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Select the ONE answer that is BEST in each case.
A 22-year-old recent immigrant to the United States has never been vaccinated for tetanus. He sustains a minor, but soil-contaminated, injury. Which of the following statements is correct?
In tetanus, an acute onset is usual. The median onset is 7 days, and 90% present within 14 days of injury. The organism is an anaerobic, motile Gram-positive rod. It has the ability to survive for years in the form of spores, which are resistant to disinfectants and heat. Tetanus can occur in nonimmunized individuals, or those who have neglected their booster shots. Penicillin, or metronidazole, is used in treatment, but their efficacy is not clear.
See all quizzes of the Infection diseases at here:
|1. A 22-year-old recent immigrant to the United States has never been vaccinated for tetanus. He sustains a minor, but soil-contaminated, injury. Which of the following statements is correct?
(A) tetanus usually develops within 2 weeks following exposure
(B) tetanus always develops within 4 hours following exposure in patients who have not been previously immunized
(C) tetanus may develop many months or years following exposure in susceptible individuals
(D) the usual incubation period for tetanus is 48 hours
(E) tetanus may be prevented with penicillin
|2. A 19-year-old man has donated blood for the first time. Despite having no risk factors for human immunodeficiency virus (HIV) infection, his blood tests positive for HIV by enzyme immunoassay (EIA). Which of the following statements is correct?
(A) EIA is currently the most specific test for HIV
(B) he might have a false-positive secondary to an unsuspected collagen-vascular disease
(C) he has a 75% chance of truly being infected with HIV
(D) EIA is an excellent screening test
|3. A 27-year-old man presents with symptoms of fever, chills, malaise, and joint discomfort in his hands and knees. He looks unwell, his temperature is 39.4°C, blood pressure 115/70 mm Hg, pulse 110/min, head and neck is normal, and his jugular venous pressure (JVP) has a prominent c-v wave. There is also a 3/6 pansystolic murmur heard at the right sternal border that increases with respiration. His lungs are clear, abdomen is soft, and hand joints are normal. He has multiple puncture sites on his forearms from injection drug use. Which of the following is the most likely causative organism?
(A) Staphylococcus aureus
(B) Staphylococcus epidermidis
(C) Streptococcus viridans
|4. A 23-year-old woman develops vesicular lesions on an erythematous base on her vulvar area. She has tender lymphadenopathy and dysuria as well. Which of the following is the most likely causative organism?
(A) cytomegalovirus (CMV)
(C) herpes simplex virus type 2 (HSV-2)
(D) Treponema pallidum
(E) varicella zoster
|5. A 17-year-old man presents with new symptoms of fatigue, malaise, fever, and a sore throat. He has no significant past medical history and is not on any medications. Physical examination is entirely normal except for enlarged, palpable cervical, lymph nodes. He reports no weight loss or night sweats. Laboratory investigations include a normal chest x-ray, negative throat swab, but abnormal blood film with atypical lymphocytes. The hemoglobin is 15.5 g/dL; hematocrit 42%; platelets 290,000/mL; WBC 10500/mL, with 45% segmented neutrophils, 1% eosinophils, and 54% lymphocytes, of which 36% were atypical. Which of the following is the most appropriate initial diagnostic test?
(A) lymph node biopsy
(B) bone marrow
(C) erythrocyte sedimentation rate (ESR)
(D) heterophil antibody (sheep cell agglutination) test
(E) hepatic biopsy
|6. A 34-year-old man is traveling in Southeast Asia on business. He is staying in Western-style hotels and eating food in large restaurants. He has not eaten from street vendors. One week after arrival, he develops symptoms of anorexia, nausea, and abdominal cramps followed by the sudden onset of watery diarrhea. He has no fever or chills and there is no blood or pus in the stools. Which of the following is the most appropriate therapy for his condition?
(B) symptomatic therapy with loperamide
(D) oral rehydration only
(E) specific antitoxin
|7. An 18-year-old woman presents with headache, anorexia, chilly sensations, and discomfort on both sides of her jaw. She has also noticed discomfort in both lower abdominal quadrants. Physical examination reveals bilateral enlarged parotid glands that are doughy, elastic, and slightly tender; with a reddened orifice of Stensen’s duct. Her abdomen is soft with bilateral lower quadrant abdominal tenderness; a temperature of 38.5°C; and a pulse rate of 92/min. Laboratory data show hemoglobin 13 g/dL; hematocrit 40%; white blood cells (WBC) 9000/mL, with 35% segmented neutrophils, 7% monocytes, and 58% lymphocytes. Which of the following is the most likely cause for her abdominal pain and tenderness?
(A) mesenteric lymphadenitis
(D) peritoneal metastases
(E) intestinal hyperperistalsis
|8. A 32-year-old man, previously well, develops a fever and dry cough. On examination, his chest is clear and heart sounds are normal. A chest x-ray (CXR) reveals a diffuse interstitial infiltrate. Which of the following is the most likely causative organism?
|9. A 25-year-old man is admitted with fever and rust-colored sputum. He looks unwell, temperature 38.4°C, pulse 100/min, and blood pressure 115/80 mm Hg. On auscultation, there are bronchial breath sounds in the right axilla and inspiratory crackles. The CXR is shown in Fig. Which of the following is the most likely diagnosis?
(A) right middle lobe pneumonia
(B) loculated pleural effusion
(D) aspiration pneumonia
(E) right lower lobe pneumonia
|10. A 30-year-old man develops a pustular lesion at the site of a cat scratch on his forearm. This is followed 1 week later by malaise, fever, and lymphadenopathy. On examination, he has tender axillary lymph nodes. Which of the following is the most likely causative organism?
(A) Bartonella henselae
|11. A 7-year-old child, unvaccinated because of his parents’ religious beliefs, develops malaise, cough, coryza, and conjunctivitis with a high fever. Examination of his mouth reveals blue white spots on a red base beside his second molars. The next day he develops an erythematous, nonpruritic, maculopapular rash at his hairline and behind his ears, which spreads over his body. Which of the following is the most likely diagnosis?
(A) hand-foot-and-mouth disease (coxsackievirus)
(B) measles (rubeola)
(C) rubella (German measles)
|12. A 60-year-old man presents with fever and malaise 6 weeks after mitral valve replacement. On examination, his temperature is 38°C, blood pressure 130/80 mm Hg, pulse 80/min, and a loud pansystolic murmur at the apex, which radiates to the axilla. He has no skin or neurologic findings. Which of the following is the most likely causative organism?
(A) Staphylococcus aureus
(B) a fungus
(C) Staphylococcus saprophyticus
(E) Staphylococcus epidermidis
|13. A 73-year-old man from a nursing home develops headache, fever, cough, sore throat, malaise, and severe myalgia during a community outbreak affecting numerous other residents at the home. The symptoms gradually resolve after 3 days, and he starts feeling better but then there is a reappearance of his fever, with cough and yellow sputum production. On examination, his temperature is 38.5°C, pulse 100/min, respiration 24/min, oxygen saturation 88% and crackles in the right lower lung base, bronchial breath sounds and dullness on percussion. CXR reveals a new infiltrate in the right lower lobe. Which of the following is the most likely causative organism?
(A) primary viral pneumonia
(B) an autoimmune reaction
(C) Mycoplasma pneumoniae
(D) Streptococcus pneumoniae
(E) Neisseria catarrhalis
|14. A 56-year-old man is having intermittent fevers and malaise for the past 2 weeks. He has no other localizing symptoms. Two months ago, he had valve replacement surgery for a bicuspid aortic valve. Amechanical valve was inserted and his postoperative course was uncomplicated. On examination, his temperature is 38°C, blood pressure 124/80 mm Hg, pulse 72/min, and head and neck are normal. There is a 3/6 systolic ejection murmur, the second heart sound is mechanical, and a 2/6 early diastolic murmur is heard. The lungs are clear and the skin examination is normal. Three sets of blood cultures are drawn and an urgent echocardiogram is ordered. Which of the following is the most likely causative organism?
(A) Staphylococcus aureus
(B) S. epidermidis
(C) S. viridans
|15. Two students from a university dormitory building have contracted meningitis due to Neisseria meningitides. Which of the following students in the dormitory are most likely to benefit from chemoprophylaxis?
(A) everybody in the dormitory, with oral amoxicillin
(B) close contacts only, with oral amoxicillin
(C) everybody in the dormitory, with oral rifampin
(D) close contacts only, with oral rifampin
(E) everybody in the dormitory, withmeningococcal vaccine
|16. A 21-year-old woman visits her physician because of 3 weeks of a “flu-like” illness. She reports symptoms of malaise, fever, fatigue, and a sore throat. There is no weight loss or night sweats, and she has not traveled out of country. Her past medical history is not significant and she is not taking any medications. Physical examination is normal except for enlarged cervical lymph nodes. Laboratory data show hemoglobin 13.2 g/dL; hematocrit 42%; platelets 380,000/mL; WBC 8500/mL, with 35% segmented neutrophils, 1% eosinophils, and 64% lymphocytes, of which 36% were atypical. A heterophil antibody (sheep cell agglutination) test is negative. Which of the following is the most likely causative organism?
(A) herpes simplex
|17. A 23-year-old woman visits your office because of headache, malaise, anorexia, pain in both sides of her jaw, and discomfort in both lower abdominal quadrants. Physical examination reveals enlarged parotid glands; bilateral lower quadrant abdominal tenderness; a temperature of 38.7°C; and a pulse rate of 92/min. Serologic testing (IgM) confirms the diagnosis of mumps. Which of the following is the most appropriate treatment for this condition?
(C) broad-spectrum antibiotics
|18. A 10-year-old boy presents with fever, headache, photophobia, and neck discomfort in the middle of summer. He is alert and oriented, but has neck pain with flexion and extension of the head. His fundi are normal, and there are no focal neurologic findings or skin changes. A lumbar puncture reveals normal protein and glucose with a cell count of 240/mL (90% lymphocytes). Which of the following is the most likely causative organism?
(A) enterovirus (coxsackievirus or echovirus)
(B) Streptococcus pneumoniae
(C) Neisseria meningitides
(D) Listeria monocytogenes
|19. An 18-year-old woman has eaten homemade preserves. Eighteen hours later, she develops diplopia, dysarthria, and dysphagia. Which of the following is the most likely causative organism?
(A) Clostridium botulinum toxin
(B) staphylococcal toxin
|20. A previously healthy 19-year-old female university student develops myalgia, headache, fever, and malaise. Blood tests reveal lymphocytosis, with 20% of the lymphocytes being atypical. She remains tired and unwell for 6 weeks, but repeated tests for heterophil antibody are negative. Which of the following is the most likely diagnosis?
(A) Epstein-Barr virus (EBV) infection
(B) primary HIV infection
(C) human herpes virus type 7 (HHV-7)
(D) CMV infection