This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Which of the following Beta lactam can be used in an individual who is allergic to penicillin? \nSelect and explain. \nA. Imipenem, B. Carbenicillin, C. Aztreonam, D. Ticarcillin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Aztreonam is a monobactam (contains single B-lactamase ring) and is the onlly beta lactam antibiotic that can be used in patients of penicillin hypersensitivity as cross allergy is not seen with it.', 'role': 'assistant'}]