Limits...
Streptococcus pneumoniae Eradicates Preformed Staphylococcus aureus Biofilms through a Mechanism Requiring Physical Contact

View Article: PubMed Central - PubMed

ABSTRACT

Staphylococcus aureus (Sau) strains are a main cause of disease, including nosocomial infections which have been linked to the production of biofilms and the propagation of antibiotic resistance strains such as methicillin-resistant Staphylococcus aureus (MRSA). A previous study found that Streptococcus pneumoniae (Spn) strains kill planktonic cultures of Sau strains. In this work, we have further evaluated in detail the eradication of Sau biofilms and investigated ultrastructural interactions of the biofilmicidal effect. Spn strain D39, which produces the competence stimulating peptide 1 (CSP1), reduced Sau biofilms within 8 h of inoculation, while TIGR4, producing CSP2, eradicated Sau biofilms and planktonic cells within 4 h. Differences were not attributed to pherotypes as other Spn strains producing different pheromones eradicated Sau within 4 h. Experiments using Transwell devices, which physically separated both species growing in the same well, demonstrated that direct contact between Spn and Sau was required to efficiently eradicate Sau biofilms and biofilm-released planktonic cells. Physical contact-mediated killing of Sau was not related to production of hydrogen peroxide as an isogenic TIGR4ΔspxB mutant eradicated Sau bacteria within 4 h. Confocal micrographs confirmed eradication of Sau biofilms by TIGR4 and allowed us to visualize ultrastructural point of contacts between Sau and Spn. A time-course study further demonstrated spatial colocalization of Spn chains and Sau tetrads as early as 30 min post-inoculation (Pearson's coefficient >0.72). Finally, precolonized biofilms produced by Sau strain Newman, or MRSA strain USA300, were eradicated by mid-log phase cultures of washed TIGR4 bacteria within 2 h post-inoculation. In conclusion, Spn strains rapidly eradicate pre-colonized Sau aureus biofilms, including those formed by MRSA strains, by a mechanism(s) requiring bacterium-bacterium contact, but independent from the production of hydrogen peroxide.

No MeSH data available.


Related in: MedlinePlus

Spn D39 reduces the population of Sau biofilms. Sau was inoculated alone (Sau) or with Spn strain D39 (Sau+Spn) in abiotic polystyrene plates (A,C) or human pharyngeal cells (B,D). Plates were incubated for 4 or 8 h at 37°C. Planktonic cells were removed, biofilms were harvested, diluted and then plated onto salt mannitol agar plates to obtain Sau biofilm counts (cfu/ml) or blood agar plates with gentamicin to obtain Spn biofilm counts (cfu/ml). Error bars represent the standard errors of the means, calculated using data from at least three independent experiments. *statistical significance (p < 0.05) in comparison to wells inoculated only with Sau.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037180&req=5

Figure 1: Spn D39 reduces the population of Sau biofilms. Sau was inoculated alone (Sau) or with Spn strain D39 (Sau+Spn) in abiotic polystyrene plates (A,C) or human pharyngeal cells (B,D). Plates were incubated for 4 or 8 h at 37°C. Planktonic cells were removed, biofilms were harvested, diluted and then plated onto salt mannitol agar plates to obtain Sau biofilm counts (cfu/ml) or blood agar plates with gentamicin to obtain Spn biofilm counts (cfu/ml). Error bars represent the standard errors of the means, calculated using data from at least three independent experiments. *statistical significance (p < 0.05) in comparison to wells inoculated only with Sau.

Mentions: Since epidemiological reports have suggested a negative association between Sau and Spn for nasopharyngeal colonization, we assessed populations of biofilm cells when strains where co-incubated on abiotic surfaces or cultures of human pharyngeal cells. This study showed similar counts of Sau biofilms attached to abiotic surfaces, or pharyngeal cells, whether incubated alone or with Spn strain D39 for 4 h (Figures 1A,B). However, Sau biofilms were significantly reduced, but not eradicated (i.e., completely killed), 8 h post-inoculation (p = 0.03) in wells inoculated along with D39 (Figures 1A,B). Bacterial counts of Spn biofilms did not change whether incubated alone or with Sau at 4 or 8 h post-inoculation (Figures 1C,D). A non-statistically significant decrease of Spn biomass was observed, however, when incubated with Sau at 4 or 8 h post-inoculation of abiotic or human cells, respectively.


Streptococcus pneumoniae Eradicates Preformed Staphylococcus aureus Biofilms through a Mechanism Requiring Physical Contact
Spn D39 reduces the population of Sau biofilms. Sau was inoculated alone (Sau) or with Spn strain D39 (Sau+Spn) in abiotic polystyrene plates (A,C) or human pharyngeal cells (B,D). Plates were incubated for 4 or 8 h at 37°C. Planktonic cells were removed, biofilms were harvested, diluted and then plated onto salt mannitol agar plates to obtain Sau biofilm counts (cfu/ml) or blood agar plates with gentamicin to obtain Spn biofilm counts (cfu/ml). Error bars represent the standard errors of the means, calculated using data from at least three independent experiments. *statistical significance (p < 0.05) in comparison to wells inoculated only with Sau.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037180&req=5

Figure 1: Spn D39 reduces the population of Sau biofilms. Sau was inoculated alone (Sau) or with Spn strain D39 (Sau+Spn) in abiotic polystyrene plates (A,C) or human pharyngeal cells (B,D). Plates were incubated for 4 or 8 h at 37°C. Planktonic cells were removed, biofilms were harvested, diluted and then plated onto salt mannitol agar plates to obtain Sau biofilm counts (cfu/ml) or blood agar plates with gentamicin to obtain Spn biofilm counts (cfu/ml). Error bars represent the standard errors of the means, calculated using data from at least three independent experiments. *statistical significance (p < 0.05) in comparison to wells inoculated only with Sau.
Mentions: Since epidemiological reports have suggested a negative association between Sau and Spn for nasopharyngeal colonization, we assessed populations of biofilm cells when strains where co-incubated on abiotic surfaces or cultures of human pharyngeal cells. This study showed similar counts of Sau biofilms attached to abiotic surfaces, or pharyngeal cells, whether incubated alone or with Spn strain D39 for 4 h (Figures 1A,B). However, Sau biofilms were significantly reduced, but not eradicated (i.e., completely killed), 8 h post-inoculation (p = 0.03) in wells inoculated along with D39 (Figures 1A,B). Bacterial counts of Spn biofilms did not change whether incubated alone or with Sau at 4 or 8 h post-inoculation (Figures 1C,D). A non-statistically significant decrease of Spn biomass was observed, however, when incubated with Sau at 4 or 8 h post-inoculation of abiotic or human cells, respectively.

View Article: PubMed Central - PubMed

ABSTRACT

Staphylococcus aureus (Sau) strains are a main cause of disease, including nosocomial infections which have been linked to the production of biofilms and the propagation of antibiotic resistance strains such as methicillin-resistant Staphylococcus aureus (MRSA). A previous study found that Streptococcus pneumoniae (Spn) strains kill planktonic cultures of Sau strains. In this work, we have further evaluated in detail the eradication of Sau biofilms and investigated ultrastructural interactions of the biofilmicidal effect. Spn strain D39, which produces the competence stimulating peptide 1 (CSP1), reduced Sau biofilms within 8 h of inoculation, while TIGR4, producing CSP2, eradicated Sau biofilms and planktonic cells within 4 h. Differences were not attributed to pherotypes as other Spn strains producing different pheromones eradicated Sau within 4 h. Experiments using Transwell devices, which physically separated both species growing in the same well, demonstrated that direct contact between Spn and Sau was required to efficiently eradicate Sau biofilms and biofilm-released planktonic cells. Physical contact-mediated killing of Sau was not related to production of hydrogen peroxide as an isogenic TIGR4&Delta;spxB mutant eradicated Sau bacteria within 4 h. Confocal micrographs confirmed eradication of Sau biofilms by TIGR4 and allowed us to visualize ultrastructural point of contacts between Sau and Spn. A time-course study further demonstrated spatial colocalization of Spn chains and Sau tetrads as early as 30 min post-inoculation (Pearson's coefficient &gt;0.72). Finally, precolonized biofilms produced by Sau strain Newman, or MRSA strain USA300, were eradicated by mid-log phase cultures of washed TIGR4 bacteria within 2 h post-inoculation. In conclusion, Spn strains rapidly eradicate pre-colonized Sau aureus biofilms, including those formed by MRSA strains, by a mechanism(s) requiring bacterium-bacterium contact, but independent from the production of hydrogen peroxide.

No MeSH data available.


Related in: MedlinePlus