Atypical Practice Questions

Question 1

An 18-year-old male in his first year of college presents to the emergency room with a fever and a severe headache. He reports having unprotected sex with several partners over the past few weeks. Upon examination, the male demonstrates nuchal rigidity and photophobia. His past medical history is notable for a lack of vaccinations beginning from infancy due to his parents' belief that vaccinations may cause autism. The bacteria causing these symptoms would most likely demonstrate which of the following?

Accepted Answer

Gram-negative bacteria

Answer

Negative catalase test

Answer

Urease positive

Answer

Positive quellung reaction

Answer

Lactose fermentation

Question 2

A 30-year-old man is brought to the emergency department with complaints of fevers to 39.0℃ (102.2℉) and diarrhea for the past 12 hours. There is no history of headaches, vomiting, or loss of consciousness. The past medical history is unobtainable because the patient recently immigrated from abroad and has a language barrier, but his wife says that her husband had a motor vehicle accident when he was a teenager that required emergent surgery. He is transferred to the ICU after a few hours in the ED due to dyspnea, cyanosis, and hemodynamic collapse. There are no signs of a meningeal infection. The blood pressure is 70/30 mm Hg at the time of transfer. A chest X-ray at the time of admission shows interstitial infiltrates without homogeneous opacities. The initial laboratory results reveal metabolic acidosis, leukopenia with a count of 2000/mm3, thrombocytopenia (15,000/mm3), and a coagulation profile suggesting disseminated intravascular coagulation. A peripheral smear is performed as shown in the accompanying image. Despite ventilatory support, administration of intravenous fluids, antibiotics, and vasopressor agents, the patient dies the next day. The gram stain from the autopsy specimen of his lungs reveals gram-positive, lancet-shaped diplococci occurring singly and in chains. Which of the following organisms is the most likely cause for the patient’s condition?

Accepted Answer

Streptococcus pneumoniae

Answer

Neisseria meningitidis

Answer

Non-typeable H. influenzae

Answer

Staphylococcus aureus

Answer

Streptococcus pyogenes

Question 3

An investigator is studying the growth of an organism in different media. The organism is inoculated on a petri dish that contains heated sheep blood, vancomycin, nystatin, trimethoprim, and colistin. The resulting growth medium is incubated at 37°C. Numerous small, white colonies are seen after incubation for 48 hours. This organism is most likely to cause which of the following conditions?

Accepted Answer

Gonorrhea

Answer

Pontiac fever

Answer

Pseudomembranous colitis

Answer

Hemolytic uremic syndrome

Answer

Oral thrush

Question 4

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?

Accepted Answer

Insertion of drug efflux pumps

Answer

Mutation in topoisomerase II

Answer

Methylation of ribosomal binding site

Answer

Presence of a beta-lactamase

Answer

Decreased binding to RNA polymerase

Question 5

A 40-year-old man presents to the office complaining of chills, fever, and productive cough for the past 24 hours. He has a history of smoking since he was 18 years old. His vitals are: heart rate of 85/min, respiratory rate of 20/min, temperature 39.0°C (102.2°F), blood pressure 110/70 mm Hg. On physical examination, there is dullness on percussion on the upper right lobe, as well as bronchial breath sounds and egophony. The plain radiograph reveals an increase in density with an alveolar pattern in the upper right lobe. Which one is the most common etiologic agent of the suspected disease?

Accepted Answer

Streptococcus pneumoniae

Answer

Legionella pneumophila

Answer

Chlamydia pneumoniae

Answer

Mycoplasma pneumoniae

Answer

Haemophilus influenzae

Question 6

A patient is hospitalized for pneumonia. Gram-positive cocci in clusters are seen on sputum gram stain. Which of the following clinical scenarios is most commonly associated with this form of pneumonia?

Accepted Answer

Hospitalized adult with development of pneumonia symptoms 2 weeks following a viral illness

Answer

Elderly patient who has trouble swallowing and poor dentition

Answer

An alcoholic with evidence of empyema and "currant jelly sputum"

Answer

An otherwise healthy young adult with a week of mild fatigue, chills, and cough

Answer

HIV positive adult with a CD4 count less than 150 and an impaired diffusion capacity

Question 7

A 62-year-old man is brought to the emergency department with fatigue, dry cough, and shortness of breath for 3 days. He reports a slight fever and has also had 3 episodes of watery diarrhea earlier that morning. Last week, he attended a business meeting at a hotel and notes some of his coworkers have also become sick. He has a history of hypertension and hyperlipidemia. He takes atorvastatin, hydrochlorothiazide, and lisinopril. He appears in mild distress. His temperature is 102.1°F (38.9°C), pulse is 56/min, respirations are 16/min, and blood pressure is 150/85 mm Hg. Diffuse crackles are heard in the thorax. Examination shows a soft and nontender abdomen. Laboratory studies show:
Hemoglobin 13.5 g/dL
Leukocyte count 15,000/mm3
Platelet count 130,000/mm3
Serum
Na+ 129 mEq/L
Cl- 100 mEq/L
K+ 4.6 mEq/L
HCO3- 22 mEq/L
Urea nitrogen 14 mg/dL
Creatinine 1.3 mg/dL
An x-ray of the chest shows infiltrates in both lungs. Which of the following is the most appropriate next step in diagnosis?

Accepted Answer

Urine antigen assay

Answer

CT Chest

Answer

Direct immunofluorescent antibody test

Answer

Stool culture

Answer

Polymerase chain reaction

Question 8

A previously healthy 24-year-old woman comes to the physician because of a 1-day history of nausea and weakness. She is sexually active with 2 male partners and uses an oral contraceptive; she uses condoms inconsistently. Her last menstrual period was 4 days ago. Her temperature is 38.4°C (101°F). Physical examination shows right costovertebral angle tenderness. Pelvic examination is normal. Which of the following is the most likely cause of this patient's condition?

Accepted Answer

Ascending bacteria from the bladder

Answer

Noninfectious inflammation of the bladder

Answer

Ascending bacteria from the endocervix

Answer

Decreased renal calcium reabsorption

Answer

Decreased urinary pH

Question 9

A 16-year-old female presents to her pediatrician complaining of 2 weeks of fever and 1 week of swollen lumps in her left armpit. Upon examination of the left upper extremity, her physician notes the presence of a single papule which the patient claimed appeared one week ago. The patient started her first job at a pet store 2.5 weeks ago. Which of the following is the vector of transmission of the causative agent?

Accepted Answer

Cats

Answer

Rabbits

Answer

Animal urine

Answer

Parrots

Answer

Armadillos

Question 10

A 32-year-old woman comes to the emergency department with a 2-day history of abdominal pain and diarrhea. She has had about 8 voluminous stools per day, some of which were bloody. She visited an international food festival three days ago. She takes no medications. Her temperature is 39.5°C (103.1°F), pulse is 90/min, and blood pressure is 110/65 mm Hg. Examination shows a tender abdomen, increased bowel sounds, and dry mucous membranes. Microscopic examination of the stool shows polymorphonuclear leukocytes. Stool culture results are pending. Which of the following most likely caused the patient's symptoms?

Accepted Answer

Omelette

Answer

Home-canned vegetables

Answer

Yogurt dip

Answer

Reheated rice

Answer

Toxic mushrooms

Atypical

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Mycoplasma pneumoniae

Chlamydia pneumoniae

Chlamydia trachomatis

Chlamydia psittaci

Rickettsia species

Coxiella burnetii

Ehrlichia and Anaplasma

Spirochetes overview

Treponema pallidum

Borrelia species

Leptospira species

Mycobacteria overview

M. tuberculosis and non-tuberculous mycobacteria

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