Inflammation in the middle ear of children with recurrent or chronic otitis media is associated with bacterial load.
BACKGROUND
Viral upper respiratory tract infections have been described as an important factor in the development of otitis media (OM), although it is unclear whether they facilitate bacterial OM or can directly cause OM. To clarify the role of viral infections in OM, we compared the relative contribution of viruses and bacteria with the induction of inflammatory cytokine responses in the middle ear of children suffering from OM.


METHODS
Children up to 5 years of age, with recurrent or chronic episodes of OM and scheduled for ventilation tube insertion were enrolled in a prospective study. Middle ear fluids (n = 116) were collected during surgery, and quantitative polymerase chain reaction was performed to detect bacterial and viral otopathogens, that is, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and 15 respiratory viruses. Finally, concentrations of the inflammatory mediators interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17a and tumor necrosis factor-α were determined.


RESULTS
Middle ear fluids were clustered into 4 groups, based on the detection of viruses (28%), bacteria (27%), both bacteria and viruses (27%) or no otopathogens (19%). Bacterial detection was associated with significantly elevated concentrations of cytokines compared with middle ear fluids without bacteria (P < 0.001 for all cytokines tested) in a bacterial load-dependent and species-dependent manner. In contrast, the presence of viruses was not associated with changes in cytokine values, and no synergistic effect between viral-bacterial coinfections was observed.


CONCLUSIONS
The presence of bacteria, but not viruses, is associated with an increased inflammatory response in the middle ear of children with recurrent or chronic OM.
Department of Pediatrics, Radboud University, Nijmegen Medical Centre, The Netherlands.
Kim
K
Stol
Dimitri A
DA
Diavatopoulos
Kees
K
Graamans
Joost A M
JA
Engel
Willem J G
WJ
Melchers
Huub F J
HF
Savelkoul
John P
JP
Hays
Adilia
A
Warris
Peter W M
PW
Hermans
D001424:Bacterial Infections / Q000382:microbiology; D001826:Body Fluids / Q000737:chemistry / Q000382:microbiology*; D002675:Child, Preschool; D002908:Chronic Disease; D016207:Cytokines / Q000737:chemistry; D006801:Humans; D007223:Infant; D007249:Inflammation / Q000382:microbiology*; D010033:Otitis Media / Q000382:microbiology* / Q000601:surgery; D012008:Recurrence; D014777:Virus Diseases / Q000821:virology; D014780:Viruses / Q000145:classification
D016207:Cytokines