Nokea
A blood culture from a patient with sepsis revealed Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
- A. Staphylococcus epidermidis
- B. Staphylococcus aureus
- C. Streptococcus pyogenes
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. This is supported by the characteristics of Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria, as it is a common skin commensal that can cause infections in immunocompromised individuals. Staphylococcus aureus (choice B) is catalase-positive and coagulase-positive. Streptococcus pyogenes (choice C) is catalase-negative. Enterococcus faecalis (choice D) is catalase-negative and not typically seen in clusters. Therefore, based on the given information, Staphylococcus epidermidis is the most likely causative agent.
You may also like to solve these questions
A fecal smear from a patient with severe diarrhea revealed motile Gram-negative rods with a comma shape. What is the likely causative agent?
- A. Vibrio cholerae
- B. Shigella dysenteriae
- C. Salmonella typhi
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium is the likely causative agent because it is known to cause severe diarrhea, and it is characterized by its motile, comma-shaped Gram-negative rods. Vibrio cholerae produces cholera toxin, leading to profuse watery diarrhea. Shigella dysenteriae causes dysentery with bloody diarrhea, Salmonella typhi causes typhoid fever, and Escherichia coli can cause various types of diarrhea but typically does not have a comma shape.
The presence of specific antibodies in the reaction inhibition of hemagglutination is visualized by the;
- A. Absence of hemolysis
- B. Absence of hemagglutination
- C. Presence of hemagglutination
- D. Presence of hemolysis
Correct Answer: B
Rationale: The correct answer is B: Absence of hemagglutination. In the reaction inhibition of hemagglutination, specific antibodies bind to antigens on red blood cells, preventing their agglutination. This results in the absence of visible clumping of red blood cells, which is known as hemagglutination. Therefore, the presence of specific antibodies is visualized by the absence of hemagglutination.
Incorrect Choices:
A: Absence of hemolysis - Hemolysis refers to the rupture of red blood cells, which is not relevant in the context of hemagglutination.
C: Presence of hemagglutination - This is the opposite of what is expected when specific antibodies are present and inhibiting hemagglutination.
D: Presence of hemolysis - Again, hemolysis is not directly related to the inhibition of hemagglutination by specific antibodies.
The establishment and further spreading of an infectious disease within a new population is a process called:
- A. emergence
- B. adoption
- C. inclusion
- D. appearance
Correct Answer: A
Rationale: The correct answer is A: emergence. The term emergence refers to the process of a new infectious disease appearing and spreading within a population. It signifies the initial introduction and establishment of the disease in the new population.
Explanation for other choices:
B: Adoption does not accurately describe the process of a disease spreading within a new population.
C: Inclusion is not a term commonly used to describe the spread of infectious diseases.
D: Appearance is too vague and does not capture the complexity of the process of establishment and spreading of an infectious disease.
There is/are __________ level(s) of biosafety depending on the organisms handled.
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: D
Rationale: The correct answer is D (4) because biosafety levels range from 1 to 4, each corresponding to the level of containment required when handling different types of organisms. BSL-1 is for low-risk agents, while BSL-4 is for dangerous pathogens. Choice A (1) is incorrect as there are multiple levels, not just one. Choice B (2) and C (3) are incorrect as they do not account for all the levels of biosafety required for handling various organisms. Therefore, D is the correct answer as it encompasses the full range of biosafety levels.
What type of immune reaction is most common in identification of vibrio cholerae
- A. Agglutination
- B. Precipitation
- C. Western blot
- D. ELISA
Correct Answer: A
Rationale: The correct answer is A: Agglutination. Agglutination is commonly used to identify Vibrio cholerae by clumping together the bacteria with specific antibodies. This reaction occurs when antibodies bind to antigens on the bacterial surface, leading to visible clumps. In contrast, Precipitation, Western blot, and ELISA are not typically used to identify Vibrio cholerae. Precipitation involves antigen-antibody complexes becoming insoluble, Western blot is used for protein detection, and ELISA is commonly used for detecting specific antigens or antibodies in a sample. Agglutination is the most appropriate choice for identifying Vibrio cholerae due to its specific interaction with the bacteria's surface antigens.