Our previous studies have suggested a close relationship between vasopressin and endolymphatic hydrops, or the increased volume of endolymph in the inner ear. Endolymphatic hydrops is also thought to occur in Ménière's disease patients. In the kidney collecting duct, vasopressin induces the expression of aquaporin-2 (AQP2), resulting in increased water reabsorption. We explored the possibility, using a quantitative PCR method, that vasopressin regulates the expression of AQP2 mRNA in the rat inner ear, as it does in the kidney. The levels of AQP2 mRNA in the cochlea and endolymphatic sac were significantly higher in rats treated with vasopressin than the levels in control animals. We speculate that over-expression of AQP2 may be involved in the formation of endolymphatic hydrops.

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Background: Acute otitis media (AOM) is a common ear infection caused by respiratory viruses and bacteria of the nasopharynx. The present study aimed to detect various respiratory viruses and bacteria in middle ear fluid (MEF) and nasopharyngeal aspirates (NPA) using polymerase chain reaction (PCR). Methods: We collected MEF and NPA samples from 122 pediatric patients with AOM. Real-time PCR detected 11 types of respiratory viruses (respiratory syncytial virus A/B, parainfluenza virus 1/2/3, human metapneumovirus, influenza virus A/B, adenovirus, human bocavirus and rhino virus) and 7 types of bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Streptococcus pyogenes, Legionella pneumophila and Moraxella catarrhalis). MEF specimens were also examined using bacterial culture. Results: At least 1 respiratory viral or bacterial pathogen was detected in MEF of 120 cases (98%) by viral and bacterial PCR and of 93 cases (76%) by viral PCR and bacterial culture. Respiratory viruses were detected in NPA of 84 cases (69%) and MEF of 67 cases (55%). The most common virus detected in MEF was respiratory syncytial virus (21%), followed by parainfluenza virus (15%). All the viruses present in MEF were also detected in NPA specimens. Bacteria were detected by PCR in MEF of 109 cases (89%); H. influenzae was the most frequently detected (65%). Conclusions: In many cases, pediatric AOM was found to constitute a respiratory polymicrobial infection. Multiplex PCR was useful to detect multiple respiratory viruses and bacteria in AOM. To understand intractable AOM, further studies regarding the clinical features of each viral and bacterial coinfection are required.

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