Context.— Otitis media with effusion (OME) can lead to significant hearing loss
in children. Although previous studies have shown that bacterial DNA is present
in a significant percentage of effusions sterile by culture, whether the DNA
represents viable organisms or "fossilized remains" is unknown.
Objective.— To determine if bacterial messenger RNA (mRNA), as detected by a reverse
transcriptase–polymerase chain reaction (RT-PCR)–based assay,
is present in chronic pediatric middle ear effusions that contain bacterial
DNA but are sterile by standard cultural methods. Bacterial mRNAs have a half-life
measured in seconds to minutes; therefore, detection of bacteria-specific
mRNAs would be evidence that metabolically active organisms are present.
Design.— Blinded comparative study.
Patients.— A total of 93 effusions from pediatric outpatients seen for myringotomy
and tube placement for chronic (>3 months) OME (median age of children, 17
Setting.— Tertiary care pediatric hospital.
Main Outcome Measures.— Percentage of positive test results for RT-PCR–based assays compared
with culture for Haemophilus influenzae and concordance
between RT-PCR and PCR-based findings for bacterial nucleic acids.
Results.— Eleven (11.8%) of the 93 specimens tested positive by culture, PCR,
and RT-PCR for H influenzae. A total of 29 specimens
(31.2%) were positive by PCR but negative by culture for H influenzae. All 29 specimens were positive by RT-PCR for H influenzae–specific mRNA.
Conclusions.— The RT-PCR–based assay system can detect the presence of bacterial
mRNA in a significant percentage of culturally sterile middle ear effusions,
establishing the presence of viable, metabolically active, intact organisms
in some culture-negative OME.