Peritonsillar Abscess Symptoms And Causes

  • Natasha Larkin Master of Public Health - MSc, London School of Hygiene and Tropical Medicine
  • Rebecca Roy Bsc Biochemistry and Pharmacology University of Strathclyde
  • Philip James Elliott B.Sc. (Hons), B.Ed. (Hons) (Cardiff University), PGCE (University of Strathclyde), CELTA (Cambridge University) , FSB, MMCA

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A peritonsillar abscess, also known as quinsy, is a rare but serious infection that develops in the back of the throat. Whilst the exact pathophysiology of how a Quinsy develops remains unknown,1 we do have a good understanding of the symptoms it is associated with, its common causes and the factors that increase the risk of developing one.

Quick recognition and timely medical treatment of a peritonsillar abscess mean that the vast majority of patients experience an uncomplicated recovery, however, serious complications can occur particularly when diagnosis and treatment are delayed. Therefore, it is important to be able to recognise when a peritonsillar abscess may be developing and seek urgent medical care.

Read on for a list of symptoms associated with a peritonsillar abscess, as well as common causes and risk factors.

Introduction

A peritonsillar abscess is a localised collection of pus in the peritonsillar space. It forms in the space between the tonsillar capsule and the pharyngeal constrictor muscles (muscles that constrict to propel food down the throat during swallowing).2 This space is made up of loose connective tissue,  which makes it highly susceptible to the formation of an abscess (a collection of pus) following an infection.2

(insert picture of anatomy of peritonsillar abscess)

Peritonsillar abscesses have an incidence rate of 1 in 10,000.2 Although rare, it is the most common cause of acute admissions within the ENT (ear, nose, and throat) department. The incidence of developing peritonsillar abscess peaks in young adult life, between the ages 15 to 40.3 Studies have not found it to be significantly more common amongst a specific sex or race but is very rare below the age of 5.2

Tonsillitis vs peritonsillar abscess

Tonsillitis is the inflammation of the tonsils in your throat caused by either a viral or bacterial infection. A peritonsillar abscess is the formation of a pocket of pus in the space behind the tonsils caused by bacteria. It is often found as a complication of bacterial tonsillitis however it can occur without the presence of tonsillitis. 

Symptoms and causes

For the majority of people who develop a peritonsillar abscess, appropriate treatment leads to an uncomplicated full recovery. However, a minority will develop serious complications. Therefore the timely recognition and treatment of a quinsy reduces the risk of the development of life-threatening complications such as sepsis and thus it is important to be able to recognise the symptoms associated with it and to seek urgent medical advice if you have any concerns that you are developing one.3 

Symptoms of peritonsillar abscess vs tonsillitis

The symptoms of a peritonsillar abscess can be preceded by an episode of acute tonsillitis and therefore it can be initially difficult to distinguish between the two. However, as the condition progresses key differences become apparent as indicated in the table below:

TonsillitisPeritonsillar abscess2
- Fever
- Rigours (chills) 
- Sore throat
- Halitosis (foul-smelling breath)
- Dysphagia (difficulty swallowing)
- Odynophagia (painful swallowing)
- Tender cervical (neck) lymph nodes 
- Referred ear pain
- Fever
- Rigours 
- Severe sore throat - often unilateral
- Halitosis 
- Dysphagia
- Odynophagia
- Tender cervical lymph nodes
- Referred ear pain on the affected side
- Drooling
- Muffled speech
- Trismus (difficulty opening the mouth)
- Dehydration 
- Symptoms of sepsis 
- Difficulty breathing
- Swollen uvula deviating to one side (away from an abscess)

Causes of peritonsillar abscess

Peritonsillar abscesses are caused by an invasion of bacteria in the peritonsillar space which creates a pocket of pus, also known as an abscess. 

However, the exact pathophysiology by which a peritonsillar abscess develops is currently unknown.2 It is thought to occur due to a number of different mechanisms. The most commonly cited theory is that bacteria spread beyond the tonsils during an episode of acute bacterial tonsillitis which subsequently results in the infection of the connective tissue behind the tonsil and the formation of an abscess.3 

However, we also know that quinsy(peritonsillar abscess) can occur in the absence of acute tonsillitis and it has been theorised that this is due to the development of small pockets of pus within the salivary glands found in this area of the throat that then invade the peritonsillar space. The development of pus within the salivary glands can occur due to a number of reasons such as another infection, glandular fever, poor oral health or smoking.3

Which bacteria are found in a peritonsillar abscess?

We know that an abscess is created by an invasion of bacteria causing a reaction within the body leading to the death of surrounding tissue and consequently leaving a hole in the tissue which allows for the accumulation of a pocket of pus. Abscesses can form anywhere in the body, however, the location and mechanism by which they form will often provide clues as to which strain of bacteria is responsible. It is extremely important to know which bacteria(s) are responsible for the abscess so that the most effective antibiotic can be used to treat it.

In the case of peritonsillar abscesses, multiple studies have been performed in the hopes of singling out the bacteria that are most commonly responsible. Studies have revealed that the bacteria most often found in peritonsillar abscesses are:1,2,3 

  • Streptococcus pyogenes
  • Fusobacterium nucleatum
  • Fusobacterium necrophorum
  • Streptococcus milleri

In the majority of cases a single strain of bacteria was found to be present however in a significant minority (around 30% of cases) there were a number of different types of bacteria present in the extracted pus, including strains that are commonly found in the normal throat flora, making it impossible to know which were responsible for the formation of the abscess and which are just present generally.1

This makes knowing which antibiotic to use to kill the offending bacteria more difficult and is the reason why clinicians will often use a broad-spectrum antibiotic which is effective against a number of different types of bacteria.

Risk factors

A peritonsillar abscess is thought to most commonly occur as a complication of tonsillitis, however, studies have found that a significant minority occur with no preceding symptoms or diagnosis of tonsillitis.5 Studies have shown that there are a number of factors that increase the risk of quinsy developing:

  • History of tonsilitis: many patients who develop a peritonsillar abscess do so as a complication of acute tonsillitis. Therefore an increase in episodes of tonsillitis will increase your risk of developing a quinsy1,2,3
  • Age: the highest incidence of developing a peritonsillar abscess is between the mid-teens to age 40
  • Periodontal disease: this is a disease and inflammation of the gums and bones in the jaw, a high incidence of chronic periodontal disease has been significantly associated with the development of peritonsillar abscesses even in the absence of tonsillitis2,5 
  • Smoking: Smoking is linked to both periodontal disease as well as other head and neck infections. It has been found to increase the risk of developing a peritonsillar abscess2, 5 
  • Compromised immunity: a high incidence of peritonsillar abscess has been found in those who are suffering from infectious mononucleosis (glandular fever) and Kawasaki disease. Both of these diseases compromise the immune system and it is thought that a reduced immune system and inflammation in the area allow the bacteria to penetrate the connective tissue resulting in abscess formation5
  • Antibiotic use in previous sore throats: there is a positive correlation between antibiotic use in previous sore throats and the consequent development of a peritonsillar abscess. It is theorised that this may be due to the antibiotics killing pathogens commonly found in the back of a healthy throat and therefore freeing up space for more aggressive strains of bacteria to invade5

Management

The management of a peritonsillar abscess involves both surgical and medical approaches within a hospital setting. 

Initially, antibiotics through an intravenous (IV) drip line (a tube into a vein) will be started..These will likely be ‘broad spectrum’ antibiotics meaning they work against a number of different strains of bacteria. This is important in the case of peritonsillar abscesses because although there are some strains of bacteria that are more likely to cause an abscess, studies have found that in many patients a variety of bacteria are present in the abscess and it is unclear which one is primarily responsible.

IV line fluids are also initiated as many patients arrive for treatment dehydrated.2 

The second line of management is to remove the abscess.2 This will be carried out by a doctor with an ENT ( ear, nose and throat) specialisation. 

There are a number of different methods they can use to remove the abscess, including aspiration and incision with drainage. Occasionally in some patients, a tonsillectomy is also performed. For more detailed information about the treatment of a peritonsillar abscess see the article here

Preventing a peritonsillar abscess

You cannot fully mitigate the risk of developing a peritonsillar abscess, however, there are steps that can be taken to reduce the chance of one forming. Practising good oral hygiene and avoiding smoking can reduce the risk of quinsy as well as your risk of developing other head and neck diseases.5 

It has been debated that in those who suffer from multiple episodes of tonsillitis, a tonsillectomy (surgical removal of the tonsils) can reduce their risk of developing a peritonsillar abscess as they will no longer develop tonsillitis.2 

Equally debated is whether treatment with antibiotics for sore throats and tonsillitis helps or hinders the development of an abscess – some medical studies argue that prompt treatment of acute tonsillitis can reduce the development of complications such as peritonsillar abscesses, however, others argue that overtreatment with antibiotics causes a change in normal bacterial flora within the throat allowing for more aggressive species to invade.5

Summary

  • A peritonsillar abscess is a unilateral (one-sided) collection of pus in the space behind the tonsils
  • The exact pathophysiology of how they develop is currently unknown but they are often preceded by an episode of acute tonsillitis
  • It is important that you are able to quickly recognise the symptoms associated with quinsy so that appropriate medical care can be sought and treatment started
  • The vast majority of those who develop one and seek medical treatment recover quickly and without any complications
  • A number of risk factors such as recurrent tonsillitis, smoking and poor oral health increase the risks of developing one

References

  1. Mazur E, Czerwińska E, Korona-Głowniak I, Grochowalska A, Kozioł-Montewka M. Epidemiology, clinical history and microbiology of peritonsillar abscess. Eur J Clin Microbiol Infect Dis [Internet]. 2015 [cited 2024 Sep 7]; 34(3):549–54. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356895/.
  2. Gupta G, McDowell RH. Peritonsillar Abscess. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Sep 7]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK519520/.
  3. Saar M, Vaikjärv R, Parm Ü, Kasenõmm P, Kõljalg S, Sepp E, et al. Unveiling the etiology of peritonsillar abscess using next-generation sequencing. Ann Clin Microbiol Antimicrob [Internet]. 2023 [cited 2024 Sep 7]; 22:98. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10633907/.
  4. Klug TE, Greve T, Hentze M. Complications of peritonsillar abscess. Ann Clin Microbiol Antimicrob [Internet]. 30 juill 2020 [cité 7 mars 2024];19:32. Disponible sur: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391705/
  5. Powell E. A review of the pathogenesis of adult peritonsillar abscess: time for a re-evaluation. Journal of Antimicrobial Chemotherapy. sept 2013;Volume 68(Issue 9):Pages 1941-1950.

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Natasha Larkin

Doctor of medicine - BM BS, Peninsula Medical School UK
Master of Public Health - MSc, London School of Hygiene and Tropical Medicine

Natasha worked for a number of years as a junior doctor in the NHS before undertaking a MSc in Public Health and the world-renowned London School of Hygiene and Tropical Medicine. Realizing her passion and strengths lie within medical writing she is utilizing her strong medical knowledge and experience in medical research to produce high quality medical content that is aimed at and accessible to the general public.

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