BACTERIAL CHARACTERIZATION IN STAPHYLOCOCCUS-EPIDERMIDIS SEPTICEMIA

An analysis of the in vitro characteristics of Staphylococcus epidermi dis strains isolated from patients with true S. epidermidis septicemia was undertaken. From a potential population of 921 cultures from adul t patients with coagulase-negative bacteremia, highly defined selectiv e criteria limited the population to 20 patients with S. epidermidis s epsis, from whose blood cultures the study organisms were Isolated. An other population of 11 S. epidermidis blood isolates, clinically deter mined to be contaminants, were tested as a control group. In vitro ass ays performed on all isolates included slime quantification, hydrophob icity, surface hexoses, and capsule presence. Murine spleen phagocytos is of intravenously administered isolates was measured in vivo. The as sayed quantity of cell-associated bacterial hexose sugars positively c orrelated with organism virulence to the host (p = 0.02). This bacteri al population was also low in slime but varied as to the presence of c apsule and ease of phagocytosis. Permanent catheter-bearing patients' bacteria were somewhat more hydrophobic (p = 0.07). We conclude that i n vitro assays can differentiate bacteremic cultures from contaminants and that the characteristic that best relates to host toxicity in the se S. epidermidis isolates was bacterial cell surface-associated carbo hydrate.