Nokea
Routes for transmission of nosocomial infections are
- A. air droplets and fecal-oral mechanism
- B. air droplets and contact mechanism
- C. parenteral mechanism
- D. all are correct
Correct Answer: D
Rationale: The correct answer is D because nosocomial infections can be transmitted through various routes, including air droplets, fecal-oral mechanism, contact mechanism, and parenteral mechanism. Air droplets can carry infectious agents through the air, while contact with contaminated surfaces or individuals can spread infections. Fecal-oral transmission occurs through ingesting contaminated food or water. Parenteral transmission involves the introduction of pathogens directly into the bloodstream. Therefore, all the options listed in D are correct routes for transmission of nosocomial infections. Choices A, B, and C are incorrect because they do not encompass all possible routes of transmission for nosocomial infections.
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After a prolonged isoniazid treatment, the patient developed polyneuritis, paresthesia, memory disorders, and convulsions. What is the most likely mechanism of the described isoniazid side-effects?
- A. Disruption of cell membrane synthesis
- B. Inhibition of protein synthesis
- C. Inhibition of RNA-synthesis
- D. Inhibition of pyridoxal phosphate synthesis
Correct Answer: D
Rationale: The correct answer is D. Isoniazid inhibits pyridoxal phosphate synthesis, which is the active form of vitamin B6. Pyridoxal phosphate is essential for various enzymatic reactions, including neurotransmitter synthesis and myelin formation. Therefore, isoniazid-induced pyridoxal phosphate deficiency can lead to neurological symptoms like polyneuritis, paresthesia, memory disorders, and convulsions.
A: Disruption of cell membrane synthesis - This is not the mechanism of isoniazid side-effects.
B: Inhibition of protein synthesis - Isoniazid does not directly inhibit protein synthesis.
C: Inhibition of RNA-synthesis - Isoniazid does not inhibit RNA synthesis; it affects vitamin B6 metabolism.
The generation time of bacteria refers to:
- A. The time for DNA replication
- B. The time for a cell to divide and double in number
- C. The time for spore formation
- D. The time for toxin production
Correct Answer: B
Rationale: The correct answer is B: The generation time of bacteria refers to the time for a cell to divide and double in number. This is because the generation time is the period required for one bacterial cell to undergo binary fission and divide into two identical daughter cells. This process involves DNA replication, followed by cell division, resulting in an increase in the number of bacterial cells.
Incorrect choices:
A: The time for DNA replication - While DNA replication is a crucial part of bacterial growth and reproduction, it does not solely define the generation time.
C: The time for spore formation - Spore formation is a specific process in certain bacteria and is not synonymous with the generation time.
D: The time for toxin production - Toxin production is an independent process in bacteria and does not directly relate to the generation time.
A child with diarrhea had stool microscopy revealing cysts with four nuclei. What is the most likely causative agent?
- A. Entamoeba histolytica
- B. Giardia lamblia
- C. Balantidium coli
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This pathogen is known to cause amoebic dysentery, characterized by diarrhea with bloody or mucoid stools. The presence of cysts with four nuclei in the stool microscopy is a characteristic feature of Entamoeba histolytica. Other choices are incorrect because Giardia lamblia typically presents with binucleate cysts, Balantidium coli is a ciliated protozoan, and Trichomonas hominis is a non-pathogenic parasite found in the human intestine.
Bacteria that grow best in high temperatures are called:
- A. Mesophiles
- B. Psychrophiles
- C. Thermophiles
- D. Halophiles
Correct Answer: C
Rationale: The correct answer is C: Thermophiles. Thermophiles are bacteria that thrive in high temperatures, typically between 45-80 degrees Celsius. They have adapted to extreme heat environments and have enzymes that function optimally at high temperatures. Mesophiles (A) grow best at moderate temperatures, Psychrophiles (B) thrive in cold temperatures, and Halophiles (D) thrive in high salt concentrations. Therefore, only Thermophiles are specifically adapted to high temperatures, making it the correct choice.
Which of the following bacteria is capable of forming spores to survive in extreme conditions?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Escherichia coli
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B: Clostridium botulinum. This bacterium is capable of forming spores as a survival mechanism in harsh conditions. Spore formation allows it to remain dormant until conditions become favorable for growth again. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores and rely on other mechanisms for survival. Staphylococcus aureus is a common skin bacterium, Escherichia coli is a gut bacterium, and Neisseria gonorrhoeae is a sexually transmitted bacterium.