FIG. 3.

Nasal fluid from carriers supports the growth of S. aureus isolates. Nasal fluids from S. aureus carriers (C; solid circles) and healthy noncarriers (NC; open triangles) were tested in CFU microassays with an isolate of S. aureus from the donor's own nose (A); an isolate of S. aureus from another, randomly selected carrier (B); and a laboratory strain of S. aureus (C) (eight donors for each condition, with four or five replicates per condition). Each point represents the log₁₀ CFU per milliliter at 24 h. Broken lines indicate the mean and SEM. Compared to noncarrier fluid, carrier fluid permitted more rapid growth of isolates derived from either the same (P = 0.00016) or a different (P = 0.002) carrier. In contrast, the difference in the growth of the laboratory strain of S. aureus in carrier versus noncarrier fluids did not reach significance (P = 0.059).