Pharyngitis (Sore Throat)

3.12 Pharyngitis (Sore Throat)

Presentation
The patient with a bacterial pharyngitis complains of a rapid onset of throat pain worsened by swallowing. There is usually a fever, pharyngeal erythema, and a purulent, patchy, yellow, gray or white exudate, tender cervical adenopathy, headache and absence of cough. Viral infections are typically accompanied by conjunctivitis, nasal congestion, hoarseness, cough, aphthous ulcers on the soft palate and myalgias. It is helpful to differentiate pain on swallowing (odynophagia) from difficulty swallowing (dysphagia), the latter being more likely caused by obstruction or abnormal muscular movement.
What to do:



First examine the ears, nose, and mouth, which are, after all, connected to the pharynx, and often contain clues to the diagnosis.



Depress the tongue with a blade, have the patient raise his soft palate by saying " ah," inspect the posterior pharynx, and swab both tonsillar pillars for a culture. (You can decide later whether you really need to plant the culture. Rapid strep tests may provide results in a few minutes, while cultures may take 1-2 days to incubate and interpret. This delay does not alter the effectiveness of therapy, however. Treatment may begin up to nine days after symptoms and still prevent rheumatic fever.)



If you are in the middle of an epidemic of group A streptococcal pharyngitis; if the patient is between 3 and 25 years old, has a history of rheumatic fever and recurrent "strep throats" and has been exposed; and if the patient has a red throat, fever, tender anterior cervical nodes, and no viral URI symptoms (or any convincing subset of the above); give antibiotics. Throat culture is optional, at the preference of the follow-up physician. The recommended treatment for streptococcal pharyngitis is oral penicillin VK 250mg q8h for 10 days. Injectable penicillins are preferred for patients unlikely to finish ten days of pills and those with a personal or family history of rheumatic fever. Patients under 60 lbs (30 kg) get one intramuscular injection of benzathine penicillin G 600,000 units and those over 60 lbs get 1,200,000u im. For those allergic to penicillin give erythromycin 250mg qid (or 333mg of erythromycin base tid) for 10 days. Amoxicillin offers no significant advantage for treating group A strep.



When the infection is not clearly bacterial or you are unsure about the need for an antibiotic (or you or the patient "need to know" if this is a strep infection) then you may obtain a rapid strep test. If the rapid strep test is positive, then treat with antibiotics as above. If the test is negative or unavailable and you have a high clinical suspicion that this is a viral pharyngitis, provide symptomatic treatment (below), send a culture, and hold antibiotics pending results.



For reistant or recurrent infections with possible beta-lactamase- producing co-pathogens, consider instead 10 days of cephalexin (Keflex), cefadroxil (Duricef, Ultracef), cefaclor (Ceclor), or cefurooxime (Ceftin, Zinacef).



If you suspect mononucleosis, draw blood for atypical lymphocytes and a heterophile or monospot to confirm the diagnosis (see below).



Relieve pain with acetaminophen ibuprofen, aspirin, warm saline gargles, and gargles or lozenges containing phenol as a mucosal anesthetic (e.g., Chloraseptic, Cepastat). A one-to-one mixture of diphenhydramine and kaolin-pectin suspension can also provide temporary relief of throat pain. Viscous Xylocaine gargles anesthetize the throat but patients may still have difficult swallowing because of the lack of sensation. For severe pain in patients without contraindications, dexamethasone 10mg im once has been used along with antibiotics.
What not to do:



Do not miss an acute epiglottitis or supraglottitis. In a child, this presents as a sudden, severe pharyngitis, with a gutteral, rather than hoarse voice (because it hurts to speak), drooling (because it hurts to swallow), and respiratory distress (because swelling narrows the airway). Adults usually have a more gradual onset, over several days, and are not as prone to a sudden airway occlusion, unless they present later in the progression of the swelling, already with some respiratory distress.



Do not give ampicillin to a patient with mononucleosis. The resulting rash helps make the diagnosis, and does not imply ampicillin allergy, but can be uncomfortable.



Do not miss abscesses, which usually require hospitalization and intravenous penicillin, if not drainage. Peritonsillar abcesses or cellulitis make the tonsillar pillar bulge towards the midline. Retropharyngeal abscesses (and epiglottitis) may require soft tissue lateral neck films to visualize.



Do not miss gonococcal pharyngitis, which can produce a mild clinical syndrome and requires special cultures on Thayer-Martin medium.



Do not miss the rare but deadly causes of sore throat. A patient with paresthesia at the site of an old, healed bite and painful spasms when he even thinks of swallowing may have rabies. A patient with facial palsy, myocarditis, and a tough, white, membrane adherent to the posterior pharynx may have diptheria. You cannot diagnose them unless you think of them.
Discussion
The general public knows to see a doctor for a sore throat, but the actual benefit of this visit is unclear. Rheumatic fever is a sequela of about 1% of group A streptococcal infections, and only about 10% of sore throats seen by physicians represent group A streptococcal infections. Post-streptococcal glomerulonephritis is usually a self- limiting illness and is not prevented with antibiotic treatment. Penicillin therapy does avoid acute rheumatic fever and may sometimes reduce symptoms or shorten the course of a sore throat. Antibiotics probably inhibit progress of the infection into tonsillitis, peritonsillar and retropharyngeal abscesses, adenitis, and pneumonia.
Group A streptococcal infection cannot be diagnosed reliably by clinical signs and symptoms. Typically, a quarter of throat cultures grown group A strep, and half of those represent carriers who do do not raise anti-streptococcal antibodies and risk rheumatic fever. Rapid strep screens are less sensitive than cultures. The best approach to the identification and treatment of streptococcal pharyngitis depends on the prevalence of group A streptococcal infection in the patient population, the cost and availability of culture and rapid test methods, the reliability of communication and follow up and the relative values of cost, antibiotic overuse, and adverse outcomes.
References



Coonan KM, Kaplan EL: In vitro susceptibility of recent North American group A streptococcal isolates to eleven oral antibiotics. Pediatr Infect Dis J 1994;13:630-635.



Hall CB, Breese BB: Does Penicillin make Johnny's strep throat better? Pediatric Infectious Disease 1984:3:7-9.



O'Brien JF, Meade JL, Falk JL: Dexamethasone as adjuvant therapy for severe acute pharyngitis. Ann Emerg Med 1993;22:212-214.



Huovinen P, Lahhtonen R, Ziegler T et al: Pharyngitis in adults: the presence and coexistence of viruses and bacterial organisms. Ann Intern Med. 1989;110:612-616.