Effects of perfluorocarbons and perfluorocarbons/surfactant emulsions on growth and viability of group B streptococci and Escherichia coli

Objective: Partial liquid ventilation with perfluorocarbons (PFC) might be used as a new ventilatory strategy to treat respiratory insufficiency in congenital pneumonia. The present study investigates for the first time effects of PFC on growth and viability of group B streptococci (GBS) and Escherichia coli, bacteria frequently causing congenital pneumonia. Design: Prospective, in vitro study. Setting: Research laboratory in a university. Material: Group B streptococci 090 la HD Colindale and E. coli K12, JM 101. Interventions: E. coli (10⁷/mL) were grown in the absence or presence of different PFC (RM 101, PF 5080, FO 6167) for up to 6 hrs. To study bacterial viability, GBS (5 × 10⁷/mL) were incubated in saline with or without different PFC, PFC/surfactant emulsions, or surfactant (Curosurf) for up to 5 hrs. Every 2 hrs, the colony forming units were determined by plating different dilutions of bacteria on agar. Measurements and Main Results: RM 101 or PF 5080 alone and in emulsions with surfactant had no effect on viability of GBS or growth of E. coli. For FO 6167, a previously described toxicity was found, even if 1 mL of GBS suspension was incubated with only 100 μL of F0 6167, verifying the experimental design that guarantees a PFC bacteria contact. The toxic effects were almost prevented by forming a PFC-in-surfactant emulsion but not by preincubation of GBS with surfactant and subsequent F0 6167 exposure. Conclusion: RM 101 and PF 5080 did not influence bacterial growth in vitro, direct effects on bacterial proliferation during partial liquid ventilation in congenital pneumonia seem, therefore, unlikely. Interestingly, we found that the known toxic effects of F0 6167 can be prevented by covering PFC with a surfactant film. Surfactant reduced the cytotoxic effects of F0 6167, probably by preventing a direct contact between F0 6167 and the bacterial cell wall.