Antimicrobials — MCQs

A 38-year-old man is brought to the emergency room because of diarrhea for 2 days. He has abdominal cramps and has also noticed a dark red tint to his stool. He returned from a trip to Mexico 3 weeks ago, where he completed a marathon. He has a history of mild anemia. He does not smoke and drinks 3–4 beers on weekends. He takes fish oil, a multivitamin, and iron supplements to improve his athletic performance. His temperature is 101.8°F (38.8°C), pulse is 65/min, and blood pressure is 120/75 mm Hg. Lungs are clear to auscultation. Cardiac examination shows no abnormalities. There is mild tenderness to palpation of the left lower quadrant without rebound or guarding. Laboratory studies show: Hematocrit 37.1% Leukocyte count 4,500/mm3 Platelet count 240,000/mm3 Serum Na+ 136 mEq/L K+ 4.5 mEq/L Cl- 102 mEq/L HCO3- 26 mEq/L Urea nitrogen 14 mg/dL Creatinine 1.2 mg/dL Stool culture demonstrates organisms with ingested erythrocytes. In addition to supportive therapy, which of the following is the most appropriate next step in management?

A healthy 34-year-old woman comes to the physician for advice on UV protection. She works as an archaeologist and is required to work outside for extended periods of time. She is concerned about premature skin aging. The physician recommends sun-protective clothing and sunscreen. In order to protect effectively against photoaging, the sunscreen should contain which of the following active ingredients?

A 3-year-old girl with cystic fibrosis is brought to the physician for a follow-up examination. Her mother has noticed that the child has had multiple falls over the past 4 months while walking, especially in the evening. Her current medications include pancreatic enzyme supplements, an albuterol inhaler, and acetylcysteine. She is at the 10th percentile for height and the 5th percentile for weight. Examination shows dry skin, and cone shaped elevated papules on the trunk and extremities. There is an irregularly shaped foamy gray patch on the left conjunctiva. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate next step in management?

A 23-year-old woman presents to her primary care provider complaining of diarrhea. She reports a 2 month history of 3-4 bloody stools per day as well as 10 pounds of unexpected weight loss. She has also developed intermittent mild gnawing lower abdominal pain. Her past medical history is unremarkable. She takes no medications and denies any drug allergies. Her family history is notable for colon cancer in her maternal aunt, rheumatoid arthritis in her paternal aunt, and Sjogren syndrome in her paternal grandmother. Her temperature is 99.1°F (37.3°C), blood pressure is 120/85 mmHg, pulse is 85/min, and respirations are 18/min. On exam, she has mild hypogastric tenderness to palpation. A stool guaiac test is positive. Flexible sigmoidoscopy demonstrates hyperemic and friable rectal mucosa. She is started on a medication to address her condition but presents to her physician one week later with a severe sunburn and skin itchiness following limited exposure to sunlight. Which of the following is the mechanism of action of the medication she received?

A 6-year-old boy is brought to the physician because of headache, cough, runny nose, and a low-grade fever since waking up that morning. He has been healthy except for a urinary tract infection one week ago that has resolved with trimethoprim-sulfamethoxazole therapy. Both parents have a history of allergic rhinitis. His temperature is 37.8°C (100°F). Physical exam shows rhinorrhea and tenderness over the frontal and maxillary sinuses. There is cervical lymphadenopathy. Laboratory studies show: Hemoglobin 14.2 g/dL Leukocyte count 2,700/mm3 Segmented neutrophils 30% Bands 1% Eosinophils 4% Basophils 0% Lymphocytes 56% Monocytes 9% Platelet count 155,000/mm3 Which of the following is the most likely underlying cause of this patient's symptoms?

A 54-year-old woman is brought to the emergency department by a nurse 30 minutes after receiving scheduled radiation therapy for papillary thyroid cancer. After the radioisotope was ingested, the physician realized that a much larger fixed dose was given instead of the appropriate dose based on radiation dosimetry. Which of the following pharmacotherapies should be administered immediately to prevent complications from this exposure?

A 13-year-old Caucasian male presents with his father to the pediatrician’s office complaining of left lower thigh pain. He reports slowly progressive pain over the distal aspect of his left thigh over the past three months. He denies any recent trauma to the area. His temperature is 100.9°F (38.3°C). On exam, there is swelling and tenderness overlying the inferior aspect of the left femoral diaphysis. Laboratory evaluation is notable for an elevated white blood cell (WBC) count and erythrocyte sedimentation rate (ESR). Biopsy of the lesion demonstrates sheets of monotonous small round blue cells with minimal cytoplasm. He is diagnosed and started on a medication that inhibits transcription by intercalating into DNA at the transcription initiation complex. Which of the following adverse events will this patient be at highest risk for following initiation of this medication?

A 60-year-old female presents to her primary care physician complaining of bloating and fatigue over the past year. On examination, she has abdominal distension and ascites. Abdominal imaging reveals a mass-like lesion affecting the left ovary. A biopsy of the lesion demonstrates serous cystadenocarcinoma. She is subsequently started on a chemotherapeutic medication known to stabilize polymerized microtubules. Which of the following complications should this patient be monitored for following initiation of this medication?

A 26-year-old man comes to the emergency department because of a 1-week history of worsening fatigue, nausea, and vomiting. Six weeks ago, he was diagnosed with latent tuberculosis and appropriate low-dose pharmacotherapy was initiated. Physical examination shows right upper quadrant tenderness and scleral icterus. Laboratory studies show elevated aminotransferases. Impaired function of which of the following pharmacokinetic processes is the most likely explanation for this patient's symptoms?

A 67-year-old male with a past medical history of diabetes type II, obesity, and hyperlipidemia presents to the general medical clinic with bilateral hearing loss. He also reports new onset vertigo and ataxia. The symptoms started a day after undergoing an uncomplicated cholecystectomy. If a drug given prophylactically just prior to surgery has caused this patient’s symptoms, what is the mechanism of action of the drug?