SUMMARY: Results of studies are reported on the carbohydrate metabolic capabilities of cells of grown in human serum at varied percentage iron-saturations of its contained siderophilin; on the production by such cells of coagulase, hyaluronidase, staphylokinase, and haemolysins; and on the effectiveness of some antibiotics as growth inhibitors under similar growth conditions. Cocci grown in serum at a normal serum iron level and percentage of iron-saturation show a significant reduction in their endogenous respiration, in their capacity to attack lactate, a complete loss of ability to oxidize formate, and a several-fold increase in anaerobic glycolytic capacity as compared to those cocci grown in serum containing unchelated free ionic iron. These metabolic changes, in conjunction with an observed increased rate of acid production and rate of glucose utilization by the growing culture of ‘low-iron’ cells the ‘high-iron’ cells, indicate an increased dependence upon glycolytic rather than oxidative energy production processes by the iron-restricted cells. The strain of employed in these studies, although characterized by conventional methods as a producer of coagulase, hyaluronidase, haemolysins, and staphylokinase, did not elaborate any of these pathogenesis-linked factors at detectable levels when grown in normal serum. Coagulase, alone, was found at ‘high-iron’ levels. The amount of dimethoxyphenyl penicillin required to inhibit growth of our strain grown in serum increased with increasing percentage of iron saturation of the siderophilin while the effectiveness of a given inhibitory concentration of kanamycin and chloramphenicol was indifferent to any variation in the iron-saturation value.


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