Nokea
Which of the following bacteria are capable of surviving in low-oxygen environments?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: B
Rationale: The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both oxygen-rich and oxygen-poor environments by switching between aerobic and anaerobic metabolism. They have the flexibility to use oxygen if present but can also ferment in the absence of oxygen. Obligate anaerobes (A) cannot survive in the presence of oxygen, obligate aerobes (C) require oxygen for survival, and microaerophiles (D) require low levels of oxygen for growth, unlike facultative anaerobes.
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Which statement about the epidemiology and specific prophylactic of Haemophilus influenzae is NOT CORRECT?
- A. Non-encapsulated strains can be isolated from healthy carriers
- B. There is an effective killed vaccine, protective against all capsular types of Haemophilus spp.
- C. The infection is airborne
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B because there is no effective killed vaccine that is protective against all capsular types of Haemophilus spp. The Haemophilus influenzae vaccine primarily targets specific capsular types, not all of them. Choice A is incorrect because non-encapsulated strains can indeed be isolated from healthy carriers. Choice C is incorrect as Haemophilus influenzae is primarily transmitted through respiratory droplets, not through the air. Choice D is not correct because Choice B is indeed incorrect, making it the right answer.
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 responsible for causing peptic ulcers?
- A. Escherichia coli
- B. Helicobacter pylori
- C. Streptococcus pyogenes
- D. Mycobacterium tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is known to be the primary cause of peptic ulcers by colonizing the stomach lining and causing inflammation. It produces urease enzyme to neutralize stomach acid and has a flagellum for mobility. Escherichia coli (A) is mainly associated with foodborne illnesses. Streptococcus pyogenes (C) causes strep throat and skin infections. Mycobacterium tuberculosis (D) causes tuberculosis, a respiratory infection. Therefore, Helicobacter pylori is the correct choice for peptic ulcers based on its unique characteristics and pathogenicity.
Which is correct for bacterial growth?
- A. Most of the bacteria can grow in absence or in presence of oxygen
- B. All bacteria grow in absence of oxygen
- C. All bacteria are microaerophiles
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because most bacteria can grow in both the presence and absence of oxygen. Some bacteria are aerobic and require oxygen for growth, while others are anaerobic and can grow in the absence of oxygen. Choice B is incorrect because not all bacteria grow in the absence of oxygen. Choice C is incorrect because not all bacteria are microaerophiles, which are bacteria that require a low level of oxygen for growth. Choice D is incorrect because most bacteria exhibit flexibility in their oxygen requirements.
Which of the following viruses can cause hemorrhagic cystitis?
- A. BK virus
- B. Enteroviruses
- C. Flaviviruses
- D. Coronaviruses
Correct Answer: A
Rationale: The correct answer is A: BK virus. BK virus is a common cause of hemorrhagic cystitis, especially in immunocompromised individuals. It infects the urinary tract, leading to inflammation and bleeding in the bladder. Enteroviruses, Flaviviruses, and Coronaviruses do not typically cause hemorrhagic cystitis. Enteroviruses usually cause respiratory and gastrointestinal infections, Flaviviruses are commonly associated with diseases like dengue fever and Zika virus, and Coronaviruses are known for causing respiratory illnesses such as COVID-19. Hence, the correct answer is A as it is the only virus among the options known to cause hemorrhagic cystitis.