What are middle ear infections?

Middle ear infections occur when fluid trapped behind the eardrum (tympanic membrane) becomes infected with a virus or bacteria, causing an earache, fever and temporary hearing loss. The medical name for the condition is acute otitis media.

Although middle ear infections can occur in anyone, they are most common in infants aged 6-18 months and children who are starting school. 

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

The middle ear

The ear is made up of three main parts - the outer ear, middle ear and inner ear. Two narrow passages, known as Eustachian tubes, connect each middle ear to the back of the throat. These parts work together to control hearing and balance.

The outer ear collects soundwaves and channels them through the ear canal to the eardrum. In a healthy state, the middle ear is an air-filled space that contains three tiny bones, known as the malleus ('hammer'), incus ('anvil') and stapes ('stirrup'). These bones pass soundwaves to the inner ear. The fluid-filled inner ear then converts soundwaves into electrical signals, which are sent to the brain for processing.

Cross-section of an ear.The anatomy of the ear. 

Inner ear

The innermost portion of the ear embedded in the temporal bone, including the semicircular canals and the cochlea.

Outer ear

The external part of the ear, made of cartilage and bone, leading to the eardrum.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Causes

Middle ear infections occur when a Eustachian tube becomes blocked, allowing fluid and pus to build up behind the eardrum. Fluid trapped in the middle ear provides an ideal environment for microorganisms to thrive. In most cases, the cause of infection is a cold or flu virus, such as rhinovirus, coronavirus, parainfluenza, adenovirus or respiratory syncytial virus (RSV). Bacterial infections are usually caused by Streptococcus pneumoniaeMoraxella catarrhalis or Haemophilus influenzae

Pain can be felt when there is a build-up of fluid, which stretches the eardrum.

 

Middle ear infection is characterised by the presence of infected fluid in the Eustachian tube. 

Although middle ear infections are not technically contagious, the viruses and bacteria that cause them are spread by an infected person sneezing or coughing droplets of fluid into the air that are then breathed in by another person. Similarly, the infections can be passed on by close contact, or by sharing contaminated towels, bed linen or clothing.

Pus

A bodily fluid that is the result of an inflammatory response at an infection site. Its colour can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Risk factors

Children, especially younger than seven years old, are more prone to middle ear infections than adults. This is partly because they have shorter, more horizontal Eustachian tubes. This results in more infections due to the decreased distance for microorganisms to travel and less effective fluid drainage from the ear.

Children have shorter Eustachian tubes compared to adults. 

Other risk factors that can increase your child's likelihood of developing middle ear infections include:

  • Being prone to colds;
  • Eustachian tube abnormalities;
  • Having a weakened immune system;
  • Exposure to crowded environments, such as day-care centres and schools;
  • A personal or family history of middle ear infections;
  • Certain medical conditions such as cleft palate or Down syndrome;
  • Premature birth;
  • Exposure to tobacco smoke;
  • Lying on the back while drinking or feeding;
  • Bottle-feeding, and;
  • Using a dummy.

In adults, the risks of developing middle ear infections are being prone to colds, having a weakened immune system and a history of the condition.

Immune system

The organs and cells involved in protecting the body against infection.

Signs and symptoms

Middle ear infections usually develop suddenly after a cold or sore throat. Common symptoms across all ages include:

  • Earache, particularly when lying down;
  • Fever;
  • Temporary reduction in hearing or hearing loss;
  • Feeling sick, and;
  • Redness of the eardrum (only visible on internal examination by your doctor).

In young children who are unable to voice what they are feeling, you may also notice:

  • Loss of balance;
  • Reduced hunger;
  • Disrupted sleep;
  • Irritation and behavioural problems, and;
  • Pulling or rubbing the ears.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Methods for diagnosis

Your doctor will most likely diagnose middle ear infections by asking about symptoms and looking in the ear with an instrument called an otoscope. From this examination, your doctor may be able to see signs of infection, including:

  • A bulging eardrum that looks red or cloudy;
  • Fluid, blood or pus behind the eardrum, or;
  • A burst eardrum.

If further tests are needed, you may be referred to an ear, nose and throat (ENT) specialist. 

An otoscope is used to diagnose an ear infection. 

Pus

A bodily fluid that is the result of an inflammatory response at an infection site. Its colour can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Types of treatment

Middle ear infections in children usually clear completely in 1-2 weeks without any treatment. In most cases, the earache does not last longer than 2-3 days. For this reason, your doctor may suggest a 'watchful waiting' period of 48 hours before prescribing your child any specific treatment.

Self care

During this time, some home measures to relieve pain could include applying a warm compress to the affected ear or giving an over-the-counter medication, such as paracetamol or ibuprofen.

Antibiotics

If symptoms still remain after 48 hours, an antibiotic medication such as amoxicillin or cefaclor may then be prescribed by a doctor.

However, antibiotics are also sometimes prescribed without a 'watchful waiting' period if symptoms are particularly severe or there is an increased risk of complications. For example, children are considered to be at greater risk if they are under six months old or have another issue, such as a weakened immune system, burst eardrum or infection in both ears.

In adults, most middle ear infections clear without treatment in a few days, although antibiotics may be prescribed if symptoms are severe or ongoing.

Immune system

The organs and cells involved in protecting the body against infection.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Potential complications

Middle ear infections in children and adults who are otherwise healthy usually clear completely. However, if an infection is ongoing or keeps coming back, the following complications are a possibility:

Temporary hearing loss

In most cases of middle ear infections the fluid remains behind the eardrum for a short time after the infection has passed, causing mild, short-term hearing loss. However, hearing usually returns to normal after the fluid has drained away. Prolonged hearing loss in children and infants can sometimes lead to reduced responsiveness or developmental delays in speech and social skills.

Burst eardrum

Middle ear infections can sometimes cause an eardrum to burst. Signs of a burst eardrum include sudden pain relief and fluid leaking from the ear. In most cases, the eardrum will heal in a few days without any lasting damage. Sometimes though, medication or surgery may be required to repair the eardrum. The medical name for an ongoing ear infection that results in a burst eardrum is chronic suppurative otitis media.

Fluid can sometimes leak from the ear for weeks or even months after an infection has cleared. When there is fluid in the middle ear without infection, the condition is known as otitis media with effusion, or glue ear. Mild hearing loss may continue until the fluid drains, but most cases pass without the need for treatment.

Recurrent infection

Recurrent otitis media describes middle ear infections that have occurred three times in six months, or four times in 12 months. These types of infections are sometimes treated with a surgical procedure known as a myringotomy. During this procedure, a small plastic tube (grommet) is placed into the eardrum to help fluid drain from the middle ear. The eardrum usually heals after the tube falls out, or is removed by your doctor.

Although rare, sometimes a recurrent infection can lead to an abnormal collection of skin cells in the ear (cholesteatoma), or a pus-filled swelling in the brain (abscess).

Temporary facial paralysis

In very rare situations, swelling associated with middle ear infections can press on a section of the nerve that controls facial expressions. When this occurs, all or part of the face may become paralysed. Although this can be frightening, full movement and control usually returns once the infection clears and swelling goes down.

Spread of infection

If middle ear infections recur or are left untreated, they can spread and cause infection in the following areas:

  • Mastoid bone behind the ear (mastoiditis);
  • Inner ear (labrynthitis), and;
  • Brain and its lining (meningitis).

Such a spread of infection is rare, but can be serious or life-threatening if not treated quickly. Seek urgent medical attention if symptoms progress to include hearing loss, swelling behind the ear, dizziness, loss of balance, confusion, headache, fever, seizures, weakness, paralysis, rapid breathing or a blotchy rash.

Inner ear

The innermost portion of the ear embedded in the temporal bone, including the semicircular canals and the cochlea.

Pus

A bodily fluid that is the result of an inflammatory response at an infection site. Its colour can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.

Eardrum

The thin membrane between the external and middle ear that converts soundwaves into vibrations, which are then transmitted to the inner ear.

Prognosis

In most cases of middle ear infections, the earache passes in 2-3 days without the need for antibiotic medications or other treatments. The overall infections and any associated hearing loss usually clear completely within 1-2 weeks. Antibiotics may be prescribed if symptoms are severe, or if other factors increase the risk of complications.

Generally though, the outlook for middle ear infections is very good and serious complications are now rare in developed countries. Some children may experience several ear infections, but most outgrow the condition without any lasting damage or hearing problems.

Prevention

In most cases, middle ear infections cannot be prevented. However, it may be possible to reduce the chances of developing an initial viral infection by keeping children away from people with cold or flu symptoms. Similarly, teaching children good hygiene habits, such as washing hands and covering their mouth when coughing or sneezing can also help to prevent the spread of viral infections. 

Vaccinations against Streptococcus pneumonia (pneumococcal bacteria), Haemophilus influenzae type B (Hib) and the seasonal flu virus can also help to prevent middle ear infections.

Breastfeeding your child, eliminating household tobacco smoke and discontinuing dummy use after 6-12 months of age may also help to prevent the likelihood of contracting middle ear infections. If bottle-feeding, it is generally recommended to do so with the child sitting upright and not lying down. 

Vaccinations

The practice of administering a vaccine, a solution containing a microorganism (that causes a specific disease) in a dead or weakened state, or parts of it, for the purpose of inducing immunity in a person to that microorganism.