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Lung clearance of Staphylococcus aureus strains with differing protein A content: protein A effect on in vivo
Abstract:
We have studied the clearance from murine lungs of two strains of Staphylococcus aureus, one possessing high and the other possessing low levels of protein A.S. aureus FDA 209 and S. aureus Wood 46 were assayed for their ability to bind mouse immunoglobulin G, using an indirect radioimmunoassay. S. aureus FDA 209 binding of mouse immunoglobulin was significantly greater than that of S. aureus Wood 46 (118,909 versus 37,845 cpm). Clearance of these two strains from the lung after a 30-min aerosol inoculation period was not significantly different. The percentage of bacteria remaining in the lung was 49.2 and 55.0% at 2h, 31.8 and 33.2% at 3 h, and 25.4 and 17.2% at 4 h for protein A-rich and protein A-poor strains, respectively (P greater than 0.20 at each time). These data suggest that the previously demonstrated in vitro antiphagocytic effect of protein A may not be relevant to pulmonary clearance mechanisms.
Insights
This study found that Staphylococcus aureus strains with high or low levels of protein A showed similar clearance rates from mouse lungs. Protein A
Area of Science:
- Microbiology
- Immunology
- Pulmonary Medicine
Background:
- Protein A is a surface protein found in Staphylococcus aureus.
- Protein A is known to have antiphagocytic properties in vitro.
- The role of protein A in bacterial clearance from the lungs is not well understood.
Purpose of the Study:
- To investigate the effect of protein A levels on the clearance of Staphylococcus aureus from murine lungs.
- To determine if the in vitro antiphagocytic effect of protein A is relevant to pulmonary clearance.
Main Methods:
- Two strains of Staphylococcus aureus, one high (FDA 209) and one low (Wood 46) in protein A, were used.
- Bacterial binding to mouse immunoglobulin G was measured using indirect radioimmunoassay.
- Clearance from murine lungs was assessed after aerosol inoculation.
Main Results:
- The high-protein A strain (FDA 209) showed significantly greater binding to mouse immunoglobulin G than the low-protein A strain (Wood 46).
- Pulmonary clearance rates for both strains were not significantly different at 2, 3, and 4 hours post-inoculation.
- Percentage of bacteria remaining in the lung was comparable between the two strains over time.
Conclusions:
- The level of protein A in Staphylococcus aureus does not significantly impact its clearance from the murine lung.
- The in vitro antiphagocytic effect of protein A may not be a critical factor in pulmonary bacterial clearance mechanisms.