Interleukin 8 in middle ear fluid during acute otitis media: correlation with aetiology and bacterial eradication

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Abstract
OBJECTIVES To study the concentration of interleukin 8 (IL-8) in the middle ear fluid of children with acute otitis media and the association between IL-8 concentrations, aetiology of acute otitis media, and bacteriological sterilisation. STUDY DESIGN Middle ear fluid was obtained by tympanocentesis at enrolment (day 1) and on day 4–5 in 81 children aged 3–36 months with acute otitis media who received antibiotic treatment. IL-8 concentrations were measured by enzyme linked immunosorbent assay. RESULTS 101 samples were obtained on day 1 and 47 samples on day 4–5. 94 pathogens were isolated in 79 of 101 samples obtained on day 1: 56Haemophilus influenzae, 35Streptococcus pneumoniae,2 Moraxella catarrhalis, and 1Streptococcus pyogenes. Among 40 paired, initially culture positive samples, sterilisation was achieved on day 4–5 in 22 but not in 18 (13 H influenzae, 2S pneumoniae, and 3 H influenzae and S pneumoniae concomitantly). IL-8 was detected in 96 of 101 and 46 of 47 samples obtained on days 1 and 4–5, respectively. Mean (SD) IL-8 concentration on day 1 was significantly higher in culture positive than in negative samples (12 636 (23 317)v 5920 (7080) pg/ml). In paired samples, IL-8 concentration fell in 12 of 22 ears in which sterilisation was achieved and in 9 of 21 ears with persistent or new infection. Mean (SD) IL-8 concentrations on day 4–5 were significantly higher in culture positive than in negative samples (15 420 (15 418)v 6695 (5092) pg/ml). CONCLUSIONS Higher IL-8 concentrations are found in culture positive middle ear fluid in acute otitis media. Bacterial eradication is associated with a fall in these concentrations.