Which of the following best describes the Gram stain process?

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microbiology chapter 14 test bank Questions

Question 1 of 9

Which of the following best describes the Gram stain process?

Correct Answer: C

Rationale: The Gram stain process involves staining bacterial cells with crystal violet and iodine, followed by decolorization and counterstaining. The primary differentiation is based on the cell wall structure, distinguishing bacteria into Gram-positive (retain purple color) and Gram-negative (lose purple color). This classification is crucial in microbiology for treatment decisions as it correlates with different antibiotic susceptibilities. Choices A, B, and D are incorrect because the Gram stain process does not primarily focus on flagella, shape, or motility of bacteria.

Question 2 of 9

A patient underwent esophagogastroduodenoscopy. Analysis of the biopsy material enabled doctors to diagnose him with helicobacteriosis. What property of the bacteria found in this patient had to be obligatory taken into account during their cultivation?

Correct Answer: A

Rationale: Step-by-step rationale for why choice A is correct: 1. Helicobacter pylori, the bacteria causing helicobacteriosis, is microaerophilic, requiring low oxygen levels. 2. Cultivation conditions must mimic the natural environment of the bacteria. 3. Failure to provide a microaerophilic environment can hinder bacterial growth. 4. Thus, the ability to cultivate these bacteria requires consideration of their microaerophilic nature. Summary: - Choice A is correct because Helicobacter pylori is a microaerophilic bacteria. - Choice B (Presence of urease) is incorrect as it is a characteristic used for diagnosis, not cultivation. - Choice C (Absence of spores and capsules) is incorrect as it does not relate to cultivation requirements. - Choice D (Colonization of gastral cells) is incorrect as it pertains to bacterial behavior, not cultivation needs.

Question 3 of 9

Which organism is responsible for cholera?

Correct Answer: B

Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by this specific bacterium. Vibrio cholerae produces a toxin that leads to severe diarrhea and dehydration. Salmonella typhi causes typhoid fever, Escherichia coli can cause various infections but not cholera, and Shigella dysenteriae causes dysentery, not cholera. Therefore, the correct choice is B.

Question 4 of 9

Nigrosin is a stain used in:

Correct Answer: C

Rationale: Nigrosin is used in negative staining, where the background is stained instead of the cells themselves. This technique helps highlight the morphology and structure of cells that may be damaged by traditional staining methods. Nigrosin is negatively charged and repels the negatively charged bacterial cells, resulting in a clear halo around the cells. This process is particularly useful for observing capsules and determining cell size and shape. The other options are incorrect because simple staining uses a single dye to color the entire cell, gram staining involves a series of dyes to differentiate between gram-positive and gram-negative bacteria, and acid-fast staining is used to detect acid-fast organisms like Mycobacterium.

Question 5 of 9

A 22-year-old patient is a clerk. His working day runs in a conditioned room. In summer he was taken by an acute disease with the following symptoms: fever, dyspnea, dry cough, pleural pain, myalgia, arthralgia. Objectively: moist rales on the right, pleural friction rub. X-ray picture showed infiltration of the inferior lobe. In blood: WBC - 11 · 109/l, stab neutrophils - 6%, segmented neutrophils - 70%, lymphocytes - 8%, ESR - 42 mm/h. What is the etiological factor pneumonia?

Correct Answer: C

Rationale: The correct answer is C: Streptococcus. Streptococcus pneumoniae is the most common etiological factor for community-acquired pneumonia in young adults. The symptoms described align with typical pneumococcal pneumonia presentation. Presence of pleural friction rub and infiltration in the X-ray support the diagnosis. The blood work showing elevated WBC count with a left shift (increased neutrophils and low lymphocytes) and elevated ESR is consistent with a bacterial infection. Legionella and Mycoplasma typically present with atypical pneumonia symptoms such as headache, confusion, and GI symptoms, which are not described in the case. Staphylococcus pneumonia is not a common cause of community-acquired pneumonia in young adults.

Question 6 of 9

A 45-year-old patient has foul-smelling diarrhea. Stool examination revealed large ciliated protozoa with a kidney-shaped macronucleus. What is the causative agent?

Correct Answer: A

Rationale: The correct answer is A: Balantidium coli. This large ciliated protozoa with a kidney-shaped macronucleus is characteristic of Balantidium coli, an intestinal parasite known to cause foul-smelling diarrhea in humans. Balantidium coli is the only option among the choices that fits this specific description. Entamoeba histolytica causes amoebic dysentery, Giardia lamblia causes giardiasis, and Trichomonas hominis is a non-pathogenic protozoa found in the intestinal tract. Therefore, based on the morphology described in the question, Balantidium coli is the correct causative agent.

Question 7 of 9

Which statement related to the mumps vaccine is true:

Correct Answer: D

Rationale: The correct answer is D: it is a live attenuated vaccine. This is true because the mumps vaccine is indeed a live attenuated vaccine, meaning it contains a weakened form of the virus to stimulate an immune response without causing the disease. This type of vaccine provides long-lasting immunity. A, B, and C are incorrect: A: the vaccine is recommended, not obligatory - this is incorrect because the mumps vaccine is typically recommended for all individuals to prevent the spread of the disease. B: the vaccine is not given in combination with other vaccines - this is incorrect as the mumps vaccine is often given in combination with measles and rubella vaccines as the MMR vaccine. C: the vaccine is administered orally - this is incorrect because the mumps vaccine is usually administered via injection, not orally.

Question 8 of 9

A duodenal content smear of a patient with indigestion contains protozoa 10-18 mcm large. They have piriform bodies, 4 pairs of filaments, two symmetrically located nuclei in the broadened part of body. What kind of the lowest organisms is it?

Correct Answer: A

Rationale: The correct answer is A: Lamblia. The description matches the characteristics of Giardia lamblia - a protozoan parasite that causes giardiasis. The piriform bodies, 4 pairs of filaments, and two symmetrically located nuclei are specific to Giardia lamblia. It is important to differentiate it from the other choices. Dysentery ameba (choice B) typically has a single nucleus and lacks the specific characteristics described. Trichomonas (choice C) is a flagellated protozoan with different morphology and does not match the given description. Intestinal ameba (choice D) such as Entamoeba histolytica usually has a single nucleus and different body shape compared to the described organism.

Question 9 of 9

Which ones of the following symptoms are NOT typical for botulism

Correct Answer: C

Rationale: The correct answer is C because chills, fever, and loss of consciousness are not typical symptoms of botulism. Botulism is characterized by descending, flaccid paralysis (choice A), dry mouth, difficulty swallowing, and speaking (choice B), and blurred vision, diplopia (choice D). These symptoms result from the neurotoxin produced by Clostridium botulinum, leading to muscle weakness and paralysis. Chills, fever, and loss of consciousness are more commonly associated with infections or other conditions, not botulism.

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