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Differential Role of the T6SS in Acinetobacter baumannii Virulence.

Repizo GD, Gagné S, Foucault-Grunenwald ML, Borges V, Charpentier X, Limansky AS, Gomes JP, Viale AM, Salcedo SP - PLoS ONE (2015)

Bottom Line: The T6SS genomic locus is present and was actively transcribed in all of the above strains.In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections.Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.

View Article: PubMed Central - PubMed

Affiliation: Bases Moléculaires et Structurales des Systèmes Infectieux, CNRS UMR 5086, Université Lyon 1, Institut de Biologie et Chimie des Protéines, Lyon, France.

ABSTRACT
Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR) strains. Herein, we compared a type strain (ATCC17978), a non-clinical isolate (DSM30011) and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825), revealing distinct patterns of type VI secretion system (T6SS) functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.

No MeSH data available.


Related in: MedlinePlus

Competition between A. baumannii species.A) Survival of tetracycline-resistant (TcR) ATCC17978-CTX1 strain after incubation in growth medium (control) or with the DSM30011 wild type, tssM deleted or complemented strains at 1:1 (left panel) or 10:1 (right panel) ratios and B) corresponding quantification (N = 4).
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pone.0138265.g004: Competition between A. baumannii species.A) Survival of tetracycline-resistant (TcR) ATCC17978-CTX1 strain after incubation in growth medium (control) or with the DSM30011 wild type, tssM deleted or complemented strains at 1:1 (left panel) or 10:1 (right panel) ratios and B) corresponding quantification (N = 4).

Mentions: It has recently been shown that different V. cholerae strains can out-compete each other in a T6SS-dependent manner [27]. When bacteria from DSM30011 and ATCC17978 strains were co-incubated (1:1 ratio), we observed a reduction in CFU counts for the tetracyclin-resistant prey ATCC17978. This tendency increased when the strains were mixed in a 10:1 ratio (Fig 4A and 4B). This decrease was not observed with the DSM30011 ΔtssM deficient strain but restored in the complemented tssM strain (Fig 4A and 4B), showing that DSM30011 is able to use its T6SS to kill ATCC17978. When the attacker and prey were switched and mixed in a 10:1 ratio, a decrease was observed for the gentamicin-resistant DSM30011 prey when mixed with the wild type or ΔtssM ATCC17978 strain (S3 Fig), indicating that ATCC17978 is able to outcompete the DSM30011 strain by a T6SS-independent mechanism, as observed for E. coli (Fig 3A and 3B).


Differential Role of the T6SS in Acinetobacter baumannii Virulence.

Repizo GD, Gagné S, Foucault-Grunenwald ML, Borges V, Charpentier X, Limansky AS, Gomes JP, Viale AM, Salcedo SP - PLoS ONE (2015)

Competition between A. baumannii species.A) Survival of tetracycline-resistant (TcR) ATCC17978-CTX1 strain after incubation in growth medium (control) or with the DSM30011 wild type, tssM deleted or complemented strains at 1:1 (left panel) or 10:1 (right panel) ratios and B) corresponding quantification (N = 4).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581634&req=5

pone.0138265.g004: Competition between A. baumannii species.A) Survival of tetracycline-resistant (TcR) ATCC17978-CTX1 strain after incubation in growth medium (control) or with the DSM30011 wild type, tssM deleted or complemented strains at 1:1 (left panel) or 10:1 (right panel) ratios and B) corresponding quantification (N = 4).
Mentions: It has recently been shown that different V. cholerae strains can out-compete each other in a T6SS-dependent manner [27]. When bacteria from DSM30011 and ATCC17978 strains were co-incubated (1:1 ratio), we observed a reduction in CFU counts for the tetracyclin-resistant prey ATCC17978. This tendency increased when the strains were mixed in a 10:1 ratio (Fig 4A and 4B). This decrease was not observed with the DSM30011 ΔtssM deficient strain but restored in the complemented tssM strain (Fig 4A and 4B), showing that DSM30011 is able to use its T6SS to kill ATCC17978. When the attacker and prey were switched and mixed in a 10:1 ratio, a decrease was observed for the gentamicin-resistant DSM30011 prey when mixed with the wild type or ΔtssM ATCC17978 strain (S3 Fig), indicating that ATCC17978 is able to outcompete the DSM30011 strain by a T6SS-independent mechanism, as observed for E. coli (Fig 3A and 3B).

Bottom Line: The T6SS genomic locus is present and was actively transcribed in all of the above strains.In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections.Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.

View Article: PubMed Central - PubMed

Affiliation: Bases Moléculaires et Structurales des Systèmes Infectieux, CNRS UMR 5086, Université Lyon 1, Institut de Biologie et Chimie des Protéines, Lyon, France.

ABSTRACT
Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR) strains. Herein, we compared a type strain (ATCC17978), a non-clinical isolate (DSM30011) and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825), revealing distinct patterns of type VI secretion system (T6SS) functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner.

No MeSH data available.


Related in: MedlinePlus