<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 56-year-old man presents with breathlessness and altered mental status. The patients daughter says that he has been having high fever and cough for the last 3 days. Past medical history is significant for a recent hospitalization 5 days ago, following a successful coronary artery bypass grafting CABG. In the post-operative period, he was in an intensive care unit ICU for 6 days, including 12 hours on mechanical ventilation. Current medications are aspirin and rosuvastatin. The patients daughter mentions that he has had anaphylactic reactions to penicillin in the past. His temperature is 39.4C 103F, pulse rate is 110min, blood pressure is 10478 mm Hg, and respiratory rate is 30min. On physical examination, the patient is confused and disoriented and shows signs of respiratory distress and cyanosis. On chest auscultation, there is crepitus in the right lung. The patient is immediately started on oxygen therapy, intravenous fluids, and supportive care. After the collection of appropriate samples for bacteriological culture, treatment with empirical intravenous antibiotics are started. After 24 hours of treatment, the microbiology results indicate Pseudomonas aeruginosa infection. Antibiotic therapy is changed to a combination of aztreonam and tobramycin. Which of the following best describes the rationale for choosing this antibiotic combination?? A: Broad-spectrum coverage against gram-positive cocci by adding tobramycin to aztreonam, B: Effective combination of a bactericidal and a bacteriostatic antimicrobial against Pseudomonas aeruginosa, C: Reduction of the side-effects of both aztreonam and tobramycin, D: Synergism of aztreonam with tobramycin, E: Broad-spectrum coverage against anaerobes by adding tobramycin to aztreonam,  <response>: This is a clinical case of a 56-year-old man with fever, cough, breathlessness, and altered mental status. He has a history of recent CABG surgery and was on mechanical ventilation. He has penicillin allergy. Initial findings suggest pneumonia likely due to hospital-acquired infection. Empirical IV antibiotics were started and later changed based on culture reports showing Pseudomonas aeruginosa infection. The question asks to identify the rationale behind choosing the combination of aztreonam and tobramycin to treat this infection.Aztreonam is a monobactam antibiotic with activity predominantly against gram-negative bacteria including Pseudomonas aeruginosa. It is bactericidal. Tobramycin is an aminoglycoside antibiotic with activity against gram-negative bacteria including Pseudomonas aeruginosa. It is also bactericidal.The correct rationale for using this combination is synergistic activity between the two drugs against Pseudomonas aeruginosa. The other options can be ruled out.D: Synergism of aztreonam with tobramycin 