Halothane reversibly inhibits human neutrophil bacterial killing

The effect of halothane, at clinically relevant concentrations on the ability of human polymorphonuclear leukocytes (PMNL) to kill the most frequently isolated gram-negative organisms responsible for human bacteremias, Escherichia coli and Klebsiella pneumoniae, was studied. Exposure of PMNL to 0.75 per cent halothane is air significantly inhibited the killing of E. coli (from 81 per cent to 65 per cent) but not K. pneumoniae. At 1.0 per cent halothane there was no killing of E. coli and the killing of K. Pneumoniae was reduced from 98 per cent to 82 per cent. With 1.5 per cent halothane, the killing of K. pneumoniae by PMNL was further reduced to 65 per cent. This inhibition of bacterial killing could be reversed after exposure of halothane-treated PMNL to air. The mechanism of inhibition may be due in part to a deleterious effect of halothane on the oxidative microbicidal activity of human PMNL. Although halothane reversibly inhibits the ability of PMNL to kill bacteremic culture isolates, the degree of susceptibility of bacteria to halothane-treated PMNL may vary.