The effect of ethanol ingestion on killing of Streptococcus pneumoniae, Staphylococcus aureus and Staphylococcus epidermidis by rat neutrophils.

The precise effects of chronic ethanol ingestion on the role of neutrophil function in pneumococcal pneumonia have not been fully delineated. In this study, the bactericidal capacity of polymorphonuclear leucocytes (PMNL) from rats pair-fed an ethanol-containing liquid diet or a liquid control diet was compared both in vitro and in vivo. The PMNL were allowed to phagocytose several bacterial species in vitro, and intracellular killing after 1h was determined by plate counts. There was no significant difference in killing of Streptococcus pneumoniae types 6B or 37, Staphylococcus aureus or Staphylococcus epidermidis by PMNL from ethanol-fed and pair-fed rats (E-PMNL and P-PMNL, respectively). However, E-PMNL killed significantly less of Streptococcus pneumoniae types 10A, 14 and 19F. To corroborate these results in vivo, rats were infected transtracheally, and quantitative lung counts were performed 1 week post infection. Streptococcus pneumoniae types 6B and 37, as well as Staphylococcus aureus, were effectively cleared from the lungs of both groups of rats. Streptococcus pneumoniae types 10A, 14 and 19F, however, were cleared well from the lungs of pair-fed but not ethanol-fed animals. These data suggest that chronic ethanol ingestion induces a strain-specific deficit in neutrophil bactericidal activity against certain S. pneumoniae which does not extend to commonly encountered staphylococci.