Prospective observational case series evaluating middle ear fluid and tympanostomy tubes through pyrosequencing.

OBJECTIVE

One of the most common sequelae of tympanostomy tube (TT) placement is post-tympanostomy tube otorrhea (PTTO). Granulation tissue formation has been reported in 5-13.8% of patients with TT placement. The purpose of this study is to determine the biodistribution of microorganisms on TTs and middle ear fluid obtained from patients with PTTO.

METHODS

This was a prospective observational study of subjects (6-months-16-years) who underwent standard of care treatment for chronic PTTO. Data was collected on diagnosis, existence of antibiotic resistance, duration of tube placement, and evidence of recurrent infection and/or PTTO. TTs and middle ear fluid were subjected to pyrosequencing; additionally, ear fluid samples were sent for culture-based laboratory diagnostics.

RESULTS

DNA-pyrosequencing analysis of bacteria from fluid and TTs of pediatric subjects with PTTO revealed a mixture of both aerobic and anaerobic populations. Retained tubes with minimal otorrhea revealed a predominance of Staphylococcus species, normal external auditory canal (EAC) microbiome, within middle ear fluid as well as on TTs. However, TTs with active mucopurulent otorrhea and granulation tissue unveiled prominence of Gram-negative facultative anaerobes such as Pseudomonas and Eikenella. Discrepancies in prominent bacteria were seen between standard culture-based techniques versus pyrosequencing.

CONCLUSION

Retained tympanostomy tubes are colonized primarily with normal flora of the EAC. However, mucopurulent otorrhea associated with granulation tissue formation revealed a prominence of Gram-negative facultative anaerobes. Standard culture-based diagnostics may identify bacteria, which are not predominant species of infection. Future studies are necessary to assess the association of Gram-negative facultative anaerobes with granulation tissue formation.