Tetracyclines and glycylcyclines — MCQs

An 8-year-old girl is brought to the emergency room for a 6-hour history of fever, sore throat, and difficulty swallowing. Physical examination shows pooling of oral secretions and inspiratory stridor. Lateral x-ray of the neck shows thickening of the epiglottis and aryepiglottic folds. Throat culture with chocolate agar shows small, gram-negative coccobacilli. The patient's brother is started on the recommended antibiotic for chemoprophylaxis. Which of the following is the primary mechanism of action of this drug?

A 37-year-old woman with a history of anorectal abscesses complains of pain in the perianal region. Physical examination reveals mild swelling, tenderness, and erythema of the perianal skin. She is prescribed oral ampicillin and asked to return for follow-up. Two days later, the patient presents with a high-grade fever, syncope, and increased swelling. Which of the following would be the most common mechanism of resistance leading to the failure of antibiotic therapy in this patient?

A 39-year-old man presents to his primary care physician with a high fever, cough, and malaise. One week ago, he returned from a vacation to Hawaii where he went waterskiing with his family. Three days before presentation, he started experiencing intermittent abdominal pain, which was followed by flu-like symptoms, itchiness in his eyes, and photosensitivity. On presentation, his temperature is 103°F (39.4°C), blood pressure is 114/72 mmHg, pulse is 105/min, and respirations are 18/min. Physical exam reveals conjunctivitis and mild jaundice. Which of the following treatments could be used to treat this patient's condition?

A 42-year-old woman with a history of multiple sclerosis and recurrent urinary tract infections comes to the emergency department because of flank pain and fever. Her temperature is 38.8°C (101.8°F). Examination shows left-sided costovertebral angle tenderness. She is admitted to the hospital and started on intravenous vancomycin. Three days later, her symptoms have not improved. Urine culture shows growth of Enterococcus faecalis. Which of the following best describes the most likely mechanism of antibiotic resistance in this patient?

An investigator is studying the chemical structure of antibiotics and its effect on bacterial growth. He has synthesized a simple beta-lactam antibiotic and has added a bulky side chain to the molecule that inhibits the access of bacterial enzymes to the beta-lactam ring. The synthesized drug will most likely be appropriate for the treatment of which of the following conditions?

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?

An experimental drug, ES 62, is being studied. It prohibits the growth of vancomycin-resistant Staphylococcus aureus. It is highly lipid-soluble. The experimental design is dependent on a certain plasma concentration of the drug. The target plasma concentration is 100 mmol/dL. Which of the following factors is most important for calculating the appropriate loading dose?

A 30-year-old female with a history of epilepsy becomes pregnant. Her epilepsy has been well controlled by taking a medication that inhibits GABA transaminase and blocks voltage-gated sodium and calcium channels. Her obstetrician informs her that her epilepsy medication has been shown to have teratogenic effects. Of the following, which teratogenic effect is this woman's medication most likely to cause?

A 3-year-old girl is brought to the physician for a well-child visit. Her father is concerned about the color and strength of her teeth. He says that most of her teeth have had stains since the time that they erupted. She also has a limp when she walks. Examination shows brownish-gray discoloration of the teeth. She has lower limb length discrepancy; her left knee-to-ankle length is 4 cm shorter than the right. Which of the following drugs is most likely to have been taken by this child's mother when she was pregnant?

A 35-year-old woman visits the office with complaints of yellowish vaginal discharge and increased urinary frequency for a week. She also complains of pain during urination. Past medical history is irrelevant. She admits to having multiple sexual partners in the past few months. Physical examination is within normal limits except for lower abdominal tenderness. Urine culture yields Chlamydia trachomatis. What is the most appropriate next step in the management of this patient?