GAS pharyngitis or 'strep throat'
Acute pharyngitis due to GAS infection can be differentiated from a viral sore throat by the presence of high temperature (>38degC), swollen cervical lymph nodes, swollen tonsils with or without exudate (pus), and the absence of a cough or coryza (runny nose, etc.). (11) High-risk groups and those with confirmed GAS infection are treated with a 10-day course of oral penicillin or amoxicillin. There is evidence that as long as therapy starts within nine days of the onset of symptoms, the risk of progression to ARF is minimised. (9)
GAS is vulnerable to the effects of penicillin, which is remarkable considering the extensive use of the antibiotic and the development of resistance to it by many other types of bacteria. Most resistance to penicillin is conferred by beta-lactamase activity in a bacterial species. GAS does not possess the gene for beta-lactamase, possibly because it (the enzyme) may be toxic to GAS. An alternative mechanism of resistance is modification of the penicillin binding protein (PBP) in the bacterial cell wall. When GAS with modified PBPs were created in the laboratory, there were such severe changes in the bacteria structure and function that they could not survive. (12)
Amoxicillin is a broader spectrum antibiotic. It is as effective as penicillin but may have better compliance due to more palatable taste, once-daily dosing and because it does not need to be administered on an empty stomach