Hospital-acquired infections Practice Questions

Question 1

The surgical equipment used during a craniectomy is sterilized using pressurized steam at 121°C for 15 minutes. Reuse of these instruments can cause transmission of which of the following pathogens?

Accepted Answer

Prions

Answer

Non-enveloped viruses

Answer

Sporulating bacteria

Answer

Enveloped viruses

Answer

Yeasts

Question 2

A 33-year-old woman presents to the urgent care center with 4 days of abdominal pain and increasingly frequent bloody diarrhea. She states that she is currently having 6 episodes of moderate volume diarrhea per day with streaks of blood mixed in. Her vital signs include: blood pressure 121/81 mm Hg, heart rate 77/min, and respiratory rate 15/min. Physical examination is largely negative. Given the following options, which is the most likely pathogen responsible for her presentation?

Accepted Answer

Shigella

Answer

Campylobacter

Answer

Salmonella

Answer

Clostridium difficile

Answer

E. coli O157:H7

Question 3

A 33-year-old female comes to her primary care physician with complaints of fatigue and nausea. She has also noticed that her skin tone is darker than it used to be. On exam, the physician notes that the woman appears to be jaundiced and obtains liver enzymes which demonstrate an elevated AST and ALT. Further testing subsequently confirms the diagnosis of hepatitis B (HBV). The woman is extremely concerned about transmitting this disease to her loved ones and ask how HBV is transmitted. By which of the following routes can HBV be spread? (I) blood, (II) sexual contact, (III) maternal-fetal, and/or (IV) breast milk?

Accepted Answer

I, II, III

Answer

II, III

Answer

I, II, III, IV

Answer

I, III, IV

Answer

I only

Question 4

A 65-year-old woman undergoes an abdominal hysterectomy. She develops pain and discharge at the incision site on the fourth postoperative day. The past medical history is significant for diabetes of 12 years duration, which is well-controlled on insulin. Pus from the incision site is sent for culture on MacConkey agar, which shows white-colorless colonies. On blood agar, the colonies were green. Biochemical tests reveal an oxidase-positive organism. Which of the following is the most likely pathogen?

Accepted Answer

Pseudomonas aeruginosa

Answer

Staphylococcus aureus

Answer

Enterococcus faecalis

Answer

Streptococcus pyogenes

Answer

Staphylococcus epidermidis

Question 5

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 6

A 25-year-old construction worker presents to the office due to a yellowish discoloration of his skin and eyes for the past 2 weeks. He also complains of nausea and loss of appetite for the same duration. The past medical history is insignificant. He is a smoker, but recently has grown a distaste for smoking. The vital signs include: heart rate 83/min, respiratory rate 13/min, temperature 36.5°C (97.7°F), and blood pressure 111/74 mm Hg. On physical examination, there is mild hepatomegaly. The results of the hepatitis viral panel are as follows:
Anti-HAV IgM positive
HBsAg negative
IgM anti-HBc negative
Anti-HCV negative
HCV-RNA negative
Anti-HDV negative
Anti-HEV negative
What is the most common mode of transmission for this patient’s diagnosis?

Accepted Answer

Fecal-oral

Answer

Breast milk

Answer

Perinatal

Answer

Blood transfusion

Answer

Sexual contact

Question 7

A regional academic medical center has 10 cases of adenovirus in the span of a week among its ICU patients. A committee is formed to investigate this outbreak. They are tasked with identifying the patients and interviewing the care providers to understand how adenovirus could have been spread from patient to patient. This committee will review charts, talk to the care provider teams, and investigate current patient safety and sanitation measures in the ICU. The goal of the committee is to identify weaknesses in the current system and to put in place a plan to help prevent this sort of outbreak from reoccurring in the future. The committee is most likely using what type of analysis?

Accepted Answer

Root cause analysis

Answer

Simulation

Answer

Algorithmic analysis

Answer

Heuristic analysis

Answer

Failure mode and effects analysis

Question 8

A 65-year-old man is admitted to the hospital because of a 1-month history of fatigue, intermittent fever, and weakness. Results from a peripheral blood smear taken during his evaluation are indicative of possible acute myeloid leukemia. Bone marrow aspiration and subsequent cytogenetic studies confirm the diagnosis. The physician sets aside an appointed time-slot and arranges a meeting in a quiet office to inform him about the diagnosis and discuss his options. He has been encouraged to bring someone along to the appointment if he wanted. He comes to your office at the appointed time with his daughter. He appears relaxed, with a full range of affect. Which of the following is the most appropriate opening statement in this situation?

Accepted Answer

What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies?

Answer

Your lab reports show that you have an acute myeloid leukemia

Answer

You must be curious and maybe even anxious about the results of your tests.

Answer

I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.

Answer

Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?

Question 9

A 13-year-old boy is brought to the emergency department because of vomiting, diarrhea, abdominal pain, and dizziness for the past 3 hours with fever, chills, and muscle pain for the last day. He had presented 5 days ago for an episode of epistaxis caused by nasal picking and was treated with placement of anterior nasal packing. His parents report that the bleeding stopped, but they forgot to remove the nasal pack. His temperature is 40.0°C (104.0°F), pulse is 124/min, respirations are 28/min, and blood pressure is 96/68 mm Hg. He looks confused, and physical exam shows conjunctival and oropharyngeal hyperemia with a diffuse, erythematous, macular rash over the body that involves the palms and the soles. Removal of the anterior nasal pack shows hyperemia with purulent discharge from the underlying mucosa. Laboratory studies show:
Total white blood cell count 30,000/mm3 (30 x 109/L)
Differential count
Neutrophils 90%
Lymphocytes 8%
Monocytes 1%
Eosinophils 1%
Basophils 0%
Platelet count 95,000/mm3 (95 x 109/L)
Serum creatine phosphokinase 400 IU/L
What is the most likely diagnosis for this patient?

Accepted Answer

Toxic shock syndrome

Answer

Stevens-Johnson syndrome

Answer

Measles

Answer

Disseminated gonococcal infection

Answer

Herpes simplex virus type 2 (HSV-2) meningitis

Question 10

An 83-year-old male presents to the emergency department with altered mental status. The patient’s vitals signs are as follows: temperature is 100.7 deg F (38.2 deg C), blood pressure is 143/68 mmHg, heart rate is 102/min, and respirations are 22/min. The caretaker states that the patient is usually incontinent of urine, but she has not seen any soiled adult diapers in the past 48 hours. A foley catheter is placed with immediate return of a large volume of cloudy, pink urine. Which of the following correctly explains the expected findings from this patient’s dipstick urinalysis?

Accepted Answer

Detection of urinary nitrate conversion by gram-negative pathogens

Answer

Detection of an enzyme produced by white blood cells

Answer

Detection of an enzyme produced by red blood cells

Answer

Detection of urinary nitrate conversion by gram-positive pathogens

Answer

Direct detection of white blood cell surface proteins

Hospital-acquired infections

Study Resources

Lessons

Questions

Flashcards

Lessons

Catheter-associated urinary tract infections

Central line-associated bloodstream infections

Ventilator-associated pneumonia

Surgical site infections

Clostridium difficile infection

Multi-drug resistant organism transmission

Environmental reservoirs in healthcare settings

Infection control practices

Outbreak investigation

Surveillance methodologies

Hand hygiene compliance

Isolation precautions

Prevention bundles and checklists

Practice Questions

Flashcards

About Hospital-acquired infections for USMLE

Lessons in Hospital-acquired infections

Master Hospital-acquired infections