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Updated: Aug 4, 2026
Air-sampled Filter Analysis for Endotoxins and DNA Content
Published on: March 7, 2016
Correlation between presence of viable bacteria and presence of endotoxin in middle-ear effusions
J R Dingman1, M G Rayner, S Mishra
1Center for Genomic Sciences, Allegheny University of the Health Sciences, Pittsburgh, Pennsylvania 15212, USA.
Abstract:
The presence of endotoxin (detected by the Limulus amebocyte lysate assay) was compared to the presence of viable Haemophilus influenzae and Moraxella catarrhalis (detected by PCR) in 106 middle-ear effusions from pediatric patients with chronic otitis media. Endotoxin was found in 81 of the 106 specimens. Of these 81 specimens, 66 (81.5%) also tested positive for one or both of the gram-negative bacteria H. influenzae and M. catarrhalis. The data suggest that viable gram-negative bacteria, detectable by PCR but often undetectable by culture, may be the source of endotoxin in middle-ear effusions.
Insights
Endotoxin was frequently detected in middle-ear fluid from children with chronic otitis media. This endotoxin likely originates from viable gram-negative bacteria, such as Haemophilus influenzae and Moraxella catarrhalis, identified via PCR.
Area of Science:
- Microbiology
- Pediatric Otolaryngology
- Molecular Diagnostics
Background:
- Chronic otitis media is a common pediatric condition.
- Endotoxin presence in middle-ear effusions (MEE) is linked to inflammation.
- The source of endotoxin in MEE is not fully understood.
Purpose of the Study:
- To investigate the association between endotoxin and viable gram-negative bacteria in pediatric chronic otitis media.
- To determine if PCR can identify bacteria missed by traditional culture methods in MEE.
Main Methods:
- Limulus amebocyte lysate (LAL) assay was used to detect endotoxin in 106 MEE specimens.
- Polymerase chain reaction (PCR) was employed to detect viable Haemophilus influenzae and Moraxella catarrhalis.
- Specimens were obtained from pediatric patients diagnosed with chronic otitis media.
Main Results:
- Endotoxin was detected in 81 out of 106 (76.4%) MEE specimens.
- Of the endotoxin-positive specimens, 66 (81.5%) also tested positive for H. influenzae and/or M. catarrhalis via PCR.
- PCR identified viable gram-negative bacteria in cases where culture methods might have failed.
Conclusions:
- Viable gram-negative bacteria, particularly H. influenzae and M. catarrhalis, are a likely source of endotoxin in pediatric chronic otitis media.
- PCR is a valuable tool for detecting viable bacteria in MEE, potentially offering a more comprehensive etiological diagnosis.
- Understanding the source of endotoxin may inform future therapeutic strategies for chronic otitis media.
