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Bacterial infections are unique, and the different types of bacteria have greater or lesser resistance to certain forms of antibiotics. In the case of strep throat, the causal bacterium is group A streptococcus, and it is effectively eliminated by several groups of antibiotic medicines. The groups of antibiotics for strep throat that are most used are Beta-lactam antibiotics (penicillins), cephalosporins (drugs like Keflex®), and macrolides (erythromycin and others). Determining which drug is most appropriate for treatment involves consideration of the individual patient and his or her medical history.
One of the most common antibiotics used to treat strep throat is penicillin or related medicines like ampicillin and amoxicillin. A two-week course of these drugs shows good results in eliminating group A streptococcus. In recent times, though, research on strep behavior suggests growing treatment resistance of strep to the Beta-lactam group. This necessitates having back-up medicines that can work when penicillin or its relatives are ineffective.
Studies on antibiotics for strep throat suggest that using medications from the cephalosporin group is more effective than treatment with medicines in the beta-lactam group. There are many potential cephalosporins to use, but the most common one prescribed for strep is cephalexin or Keflex®. In many cases, strep can still be eliminated with either medication group, but if the illness is not responding to treatment with one group, switching to the other could be recommended to eradicate the illness.
With both penicillin types and cephalosporins there are potential problems. First, people can be allergic to penicillin and its relatives, making these inappropriate for treatment. Second, many people allergic to Beta-lactam medicines are also allergic to cephalosporins. This means some people can’t be treated with either of these groups of medicines and require an alternative.
The alternative is treatment with antibiotics from the macrolide class, including medicines like erythromycin, clarithromycin (Biaxin®), and azithromycin (Zithromax®). Some of these drugs can have decided advantages. Zithromax® is taken for four to five days instead of for two weeks straight.
Macrolides also have disadvantages, including much higher incidence of stomach upset. Such side effects are usually considered a small price to pay for killing strep bacteria, but in a small percentage of people, adverse effects are so severe that it can make some of these medicines difficult to take. The newer macrolides tend to have a lower side effect profile and may be better tolerated.
Ultimately, discussion of the best antibiotics for strep throat must be held with a treating medical professional. A history of allergy or adverse effects to certain drugs could rule out some treatments, and make others the most appropriate. It’s also important to observe that, while these three classes of medicine are most often used, there are other antibiotics that can be tried if no medicine from these classes will work.