microbiology chapter 10 test bank -Nurselytic

Correct Answer: A

Rationale: The correct answer is A: Candida. The whitish spots resembling coagulated milk on the mucous membranes are characteristic of oral thrush, a condition caused by Candida species. Candida is a gram-positive oval yeast-like fungus commonly found in the oral cavity. Staphylococci (
B) are gram-positive cocci, not yeast-like cells. Diphtheria bacillus (
C) causes diphtheria, not oral thrush. Actinomycetes (
D) are filamentous bacteria, not yeast-like cells typically seen in oral thrush.
Therefore, A is the correct answer based on the clinical presentation and microscopic findings.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. This is because Staphylococcus aureus is Gram-positive, catalase-positive, and coagulase-positive, which matches the characteristics described in the question. Staphylococcus epidermidis is also Gram-positive but is coagulase-negative. Streptococcus pneumoniae is Gram-positive but is catalase-negative. Enterococcus faecalis is Gram-positive but is catalase-negative and coagulase-negative.
Therefore, based on the given information, Staphylococcus aureus is the likely causative agent of the wound infection.

Correct Answer: A

Rationale: The correct answer is A: Yersinia pestis. Y. pestis is a Gram-negative rod that exhibits a 'safety pin' appearance on staining due to bipolar staining. This bacterium is the causative agent of plague, which can present as painful ulcers known as buboes. Y. pestis is transmitted by fleas and can cause outbreaks in humans.

Summary:
- B: Francisella tularensis causes tularemia, not typically associated with painful ulcers.
- C: Brucella abortus causes brucellosis, which does not typically present with painful ulcers.
- D: Clostridium botulinum causes botulism, characterized by muscle weakness and paralysis, not painful ulcers.

Correct Answer: D

Rationale: The correct answer is D: scanning electron microscope. A scanning electron microscope provides a three-dimensional image of a specimen by scanning a focused electron beam across the surface of the specimen, detecting the electrons that are emitted from the surface, and creating a detailed image. This is achieved through the detection of secondary electrons, backscattered electrons, and X-rays emitted from the specimen surface.

A dark-field microscope (choice
A) utilizes oblique lighting to enhance contrast and is not specifically designed to provide a 3D image. A transmission electron microscope (choice
B) uses a beam of electrons transmitted through a specimen to create a 2D image at high magnification. A bright-field microscope (choice
C) is a basic microscope that illuminates a specimen with uniform light and does not provide a 3D image like a scanning electron microscope does.

Correct Answer: A

Rationale: The correct answer is A: Nystatin. Nystatin is an antifungal medication specifically used to treat candida infections. It works by disrupting the cell membrane of the fungus, leading to its death. Penicillin (
B) is an antibiotic effective against bacterial infections, not fungal. Streptomycin (
C) is also an antibiotic used for bacterial infections. Isoniazid (
D) is used to treat tuberculosis, not candida infections.
Therefore, Nystatin is the best choice for treating candida infections due to its antifungal properties.