Final answer:
Cephalosporins are the likely antibiotic class to cause cross-sensitivity in patients with penicillin allergies due to the presence of the β-lactam ring, which is similar to that of penicillins.
Step-by-step explanation:
When a patient exhibits cross-sensitivity to an antibiotic because of a previous penicillin allergy, the patient was likely given a drug from a class that is structurally and mechanistically similar to penicillins. The correct non-penicillin class of antibiotics in this scenario is cephalosporins, which, like penicillins, belong to the larger class of β-lactam antibiotics. Both penicillins and cephalosporins share a similar β-lactam ring within their molecular structures, which is responsible for their antibiotic activity. This β-lactam ring is also the reason why cross-sensitivity can occur. Patients with penicillin allergies may react to other β-lactam antibiotics because their immune systems recognize the similar structural features. The other options, such as macrolides, tetracyclines, and fluoroquinolones, do not contain the β-lactam ring and thus are less likely to cause cross-sensitivity in patients allergic to penicillin.
The final answer is: B. Cephalosporins, due to their similarity to penicillins in chemical structure and mode of action, involving the inhibition of cell wall synthesis.
In two line explanation: Cross-sensitivity in a patient with a penicillin allergy occurs most likely due to taking cephalosporins, which share the β-lactam ring with penicillins.