Nitric oxide and tnf-á induction by innate immune cells stimulated by Staphyloccocus aureus slime-positive and multi-resistant strains.

SILVIA DáVILA, VIRGINIA RIVERO, JULIO ARCE MIRANDA, MARIA GABRIELA PARAJE, LUCíA E. ALCARáZ, SARA SATORRES.

Encuentro; VI Congreso Argentino de Microbiología General.; 2009

Staphylococcus aureus is a well defined and more common coagulasepositive specie of the genus Staphylococcus being one of most significant pathogen for the human. Epithelial colonization by S. aureus is an important risk factor for infection by this organism in both community and hospital settings. The gradual increase of multi-resistant and methicillin-resistant S. aureus strains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegativeis a well defined and more common coagulasepositive specie of the genus Staphylococcus being one of most significant pathogen for the human. Epithelial colonization by S. aureus is an important risk factor for infection by this organism in both community and hospital settings. The gradual increase of multi-resistant and methicillin-resistant S. aureus strains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegativeStaphylococcus being one of most significant pathogen for the human. Epithelial colonization by S. aureus is an important risk factor for infection by this organism in both community and hospital settings. The gradual increase of multi-resistant and methicillin-resistant S. aureus strains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegativeS. aureus is an important risk factor for infection by this organism in both community and hospital settings. The gradual increase of multi-resistant and methicillin-resistant S. aureus strains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegativeS. aureus strains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegativestrains has complicated the therapeutic antibiotic for these infections. In addition, biofilm formation is considered to be a virulence factor because bacteria in biofilms are less accessible to antibiotics and immune defenses. In the present work, we analyzed the capacity of slime-positive or slimenegative S. aureus strains to stimulate the induction of nitric oxide (NO) by macrophages. Moreover, we analyzed the ability of multi-resistant and methicillin-resistant S. aureus strains to stimulate the induction NO and inflammatory cytokines in macrophages and epithelial cells. Sixteen clinical strains of S. aureus isolated from blood cultures and catheters of hospitalized patients were included in our study. Slime formation was detected by three methods that include tissue culture plate, tube method and Congo red agar. Antibiotic susceptibility was tested by the disc diffusion method (CLSI). Bacteria were incubated with RAW 264.7 or A549 cells and 48 hours later the production of NO and TNF-á was detected by the Griess’s technique and capture ELISA respectively. NO levels produced by macrophages incubated with slime-positive or slimenegativestrains to stimulate the induction of nitric oxide (NO) by macrophages. Moreover, we analyzed the ability of multi-resistant and methicillin-resistant S. aureus strains to stimulate the induction NO and inflammatory cytokines in macrophages and epithelial cells. Sixteen clinical strains of S. aureus isolated from blood cultures and catheters of hospitalized patients were included in our study. Slime formation was detected by three methods that include tissue culture plate, tube method and Congo red agar. Antibiotic susceptibility was tested by the disc diffusion method (CLSI). Bacteria were incubated with RAW 264.7 or A549 cells and 48 hours later the production of NO and TNF-á was detected by the Griess’s technique and capture ELISA respectively. NO levels produced by macrophages incubated with slime-positive or slimenegativeS. aureus strains to stimulate the induction NO and inflammatory cytokines in macrophages and epithelial cells. Sixteen clinical strains of S. aureus isolated from blood cultures and catheters of hospitalized patients were included in our study. Slime formation was detected by three methods that include tissue culture plate, tube method and Congo red agar. Antibiotic susceptibility was tested by the disc diffusion method (CLSI). Bacteria were incubated with RAW 264.7 or A549 cells and 48 hours later the production of NO and TNF-á was detected by the Griess’s technique and capture ELISA respectively. NO levels produced by macrophages incubated with slime-positive or slimenegativeS. aureus isolated from blood cultures and catheters of hospitalized patients were included in our study. Slime formation was detected by three methods that include tissue culture plate, tube method and Congo red agar. Antibiotic susceptibility was tested by the disc diffusion method (CLSI). Bacteria were incubated with RAW 264.7 or A549 cells and 48 hours later the production of NO and TNF-á was detected by the Griess’s technique and capture ELISA respectively. NO levels produced by macrophages incubated with slime-positive or slimenegativemethods that include tissue culture plate, tube method and Congo red agar. Antibiotic susceptibility was tested by the disc diffusion method (CLSI). Bacteria were incubated with RAW 264.7 or A549 cells and 48 hours later the production of NO and TNF-á was detected by the Griess’s technique and capture ELISA respectively. NO levels produced by macrophages incubated with slime-positive or slimenegative S. aureus strains did not demonstrate differences, indicating that discrimination of S. aureus based on the expression of this virulence factor did not correlate with a higher capability to activate immune cells. When we analyzed NO and TNF-á levels produced by macrophages or epithelial cells incubated with multi-resistant or methicillin-resistant S. aureus strains, we observed that these strains were poor inductors of NO and TNF-á (p<0.05). Our results show that multi-resistant and methicillin-resistant S. aureusstrains did not demonstrate differences, indicating that discrimination of S. aureus based on the expression of this virulence factor did not correlate with a higher capability to activate immune cells. When we analyzed NO and TNF-á levels produced by macrophages or epithelial cells incubated with multi-resistant or methicillin-resistant S. aureus strains, we observed that these strains were poor inductors of NO and TNF-á (p<0.05). Our results show that multi-resistant and methicillin-resistant S. aureusS. aureus based on the expression of this virulence factor did not correlate with a higher capability to activate immune cells. When we analyzed NO and TNF-á levels produced by macrophages or epithelial cells incubated with multi-resistant or methicillin-resistant S. aureus strains, we observed that these strains were poor inductors of NO and TNF-á (p<0.05). Our results show that multi-resistant and methicillin-resistant S. aureusS. aureus strains, we observed that these strains were poor inductors of NO and TNF-á (p<0.05). Our results show that multi-resistant and methicillin-resistant S. aureusS. aureus strains have reduced ability to activate innate immune cells, fact that may be related to their high virulence.