Influence of various antimicrobial agents on the chemiluminescence of phagocytosing human granulocytes.

In a standardized experimental model 51 antimicrobial agents were coincubated with polymorphonuclear granulocytes (PNG) of healthy human donors and then screened for a modulation of chemiluminescence (CL) reaction during zymosan phagocytosis. Initial studies with low, therapeutic and high, nontherapeutic concentrations showed CL suppression by amoxicillin, tetracycline, doxycycline, trimethoprim, sulfamethoxazol, clindamycin, fusidic acid, rifampicin, isoniazid and amphotericin B, yet stimulation of CL reaction by ceftriaxone, enoxacin, and norfloxacin. Dose-effect relationships for most of these substances showed a sigmoid-like graph with little influence upon most of the therapeutic range, but markedly increasing suppression (or stimulation) from a certain 'threshold' concentration. For certain substances this curve might indicate a narrowed therapeutic range of antimicrobial chemotherapy due to impairment of phagocytic functions.