Micro - Quiz 1

Micro - Quiz 1 - Question Feedback 1 of 20 An outbreak of...

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Question Feedback 1 of 20 An outbreak of sepsis caused by Staphylococcus aureus has occurred in the newborn nursery. You are called to investigate. According to you knowledge of the normal flora, what is the MOST likely source of the organism? A. Colon B. Nose C. Throat D. Vagina 1 out of 1 The correct answer IS B. Staphylococcus aureus is usually found in the nares and the skin of humans. Culturing the organism from nares is usually done to identify carriers for the organism. It is actually required by law in California that “high-risk” patients admitted to hospitals are screened for methicillin-resistant S. aureus. These “high-risk” patients include patients admitted to ICUs or burn units, receiving dialysis, for elective surgery, and patients who were in a hospital nursing home within the past 30 days. (Learning Objective MI-13 f,g,i) 2 of 20 Each of the following statements is true about the peptidoglycan of S. aureus EXCEPT: A. It has a backbone composed of alternating units of muramic acid and acetylglucosamine B. Cross-links between the tetrapeptides involve D-alanine C. It is thinner in gram-positive bacteria than in gram-negative bacteria D. It can be degraded by lysozyme 1 out of 1 C is the correct answer. The peptidoglycan layer of gram-positive bacteria is made up of multiple layers on the outside of the cell membrane. In gram-negative bacteria, there is a single peptidoglycan layer between an inner and an outer cell membrane. (Learning Objective MI-13c,d) 3 of 20 Which one of the statements comparing human, bacterial, and fungal cells is true? A. Human cells undergo mitosis, but not bacteria nor fungi B. Human and fungal cells have a similar cell wall, in contrast to bacteria, whose cell wall contains peptidoglycan C. Human and bacterial cells have plasmids, while fungal cells do not D.Human and fungal cells have similar ribosomes, while bacterial ribosomes are different
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D is the correct answer. Prokaryotes have ribosomes, which are made up of a 30s and a 50s subunits for a total of 70s. Eukaryotic are made up of a 40s and a 60s subunits for a total of 80s. The different ribosomes of prokaryotes are an important target for antibiotics that inhibit protein synthesis, such as aminoglycosides. (Learning Objective MI-13a,b) 4 of 20 The pneumococcal capsule: A. Is necessary for virulence B. Is non-antigenic C. Is chemotactic for neutrophils D. Is a glycolipid 1 out of 1 A is the correct answer. The capsule of S. pneumoniae IS necessary for virulence, is VERY antigenic, yet does not produce a powerful inflammatory response. The capsule is made of antigenically distinct polysaccharides, which form the basis of the pneumococcal vaccine (23-valent). (Learning Objective MI-15. M) 5 of 20 All of the following are true of Group B streptococci ( S. agalactiae ) EXCEPT: A. They infect cows but not humans B. They cause pneumonia in premature newborns C. They can colonize the vagina of pregnant women asymptomatically D. A single capsular type is responsible for nearly all cases of meningitis in infants.
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This note was uploaded on 09/14/2011 for the course PHARM mb taught by Professor Staff during the Spring '11 term at UCSD.

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Micro - Quiz 1 - Question Feedback 1 of 20 An outbreak of...

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