Impact of the immune response modification by lysophosphatidylcholine in the efficacy of antibiotic therapy of experimental models of peritoneal sepsis and pneumonia by Pseudomonas aeruginosa: LPC therapeutic effect in combined therapy.

Introduction: Immune response stimulation may be an adjuvant to antimicrobial treatment. Here, we evaluated the impact of immune response modification by lysophosphatidylcholine (LPC), combined with imipenem or ceftazidime, in murine models of peritoneal sepsis (PS) and pneumonia induced by Pseudomonas aeruginosa.

Methods: The imipenem and ceftazidime-susceptible strain (Pa39) and imipenem and ceftazidime-resistant strain (Pa238) were used. Ceftazidime pharmacokinetic and pharmacodynamic parameters were determined. The therapeutic efficacy and TNF-α and IL-10 levels were determined in murine models of PS and pneumonia induced by Pa39 and Pa238 and treated with LPC, imipenem or ceftazidime, alone or in combination.

Results: In the PS model, LPC+ceftazidime reduced spleen and lung Pa238 concentrations (-3.45 and -3.56logCFU/g; P<0.05) to a greater extent than ceftazidime monotherapy, while LPC+imipenem maintained the imipenem efficacy (-1.66 and -1.45logCFU/g; P>0.05). In the pneumonia model, LPC+ceftazidime or LPC+imipenem reduced the lung Pa238 concentrations (-2.37logCFU/g, P=0.1, or -1.35logCFU/g, P=0.75). For Pa39, no statistically significant difference was observed in the PS and pneumonia models between combined therapy and monotherapy. Moreover, LPC+imipenem and LPC+ceftazidime significantly decreased and increased the TNF-α and IL-10 levels, respectively, in comparison with the untreated controls and monotherapies.

Conclusions: These results demonstrate the impact of immune response modification by LPC plus antibiotics on the prognosis of infections induced by ceftazidime-resistant P. aeruginosa.