Letters to the Editor

Antibiotic Use for Streptococcal Pharyngitis Groups C and G


Am Fam Physician. 2005 Jun 1;71(11):2050.

to the editor: The article1 by Vincent and colleagues in American Family Physician reviews a topic that is highly relevant to my everyday practice in primary care: pharyngitis. Thank you for articles on such topics. I would like to ask the authors if they have any information on the need or validity of offering antibiotic treatment to patients whose throat cultures reveal groups of streptococci other than A? My laboratory routinely evaluates for groups C and G, and there is some literature25 that suggests that treating these groups of patients may be clinically beneficial. However, I am loath to extend the use of antibiotics further in an era of significant rates of microbial resistance and physician tendency to offer treatments without good evidence of efficacy.


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1. Vincent MT, Celestin N, Hussain AN. Pharyngitis. Am Fam Physician. 2004;69:1465–70....

2. Dale DC, Federman DD. ACP medicine: a publication of the American College of Physicians. New York, N.Y.: WebMD, 2004.

3. Zaoutis T, Attia M, Gross R, Klein J. The role of group C and group G streptococci in acute pharyngitis in children. Clin Microbiol Infect. 2004;10:37–40.

4. Dierksen KP, Tagg JR. Haemolysin-deficient variants of Streptococcus pyogenes and S. dysgalactiae subsp. equisimilis may be overlooked as aetiological agents of pharyngitis. J Med Microbiol. 2000;49:811–6.

5. Woo PC, Teng JL, Lau SK, Lum PN, Leung KW, Wong KL, et al. Analysis of a viridans group strain reveals a case of bacteremia due to lancefield group G alpha-hemolytic Streptococcus dysgalactiae subsp equisimilis in a patient with pyomyositis and reactive arthritis. J Clin Microbiol. 2003;41:613–8.

in reply: I would like to thank Dr. Mosby for a most intriguing question. Groups C and G beta-hemolytic streptococci certainly have caused well-documented epidemics of acute pharyngitis. These outbreaks often have been associated with contaminated foods (group C with milk-borne outbreaks and group G with infected egg salad and chicken salad). Groups C and G streptococci also are frequently isolated from asymptomatic persons. Groups C and G streptococci express the virulence factor, M protein.6 It is difficult to differentiate between colonization and infection. The benefit of antimicrobial therapy has not been established. One author advises that patients with streptococci C and G be treated solely for symptomatic relief.7 Others state that there is no proven benefit in treating any pharyngitides other than group A beta-hemolytic strep, Corynebacterium diphtheriae, and Neisseria gonorrhoeae.8,9 It would appear that we do not understand the pathogenic burden of these organisms, although it is known that the more virulent strains express a C5a peptidase enzyme similar to group A beta-hemolytic strep.10 My conclusion is that local strain virulence results in the different clinical pathogenic presentations of the organisms under question. The answer: we don’t know if groups C and G streptococci deserve antibiotic therapy, and, of course, we never routinely know if they express C5a peptidase.


show all references

1. Efstratiou A, Teare EL, McGhie D, Colman G. The presence of M proteins in outbreak strains of Streptococcus equismilis T-type 204. J Infect. 1989;19:105–11....

2. Middleton DB. Pharyngitis. Prim Care. 1996;23:719–39.

3. Bisno AL. Acute pharyngitis. N Engl J Med. 2001;344:205–11.

4. Bisno AL, Gerber MA, Gwaltney JM Jr, Kaplan EL, Schwartz RH. Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. Infectious Diseases Society of America. Clin Infect Dis. 2002;35:113–25.

5. Cleary PP, Peterson J, Chen C, Nelson C. Virulent human strains of group G streptococci express a C5a peptidase enzyme similar to that produced by group A streptococci. Infect Immun. 1991;59:2305–10.

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This series is coordinated by Kenny Lin, MD, MPH, Associate Deputy Editor for AFP Online.



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