Acute pharyngitis is usually a mild and self-limited disease caused in most cases by some virus - this should be explained to the patient too.
A group A streptococci rapid test is the primary option for a patient with throat pain symptoms and a Centor score of 3 or 4 (history of or measured fever exceeding 38 °C, absence of cough, tenderness and swelling of submandibular lymph nodes, tonsillar swelling or exudate). This will make it possible to begin treatment sooner.
Alternatively (or if symptoms persist), throat culture (streptococcal culture) should be performed, which will also detect group C and G streptococci. A comprehensive throat culture may be necessary to detect pathogens other than streptococci, in case of an atypical clinical picture, in particular.
Antimicrobials are indicated in symptomatic infections caused by group A streptococci. Pharyngitis with high fever and severe symptoms caused by C or G streptococci should also be treated with antimicrobials.
In recurrent tonsillitis, tonsillectomy is considered if an antimicrobial trial with a first-generation cephalosporin or clindamycin does not help and there are acute infections at least 3 times within 6 months or 4 times within a year.
Epidemics should be recognized and their spread prevented by giving antimicrobial treatment also to asymptomatic carriers (even when caused by group C or G streptococci).
In the majority of cases, sore throat has a viral aetiology. Adenovirus is the most common causative virus. Viruses can also cause a clinical picture similar to a streptococcal disease with high fever, rash and pharyngeal exudate.
Group A streptococci (StrA) cause 14% of all cases of tonsillitis in adults and 37% of all cases of tonsillitis in children. Check also local epidemiology.
The more symptoms there are, the greater the likelihood of a bacterial aetiology.
Throat culture from teenage or adult patients with pharyngitis and a Centor score of 3 or 4 (see Table T1) shows StrA in about 50% and StrC or StrG in about 25% of cases. In addition, throat infections caused by the anaerobic Fusobacteria resemble those caused by StrA. All the above pathogens are sensitive to penicillin.
Adenovirus infections are common especially among children less than 5 years of age but they are found in all age groups.
Epstein-Barr virus (EBV) causes typical mononucleosis Mononucleosis in adolescents, but a similar clinical picture is also seen in small children. Mononucleosis should be recognized because of the prolonged clinical course and the potential complications. In other age groups the symptoms are usually mild.
Besides infections caused by group StrA, specific diagnosis should be pursued in rare bacterial throat infections caused by gonococci Gonorrhoea and diphtheria Diphtheria. If the patient has a history of high-risk behaviour predisposing to sexually transmitted disease or if vaccination protection against diphtheria is deficient, these rare pathogens should be considered and their culture separately requested.
Mycoplasma and chlamydia infections rarely present with sore throat only, and need not be searched for.
Clinical examination
Examination of the pharynx
Inspection: erythema, exudate, peritonsillar oedema, opening of the mouth, air space
Palpation if needed (e.g. using a wooden spatula or cotton swab): in peritonsillar abscess the peritonsillar space is swollen, tender and taut
Palpation of the neck
Tender, swollen submandibular lymph nodes anterior to the sternocleidomastoid muscle increase the probability of both streptococcal aetiology and mononucleosis.
Additional findings increasing the probability of StrA infection include strawberry tongue, pharyngeal petechia, scarlet-fever type rash, perianal streptococcal rash, paronychia and impetigo.
Oedema of the eye lids: mononucleosis? Mononucleosis
Other focuses of infection (sinuses, ears, teeth, lower respiratory tract)
By inspection of the pharynx, infection caused by a virus cannot be told apart from bacterial tonsillitis; for example, coating on the tonsils can be found in both.
Interpretation of throat smear results depends on how probable StrA is based on the clinical picture.
38-57% of patients with a Centor score 3-4 show StrA in throat culture.
At a Centor score level of 3-4, the StrA antigen test is accurate and detects 91-95% of patients who truly have StrA. Its sensitivity is worse, i.e. the antigen test remains negative in some patients (11-22%). Therefore, if a patient with severe symptoms has a negative antigen test, the result should be confirmed by throat culture. The procedure should be agreed locally.
About 20% of adults and about 30% of children with a Centor score of 2 show StrA in throat culture. In such cases, avoid taking a throat smear.
This applies in settings where the risk of severe complications, such as rheumatic fever or glomerulonephritis, is low.
Pharyngitis also resolves without treatment.
Antimicrobial treatment has adverse effects, too.
Children, in particular, are quite commonly asymptomatic carriers of StrA.
Check also local policies concerning Centor score and testing.
Usually the result of a rapid test for StrA will be ready during consultation.
The result of a throat culture is read after 18-24 hours after collection of specimen. If the result is negative, the growth should be re-examined the next day.
The precision of throat culture in detecting StrA varies depending on the method and the user's training.
Samples should be taken by a health care professional.
Use an appropriate sterile cotton-tipped swab to obtain the sample.
Press the tongue firmly with a wooden spatula and use a well-focused light (a headlamp).
Take the sample from both tonsils and the posterior pharyngeal wall by pressing the cotton tip firmly against the mucosa and making circular movements. Avoid touching the lips or the tongue with the swab.
During an epidemic, throat culture is used. It also provides antimicrobial sensitivity testing.
The physician should see all children and those adults who have deteriorated general condition, significant difficulty swallowing, a primary disease that may be worsened by the throat infection, or who otherwise present with an atypical clinical picture or with signs or symptoms suggesting complications.
Alarm symptoms include
Poor general condition
Respiratory difficulty
Trismus (lockjaw)
Peritonsillar asymmetry
Tenderness or erythema of the anterior neck
Head turning limited
Adult patients in good condition can be examined by a trained nurse. A throat swab should be taken from symptomatic patients according to Centor symptom score, and further measures should be agreed on locally.
Antimicrobials are indicated only for patients with a positive rapid test or culture for either
group A streptococci or
any streptococci if the symptoms are severe, particularly during an epidemic.
The aim of antimicrobial treatment is to shorten the duration of symptoms.
Antimicrobials somewhat shorten the duration of symptoms in patients with StrA, apparently by about 2.5 days.
In patients with StrC or StrG, the duration of symptoms is shortened by an average of 1.3 days.
If the patient is asymptomatic by the time the results of throat culture are available, antimicrobial treatment would probably be of insignificant benefit.
The initiation of medication can well be postponed until the rapid test or culture result confirms the diagnosis provided that the patient doesn't have a high fever.
Empiric antimicrobial treatment should be considered if there are additional findings suggesting streptococcal disease (strawberry tongue, pharyngeal petechia, scarlet-fever type rash, perianal streptococcal rash, paronychia, impetigo).
In teenagers and young adults, high fever increases the probability of bacterial aetiology. Consider mononucleosis in differential diagnosis.
Follow-up throat culture after treatment is not necessary.
Weight-based dosing of oral amoxicillin suspension is an alternative especially for small children who are not able to take penicillin.
The second line antimicrobial drug is cephalexinhttp://www.dynamed.com/management/antibiotics-for-streptococcal-pharyngitis#CEPHALOSPORINS For adults the dose is 500 mg 3 times daily and for children 40-50 mg/kg/24 h divided into 3 daily doses. The duration of treatment is 10 days. Macrolides are recommended only if the resistance situation in the region allows it and sensitivity testing has been performed.
Mononucleosis Mononucleosis should not be treated with antimicrobials. Mixed infection is possible, and, in that case, starting antimicrobial medication should be considered based on throat smear.
Pharyngeal gonorrhea often causes only mild symptoms. Remember the provision of possibly free antimicrobials for STD (check local policies) and tracing of the contacts Gonorrhoea.
The clinical picture of subacute thyroiditis Subacute Thyroiditis may resemble that of an acute throat infection.
Syphilis, primary HIV infection and diphtheria should be kept in mind as rare causes.
Recurrent tonsillitis
Tonsillitis at least 3 times within 6 months or 4 times within a year
The most common causes of recurrence: beta-lactamase-producing normal flora in the throat, poor adherence to treatment, streptococcal carrier state, new infection from a person in near contact
In recurrent infection first-line therapy is cephalexin (500 mg 3 times daily for 10 days) which eradicates StrA even more efficiently than penicillin. Clindamycin (300 mg 3-4 times daily for 10 days) also eradicates StrA efficiently and prevents recurrent tonsillitis caused by other bacteria as well.
Therapy with clindamycin should be considered in cases of recurrent tonsillitis before referring the patient for an assessment concerning tonsil surgery.
Emergency referral: complications of acute tonsillitis, such as peritonsillar abscess or sepsis
Referral for a consultation within a few days: suspicion of malignancy based on strong asymmetry or local tissue change in an adult, particularly in the absence of clear symptoms of an infection
A streptococcal epidemic should be suspected if several patients fall ill in the same location within a short time (15-20% of the same group of people within two weeks or several family members within one month).
Epidemics commonly occur in child day-care settings, schools, military units and care institutions.
If the epidemic is severe, consider also the possibility of a food-borne infection Food Poisoning.
Throat cultures should be taken from all symptomatic and asymptomatic persons belonging in the group; in the initial phase, cultures can at discretion also be taken from their symptomatic family members.
All persons with positive cultures should be treated simultaneously and the spread of infection should be prevented by avoiding contacts with other persons for 24 hours whether they have symptoms or not. After 24 hours from the beginning of antimicrobial treatment, they can return to school or day care centre if their symptoms do not require a longer absence. Follow-up samples are not needed after treatment.
References
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Holm S, Henning C, Grahn E, et al. Is penicillin the appropriate treatment for recurrent tonsillopharyngitis? Results from a comparative randomized blind study of cefuroxime axetil and phenoxymethylpenicillin in children. The Swedish Study Group. Scand J Infect Dis 1995;27(3):221-8 [PubMed]