Nokea
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.
You may also like to solve these questions
Which of the following bacteria is responsible for causing the disease known as pneumonia?
- A. Streptococcus pneumoniae
- B. Mycobacterium tuberculosis
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: Rationale:
1. Streptococcus pneumoniae is a common cause of bacterial pneumonia.
2. Mycobacterium tuberculosis can cause a type of pneumonia called tuberculosis.
3. Escherichia coli is not typically associated with pneumonia.
4. "All of the above" includes both Streptococcus pneumoniae and Mycobacterium tuberculosis, which are known to cause pneumonia. Therefore, D is the correct answer.
According to the location of flagella on their surface, bacteria can be:
- A. Monotrichous
- B. Amphitrichous
- C. Peritrichous
- D. All of these
Correct Answer: D
Rationale: The correct answer is D, "All of these." Monotrichous bacteria have a single flagellum at one end, amphitrichous have flagella at both ends, and peritrichous have flagella distributed all over the surface. The answer D is correct because it includes all these possibilities based on flagella location. Monotrichous is incorrect as it only refers to a single flagellum, amphitrichous is incorrect as it only refers to flagella at both ends, and peritrichous is incorrect as it only refers to flagella all over the surface. Therefore, the correct answer encompasses all these options.
The most commonly acquired laboratory infections are caused by
- A. bacteria.
- B. viruses.
- C. protozoans.
- D. prions.
Correct Answer: A
Rationale: The correct answer is A: bacteria. Bacteria are the most common cause of laboratory-acquired infections due to their ability to survive and multiply in various environments. They can easily contaminate lab equipment and surfaces, leading to infections if proper precautions are not taken. Viruses (choice B) are less common in laboratory-acquired infections as they require specific conditions to survive outside a host. Protozoans (choice C) are larger and less likely to be transmitted in a laboratory setting. Prions (choice D) are misfolded proteins and are not considered living organisms, making them an unlikely source of laboratory infections.
The Wasserman reaction is markedly positive (++++) in a 30-year-old man. What infectious disease is diagnosed using the Wasserman reaction?
- A. Brucellosis
- B. Syphilis
- C. Poliomyelitis
- D. Influenza
Correct Answer: B
Rationale: The correct answer is B: Syphilis. The Wasserman reaction is a test for syphilis, specifically for detecting antibodies against the bacterium Treponema pallidum. In a 30-year-old man with a markedly positive Wasserman reaction, it indicates an active syphilis infection. Brucellosis (Choice A) is not diagnosed using the Wasserman reaction. Poliomyelitis (Choice C) is a viral infection affecting the spinal cord, not diagnosed using the Wasserman reaction. Influenza (Choice D) is a respiratory viral infection, not associated with the Wasserman reaction.
The most common bacterial species in hospital environment is:
- A. Borrelia burgdorferi
- B. Staphylococcus aureus
- C. Bacillus cereus
- D. Staphylococcus haemolyticus
Correct Answer: B
Rationale: The correct answer is B: Staphylococcus aureus. This bacterium is commonly found in hospital environments due to its ability to colonize human skin and mucous membranes. It is a leading cause of hospital-acquired infections. Borrelia burgdorferi is mainly associated with Lyme disease transmitted by ticks, not commonly found in hospitals. Bacillus cereus is a foodborne pathogen, not typically prevalent in hospital settings. Staphylococcus haemolyticus is a coagulase-negative staphylococcus species, less pathogenic and less common in hospitals compared to Staphylococcus aureus.