ATI RN
microbiology an introduction 12th edition test bank Questions
Question 1 of 9
A patient with chronic diarrhea had stool microscopy revealing flagellated protozoa with two nuclei. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Giardia lamblia. Giardia lamblia is a flagellated protozoan with two nuclei found in the stool. It commonly causes chronic diarrhea. The other choices are incorrect because B: Entamoeba histolytica causes dysentery, not chronic diarrhea; C: Trichomonas vaginalis is a sexually transmitted infection, not typically found in stool; D: Balantidium coli is a ciliated protozoan, not flagellated.
Question 2 of 9
The causative agent of typhoid fever is:
Correct Answer: C
Rationale: The correct answer is C: Salmonella typhi. Typhoid fever is caused by the bacterium Salmonella typhi, specifically transmitted through contaminated food and water. Shigella dysenteriae causes bacillary dysentery, Vibrio cholerae causes cholera, and Escherichia coli can cause various gastrointestinal illnesses, but not typhoid fever. Identifying the causative agent is crucial for effective treatment and prevention strategies.
Question 3 of 9
The most rapid rate of drug absorption is achieved by __________ administration.
Correct Answer: B
Rationale: The correct answer is B: intravenous administration. This route bypasses the first-pass metabolism, allowing the drug to directly enter the bloodstream for immediate distribution. In contrast, on the skin (A) and sublingual (D) routes have slower absorption rates due to barriers like skin layers or mucous membranes. Intramuscular (C) absorption is slower than intravenous due to slower perfusion rates in muscle tissues. Overall, intravenous administration provides the fastest and most direct route for drug absorption, making it the most rapid method.
Question 4 of 9
A stool sample from a patient with chronic diarrhea revealed cysts with four nuclei. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This is because it is a protozoan parasite known to cause amoebic dysentery, presenting with chronic diarrhea and cysts with four nuclei in the stool sample. Giardia lamblia (B) causes giardiasis with trophozoites and cysts with two nuclei. Balantidium coli (C) is a ciliated parasite causing dysentery with large trophozoites. Trichomonas hominis (D) is a non-pathogenic flagellate often found in the human intestine. Thus, based on the specific characteristics of the cysts and clinical presentation, Entamoeba histolytica is the most likely causative agent.
Question 5 of 9
In the South and Central America there can be found a species of trypanosomes that is the causative agent of Chagas disease. What animal is the infection carrier specific to this disease?
Correct Answer: A
Rationale: The correct answer is A: Triatomine bug. Triatomine bugs, also known as "kissing bugs," are the specific carrier of the trypanosomes that cause Chagas disease. These bugs transmit the parasite through their feces, which contain the infectious forms of the trypanosomes. When the bug bites a human or animal, it defecates near the bite wound, allowing the parasites to enter the bloodstream through the broken skin. Mosquitoes (B) transmit diseases like malaria and dengue fever, not Chagas disease. Tsetse flies (C) are known for transmitting African trypanosomiasis (sleeping sickness), not Chagas disease. Cockroaches (D) are not known to transmit Chagas disease.
Question 6 of 9
Gram-negative rods producing red colonies on Endo agar were isolated from a fecal sample. The bacteria were lactose-fermenting. What microorganism is likely responsible?
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. E. coli is a Gram-negative rod that ferments lactose, leading to red colonies on Endo agar. This bacterium is commonly found in the human gut and is known for its ability to ferment lactose. Salmonella and Shigella are also Gram-negative rods but do not ferment lactose, so they would not produce red colonies on Endo agar. Proteus is a Gram-negative rod that is not known for its lactose-fermenting ability and would not produce red colonies on Endo agar. Therefore, based on the characteristics provided, E. coli is the most likely microorganism responsible for the red colonies on Endo agar.
Question 7 of 9
Which of the following bacteria is capable of producing an endotoxin that can lead to septic shock?
Correct Answer: D
Rationale: The correct answer is D: All of the above. 1. Escherichia coli can produce endotoxin due to its lipopolysaccharide component. 2. Salmonella enterica also produces endotoxin as part of its cell wall structure. 3. Pseudomonas aeruginosa is known to produce endotoxin as well. Therefore, all of these bacteria are capable of producing endotoxin, which can trigger an excessive immune response leading to septic shock. Other choices are incorrect because they do not cover all the bacteria mentioned in the question that are capable of producing endotoxin.
Question 8 of 9
Enzymes that remove functional groups from a substrate without adding water, or that add functional groups to a double bond, are called
Correct Answer: D
Rationale: The correct answer is D: lyases. Lyases are enzymes that catalyze the breaking of chemical bonds without the addition of water. They can remove functional groups from substrates or add functional groups to double bonds without the use of water. A: Oxidoreductases involve the transfer of electrons. B: Transferases transfer functional groups from one molecule to another. C: Hydrolases catalyze the breaking of bonds by adding water.
Question 9 of 9
The etiological agent of Q-fever is:
Correct Answer: B
Rationale: The correct answer is B: Coxiella burnetii. Q-fever is caused by the bacterium Coxiella burnetii. It is not caused by viruses like Bunyaviridae or Filoviridae. Rickettsia conorii causes Mediterranean spotted fever, not Q-fever. Coxiella burnetii is the only bacterium among the choices known to be the etiological agent of Q-fever.