Question: What causes tonsillitis?

Tonsillitis



Tonsillitis is inflammation of the tonsils, typically of rapid onset.[1] It is a type of pharyngitis.[7] Symptoms may include sore throat, fever, enlargement of the tonsils, trouble swallowing, and large lymph nodes around the neck.[1] Complications include peritonsillar abscess.[2]

Tonsillitis is most commonly caused by a viral infection, with about 5% to 40% of cases caused by a bacterial infection.[4][5] When caused by the bacterium group A streptococcus, it is referred to as strep throat.[8] Rarely bacteria such as Neisseria gonorrhoeae, Corynebacterium diphtheriae, or Haemophilus influenzae may be the cause.[4] Typically the infection is spread between people through the air.[5] A scoring system, such as the Centor score, may help separate possible causes.[4] Confirmation may be by a throat swab or rapid strep test.[4]

Treatment efforts involve improving symptoms and decreasing complications.[4] Paracetamol (acetaminophen) and ibuprofen may be used to help with pain.[4] If strep throat is present the antibiotic penicillin by mouth is generally recommended.[4] In those who are allergic to penicillin, cephalosporins or macrolides may be used.[4] In children with frequent episodes of tonsillitis, tonsillectomy modestly decreases the risk of future episodes.[9]

About 7.5% of people have a sore throat in any three-month period and 2% of people visit a doctor for tonsillitis each year.[6] It is most common in school aged children and typically occurs in the fall and winter months.[4][5] The majority of people recover with or without medication.[4] In 40% of people, symptoms resolve within three days, and in 80% symptoms resolve within one week, regardless of if streptococcus is present.[3] Antibiotics decrease symptom duration by approximately 16 hours.[3]
Signs and symptoms

Common signs and symptoms include:[10][11][12][13]
sore throat
red, swollen tonsils
pain when swallowing
high temperature (fever)
headache
tiredness
chills
a general sense of feeling unwell (malaise)
white pus-filled spots on the tonsils
swollen lymph nodes (glands) in the neck
pain in the ears or neck
weight loss
difficulty ingesting and swallowing meal/liquid intake
difficulty sleeping
Less common symptoms include:
nausea
fatigue
stomach ache
vomiting
furry tongue
bad breath (halitosis)
voice changes
difficulty opening the mouth (trismus)
loss of appetite
anxiety/fear of choking
In cases of acute tonsillitis, the surface of the tonsil may be bright red and with visible white areas or streaks of pus.[14]
Tonsilloliths occur in up to 10% of the population frequently due to episodes of tonsillitis.[15]
Causes

The most common cause is viral infection and includes adenovirus, rhinovirus, influenza, coronavirus, and respiratory syncytial virus.[10][11][12][13] It can also be caused by Epstein-Barr virus, herpes simplex virus, cytomegalovirus, or HIV.[10][11][12][13]  The second most common cause is bacterial infection of which the predominant is Group A β-hemolytic streptococcus (GABHS), which causes strep throat.[10][11][12][13]  Less common bacterial causes include: Staphylococcus aureus (including methicillin resistant Staphylococcus aureus or MRSA ),[16] Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis, Fusobacterium sp., Corynebacterium diphtheriae, Treponema pallidum, and Neisseria gonorrhoeae.[10][11][12][13]
Anaerobic bacteria have been implicated in tonsillitis and a possible role in the acute inflammatory process is supported by several clinical and scientific observations.[17]
Under normal circumstances, as viruses and bacteria enter the body through the nose and mouth, they are filtered in the tonsils.[18][19] Within the tonsils, white blood cells of the immune system destroy the viruses or bacteria by producing inflammatory cytokines like phospholipase A2,[20] which also lead to fever.[18][19]  The infection may also be present in the throat and surrounding areas, causing inflammation of the pharynx.[21]
Sometimes, tonsillitis is caused by an infection of spirochaeta and treponema, in this case called Vincent's angina or Plaut-Vincent angina.[22]
Diagnosis

The diagnosis of group A beta-hemolytic streptococcus (GABHS) tonsillitis can be confirmed by culture of samples obtained by swabbing both tonsillar surfaces and the posterior pharyngeal wall and plating them on sheep blood agar medium.  The isolation rate can be increased by incubating the cultures under anaerobic conditions and using selective growth media. A single throat culture has a sensitivity of 90–95% for the detection of GABHS (which means that GABHS is actually present 5–10% of the time culture suggests that it is absent). This small percentage of false-negative results are part of the characteristics of the tests used but are also possible if the patient has received antibiotics prior to testing. Identification requires 24 to 48 hours by culture but rapid screening tests (10–60 minutes), which have a sensitivity of 85–90%, are available. Older antigen tests detect the surface Lancefield group A carbohydrate. Newer tests identify GABHS serotypes using nucleic acid (DNA) probes or polymerase chain reaction. Bacterial culture may need to be performed in cases of a negative rapid streptococcal test.[23]
True infection with GABHS, rather than colonization, is defined arbitrarily as the presence of >10 colonies of GABHS per blood agar plate. However, this method is difficult to implement because of the overlap between carriers and infected patients. An increase in antistreptolysin O (ASO) streptococcal antibody titer 3–6 weeks following the acute infection can provide retrospective evidence of GABHS infection[24] and is considered definitive proof of GABHS infection.
Increased values of secreted phospholipase A2[20] and altered fatty acid metabolism[25] in patients with tonsillitis may have diagnostic utility.
Treatment
Treatments to reduce the discomfort from tonsillitis include:[10][11][12][13][21][26][27]
pain and fever reducing medications such as paracetamol (acetaminophen) and ibuprofen
warm salt water gargle, lozenges, or warm liquids
When tonsillitis is caused by a virus, the length of illness depends on which virus is involved. Usually, a complete recovery is made within one week; however, symptoms may last for up to two weeks.
Antibiotics
If the tonsillitis is caused by group A streptococcus, then antibiotics are useful, with penicillin or amoxicillin being primary choices.[28] Cephalosporins and macrolides are considered good alternatives to penicillin in the acute setting.[29] A macrolide such as azithromycin or erythromycin is used for people allergic to penicillin. Individuals who fail penicillin therapy may respond to treatment effective against beta-lactamase producing bacteria[30] such as clindamycin or amoxicillin-clavulanate. Aerobic and anaerobic beta lactamase producing bacteria that reside in the tonsillar tissues can "shield" group A streptococcus from penicillins.[31]
Surgery
Chronic cases can be treated with tonsillectomy (the surgical removal of tonsils) as a choice for treatment.[32] Children have had only a modest benefit from tonsillectomy for chronic cases of tonsillitis.[33]
Prognosis
Since the advent of penicillin in the 1940s, a major preoccupation in the treatment of streptococcal tonsillitis has been the prevention of rheumatic fever, and its major effects on the nervous system (Sydenham's chorea) and heart. Recent evidence would suggest that the rheumatogenic strains of group A beta hemolytic strep have become markedly less prevalent and are now only present in small pockets such as in Salt Lake City, USA.[34] This brings into question the rationale for treating tonsillitis as a means of preventing rheumatic fever.
Complications may rarely include dehydration and kidney failure due to difficulty swallowing, blocked airways due to inflammation, and pharyngitis due to the spread of infection.[10][11][12][13][21]
An abscess may develop lateral to the tonsil during an infection, typically several days after the onset of tonsillitis. This is termed a peritonsillar abscess (or quinsy).
Rarely, the infection may spread beyond the tonsil resulting in inflammation and infection of the internal jugular vein giving rise to a spreading septicaemia infection (Lemierre's syndrome).
In chronic/recurrent cases (generally defined as seven episodes of tonsillitis in the preceding year, five episodes in each of the preceding two years or three episodes in each of the preceding three years),[35][36][37] or in acute cases where the palatine tonsils become so swollen that swallowing is impaired, a tonsillectomy can be performed to remove the tonsils. Patients whose tonsils have been removed are still protected from infection by the rest of their immune system.
In strep throat, very rarely diseases like rheumatic fever[3] or glomerulonephritis[38] can occur. These complications are extremely rare in developed nations but remain a significant problem in poorer nations.[39][40] Tonsillitis associated with strep throat, if untreated, is hypothesized to lead to pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS).[41]