Boy presents with sore ear, swelling

March 24, 2022

2 min read

A 4-year-old boy comes to your office with a sore right ear. The problem was first noted about 3 days ago with the onset of some minor discomfort.

As the pain worsened, the parent noted that there was some swelling near the ear canal. They deny any direct injury, but there have been several insect bites about the face and neck area associated with lots of outdoor play activity. There are no other complaints, and the boy's immunizations are up to date.

Figure 1. Swollen tragus with shiny overlying skin. Source: James H. Brien, DO.

Examination reveals normal vital signs and a swollen left tragus, with shiny overlying skin and erythema involving the surrounding area (Figure 1). There is also a small mark just inferior of the tragus, which appears to have a small scab, likely representing an old insect bite that was scratched open. You diagnose a tragus abscess with mild cellulitis and consult an otolaryngologist for drainage (Figure 2).

Figure 2. Surgical drainage of tragus abscess. Source: James H. Brien, DO.

What's your diagnosis (most likely cause)?

A. Haemophilus influenzae type b
B. Pseudomonas aeruginosa
C. Staphylococcus aureus
D. Streptococcus pyogenes

Figure 3. Purulent drainage of tragus abscess. Source: James H. Brien, DO.

Answer and discussion:

Staphylococcus aureus (choice C) grew from the culture of the pus drained by the otolaryngologist (Figure 3). The port of entry was likely the break in the skin from the insect bite nearby. Statistically, staph would be expected to be the most likely cause of any skin infection in an otherwise healthy, immunized young child. Infected earring placement is another mechanism of unusual infections about the auricle and is almost always caused by S. aureus. Streptococcus pyogenes (group A strep, or GAS) is also possible, just not as likely, especially with abscess formation and relatively slow progression. GAS soft tissue infections typically result in rapidly spreading cellulitis or erysipelas, an infection that spreads through the superficial lymphatic vessels of the upper layers of the dermis, with a sharply defined, slightly raised border. The focus can originate in the ear canal, with colonization and skin breakdown (Figure 4).

Figure 4. Group A strep erysipelas involving the face, ear canal and auricle. Source: James H. Brien, DO.

Infections about the ear can also be caused by gram-negative bacilli, most notably Pseudomonas aeruginosa, particularly in older patients, but they are not necessarily associated with a break in the skin. Haemophilus influenza type b infections, such as buccal cellulitis (Figure 5), are very rare in immunized children. However, when it was commonly seen before the mid-1980s, cellulitis was a common presentation due to bacteremia (Haemophilus is Greek for "blood loving"), with facial/buccal cellulitis being a typical manifestation, and it was frequently associated with bacteremia and meningitis.

Figure 5. Haemophilus influenzae type b buccal cellulitis. Source: James H. Brien, DO.

Spontaneous swelling and erythema of the auricle without a traumatic port of entry for bacteria may be initiated by other processes, such as damage of the skin due to a herpes virus — including herpes simplex virus (Figure 6) or varicella zoster virus — or damage from atopic dermatitis.

Figure 6. Herpes simplex virus infection of the auricle. Source: James H. Brien, DO.

For more information:

Brien is a member of the Healio Pediatrics and Infectious Disease News Editorial Boards, and an adjunct professor of pediatric infectious diseases at McLane Children's Hospital, Baylor Scott & White Health, in Temple, Texas. He can be reached at jhbrien@aol.com.

Pseudomonas Aeruginosa Treatment