FIG. 3.

Mean competitive indices of V. cholerae O1 present in different fractions of phage-positive and phage-negative cholera stool samples, shown in panels A and B, respectively, against a reference strain grown to exponential phase. The mean infectivities of clumped cell fractions were significantly higher than those of the planktonic cell fractions in phage-negative cholera stools (P = 0.0041). However, the difference in infectivity of these two cell populations in phage-positive stools was significantly less than that in phage-negative stools (P = 0.0006).