What Is the Recommended Treatment for Bacterial Tonsillitis?

Wendy L. Wright, MS, RN, ARNP, FNP, FAANP


February 27, 2001


When treating bacterial tonsillitis, what is the specific antibiotic of choice and why? How does it differ from other antibiotics of that class?

Elvira Velez, ARNP, MPH


Response From the Expert

Wendy L. Wright, MS, RN, ARNP, FNP, FAANP:

Tonsillitis and pharyngitis are conditions caused by an inflammation of the tonsils and pharynx, respectively. These 2 conditions will be discussed together and referred to as tonsillopharyngitis.

There are approximately 30 million cases of tonsillopharyngitis diagnosed yearly, the majority of which are caused by a viral illness. Viral causes include the rhinovirus, adenovirus, coxsackievirus, echovirus, coronavirus, and the Epstein-Barr virus (mononucleosis). There are also many known bacterial causes. The most common bacterial cause and perhaps the most serious in terms of sequelae is group A beta hemolytic streptococci. This bacterium has been associated with such complications as peritonsillar abscess, rheumatic fever, necrotizing fasciitis, and meningitis. Other less frequent bacterial causes include: Neisseria gonorrhoeae, Corynebacterium diphtheriae (diphtheria), Haemophilus influenzae, Moraxella catarrhalis, and group C and G streptococcus.[1]

When initiating treatment for tonsillopharyngitis, it is essential to first differentiate between viral and bacterial etiologies. Because history and physical examination correctly identifies the etiology only 50% of the time, a throat culture must be obtained.[2] Some healthcare professionals continue to use the rapid strep screen despite a false-negative rate that ranges from 5% to 40%. In addition, this test is diagnostic only for group A beta hemolytic streptococci. These 2 factors have led many health professionals to abandon the rapid strep screen and use the standard throat culture. Although results of this throat culture may not be available for 48 hours, the accuracy of the test is far superior to the rapid screen.

Group A beta hemolytic streptococci, a gram-positive bacteria, is the most common bacterial cause of tonsillopharyngeal infections and will be the subject of the remainder of this discussion. It is responsible for one third to one half of all cases of tonsillopharyngitis in children between 2 and 14 years of age and approximately 10% of all infections in adults.[2] The current recommended treatment for this infection is penicillin V 25-50 mg/kg/day divided into a 4-dose-per-day schedule for 10 days.[3] If the patient is likely to be compliant, penicillin V may be administered in a twice-daily dosing schedule instead of 4 times a day but compliance with this modified dosing regimen is essential.

If the patient is unlikely to be compliant with either of these regimens, benzathine penicillin (penicillin G) 25,000 u/kg intramuscular as a single injection may be used.[3] Both medications are highly efficacious against group A beta hemolytic streptococci. While both medications are classified as penicillins, penicillin V is administered orally while benzathine penicillin is administered via an injection because of its poor absorption from the gastrointestinal system when taken orally. Given the mode of administration, the risk of an allergic reaction is higher with the benzathine.

Another acceptable alternative for the treatment of group A beta hemolytic strep, and one that is utilized frequently in clinical practice, is amoxicillin. Amoxicillin is an aminopenicillin and should be administered in the amount of 40-50 mg/kg/day, divided into 3 doses.[4] This medication is as efficacious as penicillin V and is often more palatable to children. Side effects include nausea, diarrhea, and rash but these are similar to other penicillins. In contrast to the penicillin class, amoxicillin provides coverage against both gram-positive and gram-negative pathogens. Some experts propose that amoxicillin should be avoided for strep tonsillopharyngitis because of its broader spectrum of coverage. Another aminopenicillin with group A beta hemolytic strep coverage is ampicillin. Ampicillin use is currently discouraged because it is administered 4 times daily and has an increased diarrhea rate when compared with similar doses of amoxicillin.

If a patient is penicillin-allergic, erythromycin 30 mg/kg/day divided into 3 doses provides good group A streptococci coverage. Although very effective when taken as prescribed, the majority of patients fail to take as directed due to side effects. Approximately 20% to 25% of individuals taking erythromycin report diarrhea, abdominal pain, or nausea.

Clarithromycin (Biaxin) and azithromycin (Zithromax), like erythromycin, are macrolides and provide excellent group A strep coverage. Unlike erythromycin, clarithromycin is dosed twice daily for 10 days and azithromycin is given once daily for 5 days only. The easier dosing schedule and fewer side effects of both of these products improve compliance over traditional erythromycin. The prescriber needs to keep in mind that erythromycin and clarithromycin are metabolized through the cytochrome P450 3A4 pathway and therefore interact with a number of other medications using the same pathway. These 2 medications should not be coadministered with carbamazepine or theophylline. This coadministration has resulted in increased levels of carbamazepine and theophylline. Another difference between erythromycin and the other macrolides is the spectrum of antimicrobial coverage. Erythromycin has primarily gram-positive and atypical pathogen (Mycoplasma, chlamydia) coverage whereas azithromycin and clarithromycin have gram-positive, atypical, and gram-negative coverage. Prescribing these broader spectrum macrolides for strep throat may not be necessary and may contribute to antimicrobial resistance.

Another antimicrobial option for the patient with group A beta hemolytic strep tonsillopharyngitis is a cephalosporin. There are currently 3 generations of cephalosporins used in the ambulatory patient. First-generation cephalosporins have excellent activity against gram-positive bacteria and would be the class of choice if a cephalosporin is needed for group A beta hemolytic streptococci. The 2 most widely used first-generation cephalosporins are cephalexin (Keflex) and cefadroxil (Duricef). These medications are utilized in some penicillin allergic individuals when erythromycin cannot be used. It is important to keep in mind that approximately 3% to 5% of individuals with a penicillin allergy will have a reaction to a cephalosporin. Therefore, if a patient has experienced a rash from amoxicillin or penicillin, many providers will administer a cephalosporin and watch the patient carefully. Conversely, if a patient has a history of penicillin-induced anaphylaxis, cephalosporins should be avoided. Both medications are equally efficacious. Cephalexin is dosed at 30 mg/kg/day in a twice-daily or 3-times-daily schedule whereas cefadroxil may be administered once daily. Because cephalexin is available as a generic product, it is generally less costly than cefadroxil.

Second-generation cephalosporins also eradicate group A beta hemolytic strep but have a broader spectrum of coverage than is generally needed. Examples of this class include cefaclor (Ceclor) and cefprozil (Cefzil). These antibiotics cover both gram-positive and gram-negative pathogens and therefore should not be used as first-line therapy. Third-generation cephalosporins such as cefixime (Suprax) and ceftibuten (Cedax) have primarily gram-negative coverage and would not be appropriate antibiotics for group A beta hemolytic streptococci infections. Fluoroquinolones offer coverage against group A beta hemolytic strep but would not be appropriate antibiotics for this infection because their spectrum of coverage is broader than clinically indicated.

In summary, group A beta hemolytic streptococci is the most common bacterial cause of tonsillopharyngitis in the United States. First-line medication for the treatment of this condition should be either penicillin V or penicillin G (administered IM). An acceptable substitution is amoxicillin. For individuals allergic to penicillin, erythromycin or a first-generation cephalosporin may be appropriate.


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