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A fecal sample cultured on Endo agar revealed colorless colonies. The bacteria were Gram-negative rods and lactose non-fermenters. What microorganism is most likely?
- A. Salmonella
- B. Escherichia coli
- C. Shigella
- D. Proteus
Correct Answer: C
Rationale: The correct answer is Shigella (Choice C) because it matches the description of being Gram-negative rods and lactose non-fermenters. Shigella is a non-lactose fermenting, Gram-negative rod that typically produces colorless colonies on Endo agar. Salmonella (Choice A) and Escherichia coli (Choice B) are both lactose fermenters and would produce pink colonies on Endo agar. Proteus (Choice D) is also a lactose fermenter and would appear pink on Endo agar. Therefore, based on the characteristics provided, Shigella is the most likely microorganism in this scenario.
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A female patient has symptoms of inflammation of urogenital tracts. A smear from the vaginal mucous membrane contained big unicellular pyriform organisms with a sharp spike on the back end of their bodies; big nucleus and undulating membrane. What protozoa were revealed in the smear?
- A. Trichomonas vaginalis
- B. Trichomonas hominis
- C. Trichomonas buccalis
- D. Trypanosoma gambiense
Correct Answer: A
Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a protozoan parasite that causes trichomoniasis, a sexually transmitted infection characterized by inflammation of urogenital tracts. The description of big unicellular pyriform organisms with a sharp spike on the back end of their bodies, big nucleus, and undulating membrane matches the morphology of Trichomonas vaginalis. Trichomonas hominis and Trichomonas buccalis are different species that do not cause urogenital infections. Trypanosoma gambiense is a protozoan parasite causing African trypanosomiasis and does not match the described morphology or symptoms.
Etiological cause of bacteremia could be:
- A. S.epidermidis, E.coli, S. aureus
- B. P.aeruginosa, K. pneumoniae, E.coli
- C. Resident skin diphtheroids
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because bacteremia can be caused by a variety of bacteria including S.epidermidis, E.coli, S.aureus, P.aeruginosa, K.pneumoniae, and resident skin diphtheroids. Bacteremia refers to the presence of bacteria in the bloodstream, which can occur due to infections from various sources. Choices A and B include common bacteria known to cause bacteremia, while choice C refers to resident skin diphtheroids that can also enter the bloodstream under certain conditions. Therefore, the correct answer is D as it encompasses all the possible etiological causes of bacteremia.
Growth of bacteria is a result of:
- A. Air consumption
- B. Water adsorption
- C. Enzyme production
- D. Radio isotopes
Correct Answer: B
Rationale: The growth of bacteria is a result of water adsorption because water is essential for various metabolic processes within the bacterial cells, such as nutrient uptake, energy production, and waste removal. Water serves as a medium for chemical reactions to occur and provides structural support to the bacteria. Without sufficient water, bacteria cannot thrive and reproduce.
A: Air consumption is incorrect because while bacteria may require oxygen for respiration, it is not the primary factor for their growth.
C: Enzyme production is incorrect because enzymes are important for various cellular functions but do not directly influence bacterial growth.
D: Radio isotopes are incorrect as they are not essential for bacterial growth and can even be harmful to bacterial cells.
A child with a persistent sore throat and fever had a smear from the throat revealing rod-shaped bacteria with dark blue polar granules. What is the likely causative agent?
- A. Corynebacterium diphtheriae
- B. Streptococcus pyogenes
- C. Haemophilus influenzae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Corynebacterium diphtheriae. The presence of rod-shaped bacteria with dark blue polar granules suggests the presence of Corynebacterium diphtheriae, the causative agent of diphtheria. This bacterium is known for causing sore throat and fever, and the characteristic appearance on smear helps identify it. Streptococcus pyogenes (Choice B) typically appears as chains of cocci and is associated with strep throat. Haemophilus influenzae (Choice C) is a small, pleomorphic Gram-negative coccobacillus and is more commonly associated with respiratory infections. Klebsiella pneumoniae (Choice D) is a Gram-negative bacillus and is not typically associated with sore throat and fever in children.
The fluidlike portion of a cell is referred to as:
- A. cytosol
- B. nucleoplasm
- C. cytoplasmic membrane
- D. inclusion
Correct Answer: C
Rationale: The correct answer is C: cytoplasmic membrane. The cytoplasmic membrane is the fluidlike portion of a cell that separates the cell's contents from the external environment. It regulates the passage of substances in and out of the cell, maintains cell shape, and provides protection.
Rationale:
1. Cytosol (choice A) is the liquid component of the cytoplasm where organelles are suspended, not the fluidlike portion of the cell.
2. Nucleoplasm (choice B) refers to the liquid component of the nucleus, not the entire cell.
3. Inclusion (choice D) refers to non-living substances within the cell that are not considered the fluidlike portion.
Summary:
The cytoplasmic membrane is the correct answer as it encompasses the entire cell and is responsible for maintaining cell integrity and regulating transport. Choices A, B, and D are incorrect as they do not represent the fluidlike portion of the cell.