Paracoccidioides brasiliensis isolate Pb18 yeast cell viability and infection index after co-culture with alveolar macrophage (MH-S) cells. (A) CFU of P. brasiliensis isolate Pb18 yeast cells; (B) Infection index of in-vitro MH-S cells in the presence of alexidine dihydrochloride (0.25 μM) and pulmonary surfactant (100 μg.mL-1). Percentage of MH-S cells infected with P. brasiliensis yeast cells - adhered (black bar) or internalized (white bar). In all experiments, MH-S cells and opsonized yeast cells were incubated at a yeast-to-macrophage ratio of 1:5, at 37°C in an atmosphere of 5% CO2 as described in the Materials and Methods. Data shown are derived from two in-vitro independent experiments performed in triplicate (mean ± SEM, with *significance assumed in the range of P < 0:05); ns = non-significantly (P < 0.05); **Significantly different from the untreated control P < 0.001 by the paired 2-tailed Student's t-test.