Tkg asked
What is the best antibiotic for strep throat? I was prescribed azithromycin Z-pack but after researching, it seems it may not be the best option. I saw "unfortunately, the increased incidence of macrolide-resistant group A strep has limited the utility of azithromycin for the treatment of strep throat.” Should I go back to the doc with this info or go ahead with taking the medication?
Answer
The Infectious Diseases Society of America has specific guidelines for the treatment of streptococcal pharyngitis, also known as "strep throat". Penicillin or amoxicillin are the "first-line" treatment options because they specifically target gram positive streptococcus organisms, are well tolerated and are relatively inexpensive.
For those with a penicillin allergy (which would also remove amoxicillin as a therapy option), alternative antibiotics include:
- First-generation cephalosporins (e.g. cephalexin)
- Clindamycin
- Clarithromycin (Biaxin)
- Azithromycin (Zithromax)
The full antibiotic treatment options can be viewed here: Treatment Regimens for Group A Streptococcal Infection
Additional Information About Azithromycin For Strep Throat Infections
Streptococcal pharyngitis (i.e. strep throat) is most often caused by group A streptococcus (Streptococcus pyogenes). In fact, streptococcus pyogenes is thought to be responsible for 5-15% of all pharyngitis infections in adults, and even more in children according to a study in the New England Journal of Medicine.
Per published guidelines, macrolide antibiotics, of which azithromycin is a member, should be limited for use in those who are penicillin-allergic. This is for a few reasons:
- Azithromycin is a broad spectrum antibiotic, meaning it covers a variety of bacteria including both gram positive and gram negative organisms. Broad spectrum antibiotics are more likely to lead to drug resistant organisms with overuse.
- Azithromycin is more expensive than other effective antibiotics for strep throat, such as penicillin and amoxicillin.
- It has been reported that 5% to 8% of group A streptococcus are resistant to azithromycin. Bacterial resistance to penicillin in regard to strep is much lower.
- Azithromycin is associated with more drug interactions than many other antibiotic choices and has the risk of causing QT prolongation in susceptible individuals.
Now, while there are many reasons not to use azithromycin as a first line treatment for strep thoat, there is certainly a place in therapy for it. Your doctor may have prescribed azithromycin because:
- Azithromycin is a broad spectrum antibiotic. If your doctor is unsure of the bacteria causing your infection (i.e. they may think it is not strep), they are more likely to prescribe an antibiotic that covers more than just streptococcus.
- Azithromycin is easier to dose than other antibiotics. All it takes is a once daily dose versus 3 to 4 times daily dosing for other antibiotics.
- Your doctor may think you have a penicillin sensitivity or may have record of you not tolerating penicillin well in the past.
Lastly, resistance to azithromycin is typically geographical, and it is most likely known whether or not the area you live in has reports of resistant organisms. If not, you doctor may think it is the most effective, best tolerated and appropriate choice for your specific situation.
Nevertheless, if you are concerned, it is never a bad idea to speak with your doctor or office regarding the best course of therapy for you.
