Final answer:
Individuals allergic to penicillin should avoid β-lactam antibiotics, which include penicillins, cephalosporins, monobactams, and carbapenems. Suitable alternatives are tetracyclines, macrolides, and other classes like chloramphenicol and sulfonamides. Care must be taken to prevent severe allergic reactions.
Step-by-step explanation:
The drug class of antibiotic that should not be used if a patient is allergic to penicillin are the β-lactam antibiotics. This group includes the penicillins, cephalosporins, monobactams, and carbapenems, and is characterized by the presence of a β-lactam ring within the drug molecule. The similarity of the β-lactam structure to the peptidoglycan subunit targeted by bacterial enzymes can cause cross-reactivity in patients with penicillin allergies, posing serious health risks.
For patients with penicillin allergies, alternative classes of antibiotics such as tetracyclines, macrolides (e.g., azithromycin, erythromycin), and others like chloramphenicol, sulfonamides, and trimethoprim can be considered. These alternatives do not share the same structure as β-lactam antibiotics and are less likely to cause allergic reactions in individuals who are allergic to penicillin.
It is crucial for healthcare providers to be aware of a patient's allergy profile before prescribing antibiotics, to prevent potentially severe allergic reactions such as anaphylaxis. In the case of bacteria that have developed resistance to penicillin by producing penicillinase, synthesizing penicillin analogs such as methicillin has been used to overcome this resistance. However, methicillin is also a β-lactam antibiotic and should be avoided in allergic individuals.