Objectives

• Understand the pathophysiology of an ear infection
• Identify the common agents that cause ear infections
• Recognize the common presenting complaints for otitis media and otitis externa
• Discuss the current treatments for ear infections and special considerations
  

Introduction

Pediatric ear infections are one of the most pervasive illnesses in infants and children, arising with wide ethnic variation. Infections frequently occur in the middle or external ears. Acute otitis media (AOM) constitutes 13% of all emergency department visits and more than 70% of children <2 years old experience at least one episode. As the leading cause of conductive hearing loss, it is important to correctly diagnose, treat and prevent this condition. A recent decline in AOM coincides with the introduction of pneumococcal conjugate vaccine (PCV) in 2000. Otitis externa (OE) is a condition often seen in children who have a history of aquatic activities or over-manipulation of the ear canal, as with scratching.

Acute otitis media begins with a precipitating event, most commonly viral upper respiratory tract infections (URI). URIs cause inflammation of the nasopharynx, building edema and secretions.  Eustachian tube dysfunction or anatomical abnormalities contribute to a higher risk of colonization; for example, shorter auditory tubes provide shorter paths for the bacterial pathogens to transit from the nasopharynx to the ear. Additionally, horizontal arrangement of tubes prevents proper drainage of fluids.  Pathogens can secondarily infect this stagnant fluid, adding painful negative pressure in the Eustachian tube. The most common bacteria agents are Streptococcus pneumonia, non-typeable Haemophilus influenza, and Moraxella catarrhalis. Young children with immunologic naiveté may not have achieved protection even after several doses of effective vaccines, contributing higher risk for infection.

Chief complaints of AOM include ear pain, headache, vomiting and otalgia. The differential diagnosis includes otitis media with effusion (OME), tympanic membrane (TM) perforation, cholesteatoma, traumatic disruption of ossicles, hemotympanum or basilar skull fractures.  It is important to distinguish AOM and OME. OME is a condition involving asymptomatic middle ear effusion without acute signs of infection.  Ninety percent of children experience this before 5 years of age, making it a more common diagnosis than AOM. It may precede or be an inflammatory response following AOM and does not signify an infection necessitating antibiotics.

OE is a superficial infection of the external ear, developing from obstruction, absence of cerumen, trauma or alteration of the pH in the ear canal. These situations cause a buildup fluid, as with AOM, and provide a suitable environment for infection. The condition is often caused by the Pseudomonas or Staphylococcusbacterial species.  Otitis externa commonly presents with otalgia, pruritis, conductive hearing loss, tinnitus or discharge.  Differential diagnoses include furunclulosis, contact dermatitis, chondritis, AOM with perforated TM or malignant otitis externa.

Initial Actions and Primary Survey

If ear infection is suspected, pneumatic otoscopy can be used to examine the external auditory canal, TM, middle ear and assess TM mobility. The lateral expansion of the TM, upon pressure release from the pneumatic attachment, is important in diagnosing AOM.

Presentation

In general, clinical history is not helpful in making an AOM diagnosis, because it is often indistinguishable from URIs.  Classically, AOM presents with rapid, acute onset and a host of nonspecific symptoms such as fever, irritability, feeding problems, discharge, headache, ear-pulling, anorexia, and vomiting.  Otalgia is the most consistent sign, with a distinctively, strongly or moderately red TM on physical exam being 51-60% predictive.  Cloudiness, bulging or immobility of the TM are also indicative associations.  It is important to remove cerumen via irrigation or manual extraction to clearly check the TM for color, opacification, position and mobility; normally the TM is translucent, pearly gray with visible landmarks. The American Academy of Pediatrics further defines an AOM diagnosis as including: 1) moderate-to-severe bulging of TM or new onset of otorrhea or 2) mild bulging of the TM + acute onset of ear pain or intense erythema of TM.  Pneumatic pressure resulting in immobile or bulging TM is used to rule out OME and OE.

The clinical history for OE may be more helpful in assessing history of swimming, scratching or excessive cleaning.  On physical exam, external ear may be erythematous with edema and exudate.  The TM should be mobile as opposed to AOM. Pull on the tragus to assess pain and tenderness.  The mastoid bone should be palpated for tenderness to rule out mastoiditis.  The internal ear should be examined with otoscope for redness, swelling, discharge or masses.

Diagnostic Testing

Tympanocentesis can be performed to obtain culture of the external or middle ear. Complete blood counts are obtained for serious infections. These diagnostics are especially relevant for recurrent infections or immunocompromised patients to identify the precise pathogens. CT scans are performed to exclude basilar skull fractures, mastoiditis and malignancies.

Treatment

According to 2013 AAP guidelines, first line treatment for AOM is high dose amoxicillin (80-90 mg/kg/day) in 2 doses, which is effective against common AOM pathogens. This drug is safe, low cost, with acceptable taste and a narrow microbiological spectrum.  Patients who received amoxicillin in the last 30 days should be treated with high dose amoxicillin-clavulanate (90/6.4 mg/kg/day in 2 doses).  Alternatives include 2nd or 3rd generation cephalosporins, such as cefdinir, cefuroxime, cefpodoxime, or ceftraiaxone. The standard duration for treatment is 10 days for children under 2 years. A 5-7 day course is recommended for older children with mild to moderate AOM.

There has been recent debate regarding the benefits of “watchful waiting” as a treatment option. Hoberman et al. and Tähtinene et al. conducted placebo-controlled trials of amoxicillin-clavulanate for AOM in children under 3 years. These two randomized trials found modest, statistically significant, positive effects of antimicrobial treatment. However, antimicrobials can produce undesirable side effects, such as diarrhea and contribute to the emergences of antibacterial-resistant bacterial strains. There is also debate over the observation that many ear infections resolve well without antimicrobial intervention. The controversy over observation without antimicrobial therapy remains, although the majority of ear infections are treated in the U.S.

Ear pain should be treated regardless of the antibiotic regimen, typically with oral ibuprofen or acetaminophen.  Topical agents, such as antipyrine solution, lignocaine, naturopathic solution are used for short-term relief in older children.

References

1. Lee, Hobart, Jeffrey Kim, and Van Nguyen. “Ear Infections: Otitis Externa and Otitis Media.” Primary Care 40, no. 3 (September 2013): 671–86. PMID: 23958363.
2. Mandel, Ellen M., and Margaretha L. Casselbrant. “Treatment of Acute Otitis Media in Young Children.” Current Allergy and Asthma Reports 12, no. 6 (December 2012): 559–63. PMID: 23011596.
3. Nesbit, Chadd E., and Margaret C. Powers. “An Evidence-Based Approach to Managing Acute Otitis Media.” Pediatric Emergency Medicine Practice 10, no. 4 (April 2013): 1–26. PMID: 23971270.
4. Pelton, Stephen I., and Eugene Leibovitz. “Recent Advances in Otitis Media:” The Pediatric Infectious Disease Journal 28 (October 2009): S133–S137. PMID:  19918136.
5. Thomas, Nicole M., and Itzhak Brook. “Otitis Media: An Update on Current Pharmacotherapy and Future Perspectives.” Expert Opinion on Pharmacotherapy 15, no. 8 (June 2014): 1069–83. PMID: 24793547.