Page 137 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com mebooksfree.com 10. Infections by which one of the following bacteria are typically mebooksfree.com
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PART II Clinical Bacteriology
126
(C) Endotoxin
treated with penicillins such as amoxicillin, because they exhibit
(D) Protein A
(E) Teichoic acid
neither low-level resistance nor high-level resistance and synergy
4. The main reason why methicillin-resistant Staphylococcus aureus
with an aminoglycoside is not required in order for penicillins to
(MRSA) strains are resistant to methicillin and nafcillin is:
be effective?
(A) Enterococcus faecalis
(A) they produce β-lactamase that degrades the antibiotics.
(B) they have altered penicillin-binding proteins that have
(B) Staphylococcus aureus
reduced binding of the antibiotics.
(C) Staphylococcus epidermidis
(D) Streptococcus pneumoniae
(C) they have mutant porin proteins that prevent the antibiotics
(E) Streptococcus pyogenes
from entering the bacteria. 11. Your patient in the emergency room has a 5-cm ulcer on her leg
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strain of Staphylococcus aureus? mebooksfree.com
mebooksfree.com mebooksfree.com gram-positive cocci in chains. Culture of the pus grows small mebooksfree.com
(D) they have plasmid-encoded export proteins that remove the
drug from the bacteria.
that is surrounded by a red, warm, and tender area of inflam-
mation. You do a Gram stain on pus from the ulcer and see
5. A pore-forming exotoxin produced by Staphylococcus aureus
that kills cells and is important in the severe, rapidly spreading
β-hemolytic colonies that are catalase-negative and are inhibited
necrotizing lesions caused by MRSA strains is:
by bacitracin. These results indicate that the organism causing
(A) coagulase.
her lesion is most likely:
(B) enterotoxin.
(A) Enterococcus faecalis.
(C) exfoliatin.
(D) P-V leukocidin.
(B) Staphylococcus aureus.
(E) staphyloxanthin.
(C) Streptococcus agalactiae.
6. Of the following antibiotics, which one is the most appropriate
(D) Streptococcus pneumoniae.
(E) Streptococcus pyogenes.
to treat a severe necrotizing skin infection caused by an MRSA
It was a warm day, and the food sat in the sun for several hours.
(A) Amoxicillin 12. The Jones family of four had a delicious picnic lunch last Sunday.
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mebooksfree.com mebooksfree.com mebooksfree.com 13. A 20-year-old sexually active woman reports dysuria and other mebooksfree.com
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Alas, 3 hours later, everyone came down with vomiting and non-
(B) Ceftriaxone
bloody diarrhea. In the emergency room, it was found that Mrs.
(C) Ciprofloxacin
Jones, who prepared the food, had a paronychia on her thumb.
(D) Gentamicin
Which one of the following is the most likely causative organism?
(E) Vancomycin
(A) Enterococcus faecalis
7. An outbreak of serious pneumococcal pneumonia and sepsis
(B) Staphylococcus aureus
among inmates in an overcrowded prison has occurred. Labora-
(C) Staphylococcus epidermidis
tory analysis determined that one serotype was involved. The prison
(D) Streptococcus agalactiae
physician said that the pneumococcal vaccine might have limited
the outbreak. Which one of the following structures of the pneumo-
(E) Streptococcus pyogenes
coccus is responsible for determining the serotype and is also the
immunogen in the vaccine?
reveals gram-positive cocci. Which one of the following sets of
(A) Capsule
bacteria is most likely to cause this infection?
(B) Flagellar protein
(C) O antigen symptoms of a urinary tract infection. Gram stain of the urine
(A) Staphylococcus aureus and Streptococcus pyogenes
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mebooksfree.com mebooksfree.com mebooksfree.com 14. Your patient is a 2-week-old infant who was well until 2 days ago, mebooksfree.com
(B) Staphylococcus saprophyticus and Enterococcus faecalis
(D) Peptidoglycan
(E) Pilus protein
(C) Streptococcus agalactiae and Staphylococcus epidermidis
8. Which one of the following best describes the pathogenesis of
(D) Streptococcus pneumoniae and Enterococcus faecalis
rheumatic fever?
(E) Streptococcus pyogenes and Streptococcus pneumoniae
(A) An exotoxin produced by Streptococcus pyogenes that acts as a
when she stopped feeding and became irritable. She now has a
superantigen damages cardiac muscle.
fever to 38°C, developed a petechial rash all over her body, and
(B) An exotoxin produced by Streptococcus pyogenes that ADP-
is very difficult to arouse. In the emergency room, a blood cul-
ribosylates a G protein damages joint tissue.
ture and a spinal tap were done. Gram stain of the spinal fluid
(C) Antibody to the capsular polysaccharide of Streptococcus pyo-
showed gram-positive cocci in chains. Culture of the spinal fluid
genes cross-reacts with joint tissue and damages it.
(D) Antibody to the M protein of Streptococcus pyogenes cross-
presence of bacitracin and hydrolyzed hippurate. Which one of
reacts with cardiac muscle and damages it.
the following is the most likely causative organism?
(E) Endotoxin produced by Streptococcus pyogenes activates mac-
(A) Staphylococcus aureus
rophages to release cytokines that damage cardiac muscle. on blood agar revealed β-hemolytic colonies that grew in the
9. Which one of following laboratory tests is the most appropriate
(B) Streptococcus agalactiae
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to distinguish Streptococcus pyogenes from other β-hemolytic
(C) Streptococcus mutans
streptococci?
(D) Streptococcus pneumoniae
(E) Streptococcus pyogenes
(A) Ability to grow in 6.5% NaCl
(B) Activation of C-reactive protein
acquired pneumonia caused by Streptococcus pneumoniae. Anti-
(C) Hydrolysis of esculin in the presence of bile
biotic susceptibility tests reveal an MIC of less than 0.1 mg/mL
(D) Inhibition by bacitracin
(E) Inhibition by optochin
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