Nokea
The capsule of Bacillus anthracis is made of
- A. polysaccharide
- B. polypeptide
- C. lipids
- D. they do not form capsules
Correct Answer: B
Rationale: The capsule of Bacillus anthracis is made of polypeptide. This is because the capsule is composed of a protein-based material that surrounds the bacterium, providing protection and aiding in its virulence. Polysaccharides, lipids, and the absence of capsules are not characteristic of Bacillus anthracis' capsule structure, making choices A, C, and D incorrect, respectively.
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A blood culture from a patient with sepsis revealed Gram-negative diplococci. The bacteria were oxidase-positive and fermentative. What is the most likely causative agent?
- A. Neisseria meningitidis
- B. Neisseria gonorrhoeae
- C. Moraxella catarrhalis
- D. Haemophilus influenzae
Correct Answer: A
Rationale: The correct answer is A: Neisseria meningitidis. Step 1: Gram-negative diplococci - characteristic of Neisseria species. Step 2: Oxidase-positive - Neisseria species are oxidase-positive. Step 3: Fermentative - Neisseria meningitidis is a fermentative bacterium. Therefore, Neisseria meningitidis is the most likely causative agent.
Summary:
- B: Neisseria gonorrhoeae is also a Neisseria species but is not fermentative.
- C: Moraxella catarrhalis is oxidase-positive but not fermentative.
- D: Haemophilus influenzae is not a Neisseria species and is not typically fermentative.
A fecal sample from a patient with diarrhea was cultured on Endo agar, resulting in colorless colonies. The bacteria were Gram-negative rods. What microorganism is most likely?
- A. Salmonella
- B. Shigella
- C. Escherichia coli
- D. Proteus
Correct Answer: B
Rationale: The correct answer is B: Shigella. On Endo agar, Shigella appears as colorless colonies due to its inability to ferment lactose. Shigella is a Gram-negative rod and is a common cause of diarrhea. Salmonella (A) and Escherichia coli (C) would typically produce pink colonies on Endo agar as they can ferment lactose. Proteus (D) is not commonly associated with diarrhea and would not be expected to grow on Endo agar.
Almost half of all the STIs diagnosed in the United States are among:
- A. adolescents
- B. young adults
- C. young adults
- D. the elderly
Correct Answer: C
Rationale: The correct answer is C: young adults. Young adults are at a higher risk for sexually transmitted infections (STIs) due to factors such as engaging in risky sexual behaviors, lack of awareness, and inconsistent condom use. They are more likely to have multiple sexual partners and are less likely to seek regular STI screenings. Adolescents, while also at risk, may not make up almost half of all STI cases in the U.S. The elderly, on the other hand, are generally at a lower risk due to lower levels of sexual activity compared to young adults.
Which of the following bacteria produce exotoxins that cause severe gastrointestinal illness?
- A. Clostridium botulinum
- B. Vibrio cholerae
- 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 listed produce exotoxins that cause severe gastrointestinal illness. Clostridium botulinum produces botulinum toxin causing botulism. Vibrio cholerae produces cholera toxin leading to cholera. Escherichia coli can produce various exotoxins causing different types of severe gastrointestinal illnesses like E. coli O157:H7 causing bloody diarrhea. Therefore, all choices A, B, and C are correct in this case as they all produce exotoxins causing severe gastrointestinal illness.
Treponema pallidum and Borrelia burgdorferi belong to the group of:
- A. gram-negative aerobic rods and cocci
- B. anaerobic gram-negative rods
- C. anaerobic gram-negative cocci
- D. spirochetes
Correct Answer: D
Rationale: Step-by-step rationale:
1. Treponema pallidum and Borrelia burgdorferi are both spirochetes.
2. Spirochetes are characterized by their spiral shape and unique motility.
3. Both organisms exhibit corkscrew-like movement due to axial filaments.
4. Other choices are incorrect as Treponema and Borrelia are not gram-negative rods, cocci, or anaerobic cocci.
Summary:
The correct answer is D because Treponema pallidum and Borrelia burgdorferi are spirochetes, characterized by their spiral shape and motility. Other choices are incorrect as they do not accurately describe the characteristics of these organisms.