Streptococcus pyogenes is one of the most common human pathogens. Todar's Online Textbook of Bacteriology notes that about 5 to 10 percent of healthy individuals harbor this bacteria in their respiratory tract without any symptoms. However, Streptococcus pyogenes may penetrate the defenses of individuals with reduced immunity and cause strep throat, skin and muscle infections, and streptococcal toxic shock syndrome, a condition characterized by reduced body temperature, low blood pressure and a diffused rash.
Beta-lactam Antibiotics
Beta-lactam antibiotics, such as penicillin and amoxicillin, are uniformly effective against most strains of Streptococcus pyogenes. According to the John Hopkins Point of Care Information Technology Center, penicillin V is the drug of choice for strep throat. However, this antibiotic is only effective against actively multiplying organisms, and hence may not be useful in treating deep-seated infections such as muscle and soft tissue infections.
Beta-lactam antibiotics can be taken orally or intramuscularly, and are usually prescribed for 10 days. Penicillin allergies are common and may manifest as hives, itchy skin, wheezing and rash. Other side effects may include irritation of mouth, mild diarrhea, nausea and vomiting.
Macrolides
Macrolides such as erythromycin, clarithromycin and azithromycin are used to treat Streptococcus pyogenes infections in individuals who are allergic to penicillin. Another macrolide--clindamycin--is given in combination with penicillin to treat muscle and soft tissue infections that cannot be treated by penicillin alone.
Most strains of Streptococcus pyogenes are fairly susceptible to macrolides. In a study published in the September 2005 edition of "Clinical Infectious Diseases," Dr. Sandra. S. Richter reports that less than 7 percent isolates of Streptococcus pyogenes were resistant to macrolides. Macrolides may be given orally or intravenously, depending on the condition of the patient. Common side effects include pain in the stomach, diarrhea, nausea and vomiting.
Cephalosporins
The March 2007 edition of "Diagnostic Microbiology and Infectious Diseases" notes that first-generation cephalosporins, such as cefazoline and cephradine, are suitable alternatives for patients with penicillin allergies.
Cephalosporins can be administered orally, intramuscularly or intravenously, depending on the type of the drug, site of the infection and the condition of the patient. Side effects commonly involve the digestive system, and include nausea, vomiting, diarrhea and stomach cramps.
References
- Todar's Online Textbook of Bacteriology: Streptococcus pyogenes and Streptococcal Disease
- John Hopkins POC IT Center: Streptococcus pyogenes (Group A)
- "Clinical Infectious Diseases"; Macrolide-Resistant Streptococcus pyogenes in the United States, 2002–2003; Sandra S. Richter, et al.; September 2005
- "Diagnostic Microbiology and Infectious Diseases"; The evidence base for cephalosporin superiority over penicillin in streptococcal pharyngitis; Janet R. Casey and Michael E. Pichichero; March 2007
