NURS 6501: Final Exam: Please contact Assignment Samurai for help with NURS 6501: Final Exam or any other assignment. Email: assignmentsamurai@gmail.com     A middle-aged patient with a history of urinary tract infections was recently prescribed trimethoprim-sulfamethoxazole. Within a week of starting the medication, the patient developed widespread bruising and petechiae. There were no other changes in medications or known exposures. What is the most likely mechanism of the process that caused the bruising and petechiae? Group of answer choices

• Increased consumption of platelets due to drug-induced vascular damage
• Direct bone marrow suppression leading to decreased platelet production
• Formation of drug-dependent antibodies that bind to and destroy platelets
• Impaired platelet function without affecting platelet count

  The correct answer is: Formation of drug-dependent antibodies that bind to and destroy platelets   Explanation: The most likely cause of the bruising and petechiae in this patient is drug-induced thrombocytopenia, which can occur as a result of the formation of drug-dependent antibodies. These antibodies can bind to platelets in the presence of the drug (in this case, trimethoprim-sulfamethoxazole), leading to platelet destruction. This is a well-known side effect of certain medications, including sulfonamides like trimethoprim-sulfamethoxazole.   Here’s why the other options are less likely:   Increased consumption of platelets due to drug-induced vascular damage: This mechanism is more typical of conditions like disseminated intravascular coagulation (DIC), which generally involves widespread clotting, not isolated thrombocytopenia.   Direct bone marrow suppression leading to decreased platelet production: While bone marrow suppression can cause thrombocytopenia, it would typically result in a gradual onset and overall reduction in blood cell counts, not just isolated platelet destruction with the acute onset seen in this case.   Impaired platelet function without affecting platelet count: While drugs can impair platelet function, this would typically not result in significant bruising or petechiae unless the platelet count is also severely reduced.   Thus, drug-induced thrombocytopenia due to formation of drug-dependent antibodies is the most likely mechanism in this patient with a recent prescription of trimethoprim-sulfamethoxazole.