ATI RN
microbiology chapter 13 test bank Questions
Question 1 of 5
Which of the following bacteria is known for causing dental caries (cavities)?
Correct Answer: A
Rationale:
Step 1: Streptococcus mutans is known for its ability to produce acids that contribute to the demineralization of tooth enamel, leading to dental caries.
Step 2: Streptococcus pneumoniae is a common cause of respiratory infections, not dental caries.
Step 3: Bacillus anthracis causes anthrax, a serious bacterial infection, not dental caries.
Step 4: Clostridium botulinum causes botulism, a severe form of food poisoning, not dental caries.
Summary: Streptococcus mutans is the correct answer as it is specifically associated with causing dental caries, while the other choices are linked to different diseases.
Question 2 of 5
Bacteriological laboratory examines canned meat whether it contains botulinum toxin. For this purpose an extract of test specimen and antitoxic antibotulinic serum of A, B, E types were introduced to a group of mice under examination; a control group of mice got the extract without antibotulinic serum. What serological reaction was applied?
Correct Answer: A
Rationale: The correct answer is A: Neutralization. In this scenario, the antibotulinic serum of types A, B, and E were introduced to neutralize the botulinum toxin in the test specimen. The serological reaction applied here involves the neutralization of the toxin by the specific antibodies present in the serum. This process prevents the toxin from causing harm to the mice.
Summary of other choices:
B: Precipitation - This involves the formation of insoluble complexes between antigen and antibody, not the specific neutralization seen in this case.
C: Complement binding - This involves activation of the complement system leading to cell lysis, not the direct neutralization of toxin.
D: Double immune diffusion - This technique is used to determine the presence of specific antibodies or antigens based on their diffusion patterns, not the neutralization of toxin as seen in this scenario.
Question 3 of 5
A patient with a deep tissue infection had Gram-negative rods isolated from the wound culture. The bacteria were oxidase-positive and non-lactose fermenters. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas is a Gram-negative rod, oxidase-positive, and non-lactose fermenter. These characteristics are typical of Pseudomonas species.
B: Escherichia coli is a Gram-negative rod but is lactose fermenter and usually oxidase-negative.
C: Klebsiella pneumoniae is a Gram-negative rod, non-lactose fermenter, but is usually oxidase-negative.
D: Shigella dysenteriae is a Gram-negative rod, non-lactose fermenter, but is usually oxidase-negative and is more associated with causing shigellosis rather than deep tissue infections.
Question 4 of 5
The correct descending order of taxonomic categories is
Correct Answer: C
Rationale: The correct descending order of taxonomic categories is domain, kingdom, phylum, class, order, family, genus, species. This hierarchical classification system helps organize and categorize living organisms based on their shared characteristics and evolutionary relationships.
Explanation:
- Domain is the broadest category, representing the highest level of classification.
- Kingdom further divides organisms into major groups based on similar characteristics.
- Phylum, class, order, family, and genus successively narrow down the classification based on more specific shared characteristics.
- Species is the most specific category, representing individual organisms capable of interbreeding.
Summary of other choices:
A: Incorrect as it has the incorrect order of phylum, kingdom, and division.
B: Incorrect as it has the incorrect order of family and species.
D: Incorrect as it has the incorrect order of domain, kingdom, and class.
Question 5 of 5
During the skill-building session in microbiology the students need to stain the prepared and fixed sputum smears obtained from a tuberculosis patient. What staining technique should be used in this case?
Correct Answer: C
Rationale: The correct staining technique for staining sputum smears from a tuberculosis patient is Ziehl-Neelsen staining. This technique uses a carbol fuchsin stain that specifically stains acid-fast organisms like Mycobacterium tuberculosis. The steps involved include staining with carbol fuchsin, decolorizing with acid-alcohol, counterstaining with methylene blue, and then examining under a microscope. This staining method is crucial for detecting the acid-fast bacilli characteristic of tuberculosis.
Explanation for incorrect choices:
A: Gram staining is used to differentiate bacteria into Gram-positive and Gram-negative, not suitable for acid-fast organisms like Mycobacterium tuberculosis.
B: Giemsa staining is used for detecting parasites and certain types of white blood cells, not specific for acid-fast bacteria.
D: Burry staining is not a recognized staining technique in microbiology for staining acid-fast organisms.