Bacteriology Quiz Part 3 (20 test)
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|1. A young man crashes his bicycle, injuring one leg. Bacteria from the wound and a subsequent blood culture are isolated and identified, and an acute hematogenous osteomyelitis is diagnosed. Which organism listed below most often causes this type of infection?
a. Escherichia coli
b. Proteus mirabilis
c. Staphylococcus aureus
d. Staphylococcus epidermidis
e. Streptococcus faecalis
|2. A 3-year-old girl, with no history of vaccination, is brought to the hospital with a sore throat, fever, malaise, and difficulty in breathing. Physical examination reveals a gray membrane covering the pharynx. Growth of the etiologic agent on cysteine-tellurite agar forms gray-to-black colonies with a brown halo. The major virulence factor of this organism is only produced by those strains that will most likely have which of the following characteristics?
c. Glucose fermenters
d. Lysogenic for β-prophage
e. Sucrose fermenters
|3. A 28-year-old menstruating woman appears in the emergency room with the following signs and symptoms: fever, 104°F (40°C); WBC, 16,000/μL; blood pressure, 90/65 mm Hg; a scarlatiniform rash on her trunk, palms, and soles; extreme fatigue; vomiting; and diarrhea.
Which of the following is the most likely diagnosis?
a. Chicken pox
b. Guillain–Barré syndrome
c. Scalded skin syndrome
d. Staphylococcal food poisoning
e. Toxic shock syndrome (TSS)
|4 28-year-old menstruating woman appears in the emergency room with the following signs and symptoms: fever, 104°F (40°C); WBC, 16,000/μL; blood pressure, 90/65 mm Hg; a scarlatiniform rash on her trunk, palms, and soles; extreme fatigue; vomiting; and diarrhea.
Culture of the menstrual fluid in this case cited would most likely reveal a predominance of which of the following?
|5. A 28-year-old menstruating woman appears in the emergency room with the following signs and symptoms: fever, 104°F (40°C); WBC, 16,000/μL; blood pressure, 90/65 mm Hg; a scarlatiniform rash on her trunk, palms, and soles; extreme fatigue; vomiting; and diarrhea.
Which of the following is the most likely source and characteristic finding not yet revealed in the case just presented?
|6. A severe URT outbreak occurs in the residence of students of a private school, resulting in several cases of otitis media and acute sinusitis. Some students do not have any clinical evidence of infection. The state public health laboratory receives and evaluates a new LA reagent for H. influenzae polysaccharide capsular antigen in urine (intact antigen elimination). The results, shown below, are compared with the isolation of H. influenzae from pharyngeal swabs.
LA POS, CULT POS: 25
LA POS, CULT NEG: 5
LA NEG, CULT POS: 5
LA NEG, CULT NEG: 95
Which of the following best indicates the sensitivity of LA?
|7. A severe URT outbreak occurs in the residence of students of a private school, resulting in several cases of otitis media and acute sinusitis. Some students do not have any clinical evidence of infection. The state public health laboratory receives and evaluates a new LA reagent for H. influenzae polysaccharide capsular antigen in urine (intact antigen elimination). The results, shown below, are compared with the isolation of H. influenzae from pharyngeal swabs.
LA POS, CULT POS: 25
LA POS, CULT NEG: 5
LA NEG, CULT POS: 5
LA NEG, CULT NEG: 95Which of the following best indicates the specificity of LA?
|8. A severely burned firefighter develops a rapidly disseminating bacterial infection while hospitalized. “Green pus” is noted in the burned tissue, and cultures of both the tissue and blood yield small, oxidase-positive, gram-negative rods. Which of the following statements best describes this organism?
a. Endotoxin is the only virulence factor known to be produced by these bacteria
b. Humans are the only known reservoir hosts for these bacteria
c. The bacteria are difficult to culture because they have numerous growth requirements
d. These are among the most antibiotic resistant of all clinically relevant bacteria
e. These highly motile bacteria can “swarm” over the surface of culture media
|9. Several hours after dining on sweet and sour chicken and pork fried rice at the home of an Asian friend, a 34-year-old car salesman exhibits abdominal discomfort, nausea, and vomiting. In the middle of the night he awakens with watery diarrhea. Which of the following pairs of organisms is routinely responsible for food poisoning?
a. Clostridium botulinum and Bacillus anthracis
b. Clostridium difficile and C. botulinum
c. Clostridium perfringens and B. cereus
d. Clostridium tetani and B. anthracis
e. Clostridium tetani and B. cereus
|10. MRSA is isolated from seven patients in a 14-bed intensive care unit. All patients are isolated and the unit closed to any more admissions.
Which of the following best explains these rigorous methods to control MRSA?
a. MRSA causes TSS
b. MRSA is inherently more virulent than other staphylococci
c. MRSA is resistant to penicillin
d. MRSA spreads more rapidly from patient to patient than antibiotic-susceptible staphylococci do
e. The alternative for treatment of MRSA is vancomycin, an expensive and potentially toxic antibiotic
|11. A 2-year-old infant is brought to the emergency room with hematuria, fever, and thrombocytopenia. Which one of the following bacteria would most likely be isolated from a stool specimen?
a. Aeromonas species
b. Enterobacter aerogenes
c. Escherichia coli 0157/H7
d. Salmonella enteritidis
e. Shigella flexneri
|12. A 65-year-old healthy, retired female executive goes to Mexico on her yearly vacation. Unlike her previous trips, she decides to use the local water to make her favorite punch. Thirty-six hours later, she develops profuse watery diarrhea, severe cramping, and abdominal pain. She is diagnosed with Escherichia coli-related diarrhea. Which of the following E. coli types is characterized by the presence of heat-labile (LT) and heatstable (ST) toxin proteins?
a. Enteroinvasive (EIEC)
b. Enterotoxigenic (ETEC)
c. Enterohemorrhagic (EHEC)
d. Enteropathogenic (EPEC)
|13. A 48-year-old farmer in New Mexico is bitten by a flea and, 5 days later, develops a sudden onset of fever, chills, weakness, and headache. A few hours later he develops swollen, necrotic lymph nodes (buboes) in the right axilla and groin, which are intensely painful. This patient is subsequently diagnosed with bubonic plague and does not develop any pneumonic features of the disease. Human plague can be bubonic or pneumonic. Which of the following is the primary epidemiologic difference between the two clinical forms of plague?
a. Age of the patient
b. Geographic location of the animal vector
c. Health of the animal vector
d. Route of infection
e. Season of the year
|14. A 9-year-old child is brought to the emergency room with the chief complaint of enlarged, painful axillary lymph nodes. The resident physician also notes a small, inflamed, dime-sized lesion surrounding what appears to be a small scratch on the forearm. The lymph node is aspirated and some pus is sent to the laboratory for examination. A Warthin-Starry silver impregnation stain reveals many highly pleomorphic, rod-shaped bacteria. Which of the following is the most likely cause of this infection?
a. Bartonella henselae
b. Brucella canis
c. Mycobacterium scrofulaceum
d. Yersinia enterocolitica
e. Yersinia pestis
|15. A sixth-grade boy returns from a summer camp with several minor cuts and abrasions. Within a week, extensive cellulitis develops, and it is apparent that subcutaneous tissue is involved, requiring surgical removal of nonviable tissue. Antibiotics are used aggressively. Cellulitis is usually caused by which of the following?
a. Bacillus cereus
b. Clostridium tetani
c. Group A streptococci
d. Micrococcus species
e. Staphylococcus aureus
|16. A 40-year-old female reports chronic gastritis. She tests positive for H. pylori. After a course of the appropriate antibiotic therapy, her symptoms subside. Which of the following is the most effective noninvasive test for the diagnosis of Helicobacter-associated gastric ulcers?
a. Culture of stomach contents for H. pylori
b. Detection of H. pylori antigen in stool
c. Growth of H. pylori from a stomach biopsy
d. Growth of H. pylori in the stool
e. IgM antibodies to H. pylori
|17. The following examination and test results are observed in a woman tested in November who reports being in the woods in Pennsylvania during the last summer. While there, she was bitten by a tick, and now has a flattened red area near the bite with central clearing. She also has flu-like illness with fever, myalgia, and headache. Which of the following is the most appropriate course of action?
a. Ask the patient if she has a severe headache
b. Do a spinal tap for CSF
c. Observe the lesion
d. Order a Lyme disease antibody titer
e. Start treatment with tetracycline
|18. Several white male patients, over 50 years of age and suffering from cavitary pulmonary disease, being followed and treated at a university AIDS clinic are found to be infected by Mycobacterium avium, a major opportunist pathogen. M. avium from these patients is best characterized by which one of the following statements?
a. Few isolates from AIDS patients are acid-fast.
b. Most isolates from AIDS patients are sensitive to isoniazid and streptomycin
c. M. avium can be isolated from the blood of many AIDS patients
d. M. avium isolates from AIDS patients are of multiple serovars
e. The majority of M. avium isolates from AIDS patients are nonpigmented
|19. A 12-year-old girl experiences a group A streptococcus pharyngitis and, within 3 weeks, has chest pain and develops new murmurs of mitral regurgitation. Which of the following statements best typifies the disease she is suffering from?
a. It is a complication of group A streptococcal skin disease but usually not of pharyngitis
b. It is characterized by inflammatory lesions that may involve the heart, joints, subcutaneous tissues, and CNS
c. It is very common in developing countries but extremely rare and decreasing in incidence in the United States
d. Prophylaxis with benzathine penicillin is of little value
e. The pathogenesis is related to the similarity between a staphylococcal antigen and a human cardiac antigen
|20. After extraction of a wisdom tooth, an 18-year-old male student is diagnosed with subacute bacterial endocarditis (SBE). He has a congenital heart disease that has been under control. Which of the following is the most likely organism causing the infection?
a. Staphylococcus aureus
b. Staphylococcus epidermidis
c. Streptococcus pneumoniae
d. Streptococcus viridans
e. Enterococcus faecalis