Microbiology MCQs Mock Test – Chapter 56

A 14-year-old girl develops a sore throat, fever, and earache of approximately 1 week duration. Upon examination by her physician, an erythematous rash is noted covering most of her body and her tongue appears bright red. Which of the following is the description of the causal agent?

Your patient has a brain abscess that was detected 1 month after a dental extraction. Which one of the following organisms is MOST likely to be involved?

Each of the following statements concerning infection with Chlamydia psittaci is correct EXCEPT:

Each of the following statements concerning Clostridium perfringens is correct EXCEPT:

All of the following statements correctly describes the properties of Influenza A virus EXCEPT

You suspect that your patient’s disease may be caused by Cryptococcus neoformans. Which one of the following findings would be MOST useful in establishing the diagnosis?

Your patient is a woman with a vaginal discharge. You suspect, on clinical grounds, that it may be due to Candida albicans. Which one of the following statements is LEAST accurate or appropriate?

A 12-year-old boy presents to his pediatrician with fever, malaise, and a sore throat. Physical examination reveals a fever of 103°F, cervical lymphadenopathy, and pharyngeal erythema. A swab is taken from some of the tonsillar exudate and cultured on blood agar. Culture reveals beta hemolytic, gram-positive cocci, and a rapid antigen test is positive. What is the major component that protects the causal agent from osmotic damage?

Nagler’s reaction is useful for the identification of

Each of the following statements concerning mucormycosis is correct EXCEPT:

A 50-year-old homeless alcoholic has a fever and is coughing up 1 cup of green, foul-smelling sputum per day. You suspect that he may have a lung abscess. Which one of the following pairs of organisms is MOST likely to be the cause?

Which genetic material is found in pathogenic Corynebacterium diphtheriae but not in nonpathogenic normal flora diphtheroids?

A 9-year-old child develops glomerulonephritis a week after she was treated for a sore throat. The causal agent is identified by serotyping of the

A 4-year-old girl has papular and pustular lesions on her face. The lesions are exuding a honey-colored serous fluid. You make a clinical diagnosis of impetigo. A Gram stain of the exudate reveals gram-positive cocci in chains, and a culture reveals ß-hemolytic colonies on blood agar. For which one of the following sequelae is she MOST at risk?

A 50-year-old homeless alcoholic has a fever and is coughing up 1 cup of green, foul-smelling sputum per day. You suspect that he may have a lung abscess. Which one of the following pairs of organisms is MOST likely to be the cause?

A 42-year-old man who has AIDS presents to his physician with progressively increasing dyspnea over the past 3 weeks. He also complains of a dry, painful cough, fatigue, and low-grade fever. A chest x-ray reveals bilateral symmetrical interstitial and alveolar infiltration. Which of the following agents is the most likely cause of the above?

Stormy clot reaction is useful in the identification of:

A 45-year-old man presents to the emergency department with shortness of breath and a productive cough. His sputum was gelatinous and bloody. Gram stain of the sputum revealed numerous PMNs and gram-negative rods. Which of the following descriptions is most likely to fit the patient?

Each of the following statements concerning Pneumocystis carinii is correct EXCEPT:

Each of the following statements concerning Candida albicans is correct EXCEPT:

Which one of the following organisms is MOST likely to be the cause of pneumonia in an immunocompetent young adult?

Aspergillus fumigatus can be involved in a variety of clinical conditions. Which one of the following is LEAST likely to occur?

Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:

A 33-year-old HIV-positive man complains of headache and blurred vision. Physical examination reveals papilledema and ataxia. A head CT scan is normal, but CSF obtained by lumbar puncture reveals encapsulated organisms visible by India ink. Which of the following is true concerning this organism?

The MOST important way the host counteracts the function of the pneumococcal polysaccharide capsule is via:

Which one of the following is NOT an important characteristic of Streptococcus pyogenes?

Contamination of umbilical cord at birth may lead to infection by:

A 4-year-old girl has papular and pustular lesions on her face. The lesions are exuding a honey-colored serous fluid. You make a clinical diagnosis of impetigo. A Gram stain of the exudate reveals gram-positive cocci in chains, and a culture reveals ß-hemolytic colonies on blood agar. For which one of the following sequelae is she MOST at risk?

Which genetic material is found in pathogenic Corynebacterium diphtheriae but not in nonpathogenic normal flora diphtheroids?

A 70-year-old man is found to have a hard mass in his prostate, which is suspected to be a carcinoma. Twenty-four hours after surgical removal of the mass, he develops fever to 39°C and has several shaking chills. Of the organisms listed, which one is LEAST likely to be involved?

A 22-year-old woman presents with “the worst sore throat I’ve ever had.” She also complains of fatigue and anorexia. She is not immunocompromised and has not been hospitalized recently. On examination, she is febrile to 38°C, the pharynx is inflamed, and there are a few tender cervical nodes bilaterally. There are no white lesions on the tongue or pharynx. A throat culture grows alpha-hemolytic colonies on blood agar that are optochin-resistant. Of the following, which one is the MOST likely cause?

Which one of the following organisms is MOST likely to be the cause of pneumonia in an immunocompetent young adult?

Which one of the following statements concerning Legionella pneumophila is CORRECT?

Each of the following statements concerning Staphylococcus aureus is correct EXCEPT:

A 35-year-old man who is positive for HIV develops sepsis with the subsequent development of a necrotic lesion on the buttock that has a black center and an erythematous margin. Which of the following is the most likely causal agent?

A 45-year-old homeless man presents to the emergency department with fever and night sweats, coughing up blood. Acid-fast bacilli are identified in his sputum. Which of the following virulence factors allows the causal agent to inhibit phagosome-lysosome fusion to survive intracellularly?

Several fungi are associated with disease in immunocompromised patients. Which one of the following is the LEAST frequently associated?

A 27-year-old woman, after returning home from her honeymoon, has developed urinary frequency, dysuria, and urgency. Her urine is grossly bloody. Which lab data are most likely to define the causal agent?

A 25-year-old man gets into a fight at the local bar and punches another patron in the mouth. The following day his fist becomes infected and he visits a local urgent care center. Exudate from the wound is cultured on blood and chocolate agar and reveals gram-negative rods that have a bleach-like odor. Which of the following agents is the most likely cause?

Each of the following statements concerning Corynebacterium diphtheriae is correct EXCEPT:

Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:

Acute glomerulonephritis is a nonsuppurative complication that follows infection by which one of the following organisms?

A 55-year-old man who recently recovered uneventfully from a heart valve transplant presents to the emergency room with pleuritic chest pain, hemoptysis, fever, and chills. While he is being examined, he has a myocardial infarction and the medical team is unable to revive him. An autopsy revealed septate, acutely branching hyphae in many tissues. Which of the following organisms is most likely to be identified?

You have made a clinical diagnosis of meningitis in a 50-year-old immunocompromised woman. A latex agglutination test on the spinal fluid for capsular polysaccharide antigen is positive. Of the following organisms, which one is the MOST likely cause?

The MOST important contribution of the capsule of Streptococcus pneumoniae to virulence is:

A 60-year-old woman is hospitalized following a stroke and develops a highgrade fever with chills. She is catheterized due to urinary incontinence and receives cephalosporin for treatment of pneumonia. Blood cultures and Gram stain are performed by the laboratory. The organisms isolated are gram-positive cocci that are catalase-negative and capable of growth in 6.5% sodium chloride. Which of the following is the most likely causal agent?

A 70-year-old man presents to the emergency department with a fever of 103.5°F, a dry cough, tachypnea, and chest pain. History reveals he has been smoking since he was a teen. He mentions that several people at the assisted living community where he resides have had similar symptoms. A sputum sample isolated organisms that grew on buffered charcoal yeast extract agar and stained weakly gram-negative. Which of the following properties is consistent with the above organism?

A 22-year-old woman complains of a persistent nonproductive cough and a fever of 101°F that came on slowly over the last 4 days. Physical examination reveals some rales in the left lung base. A patchy infiltrate is seen on chest X-ray. She works as a secretary in a law office and has not traveled recently. She is not immunocompromised and has not been hospitalized recently. A sample of her serum agglutinates red blood cells at 4°C but not at 37°C. Which one of the following BEST describes the organism that is the MOST likely cause of her disease?

Each of the following statements concerning clostridia is correct EXCEPT:

A 65-year-old man develops dysuria and hematuria. A Gram stain of a urine sample shows gram-negative rods. Culture of the urine on EMB agar reveals lactose-negative colonies without evidence of swarming motility. Which one of the following organisms is MOST likely to be the cause of his urinary tract infection?