FIG. 4.

Viability of SP-A-treated B. bronchiseptica. Bacteria incubated with SP-A were assessed for membrane permeability (A) or incorporation of [³H]uridine (B). (A) Membrane permeability was assessed by propidium iodide. The same field was photographed (630× magnification) with phase-contrast microscopy (phase) to show the location of all bacteria present in the field and with fluorescence microscopy with a Texas Red filter to show organisms stained by propidium iodide (PI). Arrows indicate aggregates. K. pn, K. pneumoniae; B.b. WT, B. bronchiseptica RB50. (B) Incorporation of [³H]uridine (in counts per minute [cpm]) was assessed for bacteria grown in LB broth (control), LB broth with 50 μg of SP-A/ml (+SP-A), or LB broth in the presence of the low-molecular-weight filtrate (<10,000 Da) from dialysis of SP-A (+Filtrate) lacking SP-A. Bars represent means ± standard errors of the means for three independent trials. #, significantly different cpm compared to that of the control (P < 0.002) by Student's t test.