Oxygen consumption by bacteria: a possible cause of negative middle ear pressure in ears with otitis media.

Conclusions: Oxygen consumption by bacteria could be a cause of the negative middle ear pressure in ears with otitis media (OM).

Objective: To determine whether oxygen consumption by bacteria could be a cause for production of negative pressure in ears with OM.

Materials and methods: Hermetically sealed bottles containing high dose (group A) and low dose (group B) of Streptococcus pneumoniae with air space and maintained at 37 degrees C in a water bath were connected to a micropressure sensor. The chronological pressure changes were monitored in vitro for 3-13 h and were compared with those in the control bottles containing culture medium only.

Results: The pressure of the group A samples showed significantly lower values than that of controls 3 h later (p<0.0001). In group B, the pressure was also significantly lower than that in the control group (p<0.0001). The partial pressures of oxygen measured at the beginning and end of the experiment in the six samples in group B showed significant decrease, while that in the control group showed only a slight decrease (p<0.0019).