Group C and group G streptococci. In-office isolation from children and adolescents with pharyngitis.

The importance of non-group A streptococci as etiologic agents of acute pharyngitis in endemic circumstances is unclear. The authors attempted to clarify this issue in patients undergoing throat culture for acute pharyngitis in a suburban pediatric practice. Of 6,694 throat cultures, 2,243 (34%) yielded B-hemolytic streptococci, 83 percent (1,783) of which were bacitracin-sensitive and presumptive group A organisms. A random selection of 279 of the 460 bacitracin-resistant streptococci yielded 56 group C, 42 group G, 35 group F, 2 group A, and 3 mixed groups of streptococci. Paired serologic specimens were obtained from 12 children with group C or G streptococci. Four of six group C subjects from whom paired serum specimens were obtained had a significant increase in anti-streptolysin O titer. However, no change in anti-C/G hyaluronidase or anti-C carbohydrate titer was observed. Similarly, two of six subjects with group G streptococci on throat culture in whom paired serum specimens were obtained showed an increase in ASO titer. No seroconversion to anti-C/G hyaluronidase, anti-C, or anti-G carbohydrates was demonstrated. Despite substantial clinical and circumstantial evidence, it could not be confirmed serologically that group C and G streptococci produced acute pharyngitis in this endemic setting.