Effect of Iron - Uptake Mechanisms of Staphylococcus Aureus on the Growth in Human Body Fluids

Shin, Sung Heui; Kim, Jin Ho; Lee, Kang Kil; Lee, Myung Hee; Yang, Nam Woong; Lim, Yong

Abstract

BACKGROUND: We could establish a streptonigrin-resistant strain called SR-1 strain from Staphylococcus aureus ATCC 6538 as a parental strain and characterize SR-1 strain as defective in the iron-uptake mechanisms including production of siderophores and expression of transferrin-binding protein on the cell wall. We performed this study to elucidate effect of the iron-uptake mechanisms on the growth in human body fluids.
METHODS
Growth kinetics of SR-1 strain were compared with those of the parental strain and the increase of unsaturated iron-binding capacity (UIBC) was measured. Siderophore production and expression of transferrin-binding protein were detected by CAS diffusion assay and ligand-blot method probed with human transferrin conjugated horseradish peroxidase, respectively, as the strains were cultivated in normal pooled sera, ascitic fluid and pleural effusion.
RESULTS
Siderophores activity in the body fluids could not be detected by the CAS diffusion assay. The parental strain expressed the transferrin-binding protein on the cell wall during the growth in ascites and pleural effusion except the sera whereas SR-1 strain did not. Growth kinetics showed that SR-1 strain grew sluggish compared to the parental strain. The peak of increase of UIBC of the parental strain was observed at the mid-exponential growth phase and the increase of UIBC of SR-1 strain was either lower than that of the parental strain or not changed.
CONCLUSION
The iron-uptake mechanisms of S. aureus, especially expression of transferrin-binding protein, play a significant role in growing in the body fluids.