Amoxicillin antimicrobial activity

Several natural penicillins can be produced, depending on the chemical composition of the fermentation medium used to culture penicillium. Penicillin G (benzylpenicillin) has the greatest antimicrobial activity of these natural penicillins and is the only natural penicillin used clinically. However, penicillin G is not stable it is extremely acid-labile. Only about one-third of an oral dose is absorbed under the most ideal conditions. Therefore, it is generally not given orally but is administered by intramuscular injection. Several newer derivatives of penicillin G have been developed that do have good to excellent oral absorption (e.g., cloxacillin, ampicillin, and amoxicillin). 

Parenteral preparations with antimicrobial activity, which depends on the causative pathogenic microorganism, and pharmacokinetic properties that meet most of these criteria include procaine penicillin G (aqueous suspension), amoxicillin trihydrate-clavulanate potassium combination (aqueous suspension), and enro-floxacin (solution). Enrofloxacin is not approved for use... 

Increased activity of enzymes that make drags more polar is likely to inactivate an antimicrobial drug and will not lead to increased antibacterial activity. Specific examples of mechanisms that do result in synergy include (A) the combination of trimethoprim and sulfamethoxazole (B) the combination of a penicillin and an aminoglycoside and (D) the combination of clavu-lanic acid and amoxicillin. The answer is (C). 

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