-contact dependent growth competition of L. monocytogenes strains.L. monocytogenes strains (A) PL25-RifR and (B) ScottA-StrR were grown alone (single), mixed (contact) and in the presence of the second L. monocytogenes strain separated by a 0.4 μm membrane (no-contact) in TSB-Y for 10 days at 10°C. Data represented as log (CFU/ml) are mean values ± standard deviation of three biological replicates performed in duplicate. Different letters indicate statistically significant differences between single culture, contact and non-contact co-cultivation at the different time points (P<0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4631365&req=5

pone.0141617.g005: Cell-contact dependent growth competition of L. monocytogenes strains.L. monocytogenes strains (A) PL25-RifR and (B) ScottA-StrR were grown alone (single), mixed (contact) and in the presence of the second L. monocytogenes strain separated by a 0.4 μm membrane (no-contact) in TSB-Y for 10 days at 10°C. Data represented as log (CFU/ml) are mean values ± standard deviation of three biological replicates performed in duplicate. Different letters indicate statistically significant differences between single culture, contact and non-contact co-cultivation at the different time points (P<0.05).
Mentions: Growth of strain ScottA was significantly reduced in the presence of strain PL25 separated by a membrane at day 5, 7 and 10 compared to the single strain (Fig 5B). However, growth reduction was significantly higher when cell contact between the two strains was possible (log CFU/ml reduction of 2–2.7 versus 0.8–1.1).

Bottom Line: Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell.In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures.Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece.

ABSTRACT
Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential.

No MeSH data available.


Related in: MedlinePlus