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Serum interleukin-6 in bacterial and nonbacterial acute otitis media
T Heikkinen1, F Ghaffar, A O Okorodudu
1Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas 77555-0371, USA.
Background:
Increasing prevalence of antibiotic-resistant bacteria is a serious clinical problem that calls for reduction of unnecessary use of antibiotics. Acute otitis media (AOM) is the most common reason for antibiotic therapy in the United States. Approximately 30% of AOM cases do not have a bacterial etiology. Rapid identification of these cases could help withhold unnecessary antibiotic treatment.
Objective:
To determine the usefulness of serum levels of interleukin-6 (IL-6), an acute phase cytokine shown to be a reliable marker of neonatal bacterial infection, in differentiation between bacterial and nonbacterial AOM in children.
Study Design:
IL-6 was measured in stored serum samples from 184 children (mean age, 22 months) with AOM who were enrolled in antibiotic efficacy trials at our department. The samples were obtained at enrollment and at 9 to 12 days after initiation of antibiotic therapy. Sera from 21 uninfected children (mean age, 23 months) were used as controls. The etiology of AOM was determined by bacterial and viral cultures as well as respiratory syncytial virus antigen detection in the middle ear fluids obtained by tympanocentesis.
Results:
Bacterial etiology of AOM was confirmed in 125 children (68%), whereas in 59 children (32%) no bacterial pathogen could be detected in the middle ear fluid. Children with bacterial AOM had significantly higher IL-6 levels than those with nonbacterial AOM (median, 11.5 vs 3.7 pg/mL). However, this difference was almost entirely attributable to pneumococcal AOM specifically. IL-6 levels in children with AOM caused by Streptococcus pneumoniae were significantly higher (median, 40.1 pg/mL) than in AOM caused by Haemophilus influenzae (7.3 pg/mL) or Moraxella catarrhalis (6.8 pg/mL). At the cutoff value of 30 pg/mL, the specificity of IL-6 for detection of pneumococcal AOM was 91% with a sensitivity of 61%, but its sensitivity for detection of bacterial AOM in general was only 27%.
Conclusions:
Low levels of IL-6 do not rule out bacterial etiology of AOM in general; therefore, IL-6 is not sensitive enough as a marker of bacterial AOM. Surprisingly, serum IL-6 levels in pneumococcal AOM were significantly higher than the levels associated with other bacterial AOM, and serum IL-6 levels of >30 pg/mL were highly specific for pneumococcal AOM. These findings suggest a distinctive role for S pneumoniae in the pathogenesis of AOM.
Insights
Serum interleukin-6 (IL-6) levels can help identify pneumococcal acute otitis media (AOM) but are not sensitive enough for general bacterial AOM detection. This finding suggests Streptococcus pneumoniae plays a unique role in AOM.
Area of Science:
- Pediatrics
- Infectious Diseases
- Immunology
Background:
- Antibiotic resistance is a growing concern, necessitating reduced unnecessary antibiotic use.
- Acute otitis media (AOM) is a common reason for antibiotic prescriptions, with a significant portion lacking bacterial causes.
- Accurate differentiation between bacterial and non-bacterial AOM could prevent overtreatment.
Purpose of the Study:
- To evaluate the utility of serum interleukin-6 (IL-6) levels in distinguishing bacterial from non-bacterial AOM in children.
- To assess IL-6 as a potential biomarker for bacterial infections in AOM cases.
Main Methods:
- Serum IL-6 levels were measured in 184 children diagnosed with AOM and 21 healthy controls.
- AOM etiology was determined through middle ear fluid cultures and viral antigen detection.
- IL-6 levels were analyzed at enrollment and post-antibiotic treatment.
Main Results:
- Bacterial AOM was confirmed in 68% of cases; non-bacterial AOM in 32%.
- Children with bacterial AOM showed higher median IL-6 levels (11.5 pg/mL) than non-bacterial AOM (3.7 pg/mL).
- IL-6 levels were significantly higher in *Streptococcus pneumoniae* AOM (40.1 pg/mL) compared to *Haemophilus influenzae* (7.3 pg/mL) or *Moraxella catarrhalis* (6.8 pg/mL).
- A cutoff of 30 pg/mL yielded 91% specificity and 61% sensitivity for pneumococcal AOM, but only 27% sensitivity for bacterial AOM overall.
Conclusions:
- Serum IL-6 is not sufficiently sensitive to rule out general bacterial AOM.
- Elevated IL-6 levels (>30 pg/mL) are highly specific for pneumococcal AOM.
- These findings highlight a potential distinct role of *S. pneumoniae* in AOM pathogenesis.