Nokea
A persistent infection that is not lytic but productive is called a __________ infection.
- A. chronic
- B. latent
- C. slow
- D. transforming
Correct Answer: A
Rationale: The correct answer is A: chronic. A persistent infection that is not lytic but productive is characterized by ongoing viral replication without cell lysis. This type of infection is referred to as chronic, as it persists over an extended period. Latent infections involve periods of dormancy with intermittent reactivation. Slow infections typically have a prolonged incubation period before causing symptoms. Transforming infections lead to permanent alterations in host cell behavior. The key distinction for this question is the continuous viral replication without cell destruction, which aligns with the definition of a chronic infection.
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A Gram-negative bacterium producing a blue-green pigment and having a fruity odor was isolated from a patient's wound infection. What is the likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Proteus mirabilis
Correct Answer: A
Rationale: Step-by-step rationale:
1. Blue-green pigment + fruity odor are characteristic of Pseudomonas aeruginosa.
2. P. aeruginosa is a Gram-negative bacterium commonly associated with wound infections.
3. P. aeruginosa is known for its ability to produce pyocyanin (blue-green pigment) and a sweet, fruity odor.
4. Other choices like E. coli, K. pneumoniae, and P. mirabilis do not typically produce blue-green pigment or fruity odor.
5. Therefore, based on the characteristics observed, the likely causative agent is Pseudomonas aeruginosa.
Summary of other choices:
- Escherichia coli: Does not produce blue-green pigment or fruity odor.
- Klebsiella pneumoniae: Does not typically produce blue-green pigment or fruity odor.
- Proteus mirabilis: Does not produce blue-green pigment or fruity odor.
A 19 year old woman suffers from primary syphilis. Doctor administered her complex therapy that includes benzylpenicillin sodium salt. What is the mechanism of action of this drug?
- A. It blocks synthesis of peptidoglycan of microbial membrane
- B. It blocks synthesis of cytoplasm proteins
- C. It blocks thiol enzymes
- D. It blocks RNA synthesis
Correct Answer: A
Rationale: The correct answer is A. Benzylpenicillin sodium salt, also known as penicillin G, works by blocking the synthesis of peptidoglycan in the microbial cell wall. Peptidoglycan is crucial for the structural integrity of bacterial cell walls. By inhibiting its synthesis, penicillin disrupts the cell wall formation, leading to cell lysis and bacterial death. Choices B, C, and D are incorrect because penicillin does not target cytoplasm proteins, thiol enzymes, or RNA synthesis. Penicillin's primary mode of action is specifically related to interfering with bacterial cell wall synthesis.
OSHA is a division of the
- A. National Institutes of Health.
- B. Centers for Disease Control and Prevention.
- C. U.S. Department of Labor.
- D. World Health Organization.
Correct Answer: C
Rationale: 1. OSHA stands for Occupational Safety and Health Administration.
2. OSHA is responsible for ensuring safe and healthy working conditions in the US.
3. The U.S. Department of Labor oversees OSHA's operations and regulations.
4. Therefore, the correct answer is C, as OSHA is a division of the U.S. Department of Labor.
5. Other choices are incorrect because they are not directly related to OSHA's jurisdiction or responsibilities.
A Gram-stained smear from a wound revealed Gram-positive rods with terminal spores. The bacteria were anaerobic and produced gas. What is the most likely causative agent?
- A. Clostridium perfringens
- B. Bacillus anthracis
- C. Clostridium botulinum
- D. Clostridium tetani
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This bacterium is an anaerobic, Gram-positive rod that forms terminal spores and produces gas. It is commonly associated with wound infections and gas gangrene. Clostridium botulinum causes botulism and does not typically present with gas production. Bacillus anthracis is an aerobic, Gram-positive spore-forming bacterium causing anthrax. Clostridium tetani causes tetanus and does not produce gas. Thus, based on the characteristics described in the question, Clostridium perfringens is the most likely causative agent.
The key diagnostic feature of Corynebacterium diphtheriae is:
- A. formation of spores
- B. presence of metachromatic granules
- C. production of coagulase
- D. beta-hemolysis on blood agar
Correct Answer: B
Rationale: The correct answer is B: presence of metachromatic granules. This is because Corynebacterium diphtheriae is known for containing metachromatic granules, which are characteristic of this species. These granules can be observed under a microscope and aid in the identification of the bacteria.
Explanation of other choices:
A: formation of spores - Corynebacterium diphtheriae does not form spores. Spore formation is more commonly seen in bacteria such as Bacillus and Clostridium species.
C: production of coagulase - Coagulase production is a characteristic of Staphylococcus aureus, not Corynebacterium diphtheriae.
D: beta-hemolysis on blood agar - Corynebacterium diphtheriae does not exhibit beta-hemolysis on blood agar. This type of hemolysis is more typical of Streptococcus pyogenes.