Nokea
A bacterial colony is:
- A. Visible formation, formed by clustering of cells, belonging to different bacterial species
- B. Formed only on a liquid nutrient medium
- C. Both are incorrect
- D. None of the above
Correct Answer: A
Rationale: Step 1: A bacterial colony is a visible formation: Correct as colonies are visible to the naked eye.
Step 2: Formed by clustering of cells: Correct as colonies are made up of numerous bacterial cells.
Step 3: Belonging to different bacterial species: Correct as colonies can consist of one or multiple species.
Summary:
Choice A is correct as it accurately describes a bacterial colony. Choice B is incorrect as colonies can also form on solid nutrient mediums. Choice C is incorrect as choice A is correct. Choice D is incorrect as there is a correct option provided.
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A wound infection culture 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 most likely causative agent in this case is Staphylococcus epidermidis. This conclusion can be drawn based on the characteristics provided: Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria.
Explanation of other choices:
- Staphylococcus aureus: Typically coagulase-positive, so it does not match the characteristics given.
- Streptococcus pyogenes: Gram-positive cocci in chains, not clusters. Also, it is catalase-negative.
- Enterococcus faecalis: Gram-positive cocci in pairs or chains, not clusters. Additionally, it is catalase-negative.
Therefore, Staphylococcus epidermidis is the most likely causative agent based on the provided characteristics.
Which of the following bacteria is associated with foodborne illnesses?
- A. Clostridium botulinum
- B. Salmonella enterica
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D (All of the above) because all three bacteria mentioned (Clostridium botulinum, Salmonella enterica, Escherichia coli) are associated with foodborne illnesses. Clostridium botulinum causes botulism, Salmonella enterica causes salmonellosis, and Escherichia coli can cause food poisoning. Each of these bacteria can contaminate food and lead to illnesses when consumed. Therefore, selecting all of the above is the correct choice. The other choices (A, B, C) are incorrect because each of those bacteria individually is associated with foodborne illnesses.
The most common cause of cystitis (after Escherichia coli) in healthy sexually active women is:
- A. Staphylococcus saprophyticus
- B. Proteus mirabilis
- C. Pseudomonas aeruginosa
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus saprophyticus. This bacterium is the second most common cause of cystitis in healthy sexually active women after E. coli. Staphylococcus saprophyticus is commonly found in the gastrointestinal and genital areas. It has a unique ability to adhere to uroepithelial cells, making it a common pathogen in urinary tract infections. Proteus mirabilis is more commonly associated with complicated UTIs, especially in catheterized patients. Pseudomonas aeruginosa is more commonly seen in hospitalized or immunocompromised patients. Klebsiella pneumoniae is typically associated with UTIs in elderly patients or those with structural abnormalities in the urinary tract.
When microorganisms enter the circulatory system through the lymphatic drainage and cause an infection, the condition is called:
- A. bacteremia
- B. septicemia
- C. microbemia
- D. viremia
Correct Answer: C
Rationale: The correct answer is C: microbemia. When microorganisms enter the circulatory system via the lymphatic drainage, the condition is specifically termed microbemia. This term focuses on the presence of microorganisms in the bloodstream.
Rationale:
1. Bacteremia (choice A) refers to the presence of bacteria in the bloodstream, not specifically microorganisms as a whole.
2. Septicemia (choice B) is a severe infection causing systemic inflammation due to the presence of pathogens or their toxins in the blood, not limited to microorganisms entering via lymphatic drainage.
3. Viremia (choice D) is the presence of viruses in the bloodstream, not a term used for microorganisms entering through the lymphatic drainage.
In summary, the term microbemia accurately describes the scenario of microorganisms entering the circulatory system through lymphatic drainage, making it the correct choice over the other options.
Genus Rickettsia representatives are characterized by:
- A. Gram-positive cell wall
- B. High resistance to external environment factors
- C. Intracellular parasitism
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Intracellular parasitism. Genus Rickettsia representatives are known for their ability to live and replicate inside the host's cells, making them obligate intracellular parasites. This characteristic distinguishes them from other bacteria.
A: Gram-positive cell wall is incorrect because Rickettsia have a gram-negative cell wall.
B: High resistance to external environment factors is incorrect because Rickettsia are sensitive to environmental conditions and require specific host cells for survival.
D: None of the above is incorrect because Rickettsia do exhibit the characteristic of intracellular parasitism.