The Effect of Antibiotic Treatment on the Release of Endotoxin during Nontypable Haemophilus influenzae-induced Otitis Media in the Chinchilla

Abstract

The gram negative bacteria, nontypable Haemophilus influenzae (NTHi) was used to induce otitis media in a total of 18 chinchillas. Three days post-inoculation, three cohorts of 6 chinchillas each were treated daily for four days with either ceftriaxone, chloramphenicol, or diluent without antibiotics. Middle ear fluid (MEF) was obtained daily, assayed for endotoxin content by means of the chromogenic limulus amebocyte lysate assay, and concentration of the NTHi/mL MEF determined by standard plate count. The endotoxin concentration per mL MEF from both the antibiotic treated cohorts decreased during the observation period, but increased in the MEF of the untreated control group. The data indicate that, unlike the dramatic increase in endotoxin concentration, after antibiotic treatment in the cerebrospinal fluid (CSF) during experimental Haemophilus influenzae -induced meningitis, there is no demonstrable sustained release of endotoxin in the middle ear subsequent to antibiotic treatment during experimental otitis media.