Link: http://scienceblogs.com/retrospectacle/2006/09/ear_infections_hows_this_for_p.php
Yeah, I have an ear infection (otitis media). So, why not take this opportunity to describe what an ear infection is, why it hurts, and what you can do about it.
Otitis media literally means "middle ear inflammation," but it really refers to the build-up of infected fluid in the spaces in the middle ear, behind the ear drum, which are usually filled with air. This causes pressure to accumulate in this space, which translates to pain and the feeling of "ear fullness." The pressure can distort the ear drum slightly, which also causes pain and a reduced ability to hear in that ear. Children get these types of infections much more commonly than adults.
Above is a side-view diagram of the outer, middle, and inner ear. Specifically, notice the canal in the ear called the Eustachian tube. This tube connects the middle ear to the throat, and is important in the equalization of pressure. Ever notice that when you are flying, pressure builds up--and by swallowing/drinking/etc you can clear out this pressure? That is because of the Eustachian tube. However, as it is connected to the throat, this presents a very convenient highway for bacteria from the throat to travel to the middle ear and cause an infection. As to why children get more frequent ear infections, its purely a physical problem: they are smaller, and their Eustachian tubes are shorter than adults. This equates a much smaller distance that infective bacteria have to travel. The fact that a child's immune system is less developed also plays a role.
So, the "ideal" conditions for otitis media to occur is when a person already has a throat or sinus infection, and this infection travels via the Eustachian tube to the middle ear. Streptococcus pneumoniae and Haemophilus influenzae are the most common bacterial causes of otitis media, although it can also be caused by Moraxella catarrhalis, a gram-negative, aerobic, oxidase positive diplococcus. The common cold can also induce otitis media.
In severe cases, the build up of pressure can cause the rupture of the ear drum (this is also a surgical option to remove the fluid). While this sounds traumatic, it *does* relieve the pain, and in almost all cases, the ear drum heals itself. Otitis media usually resolves itself, although antibiotics can be prescribed to treat the infection. In children, a common protocol is to wait 72 hours after the onset of infection to prescribe antibiotics, in the interest of using these drugs as sparingly as possible as to not induce drug-resistent forms of bacteria from propagating.
Shelley Batts is a Neuroscience PhD candidate at the University of Michigan. She studies hair cell regeneration in the cochlea, and is just embarking on that quixotic quest called 'thesis.' She lies awake at night pondering how science intersects with politics, culture, policy, money, medicine, and religion in an attempt to be more than just a niche scientist sitting in the oh-so-lovely ivory tower. Follow me and my parrot on the quest to get funded, get a PhD, and stay sane.
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