Bacteria — MCQs

A 59-year-old woman comes to the emergency department because of abdominal pain and bloody diarrhea that began 12 hours ago. Three days ago, she ate undercooked chicken at a local restaurant. Blood cultures grow spiral and comma-shaped, oxidase-positive organisms at 42°C. This patient is at greatest risk for which of the following complications?

A 22-year-old woman comes to the urgent care clinic with sudden onset of severe vomiting. She had been at a picnic with her boyfriend a few hours earlier, enjoying barbecue, potato salad, and cake. Shortly thereafter, she began vomiting and has vomited 5 times in the last 3 hours. She has no prior history of symptoms. After a few hours of observation, her symptoms abate, and she is safely discharged home. Which of the following is the most likely cause of her vomiting?

A 55-year-old woman presents to her primary care physician for a worsening cough. She states that she has had a cough for 5 months. Over the past 2 weeks, the cough has become more frequent and produces yellow sputum. She has dyspnea on exertion at baseline, which she feels is also worsening. She denies fever, hemoptysis, or chest pain. She has chronic obstructive pulmonary disease and mild osteoarthritis. She uses inhaled ipratropium and takes ibuprofen as needed. She received the influenza vaccine 2 months ago. She smokes a half pack a day, and denies alcohol or recreational drug use. In addition to broad-spectrum antibiotics, which of the following is indicated?

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

A 55-year-old woman comes to the physician because of fevers for 2 weeks. She works as a nurse and recently returned from a charity work trip to India, where she worked in a medically-underserved rural community. A tuberculin skin test 3 months ago prior to her trip showed an induration of 3 mm. Physical examination is unremarkable. An x-ray of the chest shows right-sided hilar lymphadenopathy. A sputum culture shows acid-fast bacilli. Which of the following immunologic processes most likely occurred first?

A 78-year-old man presented to his primary physician with a 3-month history of weight loss, fever, fatigue, night sweats, and cough. He is a former smoker. A recent HIV test was negative. A CT scan of the chest reveals a 3 cm lesion in the lower lobe of the left lung and calcification around the left lung hilus. A sputum smear was positive for acid fast organisms. These findings are most consistent with which of the following:

A 70-year-old man with loose stools over the last 24 hours, accompanied by abdominal pain, cramps, nausea, and anorexia, was hospitalized. Previously, the man was diagnosed with a lung abscess and was treated with clindamycin for 5 days. Past medical history was significant for non-erosive antral gastritis and hypertension. He takes esomeprazole and losartan. Despite the respiratory improvement, fevers and leukocytosis persisted. Which of the following pathogenic mechanisms would you expect to find in this patient?

A previously healthy 25-year-old male comes to his primary care physician with a painless solitary lesion on his penis that developed 4 days ago. He has not experienced anything like this before. He is currently sexually active with multiple partners and uses condoms inconsistently. His temperature is 37.0°C (98.7°F), pulse is 67/min, respirations are 17/min, and blood pressure is 110/70 mm Hg. Genitourinary examination shows a shallow, nontender, firm ulcer with a smooth base along the shaft of the penis. There is nontender inguinal adenopathy bilaterally. Which of the following is the most appropriate next step to confirm the diagnosis?

A 6-year-old boy presents with fever, sore throat, hoarseness, and neck enlargement. The symptoms started 3 days ago and progressed gradually with an elevated temperature and swollen lymph nodes. His family immigrated recently from Honduras. He was born via spontaneous vaginal delivery at 39 weeks after an uneventful gestational period and he is now on a catch-up vaccination schedule. He lives with several family members, including his parents, in a small apartment. No one in the apartment smokes tobacco. On presentation, the patient’s blood pressure is 110/75 mm Hg, heart rate is 103/min, respiratory rate is 20/min, and temperature is 39.4°C (102.9°F). On physical examination, the child is acrocyanotic and somnolent. There is widespread cervical edema and enlargement of the cervical lymph nodes. The tonsils are covered with a gray, thick membrane which spreads beyond the tonsillar bed and reveals bleeding, erythematous mucosa with gentle scraping. The lungs are clear to auscultation. Which of the following is the target of the virulence factor produced by the pathologic organism infecting this child?

While testing various strains of Streptococcus pneumoniae, a researcher discovers that a certain strain of this bacteria is unable to cause disease in mice when deposited in their lungs. What physiological test would most likely deviate from normal in this strain of bacteria as opposed to a typical strain?