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': 'All of the following cephalosporins are active against Pseudomonas except: \nSelect and explain. \nA. Ceftazidine, B. Cefotaxime, C. Cefoperazone, D. Cefaclor', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Third Generation Cephalosporins\n\nThese are active against gram negative organisms resistant to other beta lactam antibiotics.\nThese can also penetrate the blood brain barrier (except cefoperazone and cefixime).\nCeftazidime (maximum), ceftolozane and cefoperazone are active against pseudomonas.\nCeftazidime is drug of choice for meliodiosis (caused by Burkholderia pseudomallei).\nCeftizoxime has maximum activityy against Bacteroides.\nCeftriaxone is the first choice drug for gonorrhoea, salmonellosis (including typhoid), E. coli sepsis, Proteus, Serratia, Haemophilus and empirical therapy for bacterial meningitis.\nLong term use of > 2g/d of ceftriaxone is associated with biliary sludging syndrome and cholelithiasis due to precipitation in bile.\nMost of these drugs are reserved for serious infections.\nCeftriaxone has long plasma half life.\nCefotaxime is metabolized to an active metabolite (desacetyl-cefotaxime).\n\nNote: Cefaclor is a 2nd generation cephalosporin and is ineffective against pseudomonas and MRSA.', 'role': 'assistant'}]