A sputum culture from a cystic fibrosis patient grew Stenotrophomonas maltophila. A broth microdilution panel was inoculated. Antimicrobials tested included: ceftazidime, imipenem, ti-carcillin-clavulanate, levofloxacin, and trimethoprim-sulfamethoxazole. After 20-hour incubation at 35°C in ambient air, no growth was seen in any well of the microtiter plate. Which of the following statements is
true?
a. The isolate is susceptible to all antimicro-bials tested.
b. The microdilution plate was incubated under incorrect conditions.
c. The test results are invalid and retesting would be recommended.
d. A Cefinase test for lactamase activity should be done as an adjunct to MIC re-sults.
C
Since there was no growth in the positive (i.e., growth control well) the test is invalid and would indicate that the organism did not grow or was not inoculated. The test is invalid and must be repeated. Furthermore, this organism is known to be highly resistant to many antimicrobials and have intrinsic resistance to imipenem.
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The chemical interactions of large organic molecules are largely determined by:
a. their solubility in water. b. their functional groups. c. their polar nature. d. isomerization of these hydrocarbons into other forms. e. the hydrogens bonded to the carbon atom
You recently discovered a new element, and find that this particular element has one electron in its outer energy level. What would you expect will happen to an atom of this element if placed in water?
A. It will gain an electron forming a negative ion. B. It will lose an electron forming a negative ion. C. It will gain an electron forming a positive ion. D. It will lose an electron forming a positive ion.
In antibody-mediated immunity, what happens immediately after B cells are activated?
a. The foreign antigen-MHC complex is displayed on the cell surfaces. b. Activated T helper cells interact with the B cells. c. The B cells are cloned. d. Antibodies combine with antigens on the pathogen surface. e. The B cells becomes plasma cells.
Coral and algae which live inside the coral tissues are an example of
A. mutualism. B. commensalism. C. parasitism. D. predation. E. competition.