Background: Brief exposure of bacteria to high concentrations of some antimicrobials enhanced their susceptibility to phagocytic killing by human polymorphonuclear leucocytes. This effect was defined as Post Antibiotic Leukocyte Enhancement or PALE. In this study we have investigated the effect of prior exposure of E. coli for ten minutes to 0.99 mg/l of ciprofloxacin and 0.40 mg/l of meropenem.
Methods and results: The pretreated bacteria were incubated for three hours in a mixture containing leukocytes and leukocytes plus serum (10% v/v). Leukocytes were prepared from blood of healthful volunteers and were extracting with ammonium chloride and differential centrifugation. At one hour intervals, aliquots were taken and added to basic water to dispute leukocytes and spread onto agar plates. Viable bacteria were counted. PALE of ciprofloxacin was higher than meropenem.
Conclusion: Whether PALE is confirmed, it must be taken into consideration in dosage schedules.