The microbiologist identified an organism that produces large c-hemolytic colonies on blood agar and ...

B
Based on the information presented in the question, the microbiologist should complete a bio-chemical identification and an antibiotic susceptibility. At this point, the type of isolate is un-known and therefore, it is important to identify the species to determine the antibiotic pattern. If the organism is indeed B. anthracis, some strains produce -lactamases. CLSI has published technical guidelines and interpretive criteria for testing Bacillus spp.

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D
Various types of microorganisms require different atmospheric conditions. Microaerophiles grow best in the presence of reduced O2 and increased CO2.

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C
Enterococci are intrinsically resistant to a wide array of antimicrobial agents, and they are gener-ally resistant to killing by any of the single agents (e.g., ampicillin, vancomycin) that are bacteri-cidal for most other gram-positive cocci. Therefore, effective bactericidal activity can only be achieved with the combination of a cell wallactive agent, such as ampicillin or vancomycin, and an aminoglycoside, such as gentamicin or streptomycin.

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B
The cellular arrangement on Gram stain and the type of hemolysis are important considerations in the identification of streptococci.

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D
The characteristics in question 15 refer to S. haemolyticus. It is also the only hemolytic Sta-phylococcus listed.