Peritonsillar cellulitis and abscess

INTRODUCTION — 

The clinical features, evaluation, and management of peritonsillar cellulitis (also called peritonsillitis) and abscess will be discussed here. Cervical lymphadenitis, retropharyngeal cellulitis and abscess, and other deep neck space infections are discussed separately. (See "Cervical lymphadenitis in children: Etiology and clinical manifestations" and "Retropharyngeal infections in children" and "Deep neck space infections in adults".)

DEFINITIONS — 

Two terms are used to describe infection of the peritonsillar region:

●Peritonsillar cellulitis – Peritonsillar cellulitis is an inflammatory reaction of the tissue between the capsule of the palatine tonsil and the pharyngeal muscles (figure 1) that is caused by infection but not associated with a discrete collection of pus. An alternate term for cellulitis is phlegmon.

●Peritonsillar abscess – Peritonsillar abscess, a deep neck infection, is a collection of pus located between the capsule of the palatine tonsil and the pharyngeal muscles (picture 1).

In many patients, diagnosing the type of peritonsillar infection present requires ultrasonography, or if ultrasonography is not available, needle aspiration or incision and drainage to determine if pus is present. (See 'Drainage' below.)

Other deep neck infections include retropharyngeal abscess and parapharyngeal space abscess (also known as the pharyngomaxillary or lateral pharyngeal space abscess). These are discussed separately. (See "Retropharyngeal infections in children" and "Deep neck space infections in adults".)

ANATOMY AND PATHOGENESIS — 

The peritonsillar space consists of loose areolar tissue overlying the tonsil and is surrounded by the superior pharyngeal constrictor muscle and the anterior and posterior tonsillar pillars. The palatine tonsils are located between the palatoglossal and palatopharyngeal arches (figure 1) [1]. They are surrounded by a capsule that provides a path for blood vessels and nerves.

Peritonsillar abscess (PTA) usually occurs in the superior pole of the tonsil, manifested by a defined collection of pus between the tonsillar capsule, the superior constrictor, and the palatopharyngeus muscle (picture 1). PTA also may occur in the midpoint or inferior pole of the tonsil or may be dispersed with multiple loculations in the peritonsillar space [2].

Peritonsillar infection generally precedes tonsillitis or pharyngitis and progresses from pharyngitis to cellulitis (phlegmon) to abscess [2]. PTA also may occur without preceding infection; such cases are thought to be caused by obstruction of the Weber glands (a group of salivary glands in the soft palate just superior to the tonsil and connected to the surface of the tonsil by a duct) [3,4]. Smoking appears to be a risk factor [5,6].

Peritonsillar infection may compromise the upper airway or spread to the surrounding structures, including the masseter and pterygoid muscles and the carotid sheath (figure 2) [1,2]. (See 'Complications' below.)

EPIDEMIOLOGY — 

Peritonsillar abscess (PTA) is the most common deep neck infection in children and adolescents, accounting for at least 50 percent of cases [7,8]. It occurs most frequently in adolescents and young adults but also in younger children [9].

The estimated annual incidence of PTA is 30 per 100,000 persons 5 to 59 years of age [10]. In a population-based review, the overall incidence of suspected PTA, based upon clinical suspicion in children <18 years, was 14 per 100,000; the incidence in adolescents was 40 per 100,000 [11]. The incidence of confirmed PTA by the presence of pus with drainage procedures was 3 per 100,000 for all ages.

MICROBIOLOGY — 

Peritonsillar abscesses are often polymicrobial. The predominant bacterial species are [12-16]:

●Streptococcus pyogenes (group A streptococcus [GAS])

●Streptococcus anginosus

●Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]) and

●Respiratory anaerobes (including Fusobacteria, Prevotella, and Veillonella species)

Haemophilus species are found occasionally. Aerobes and anaerobes are commonly recovered simultaneously if appropriate microbiologic techniques are used.

EVALUATION

Assess airway — Rapid assessment of the degree of upper airway obstruction is the initial step in the evaluation of the patient with a potential peritonsillar abscess (PTA). Anxious, ill-appearing patients with drooling and tripoding (leaning forward with the head in a sniffing position) and respiratory distress must have the airway secured before evaluation. (See "Emergency evaluation of acute upper airway obstruction in children", section on 'Emergency airway assessment and management'.)

Clinical manifestations — The typical clinical presentation of PTA is a severe sore throat (usually unilateral), fever, and a "hot potato" or muffled voice. Pooling of saliva or drooling may be present. Trismus, related to irritation and reflex spasm of the internal pterygoid muscle, occurs in nearly two-thirds of patients; it helps to distinguish PTA from severe pharyngitis or tonsillitis [7,17]. Patients often have neck swelling and pain and may have ipsilateral ear pain [1]. Fatigue, irritability, and decreased oral intake may occur as a result of discomfort.

Historical features are important in guiding management. Important aspects of the history include frequency and severity of recurrent episodes of infectious pharyngitis, previous episodes of PTA, and snoring or other symptoms of obstructive sleep apnea. (See "Tonsillectomy and/or adenoidectomy in children: Overview of indications and contraindications" and "Evaluation of suspected obstructive sleep apnea in children".)

Physical examination — The presence of trismus may limit the ability to perform an adequate examination. If drooling is present, suggesting the possibility of epiglottitis, care must be taken not to be aggressive during the examination of the oral cavity. If there is doubt about whether the patient has a PTA, epiglottitis, or other deep neck space infection, imaging or examination in the operating room may be necessary. Examination in the operating room permits the controlled placement of an artificial airway [2]. (See 'Imaging' below and "Retropharyngeal infections in children" and "Epiglottitis (supraglottitis): Clinical features and diagnosis", section on 'Diagnosis'.)

●Peritonsillar abscess (PTA) – Examination findings consistent with PTA include an extremely swollen and/or fluctuant tonsil with deviation of the uvula to the opposite side (picture 1) [2,18]. Alternatively, there may be fullness or bulging of the posterior soft palate near the tonsil with palpable fluctuance (picture 2).

Bilateral PTA is rare. Clinical diagnosis may be difficult because the classic asymmetric findings are absent [19-22]. Symptoms, such as odynophagia and trismus, may suggest the diagnosis but are not always present. The uvula may be displaced anteriorly [23]. Bilateral PTA may be complicated by upper airway obstruction and snoring [19]. (See 'Complications' below.)

●Peritonsillar cellulitis – Findings in children with peritonsillar cellulitis may include an erythematous pharynx and enlarged tonsils with exudate; uvular deviation and trismus are usually absent [17].

Cervical and submandibular lymphadenopathy may be present in children with PTA or cellulitis.

By comparison, children older than three years of age with simple streptococcal pharyngitis often have enlarged tonsils with exudate with associated tonsillar and/or palatal petechiae (picture 3). (See "Group A streptococcal tonsillopharyngitis in children and adolescents: Clinical features and diagnosis", section on 'Clinical features'.)

Laboratory evaluation — Laboratory evaluation is not necessary to diagnose PTA but may help gauge the level of illness and direct therapy.

The laboratory evaluation of a child with peritonsillar infection, therefore, may include [18]:

●CBC with differential – A complete blood count (CBC) with differential: the white blood cell count (WBC) is usually elevated with a predominance of polymorphonuclear (PMN) leukocytes, although this is a nonspecific finding.

●Serum electrolytes – For patients with decreased oral intake and signs of dehydration. (See "Clinical assessment of hypovolemia (dehydration) in children".)

●Testing for group A streptococcus – Rapid antigen detection testing is preferred, but standard throat culture or molecular assays are acceptable alternatives. (See "Evaluation of acute pharyngitis in adults", section on 'Testing for GAS' and "Group A streptococcal tonsillopharyngitis in children and adolescents: Clinical features and diagnosis", section on 'Choice of test'.)

●Gram stain, culture (aerobic and anaerobic), and susceptibility testing of abscess fluid – It is helpful to send fluid obtained from a drainage procedure for microbiologic testing. Although these results do not necessarily affect the management of uncomplicated patients [10], they may help guide antimicrobial therapy in immunocompromised patients or those with complications or extension of infection. (See 'Drainage' below.)

Imaging — Imaging is not necessary to make the clinical diagnosis of PTA but may be helpful to differentiate PTA from peritonsillar cellulitis. For patients with clinical features of deep neck space infections (eg, retro- or parapharyngeal abscess) or epiglottitis, imaging may help differentiate these serious conditions from PTA.

●Ultrasonography – For patients with a clinical diagnosis of PTA, we obtain ultrasonography (US) by an experienced clinician, whenever available, to confirm the presence of an abscess prior to drainage [24-27].

Performance of intraoral US may be hampered by trismus, pain, gagging, or lack of cooperation. Submandibular or transcervical US avoids these limitations and is uniquely suited for patients with an inadequate oropharyngeal examination [28]. US of the region by either approach appears to be more sensitive and specific than clinical examination [29,30]. PTA appears as an echo-free cavity with an irregular border, and peritonsillar cellulitis appears as a homogeneous or striated area with no distinct fluid collection [24,26,31].

The use of US for the diagnosis of PTA is supported by a meta-analysis of 17 studies (812 patients, mostly adults), in which US was able to distinguish peritonsillar abscess from peritonsillar cellulitis with a pooled sensitivity of 86 percent (95% CI 78-91 percent), specificity of 76 percent (95% CI 67-82 percent), a positive likelihood ratio of 3.5, and a negative likelihood ratio of 0.19 [27]. Subgroup analysis suggested improved diagnostic characteristics for intraoral US and for radiologist-performed US. However, most patients underwent submandibular US, and the six individual studies that evaluated point-of-care US did not consistently identify the level of experience and training for the operators.

●Computed tomography – Because of the radiation exposure, computed tomography (CT) has no role solely to distinguish PTA from cellulitis. However, contrast CT may demonstrate PTA in some patients undergoing evaluation for deep neck infections. On CT with contrast, PTA appears as a hypodense mass with ring enhancement [32]. Findings consistent with peritonsillar cellulitis include soft tissue swelling, loss of the fat planes, and lack of ring enhancement.

DIAGNOSIS — 

The diagnosis of peritonsillar abscess (PTA) can often be made clinically without laboratory data or imaging in the patient with medial displacement of the tonsil and deviation of the uvula (picture 1). For patients with a clinical diagnosis of PTA, we strongly prefer ultrasonography (US) by an experienced clinician whenever available to confirm the presence of an abscess and, if present, to help guide decisions about drainage. Otherwise, the diagnosis of PTA is confirmed by the collection of pus at the time of drainage, typically needle aspiration [1,33] (algorithm 1). (See 'Imaging' above.)

Clinical features and ultrasound imaging cannot always distinguish PTA from cellulitis [11,34]. A 24-hour trial of antimicrobial therapy (with or without antecedent ultrasonography) may be helpful in this situation [34,35]. Failure to respond to a trial of appropriate antibiotic therapy suggests PTA, whereas response to therapy suggests cellulitis. Response is defined by improvement in at least one clinical parameter: sore throat, fever, trismus, or tonsillar bulge. (See 'Imaging' above and 'Needle aspiration' below and 'Approach' below.)

Imaging with computed tomography (CT) of the neck is not necessary unless there is concern for other conditions (eg, retro- or parapharyngeal infection) or complications such as jugular vein thrombosis, jugular vein suppurative thrombophlebitis (Lemierre syndrome), mediastinitis, or necrotizing fasciitis. (See 'Differential diagnosis' below.)

DIFFERENTIAL DIAGNOSIS — 

The differential diagnosis of peritonsillar abscess (PTA) includes other causes of sore throat, upper airway obstruction, and pharyngeal swelling. Clinical features may be helpful in differentiating PTA from these conditions, but in some cases (particularly in young children) imaging and/or examination in the operating room may be necessary to make a definitive diagnosis.

Major considerations in the differential diagnosis of PTA include [18]:

●Epiglottitis (supraglottitis) – The classic teaching is that epiglottitis is more rapidly progressive than PTA and occurs in younger children. However, with widespread immunization of infants against Haemophilus influenzae type b, epiglottitis is more commonly seen in older children and adults; in these patients, the presentation of epiglottitis may be subtle. Thus, epiglottitis is a diagnostic consideration in any patient with fever, sore throat, drooling, difficulty swallowing, and respiratory distress. (See "Epiglottitis (supraglottitis): Clinical features and diagnosis", section on 'Clinical presentation'.)

Patients with epiglottitis typically present with signs of upper airway obstruction and respiratory distress which typically differentiates it from PTA. Epiglottitis is less common in patients who have received vaccination against Haemophilus influenzae type b. Direct visualization of an inflamed epiglottis is the preferred method of diagnosis. However, a lateral neck plain radiograph, obtained in the presence of personnel with airway expertise and equipment to secure the airway immediately available, may be helpful in selected patients (image 1). (See "Epiglottitis (supraglottitis): Clinical features and diagnosis", section on 'Imaging'.)

Oropharyngeal examination should be avoided in patients with marked respiratory distress. These patients should first have the airway secured. A rapid overview provides the approach to diagnosis and management (table 1). (See "Epiglottitis (supraglottitis): Management", section on 'Approach to airway management'.)

●Retropharyngeal abscess or cellulitis – Retropharyngeal abscess or cellulitis occurs most commonly in younger children between two and four years of age and is associated with minimal peritonsillar findings.

Findings common to both PTA and retropharyngeal abscess include difficulty swallowing, drooling, "hot potato" or muffled voice, and trismus, although trismus is present in only about 20 percent of patients with retropharyngeal abscess. (See "Retropharyngeal infections in children", section on 'Clinical manifestations'.)

Unlike PTA, children with retropharyngeal abscess frequently have one or more of the following findings (see "Retropharyngeal infections in children", section on 'Clinical manifestations'):

•Neck stiffness

•Pain on movement that is worse with neck extension (as opposed to increased pain with flexion as observed in meningitis)

•Neck swelling or mass

•Neck tenderness

•Chest pain (patients with mediastinal extension of the abscess)

CT with intravenous (IV) contrast is the preferred imaging modality for diagnosing retro- or parapharyngeal abscess (image 2) and should be obtained instead of US in patients with suggestive clinical findings when PTA is also a consideration. When performed, careful monitoring during transportation and CT scanning is imperative; mild airway distress can be exacerbated by sedation and positioning. CT should be omitted in children with moderate to severe respiratory distress, particularly when sedation is necessary; such children generally undergo evaluation in the operating room, where an artificial airway can be established as needed. (See "Deep neck space infections in adults", section on 'Clinical suspicion and urgent imaging' and "Retropharyngeal infections in children", section on 'Evaluation and diagnosis'.)

Lateral neck radiographs can also indicate retropharyngeal abscess (image 3) but are not definitive studies to establish the diagnosis. They are most useful when normal. Magnetic resonance imaging or angiography (MRI or MRA) are seldom used during for initial diagnosis. (See "Deep neck space infections in adults", section on 'Clinical suspicion and urgent imaging' and "Retropharyngeal infections in children", section on 'Imaging'.)

●Abscess of the parapharyngeal space – In patients with abscess of the parapharyngeal space, examination may reveal bulging behind the posterior tonsillar pillar rather than superior to the tonsil [33]. Alternatively, there may be medial displacement of the lateral pharyngeal wall. The soft palate and tonsils typically appear normal.

●Severe tonsillopharyngitis – Severe tonsillopharyngitis presents with bilateral equal tonsillar swelling with viral enanthem or exudate. Common causes include Epstein-Barr virus, herpes simplex virus, coxsackievirus (herpangina), adenovirus, diphtheria, group A streptococcus, or gonorrhea. Rarely, bilateral PTA can complicate severe tonsillopharyngitis. Severe trismus is less common. The presence of palpable fluctuance or abscess on ultrasonography can help distinguish bilateral PTA from tonsillopharyngitis.

MANAGEMENT

Approach — The approach to the diagnosis and management of peritonsillar abscess and cellulitis is provided in the algorithm and is determined by clinical examination, degree of illness, and, whenever available, ultrasound (US) imaging (algorithm 1) [2].

Airway compromise — Patients with signs of peritonsillar abscess and airway compromise appear anxious, are leaning forward with the head in a "sniffing position," and have drooling, suprasternal retractions, and respiratory distress. Stridor may or may not be present. These patients require prompt involvement of an airway specialist and emergency consultation with an otolaryngologist. They should proceed to the operating room for endotracheal intubation followed by drainage of the abscess.

Peritonsillar abscess confirmed — Patients with peritonsillar abscess (PTA) confirmed by ultrasound and/or clinical findings should be managed according to the measured or predicted size of the abscess (algorithm 1):

●Small – Patients with a small PTA are nontoxic and have minimal to no trismus. We consider a small abscess to be <1 cm in diameter. However, evidence is lacking for normative values for sizing of PTA on US. These patients require antibiotics, analgesia, and may receive intravenous (IV) hydration as needed; needle aspiration or surgical drainage is not indicated. After a single dose of IV antibiotics (table 2), they can undergo outpatient management as long as they tolerate oral intake including oral antibiotics (table 3) [36].

They should undergo reevaluation within 24 to 36 hours. If there is concern about their ability to have assured outpatient follow-up, then observation should occur in the hospital.

Patients who do not improve during observation or who develop progressive swelling should undergo drainage. Children with small abscesses and without a prior history of tonsillitis are most likely to respond to antibiotics alone [2,34,37]. (See 'Drainage' below.)

●Moderate or large – Patients with a moderate to large PTA (1 cm or greater) are more ill-appearing and have moderate to severe trismus. In our experience, trismus is associated with abscesses 1 to 2 cm or greater in diameter. These patients should receive:

•Pain medication as needed (eg, IV ketorolac)

•IV rehydration with isotonic fluids as needed (eg, lactated Ringer's or normal saline)

•Abscess drainage

•At least one dose of empiric parenteral antibiotics (see 'Parenteral regimens' below)

Drainage should be performed by a properly trained and experienced physician or an otolaryngologist. For bedside drainage in cooperative patients, we suggest needle aspiration rather than incision and drainage because it is less painful and less invasive [38]. (See 'Needle aspiration' below and 'Antibiotic therapy' below.)

Patients with indications for tonsillectomy also require consultation with an otolaryngologist before drainage to decide whether immediate tonsillectomy or drainage followed by interval tonsillectomy is indicated. (See 'Tonsillectomy' below.)

These patients may require hospitalization for continued IV hydration, pain control, and parenteral antibiotics. However, many patients may be discharged home if they improve after abscess drainage and can tolerate oral intake including antibiotics and analgesia. If discharged, they should have assured follow-up within 24 to 36 hours as described above for patients with small abscesses [2,10,11,36].

Peritonsillar infection with equivocal findings — Patients with suspected peritonsillar infection and equivocal findings for abscess on examination and/or US should receive empiric antibiotics [2]. Hospitalization may be necessary for hydration and analgesia, as needed, particularly in younger children. However, patients may be discharged to home rather than being hospitalized if they are well hydrated, have no airway compromise, have assured and adequate follow-up, and can tolerate oral intake including oral antibiotics and oral analgesia (eg, ibuprofen) [36]. They should undergo reevaluation within 24 to 36 hours. If there is concern about their ability to have assured outpatient follow-up, then observation should occur in the hospital.

Drainage or tonsillectomy is reserved for those who do not respond or worsen while receiving medical therapy [34].

There is no consensus regarding the optimal initial management for the remainder of patients with suspected PTA who do not require urgent surgical intervention [10,39]. The approach depends upon a number of clinical factors, including the patient's age and cooperativeness and the degree of certainty of the diagnosis (abscess versus cellulitis). Consultation with an otolaryngologist can help determine appropriate management for the individual patient.

Treatment with antibiotics alone for patients with suspected PTA was evaluated in a retrospective series of 102 children (8 months to 19 years) [35]. Approximately 50 percent of patients responded to medical therapy, and 50 percent underwent tonsillectomy, 80 percent of whom had abscesses at the time of surgery. Children younger than six years were more likely to respond to medical therapy. Children with PTA most likely to respond to antibiotics alone are those less than six years of age, with small abscesses and fewer episodes of previous tonsillitis [37]. In another observational study of over 210 adults and children presenting with clinical features of PTA diagnosed in the emergency department and evaluated by an otolaryngologist, medical therapy (antibiotics and corticosteroids) alone without surgical drainage had similar treatment success compared with medical therapy plus surgical drainage, with less pain, opioid use, and time off from work or school, especially for patients without trismus [36].

Peritonsillar cellulitis — Patients with examination findings consistent with cellulitis and who do not have indications for tonsillectomy or urgent surgical intervention should receive empiric antibiotics and supportive care [3,7,10,34,40-45]. Inpatient versus outpatient management depends upon the patient's ability to tolerate oral medications (antibiotics and analgesics) and fluids.

Patients who are discharged home should receive oral antibiotics for 14 days (see 'Oral regimens' below). A single dose of parenteral antibiotics in the emergency department prior to initiating oral antibiotics is a reasonable option. They should have ensured follow-up within 36 to 48 hours.

Supportive care (all patients) — For all patients with peritonsillar infection, supportive care includes [2]:

●Treatment of dehydration, as needed, and maintenance of adequate hydration

●Analgesia

●Monitoring for complications

Antibiotic therapy — Antibiotic therapy is indicated for all patients with peritonsillar infection [38]. Regimens for parenteral therapy (table 2) and oral therapy (table 3) are provided in the tables and discussed below.

Antibiotic selection — Empiric therapy should include coverage for group A streptococcus, Staphylococcus aureus, and respiratory anaerobes. Antibiotic regimens should be tailored to culture and susceptibility data (if drainage is performed) or based upon clinical response to treatment. When tailoring therapy based upon culture results, the clinician should understand that PTAs are frequently polymicrobial, and not all microbes are consistently cultured.

If drainage is not performed, we decide about coverage for methicillin-resistant S. aureus (MRSA) based upon:

●Severity of illness (moderate to severe degree of illness)

●Prevalence of MRSA in the community >10 percent of S. aureus isolates)

●Increased likelihood of colonization (eg, prior hospitalizations, comorbid conditions, recent broad-spectrum antibiotic coverage, history of frequent skin abscesses)

●Although not immediately available to guide antibiotic therapy, results of a swab of the nose

Parenteral regimens — For patients with a peritonsillar abscess, we suggest at least one dose of intravenous antibiotics. (See 'Peritonsillar abscess confirmed' above.)

Empiric parenteral regimens are chosen based upon the degree of illness and whether the patient has risk factors for methicillin-resistant Staphylococcus aureus (MRSA) (table 2) [18]:

●Nontoxic appearance:

•Suggested regimen:

Ampicillin-sulbactam 50 mg/kg ampicillin per dose intravenously (IV) every six hours in children (maximum single dose 2 g ampicillin); 3 g every six hours in adults (equivalent to 2 g ampicillin and 1 g sulbactam)

•Alternative regimen (penicillin-allergic):

Linezolid:

<12 years: 10 mg/kg IV every 8 hours (maximum total daily dose 1200 mg)

≥12 years: 600 mg IV every 12 hours

Plus

Metronidazole 10 mg/kg IV every 8 hours up to the adult maximum single dose: 500 mg; in adults, 500 mg every 8 hours

If cultures indicate susceptibility, clindamycin is an option. Otherwise, we generally avoid clindamycin if possible due to the risk of Clostridioides difficile infection. In addition, depending upon local susceptibility patterns, clindamycin may not be active against methicillin-susceptible S. aureus, MRSA, or group A Streptococcus [46].

●Moderate or severe disease or empiric MRSA coverage: Patients at risk for MRSA include individuals with moderate to severe clinical disease (eg, toxic appearance, temperature >39°C, drooling, and/or respiratory distress) or have risk factors for MRSA (see 'Antibiotic selection' above). For these patients, suggested initial empiric regimens include:

•Suggested regimen:

Vancomycin:

Children and adolescents: 15 mg/kg per dose IV every six hours in children and adolescents

Adults: 15 to 20 mg/kg per dose IV every 8 to 12 hours (maintenance dose; loading dose of 20 to 35 mg/kg IV once is optional [maximal single dose 3 g])

Adjust dose based upon therapeutic monitoring if using for longer than two to three days. (See "Vancomycin: Parenteral dosing, monitoring, and adverse effects in adults".)

Plus

Ampicillin-sulbactam: Dosing as above

•Alternative:

Linezolid: Dosing as above

Plus

Ampicillin-sulbactam: Dosing as above

●No response to initial treatment with ampicillin-sulbactam: Ampicillin-sulbactam does not provide antibacterial activity against MRSA; lack of responsiveness is an indication to discontinue ampicillin-sulbactam and give:

•Vancomycin plus metronidazole: Dosing for each as above

or

•Linezolid plus metronidazole: Dosing for each as above

In addition to MRSA coverage, vancomycin or linezolid provide optimal coverage for potentially resistant Gram-positive cocci.

Oral regimens — Oral regimens are appropriate for the treatment of:

●Peritonsillar cellulitis (see 'Peritonsillar cellulitis' above)

●Small or equivocal peritonsillar abscess in patients who can tolerate oral intake and have minimal to no trismus (see 'Peritonsillar abscess confirmed' above and 'Peritonsillar infection with equivocal findings' above)

●Continuation of therapy in patients who have responded to parenteral antibiotics

Options for oral treatment include (table 3):

●Amoxicillin-clavulanate (suggested):

•Children – 7:1 formulation (amoxicillin component 200 mg per 5 mL ): 22.5 mg/kg (amoxicillin component) twice daily (maximum 875 mg amoxicillin and 125 mg clavulanate per dose)

or

4:1 formulation (amoxicillin component 125 or 250 mg per 5 mL): 10 mg/kg (amoxicillin component) 3 times daily (maximum 500 mg amoxicillin and 125 mg clavulanate per dose)

or

14:1 formulation (amoxicillin component 600 mg per 5 mL): 19 mg/kg (amoxicillin component) twice daily (maximum 875 mg amoxicillin and 64 mg clavulanate per dose)

•Adults – 875/125 mg twice daily

The 14:1 formulation maximizes the amoxicillin component and minimizes the risk of diarrhea. For larger children, many experts round off this maximum dose to 900 mg (volume 7.5 mL) for caregiver convenience with measuring and administration given minimal to no risk for this dose.

or

●Clindamycin (only for patients who have penicillin allergy or responded to parenteral clindamycin)

•Children – 10 mg/kg per dose (maximum single dose 600 mg) every eight hours

•Adults – 300 to 450 mg every six hours

We generally avoid clindamycin, if possible, due to the risk for Clostridioides difficile infection and the possibility of streptococcal and staphylococcal resistance.

When vancomycin has been added to the parenteral regimen, oral therapy can be based upon susceptibility testing of the isolates, if available. If empiric therapy was employed for presumed MRSA infection, oral regimens can include:

●Linezolid (preferred)

•Children

-<12 years old – 10 mg/kg per day three times daily

-≥12 years – 600 mg twice daily

•Adults – 600 mg twice per day

For all patients, the maximum daily dose for linezolid is 1200 mg

or

●Clindamycin as above

Duration of antibiotic therapy — The typical duration of antibiotic treatment for PTA is 14 days. For patients who receive parenteral therapy, it is continued until the patient has defervesced and clinically improved. Oral antibiotic therapy should then be continued to complete a 14-day course. Courses shorter than 10 days have been associated with recurrence [47].

Dexamethasone — We do not treat patients with PTA with dexamethasone, although other experts routinely use them [38]. Evidence regarding the benefits of glucocorticoids in the management of PTA is inconsistent [11,48,49]. In one trial of 62 patients, glucocorticoids appeared to hasten symptomatic improvement in adolescent (>16 years) and adult patients treated with needle aspiration and IV antimicrobial therapy [48]. In another small trial of 41 adult patients undergoing needle aspiration for PTA, IV dexamethasone was associated with less pain at 24 hours than placebo but no other benefits [49]. In a retrospective case series of 249 episodes of PTA in children <18 years, glucocorticoids were used in 37 percent but without clear benefit or adverse outcomes [11]. Given the small number of patients in the trials and the discrepant results of these studies, we await additional evidence supporting the efficacy and safety of dexamethasone for the treatment of PTA [3].

Drainage

Indications — Drainage of a peritonsillar abscess is indicated for patients with (see 'Approach' above):

●Airway compromise (after the airway is secured)

●Moderate to large abscess based upon ultrasound findings or clinical findings

●Patients with peritonsillar abscess or cellulitis who do not respond or worsen while receiving antibiotics and supportive care alone (see 'Response to treatment' below)

Choice of procedure — PTA often requires surgical drainage accomplished by needle aspiration, incision and drainage, or tonsillectomy, all of which are procedures typically performed by an otolaryngologist [3]. Drainage with any of these procedures, in combination with antimicrobial therapy and hydration, results in resolution in more than 90 percent of cases [3,39]. Given that the procedures are comparable in efficacy, the choice of procedure depends upon other factors, such as the skill and experience of the health care provider, age and ability of the patient to cooperate, cost, and whether the patient has indications for tonsillectomy (eg, recurrent acute throat infection). Each procedure has advantages in certain situations [2,8].

An older, cooperative child, teenager, or adult without trismus or a previous history of pharyngitis may be able to undergo a needle aspiration or simple incision and drainage procedure as an outpatient with topical anesthesia or procedural sedation [3,50-53]. However, for a young, uncooperative child, the procedure must be performed in the operating suite. Special care must be taken with the administration of procedural sedation during abscess drainage because of the increased risk of airway complications and aspiration.

In the absence of a previous history of recurrent pharyngitis, needle aspiration or incision and drainage may be sufficient. In contrast, if there have been previous episodes of pharyngitis or PTA (either of which predict the possible recurrence of the PTA), then a quinsy tonsillectomy (tonsillectomy in a patient with acute PTA) may be performed. (See 'Tonsillectomy' below.)

Needle aspiration — Needle aspiration of PTA (picture 4) may be performed in the outpatient setting with topical anesthesia by an experienced clinician (eg, an otolaryngologist or physician with training and expertise in the procedure) [3,38,43,54]. When needle aspiration is performed, we suggest ultrasound localization, whenever available, prior to the procedure rather than the landmark technique. Ultrasound may be helpful to confirm the clinical suspicion of an abscess and guide the procedure [25,30,31].

Patients generally tolerate needle aspiration better than incision and drainage because it is less invasive and less painful [10,42]. Needle aspiration is the procedure of choice for patients whose general condition is too poor to tolerate a general anesthetic and those with a bleeding diathesis who wish to avoid blood transfusion [2].

The use of ultrasonography (US) prior to needle aspiration has been associated with improved success of aspiration compared with the landmark technique (use of anatomic landmarks as has been the tradition in otolaryngology). As an example, in a trial of 28 patients undergoing evaluation for PTA in an emergency department (18 ultimately diagnosed with PTA), aspiration facilitated by intraoral US was successful in 100 percent of patients with PTA (8 of 8) compared with 50 percent undergoing aspiration using the landmark technique (5 of 10 with PTA) [30]. Thus, when readily available by an experienced practitioner, US is suggested for patients undergoing needle aspiration in the emergency department.

In randomized trials comparing needle aspiration with incision and drainage, the procedures had similar initial success rates of >90 percent [39,42,54-56]. In one meta-analysis, needle aspiration had a 94 percent success rate for acute resolution (range 85 to 100 percent) [10]. A separate meta-analysis of 10 trials (612 patients, primarily adults) found that early recurrent abscess was more likely with needle aspiration than incision and drainage (relative risk [RR] 3.7). However, there was moderate heterogeneity in this pooled estimate, and the evidence for recurrence was considered to be of very low quality [57]. Furthermore, the recurrence rate varied greatly by each procedure (5 to 80 percent in patients undergoing needle aspiration and 0 to 20 percent in patients undergoing incision and drainage), which differs markedly from the 10 to 15 percent recurrence rate typically described [10,39,47,54]. This wide variation suggests that there were likely significant differences in the competence of the physicians performing the procedures or the determination of recurrence that may have confounded the results [57].

Complications of needle aspiration may include hemorrhage and aspiration of pus and blood into the airway [58]. Carotid artery injury has not been reported as a complication of needle aspiration of PTA [3]; however, catastrophic hemorrhage may result from aspiration of a pseudoaneurysm mimicking PTA or necrosis of the carotid artery [59,60]. (See 'Differential diagnosis' above and 'Complications' below.)

The patient must be observed after the needle aspiration to make sure they can tolerate oral antimicrobial therapy, pain medications, and liquids. If the patient is not admitted to the hospital, they should be seen for follow-up in 24 to 36 hours [1]. (See 'Discharge instructions' below.)

Incision and drainage — Incision and drainage of PTA is usually performed by an otolaryngologist (picture 5) [3]. In older children, adolescents, and adults, it may be performed in the outpatient setting with topical anesthesia or procedural sedation; general anesthesia is usually required for young children [3,33,47,50,51,54].

Incision and drainage is more painful than needle aspiration and causes more bleeding [3,33]. A second procedure may be required for complete resolution. Complications may include aspiration of the abscess contents.

Patients must be observed after the procedure to make sure they can tolerate oral antimicrobial therapy, pain medications, and liquids. Patients who are not admitted to the hospital should be seen for follow-up in 24 to 36 hours [1]. (See 'Peritonsillar abscess confirmed' above.)

Tonsillectomy — Possible indications for tonsillectomy in patients with PTA include [1-3,8]:

●Significant upper airway obstruction or other complications.

●Previous episode(s) of PTA (each of which predicts the possible recurrence of PTA).

●Other indications for tonsillectomy (eg, severe recurrent pharyngitis; chronic symptoms or signs of upper airway obstruction, such as snoring). (See "Tonsillectomy in adults: Indications" and "Tonsillectomy and/or adenoidectomy in children: Overview of indications and contraindications".)

●Failure of the abscess to resolve with other drainage techniques.

If tonsillectomy is required, it may be performed immediately (quinsy tonsillectomy or "tonsillectomy a chaud") or after resolution of the acute infection (interval tonsillectomy) [8,54,61-63]. Quinsy tonsillectomy avoids the need for repeat hospitalization and anesthesia and minimizes loss to follow-up, but it may be associated with an increased risk of intraoperative bleeding. However, compared with interval tonsillectomy, postoperative bleeding does not seem to be increased based on a meta-analysis of retrospective studies that included children and adults undergoing quinsy tonsillectomy compared with historical controls [64]. Interval tonsillectomy may be more difficult technically if there is fibrosis following the acute infection.

Tonsillectomy is the most expensive of the drainage procedures, requires general anesthesia and hospitalization, and may delay drainage [3,33]. In five series involving 1027 patients, the overall incidence of bleeding after quinsy tonsillectomy in children and adults was 1 percent (range 0 to 7 percent) [2]. In the only series confined to children, none of the 55 patients had postoperative or delayed bleeding [65]. Additional complications and adverse effects of tonsillectomy are discussed separately. (See "Tonsillectomy in adults: Techniques and perioperative issues", section on 'Complications' and "Tonsillectomy and/or adenoidectomy in children: Overview of indications and contraindications".)

Discharge instructions — Patients who are discharged from the emergency department or hospital after treatment for peritonsillar infection should be instructed that prompt reevaluation is necessary for:

●Dyspnea

●Worsening throat pain, neck pain, or trismus

●Enlarging mass

●Fever

●Neck stiffness

●Bleeding

Patients who are treated as outpatients should be seen for follow-up in 24 to 36 hours. Those who have been admitted to the hospital should have follow-up within several days of discharge.

Response to treatment — Successful treatment is defined by symptomatic improvement in sore throat, fever, and/or tonsillar swelling within 24 hours of intervention.

Treatment failure is defined by lack of symptomatic improvement or worsening despite 24 hours of antimicrobial therapy (with or without surgical drainage). Treatment failure may occur in patients who have developed complications, are infected with unusual organisms, or have underlying problems (eg, congenital cyst or tract). Reevaluation of such patients may include repeat imaging (ultrasound) or surgical intervention. Broadening antimicrobial therapy may also be indicated.

COMPLICATIONS — 

Early diagnosis and prompt, appropriate management of peritonsillar infection are critical to avoiding complications. Complications of peritonsillar abscess (PTA) occur rarely but are potentially fatal. Infection can spread from the peritonsillar space to other deep neck spaces, adjacent structures, and the bloodstream.

Complications of PTA may include [1,2,66]:

●Upper airway obstruction (see "Emergency evaluation of acute upper airway obstruction in children")

●Aspiration pneumonia if the abscess ruptures into the airway (see "Aspiration pneumonia in adults" and "Pneumonia in children: Inpatient treatment", section on 'Aspiration pneumonia')

●Sepsis and septic shock (see "Evaluation and management of suspected sepsis and septic shock in adults" and "Children with sepsis in resource-abundant settings: Rapid recognition and initial resuscitation (first hour)")

●Jugular vein thrombosis or suppurative thrombophlebitis (Lemierre syndrome) [67,68] (see "Lemierre syndrome: Septic thrombophlebitis of the internal jugular vein")

●Pseudoaneurysm of the carotid artery (suggested by recurrent bleeding from the ear, nose, or throat, prolonged course, tachycardia, anemia, or 10^th or 12^th cranial nerve palsies) with potential for carotid artery rupture [69] (see "Extracranial carotid artery aneurysm")

●Mediastinitis (see "Deep neck space infections in adults", section on 'Retropharyngeal space infections')

●Necrotizing fasciitis [70,71] (see "Necrotizing soft tissue infections")

●Sequelae of group A streptococcus infection (when that organism is isolated) (see "Complications of streptococcal tonsillopharyngitis")

PROGNOSIS — 

With early and appropriate treatment, most peritonsillar infections resolve without sequelae. Recurrence is estimated to occur in 10 to 15 percent of patients [10,39,47,54]. The risk of recurrence is increased in patients with a history of recurrent tonsillitis before the development of abscess (40 versus 9.6 percent) [72].

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Peritonsillar cellulitis and abscess".)

SUMMARY AND RECOMMENDATIONS

●Definitions – Peritonsillar abscess (PTA) is a collection of pus located between the capsule of the palatine tonsil and the pharyngeal muscles (figure 1). Peritonsillar cellulitis is an inflammatory reaction of the tissue between the capsule of the palatine tonsil and the pharyngeal muscles caused by infection but not associated with a discrete collection of pus. An alternate term for cellulitis is phlegmon. (See 'Definitions' above and 'Anatomy and pathogenesis' above.)

●Clinical presentation – Patients with a PTA present with a severe sore throat, fever, a "hot potato" or muffled voice, drooling, and/or trismus. (See 'Clinical manifestations' above.)

●Physical findings – Examination findings consistent with PTA include an enlarged and fluctuant tonsil with deviation of the uvula to the opposite side (picture 1). Alternatively, there may be fullness or bulging of the posterior soft palate near the tonsil with fluctuance on palpation. (See 'Physical examination' above.)

●Diagnosis – Clinical findings are sufficient to establish the diagnosis of PTA in many patients. However, clinical features cannot always distinguish PTA from peritonsillar cellulitis. For patients with a clinical diagnosis of PTA, we strongly prefer ultrasonography (US) by an experienced clinician, whenever available, to confirm the presence of an abscess and to help guide management decisions. (See 'Diagnosis' above.)

●Management

•Supportive care – Supportive care for patients with peritonsillar infection includes (see 'Supportive care (all patients)' above):

-Rehydration, as needed (see "Treatment of hypovolemia (dehydration) in children in resource-abundant settings" and "Maintenance and replacement fluid therapy in adults")

-Analgesia according to the degree of pain (see "Pain in children: Approach to pain assessment and overview of management principles" and "Approach to the management of acute pain in adults")

-Monitoring for complications (eg, airway obstruction, aspiration pneumonia, sepsis, or suppurative complications (see 'Complications' above)

•Antibiotic therapy – All patients with suspected peritonsillar infection require empiric antibiotic therapy. The choice of medication and route of treatment depends on the degree of illness and local patterns of antibiotic resistance (algorithm 1) (see 'Antibiotic therapy' above):

-Peritonsillar abscess – For patients with a peritonsillar abscess, we suggest at least one dose of intravenous ampicillin-sulbactam (linezolid plus metronidazole for patients with penicillin allergy) rather than other antibiotics. If there is concern for MRSA, vancomycin is added (table 2). (See 'Parenteral regimens' above.)

-Peritonsillar cellulitis – For patients with no abscess on US or examination findings consistent with cellulitis, we suggest initial therapy with oral amoxicillin-clavulanic acid rather than other agents (table 3). If there is concern for MRSA, linezolid is used instead. (See 'Oral regimens' above.)

The total duration of antibiotic therapy is 14 days.

•Dexamethasone – For patients with peritonsillar infection, we suggest against dexamethasone (Grade 2C). However, some experts routinely use it for this condition. (See 'Dexamethasone' above.)

•Abscess drainage – Before drainage, the clinician should determine if the patient has indications for tonsillectomy (see below) and should consult with an otolaryngologist before abscess drainage or discharge home. The need for abscess drainage varies by clinical findings (algorithm 1):

-Potential airway compromise or comorbidities – Patients with impending airway compromise require airway management and emergency surgical intervention (drainage or tonsillectomy). (See 'Airway compromise' above.)

-Moderate to large abscess – Moderate to large abscesses (1 to 2 cm or greater in diameter confirmed on US, if available, or based on examination [ie, toxic appearance and/or trismus]) require drainage. In most patients, we suggest needle aspiration rather than incision and drainage (Grade 2C). Needle drainage is less painful and less invasive. The procedure should be performed by a properly trained and experienced physician, typically an otolaryngologist. Where available, ultrasound localization before the procedure may improve procedural success. (See 'Peritonsillar abscess confirmed' above and 'Choice of procedure' above and 'Needle aspiration' above.)

-Small abscess, equivocal findings, or no abscess – Patients with a small abscess (<1 cm on US or nontoxic appearance with minimal to no trismus), equivocal findings, or no abscess on US or examination do not require a drainage procedure. Medical therapy alone (oral antibiotics, analgesia, and IV rehydration as needed) is typically sufficient for these patients. (See 'Peritonsillar abscess confirmed' above and 'Peritonsillar infection with equivocal findings' above and 'Peritonsillar cellulitis' above.)

•Tonsillectomy – For patients with PTA who have any of the following, we suggest tonsillectomy (performed either during the acute illness [quinsy tonsillectomy or "tonsillectomy a chaud"] or after resolution of the acute infection [interval tonsillectomy]) (Grade 2C) (see 'Tonsillectomy' above):

-Acute upper airway obstruction (see 'Complications' above)

-Failure to improve despite other drainage procedures and antibiotic therapy

-Previous episode(s) of PTA or other indication for tonsillectomy (snoring with sleep disturbance or severe recurrent pharyngitis)

In addition, tonsillectomy may be warranted if the child has another indication for tonsillectomy, such as obstructive sleep apnea or severe recurrent pharyngitis, as discussed separately. (See "Tonsillectomy and/or adenoidectomy in children: Overview of indications and contraindications" and "Tonsillectomy in adults: Indications".)

•Disposition – For all types of peritonsillar infection, patients who can tolerate oral intake, including oral antibiotics, pain medication, and fluids, may be discharged home with assured follow-up within 24 to 36 hours. Otherwise, they should be admitted for parenteral antibiotics and supportive care. (See 'Approach' above and 'Discharge instructions' above.)