Bactericidal Activity of Aerobic and Anaerobic Polymorphonuclear Neutrophils

Human polymorphonuclear neutrophils (PMN) were made anaerobic by nitrogen washout (oxygen saturation <1%, Eh < -42 mV at pH 7.0), and the ability of the cells to kill bacteria was assayed and compared to the bactericidal activity of aerobic PMN. Anaerobic PMN were able to kill Staphylococcus epidermidis, Enterococcus, viridans streptococci, Pseudomonas aeruginosa, Peptostreptococcus anaerobius, Bacteroides fragilis, Clostridium perfringens, and Peptococcus magnus normally. Organisms that were not killed normally by anaerobic PMN included Staphylococcus aureus (strains Wood 46 and 502a), Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, Proteus vulgaris, and Salmonella typhimurium. These findings suggest that mechanisms other than those dependent on hydrogen peroxide may be important in the killing of some bacteria.