Inhalation of specific anti-Pseudomonas aeruginosa IgY antibodies transiently decreases P. aeruginosa colonization of the airway in mechanically ventilated piglets

Background: P. aeruginosa is a pathogen frequently resistant to antibiotics and a common cause of ventilator-associated pneumonia (VAP). Non-antibiotic strategies to prevent or treat VAP are therefore of major interest. Specific polyclonal avian IgY antibodies have previously been shown to be effective against pneumonia caused by P. aeruginosa in rodents and against P. aeruginosa airway colonization in patients. Objectives: To study the effect of specific polyclonal anti-P. aeruginosa IgY antibodies (Pa-IgY) on colonization of the airways in a porcine model. Method: The pigs were anesthetized, mechanically ventilated, and subject to invasive hemodynamic monitoring and allocated to either receive 10(9) CFU nebulized P. aeruginosa (control, n=6) or 10(9) CFU nebulized P. aeruginosa + 200 mg Pa-IgY antibodies (intervention, n=6). Physiological measurement, blood samples, and tracheal cultures were then secured regularly for 27 h, after which the pigs were sacrificed and lung biopsies were cultured. Results: After nebulization, tracheal growth of P. aeruginosa increased in both groups during the experiment, but with lower growth in the Pa-IgY-treated group during the experiment (p = 0.02). Tracheal growth was 4.6 x 10(3) (9.1 x 10(2)-3.1 x 10(4)) vs. 4.8 x 10(4) (7.5 x 10(3)-1.4 x 10(5)) CFU/mL in the intervention group vs. the control group at 1h and 5.0 x 10(0) (0.0 x 10(0)-3.8 x 10(2)) vs. 3.3 x 10(4) (8.0 x 10(3)-1.4 x 10(5)) CFU/mL at 12 h in the same groups. During this time, growth in the intervention vs. control group was one to two orders of ten lower. After 12 h, the treatment effect disappeared and bacterial growth increased in both groups. The intervention group had lower body temperature and cardiac index and higher static compliance compared to the control group. Conclusion: In this porcine model, Pa-IgY antibodies lessen bacterial colonization of the airways.