Facial skin temperature is higher for patients with rosacea. Papules and pustules might arise because bacteria behave differently at these warmer temperatures. We sought to: (1) compare bacteria from facial skin of patients with rosacea with that of control subjects; and (2) grow these bacteria at 30 degrees C and 37 degrees C to compare growth curves and secreted proteins. Bacteria isolated from pustules/skin surfaces of patients with rosacea and skin surfaces of control subjects were identified and cultured at 37 degrees C and 30 degrees C. Secreted proteins were separated by electrophoresis. We found that Staphylococcus epidermidis isolated from patients with rosacea was consistently beta-hemolytic, whereas that from control subjects were nonhemolytic. Bacteria from patients with rosacea grew at the same rate and to the same stationary phase whether cultured at 37 degrees C or 30 degrees C. Isolates from patients with rosacea secreted more proteins, and generally more of each protein at 37 degrees C compared with 30 degrees C. In conclusion, bacteria isolated from patients with rosacea secrete different proteins and different amounts of protein at different temperatures.