Pediatric Peritonsillar Abscess

Peritonsillar abscess generally occurs in the superior pole of the tonsil. It can also be present at the midpoint or inferior pole of the tonsil or have multiple loculations within the peritonsillar space. The development of the abscess is often gradual, with an early stage of peritonsillar cellulitis. If not properly treated, an abscess emerges.

Two mechanisms have been proposed to explain the development of a collection of pus in the loose connective tissue of the supratonsillar fossa. The more common explanation is that a peritonsillar abscess develops from an inadequately treated bacterial tonsillitis. An alternative explanation is that a peritonsillar abscess is an abscess formed in a group of salivary glands in the supratonsillar fossa, known as Weber glands.

Lymphatic drainage from an infected peritonsillar abscess is to the ipsilateral jugulodigastric nodes. Bacterial cultures that are also adequate for the recovery of anaerobic bacteria usually yield polymicrobial aerobic and anaerobic bacteria. Group A beta-hemolytic streptococci is recovered in 25-40% of the abscesses. Anaerobic bacteria is isolated in over 90% of aspirated pus, ^[4] and elevated antibody levels to these organisms is detected in most patients with peritonsillar abscess. ^[5] Methicillin-resistant Staphylococcus aureus (MRSA) has been isolated with greater frequency in peritonsillar abscesses in recent years. ^[6]

Most peritonsillar abscesses are polymicrobial. If appropriate microbiologic techniques are used, a positive culture of aerobic and/or anaerobic pathogens is found in 60-80% of aspirates. ^[7]

Bacterial growth is often polymicrobial, including aerobic and anaerobic bacteria of oral flora origin. More than half of the aerobic (ie, S aureus) and anaerobic (ie, Prevotella, Porphyromonas, and Fusobacterium species) isolates can be beta-lactamase producers.

Streptococcus pyogenes may be absent in over half the cases, and the causative organisms may be anaerobic bacteria. ^[8]

Aerobic bacteria implicated in peritonsillar abscess include the following:

• Group A beta-hemolytic streptococci -S pyogenes most commonly isolated aerobe; other beta-hemolytic streptococci are groups C and G

• S aureus (methicillin susceptible or methicillin resistant) ^[9]

• Alpha-hemolytic streptococci

• Coagulase-negative staphylococci

• Streptococcus pneumoniae (penicillin susceptible or penicillin resistant)

Anaerobes implicated in peritonsillar abscess include the following ^{[4, 5]} :

• Anaerobic gram-negative bacilli (eg, pigmented Prevotella and Porphyromonas species, Bacteroides species)

• Peptostreptococcus species

• Fusobacterium species (Fusobacterium nucleatum predominated in recent studies) ^[10]

Viruses do not seem to play a role in the pathogenesis of peritonsillar abscess. ^[11]

Differentiating between peritonsillar abscess and peritonsillar cellulitis is often difficult because the pathogenesis is similar and patients present with similar symptoms. ^[12]  Only patients with a peritonsillar abscess require a drainage procedure, whereas patients with either peritonsillar abscess or peritonsillar cellulitis are treated with antibiotics.

Clinical signs such as trismus and inconsistent drooling have been associated more often with peritonsillar abscess. No method to differentiate between the two is perfect; however, current methods include the following:

• Observing the patient's response to 24-48 hours of intravenous antibiotics

• Attempting needle aspiration of the site

• Using an imaging modality such as CT scanning or ultrasonography ^{[13, 14, 15]}

United States statistics

The estimated incidence in the United States is 30 cases per 100,000 person-years in patients aged 5-59 years. ^[16] The incidence in children younger than 18 years is 14 cases per 100,000 population. Approximately 25-30% of patients with peritonsillar abscess are in the pediatric age group. ^[17]

A study by Qureshi et al analyzed temporal trends in the incidence and surgical management of children with peritonsillar abscesses. The study found that there was no change in the incidence from 2000 to 2009 but there was a change in surgical management, with a significant decrease in the rate of tonsillectomy and significant increase in the rate of incision and drainage procedures. ^[18]

International statistics

The incidence of peritonsillar abscess in Ontario, Canada, was 12 cases in 100,000 population. ^[19]

The mean annual incidence of peritonsillar abscess in Europe was 41 cases in 100,000 population. ^[15]

Race-, sex-, and age-related demographics

No race predilection is known.

No sex predilection is reported.

Peritonsillar abscess most commonly occurs in the third and fourth decades of life. Pediatric cases are more common in children older than 10 years, although cases have been described in children younger than 1 year.

Prognosis is good for full recovery when patients are treated with a combination of a drainage procedure and the appropriate antibiotic therapy. After one aspiration, 80-90% of PTAs resolve. An additional 5-10% of PTAs resolve with repeat aspiration.

If patients have not already undergone an abscess tonsillectomy, PTA is considered as a relative indication for interval tonsillectomy in the following patients:

• Patients who have had recurrent tonsillitis prior to PTA

• Patients who have a recurrent PTA

In rare instances, PTA can recur after a bilateral tonsillectomy.

Morbidity/mortality

The mortality rate is unknown. Mortality is often due to aspiration of a ruptured abscess or sequelae of sepsis. Morbidity stems principally from pain and dehydration.

Complications

Note the following possible complications:

• Airway compromise

• Aspiration of abscess contents (spontaneously or with incision and drainage) and development of aspiration pneumonia

• Parapharyngeal abscess

• Septic thrombophlebitis involving the internal jugular vein (Lemierre syndrome) or internal carotid artery leading to septicemia with metastatic foci of infection, especially in the lung (Lemierre syndrome, caused by Fusobacterium)

• Carotid artery rupture

• Pseudoaneurysm of the carotid artery

• Sepsis

• Hemorrhage as a result of iatrogenic injury to major vessels on attempted aspiration or incision and drainage

• Mediastinitis

• Necrotizing fasciitis

• Contiguous spread to the pterygomaxillary space

• Septic and nonseptic complications of group A streptococcus infection

A literature review conducted by Klug et al revealed that descending mediastinitis was the most frequently reported complication in patients with peritonsillar abscess, followed by parapharyngeal and retropharyngeal abscess, necrotizing fasciitis, and Lemierre syndrome. Overall, 17 different complications were found in the studies examined, with an overall mortality rate of 10%. The researchers also reported that male gender and age over 40 years seemed to be risk factors for complications. ^[20]

Instruct patients to return for further care with occurrence of the (1) difficulty breathing and/or (2) an inability to tolerate oral intake

For patient education resources, see the WebMD articles Peritonsillar Abscess, Tonsillitis, and Antibiotics.