Lactic acid isomers and fatty acids in sinus secretion: a longitudinal study of bacterial and leukocyte metabolism in experimental sinusitis.

Concentrations of the two optic isomers of lactate (D- and L-form) as well as glucose, succinate, acetate, butyrate, isovalerate and valerate were examined in purulent sinus secretions. The samples were obtained from rabbit maxillary sinuses, experimentally infected with Streptococcus pneumoniae or Bacteroides fragilis. More soluble acids such as acetate displayed relatively low levels in the secretion, despite a high microbial production. A substantial increase in D-lactate concentration was found in secretions only the first day after induction of pneumococcal sinusitis, and not in bacteroides sinusitis. L-lactate levels were particularly high in secretions of a marked purulent character, and this isomer can be considered as indicator of anaerobic glycolysis in the leukocytes. Less diffusible fatty acids such as butyrate and isovalerate accumulated in the secretion, in spite of a relatively lower production rate, and are thus more reliable indicators of bacterial metabolism.