Oxazolidinones and streptogramins — MCQs

Part of the success of the Streptococcus pyogenes bacterium lies in its ability to evade phagocytosis. Which of the following helps in this evasion?

An 18-year old college freshman presents to his university clinic because he has not been feeling well for the past two weeks. He has had a persistent headache, occasional cough, and chills without rigors. The patient’s vital signs are normal and physical exam is unremarkable. His radiograph shows patchy interstitial lung infiltrates and he is diagnosed with atypical pneumonia. The patient is prescribed azithromycin and takes his medication as instructed. Despite adherence to his drug regimen, he returns to the clinic one week later because his symptoms have not improved. The organism responsible for this infection is likely resistant to azithromycin through which mechanism?

A 51-year-old man with alcohol use disorder comes to the physician because of a fever and productive cough. An x-ray of the chest shows a right lower lobe consolidation and a diagnosis of aspiration pneumonia is made. The physician prescribes a drug that blocks peptide transfer by binding to the 50S ribosomal subunit. Which of the following drugs was most likely prescribed?

A 65-year-old man with chronic obstructive lung disease, depression, and type 2 diabetes mellitus comes to the physician with fever, chills, dyspnea, and a productive cough for 5 days. His temperature is 38.8°C (101.8°F) and respirations are 30/min. An x-ray of the chest shows a right lower lobe infiltrate, and sputum culture grows bacteria that are sensitive to fluoroquinolone antibiotics. Pharmacotherapy with oral moxifloxacin is initiated. Three days later, the patient continues to have symptoms despite being compliant with the antibiotic. Serum moxifloxacin levels are undetectable. The lack of response to antibiotic therapy in this patient is most likely due to the concurrent ingestion of which of the following medications?

A 33-year-old woman presents to her local clinic in rural eastern India complaining of neck pain and fever. She reports a 4 day history of severe neck pain, neck stiffness, mild diarrhea, and fever. She has not taken her temperature. She works as a laborer and frequently carries heavy weights on her back. She is prescribed a medication and told to come back if her symptoms do not improve. Her symptoms resolve after a couple days. Six months later, she gives birth to a newborn male at 34 weeks gestation. His temperature is 97.8°F (36.6°C), blood pressure is 90/55 mmHg, pulse is 110/min, and respirations are 24/min. On examination, the baby is irritable with a weak cry. Ashen gray cyanosis is noted diffusely. What is the mechanism of action of the drug responsible for this child's presentation?

A 61-year-old woman who recently emigrated from India comes to the physician because of a 2-month history of fever, fatigue, night sweats, and a productive cough. She has had a 5-kg (11-lb) weight loss during this period. She has a history of type 2 diabetes mellitus and poorly controlled asthma. She has had multiple asthma exacerbations in the past year that were treated with glucocorticoids. An x-ray of the chest shows a cavitary lesion of the posterior apical segment of the left upper lobe with consolidation of the surrounding parenchyma. The pathogen identified on sputum culture is found to be resistant to multiple drugs, including streptomycin. Which of the following mechanisms is most likely involved in bacterial resistance to this drug?

A 22-year-old woman presents to the emergency department because of agitation and sweating. History shows she is currently being treated for depression with citalopram. She also takes tramadol for back pain. Her temperature is 38.6°C (101.5°F), the pulse is 108/min, the respirations are 18/min, and the blood pressure is 165/110 mm Hg. Physical examination shows hyperreflexia and mild tremors in all 4 extremities. Which of the following should be used in the next step of management for this patient?

A patient on SSRI sertraline was also prescribed amitriptyline and subsequently developed serotonin toxicity. What is the likely treatment for serotonin toxicity?

A 50-year-old woman presents with acute onset fever and chills for the past hour. She mentions earlier in the day she felt blue, so she took some St. John’s wort because she was told by a friend that it helps with depression. Past medical history is significant for hypertension, diabetes mellitus, and depression managed medically with captopril, metformin, and fluoxetine. She has no history of allergies. Her pulse is 130/min, the respiratory rate is 18/min, the blood pressure is 176/92 mm Hg, and the temperature is 38.5°C (101.3°F). On physical examination, the patient is profusely diaphoretic and extremely irritable when asked questions. Oriented x 3. The abdomen is soft and nontender with no hepatosplenomegaly. Increased bowel sounds are heard in the abdomen. Deep tendon reflexes are 3+ bilaterally and clonus is elicited. The sensation is decreased in the feet bilaterally. Mydriasis is present. Fingerstick glucose is 140 mg/dL. An ECG shows sinus tachycardia but is otherwise normal. Which of the following is the most likely cause of this patient’s condition?

A 58-year-old female presents to her primary care physician with a 1-month history of facial and chest flushing, as well as intermittent diarrhea and occasional difficulty breathing. On physical exam, a new-onset systolic ejection murmur is auscultated and is loudest at the left second intercostal space. Subsequent echocardiography reveals leaflet thickening secondary to fibrous plaque deposition on both the pulmonic and tricuspid valves. Which of the following laboratory abnormalities would most likely be found in this patient?