Role of Staphylococcus aureus Catalase in Niche Competition against Streptococcus pneumoniae

Abstract

Nasal colonization by Staphylococcus aureus is a major predisposing factor for subsequent infection. Recent reports of increased S. aureus colonization among children receiving pneumococcal vaccine implicate Streptococcus pneumoniae as an important competitor for the same niche. Since S. pneumoniae uses H 2 O 2 to kill competing bacteria, we hypothesized that oxidant defense could play a significant role in promoting S. aureus colonization of the nasal mucosa. Using targeted mutagenesis, we showed that S. aureus expression of catalase contributes significantly to the survival of this pathogen in the presence of S. pneumoniae both in vitro and in a murine model of nasal cocolonization.Staphylococcus aureus causes a wide range of infections ranging from minor skin infections to life-threatening invasive diseases. The emergence of methicillin-resistant strains with high virulence potential in both hospital and community settings is contributing to a current public health crisis (9, 12, 13).A major risk factor for S. aureus infection is antecedent colonization of the nasal mucosa (19). Successful colonization depends not only on the ability of S. aureus to survive host factors (4, 6) but also on coexistence with other bacteria (16,21).The latter concept has been underscored by two recent reports that implicate Streptococcus pneumoniae as a primary competitor for niche colonization (3,15).Specifically, one surveillance study performed in an area where pneumococcal vaccination was not practiced showed that the S. pneumoniae carriage rate in children was negatively associated with S. aureus nasal carriage (15). The other study showed that children with recurrent otitis media vaccinated with the 7-valent pneumococcal vaccine had an increased incidence of S. aureus-related acute otitis media and S. aureus colonization after vaccination (3), suggesting that there is a natural competition for colonization between S. aureus and S. pneumoniae.S. pneumoniae produces H 2 O 2 as an antimicrobial factor to reduce competition by other upper respiratory pathogens, such as Haemophilus influenzae, Neisseria meningitides, Moraxella catarrhalis, and S. aureus (14, 16). Since S. aureus is a natural colonizer of the human nares, we hypothesized that its success derives in part from a relative resistance to H 2 O 2 killing by other microflora. Here we tested this hypothesis by generating a catalase knockout mutant strain of S. aureus and examining the role of enzymatic H 2 O 2 inactivation in niche competition with S. pneumoniae. MATERIALS AND METHODSBacterial strains, media, and mice. S. aureus strains were cultured at 37°C in Todd-Hewitt broth (THB) or on Todd-Hewitt agar (THA) (Difco). S. pneumoniae TIGR4 was cultured in THB with 0.5% yeast extract (THY) at 37°C in a 5% CO 2 incubator. Eight-to 10-week old female CD1 mice were purchased from Charles River Laboratories, Wilmington, MA. When included, antibiotics were added at the following concentrations: 100 g ampicillin/ml, 50 g erythromycin/ml, and 100 g spectinomycin/ml.Generation ...

Comparative genome-scale modelling of Staphylococcus aureus strains identifies strain-specific metabolic capabilities linked to pathogenicity

“…The core metabolic network also contained known metabolic virulence determinants including catalase, an enzyme that hydrolyzes hydrogen peroxide into water and oxygen and that is used in the clinical laboratory to distinguish staphylococci from enterococci and streptococci. Catalase production and oxidant resistance have been shown to be predisposing factors for nasal colonization and subsequent infection (32).…”

Staphylococcus aureusandStreptococcus pneumoniaeinteraction and response to pneumococcal vaccination: Myth or reality?

“…In line with the theory of H 2 0 2 interference, Park et al demonstrated that S. aureus catalase expression contributes to its ability to colonize and survive in the presence of S. pneumoniae in an in vivo mouse model of nasal co-colonization. 20 However, in a neonatal rat model, Margolis observed that S. aureus density did not differ whether co-colonized with hydrogen peroxide producing or non-producing S. pneumoniae, or whether catalase or non-catalase producing S. aureus strains were tested. 21 To assess the role of hydrogen peroxide in the patterns of human co-colonization, Regev-Yochay et al assessed the variation of bactericidal activity in S. pneumoniae strains isolated from children co-colonized with S. pneumoniae and S. aureus compared to those colonized only with S. pneumoniae.…”

Analysis Of Enterococcus Faecalis, Staphylococcus Aureus, And Candida Albicans In Cast Metal Cores

“…39 Esto puede deberse a que los materiales analizados en este estudio no estuvieron en contacto con S. aureus y C. albicans o que otros tipos de microorganismos pudieron causar su inhibición. 43,44 Otra razón es la metodología utilizada, ya que el grupo de Ensinas colocó los nú-cleos en medio de enriquecimiento antes de sembrarlos en medios comunes, aumentando así la concentración de células de estos microorganismos.…”

“…39 This may be due to the fact that the materials analyzed in this study were not in contact with S. aureus and C. albicans, or other types of microorganisms could cause their inhibition. 43,44 Another reason has to do with the used methodology, since Ensinas et al placed the cores in an enrichment medium before immersing them in common media, thus increasing the concentration of cells of these microorganisms.…”