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Standardized In vitro Assays to Visualize and Quantify Interactions between Human Neutrophils and Staphylococcus aureus Biofilms
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Standardized In vitro Assays to Visualize and Quantify Interactions between Human Neutrophils and Staphylococcus aureus Biofilms

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Bactericidal activity of aerobic and anaerobic polymorphonuclear neutrophils

G L Mandell

    Infection and Immunity
    |February 1, 1974
    PubMed

    Insights

    Human neutrophils (PMN) retain bacterial killing ability under anaerobic conditions, but effectiveness varies by bacterial species. This suggests non-hydrogen peroxide mechanisms are crucial for killing certain bacteria.

    Area of Science:

    • Immunology
    • Microbiology
    • Cell Biology

    Background:

    • Human polymorphonuclear neutrophils (PMN) are key immune cells involved in bacterial killing.
    • The role of oxygen and reactive oxygen species, like hydrogen peroxide, in PMN bactericidal activity is well-established.
    • However, the efficacy of PMN against bacteria under anaerobic conditions remains less understood.

    Purpose of the Study:

    • To investigate the bactericidal capacity of human PMN under anaerobic conditions.
    • To compare the killing activity of anaerobic PMN against a panel of Gram-positive and Gram-negative bacteria with that of aerobic PMN.
    • To identify bacterial species whose killing by PMN is oxygen-dependent.

    Main Methods:

    • Human PMN were rendered anaerobic via nitrogen washout.
    • The bactericidal activity of anaerobic PMN was assayed against various bacterial species.
    • The results were compared to the killing activity of aerobic PMN.

    Main Results:

    • Anaerobic PMN effectively killed Staphylococcus epidermidis, Enterococcus, viridans streptococci, Pseudomonas aeruginosa, Peptostreptococcus anaerobius, Bacteroides fragilis, Clostridium perfringens, and Peptococcus magnus.
    • PMN exhibited reduced killing of Staphylococcus aureus (strains Wood 46 and 502a), Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, Proteus vulgaris, and Salmonella typhimurium under anaerobic conditions.
    • A clear distinction in susceptibility to anaerobic PMN killing was observed among different bacterial species.

    Conclusions:

    • Human PMN retain significant bactericidal activity against certain bacteria even in the absence of oxygen.
    • The killing of specific bacterial species, including Staphylococcus aureus and several Gram-negative bacteria, is impaired under anaerobic conditions.
    • These findings highlight the importance of oxygen-dependent mechanisms, such as hydrogen peroxide production, in the PMN-mediated killing of a subset of bacteria, suggesting alternative oxygen-independent mechanisms are also involved.

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