ATI RN
microbiology an introduction 13th edition test bank Questions
Question 1 of 9
A patient with pneumonia had sputum stained with Gram's method, revealing purple-stained diplococci with pointed ends. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium appears as purple-stained diplococci with pointed ends on Gram staining. S. pneumoniae is a common cause of pneumonia. It is encapsulated and has a lancet-shaped appearance, which is characteristic of the pointed ends seen in the staining. Staphylococcus aureus (B) typically appears as clusters of gram-positive cocci, not diplococci. Klebsiella pneumoniae (C) is a gram-negative rod, not a diplococci. Neisseria meningitidis (D) is a gram-negative diplococci but typically lacks the pointed ends seen in the staining of S. pneumoniae.
Question 2 of 9
A businessman came to India from South America. On examination the physician found that the patient was suffering from sleeping-sickness. What was the way of invasion?
Correct Answer: B
Rationale: The correct answer is B: As a result of mosquito's bites. Sleeping sickness, also known as African trypanosomiasis, is caused by the parasite Trypanosoma transmitted by tsetse flies, not mosquitoes. Tsetse flies are primarily found in Africa, not South America. Choice A is incorrect as bug bites do not transmit sleeping sickness. Choice C is incorrect as contaminated fruits and vegetables do not transmit the disease. Choice D is incorrect as dirty hands do not play a role in the transmission of sleeping sickness.
Question 3 of 9
When preparing a dental plaque smear and staining it according to the gram method, a student during microscopy detected there various violet and pink microorganisms. What structural component of microorganisms causes different response to stains?
Correct Answer: A
Rationale: The correct answer is A: Cell wall. In the Gram staining method, the primary differentiation of bacteria is based on the composition of their cell walls. Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet dye and appears purple under the microscope. On the other hand, Gram-negative bacteria have a thinner layer of peptidoglycan and an outer membrane, which allows the crystal violet dye to be washed out during the decolorization step and take up the counterstain safranin, appearing pink. The different responses to stains are primarily due to the structural differences in the cell walls of these two types of bacteria. Summary: - Choice A: Cell wall is correct because it determines the differential staining in Gram staining. - Choice B: Cytoplasm is incorrect as it does not directly influence the staining properties of bacteria. - Choice C: Cytoplasmic membrane is incorrect as it is not the main structural
Question 4 of 9
A patient presents with fever, chill and cough. From his sputum the ovoid Gram-negative bipolar- stained bacilli with a delicate capsule were secured. What is the most likely diagnosis?
Correct Answer: A
Rationale: The correct answer is A: Plague. The presence of ovoid Gram-negative bipolar-stained bacilli with a delicate capsule in the sputum is characteristic of Yersinia pestis, the causative agent of plague. Plague presents with symptoms like fever, chills, and cough. Plague is a zoonotic disease usually transmitted through fleas from rodents. The other choices (B: Tuberculosis, C: Leptospirosis, D: Brucellosis) can be ruled out based on the specific description of the bacteria in the sputum. Tuberculosis is caused by Mycobacterium tuberculosis, which is not Gram-negative. Leptospirosis is caused by Leptospira, which are spirochetes and not ovoid bacilli. Brucellosis is caused by Brucella species, which are small, coccobacilli and not ovoid bacilli.
Question 5 of 9
Chemically, most enzymes are
Correct Answer: A
Rationale: The correct answer is A: proteins. Enzymes are mostly composed of proteins due to their complex structure and specific amino acid sequences that are essential for their catalytic activity. Proteins have active sites that bind to substrates and facilitate chemical reactions. Lipids (B), nucleic acids (C), and carbohydrates (D) do not possess the necessary properties and structures to function as enzymes. Lipids serve as energy storage molecules and cell membrane components, nucleic acids store genetic information, and carbohydrates are primarily used for energy production.
Question 6 of 9
A sample of a finished dosage form was found to be contaminated with some microorganisms exhibiting the following properties: greenish fluorescent colonies of gram-negative nonsporeforming bacilli that grew on the medium for the detection of pyocyanin. The bacilli release the bluegreen pigment into the medium. What microorganisms contaminated the finished dosage form?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is a gram-negative bacilli that produce pyocyanin, a blue-green pigment. The presence of greenish fluorescent colonies of gram-negative nonsporeforming bacilli that release blue-green pigment matches the characteristics of Pseudomonas aeruginosa. Now, let's analyze the other choices: B: Enterobacteriaceae - While some Enterobacteriaceae can be gram-negative bacilli, they do not typically produce pyocyanin or exhibit the specific characteristics described in the question. C: Staphylococcus aureus - Staphylococcus aureus is a gram-positive cocci, not a gram-negative bacilli. It does not match the given description. D: Staphylococcus epidermidis - Staphylococcus epidermidis is also a gram-positive cocci, not a gram-negative bacilli. It does
Question 7 of 9
Which bacteria are commonly associated with foodborne illnesses?
Correct Answer: D
Rationale: The correct answer is D because all three bacteria - Salmonella enterica, Clostridium botulinum, and Escherichia coli - are commonly associated with foodborne illnesses. Salmonella causes gastroenteritis, Clostridium botulinum causes botulism, and E. coli can lead to severe food poisoning. Each bacterium has different mechanisms of causing illness, but all can be transmitted through contaminated food. Choices A, B, and C alone are incorrect because they do not encompass the full spectrum of bacteria commonly linked to foodborne illnesses.
Question 8 of 9
What drug should be administered for individual prevention of malaria?
Correct Answer: A
Rationale: The correct answer is A: Chingamin. Chingamin is a type of antimalarial drug that is commonly used for individual prevention of malaria. It works by targeting the malaria parasite in the body, preventing its growth and spread. Rifampicin (B), Ampicillin (C), and Gentamicin (D) are not effective for preventing malaria as they are antibiotics that target bacterial infections, not parasitic infections like malaria. Therefore, Chingamin is the most appropriate choice for individual prevention of malaria due to its specific antimalarial properties.
Question 9 of 9
Transformation in bacteria refers to:
Correct Answer: B
Rationale: The correct answer is B because transformation in bacteria refers to the uptake of naked DNA from the environment. During transformation, bacteria take up free DNA from their surroundings and incorporate it into their own genome. This mechanism allows bacteria to acquire new genetic material and traits. Explanation for other choices: A: Transfer of DNA via phages refers to transduction, not transformation. C: Transfer of DNA via direct contact is known as conjugation, not transformation. D: Spore formation is a method of bacterial survival but is not related to transformation.