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A sputum smear from a patient with pneumonia revealed Gram-positive cocci in pairs with pointed ends and capsules. What is the likely microorganism?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Klebsiella pneumoniae
- D. Neisseria meningitidis
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. The description of Gram-positive cocci in pairs with pointed ends and capsules matches the morphology of S. pneumoniae. This bacterium is known to cause pneumonia, especially in individuals with underlying conditions like COPD. Staphylococcus aureus (B) typically appears in clusters, not pairs. Klebsiella pneumoniae (C) is a Gram-negative rod, not a cocci. Neisseria meningitidis (D) is a Gram-negative diplococcus, not a cocci. Hence, based on the morphology and clinical context, Streptococcus pneumoniae is the likely microorganism causing pneumonia in this patient.
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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.
A patient's sputum was stained using Ziehl-Neelsen method, which revealed red-colored bacilli on a blue background. What structural component of the cell is responsible for this staining property?
- A. Mycolic acid
- B. Capsule
- C. Flagella
- D. Endospores
Correct Answer: A
Rationale: The correct answer is A: Mycolic acid. Ziehl-Neelsen method is used to stain acid-fast bacteria, such as Mycobacterium species. Mycolic acid in the cell wall of these bacteria resists decolorization, leading to red-colored bacilli on a blue background. Capsule, flagella, and endospores do not play a role in this staining property. Capsules are usually stained using special techniques, flagella are not typically visible with this stain, and endospores are stained using the Schaeffer-Fulton method.
A patient with a sore throat had a throat culture revealing Gram-positive cocci in chains. The bacteria were catalase-negative and beta-hemolytic on blood agar. What is the most likely causative agent?
- A. Streptococcus pyogenes
- B. Staphylococcus aureus
- C. Streptococcus pneumoniae
- D. Enterococcus faecalis
Correct Answer: A
Rationale: Step 1: Gram-positive cocci in chains suggest Streptococcus species.
Step 2: Catalase-negative eliminates Staphylococcus aureus.
Step 3: Beta-hemolytic on blood agar matches Streptococcus pyogenes.
Step 4: Streptococcus pyogenes is a common cause of sore throat (pharyngitis).
Summary:
A: Streptococcus pyogenes - Correct due to Gram-positive cocci in chains, catalase-negative, beta-hemolytic, and common cause of sore throat.
B: Staphylococcus aureus - Incorrect due to catalase-positive.
C: Streptococcus pneumoniae - Incorrect due to alpha-hemolytic.
D: Enterococcus faecalis - Incorrect due to not being beta-hemolytic.
The bacteriological laboratory needs to prepare for analysis of materials that are suspected to be contaminated with spores of anthrax causative agent. What diagnostic preparation allows for quick detection of these spores?
- A. Anti-anthrax fluorescent serum
- B. Standard anthrax antigen
- C. Anti-anthrax immunoglobulin
- D. Monoclonal antibodies to anthrax causative agent
Correct Answer: D
Rationale: The correct answer is D: Monoclonal antibodies to anthrax causative agent. Monoclonal antibodies are highly specific for detecting anthrax spores, providing quick and accurate results. They bind only to the anthrax causative agent, allowing for precise identification.
Choice A (Anti-anthrax fluorescent serum) is incorrect because it is not as specific and sensitive as monoclonal antibodies.
Choice B (Standard anthrax antigen) is incorrect as it is used to stimulate antibody production in the body, not for direct detection of spores.
Choice C (Anti-anthrax immunoglobulin) is incorrect as it is a general term for antibodies and may not be specific to anthrax spores.
In summary, monoclonal antibodies are the most suitable option for quick and accurate detection of anthrax spores due to their high specificity and sensitivity.
Name the halogen-containing antiseptic with fungicidal properties, which is used to treat dermatomycosis:
- A. Iodine solution
- B. Formalin solution
- C. Methylene blue
- D. Brilliant green
Correct Answer: A
Rationale: Rationale:
1. Iodine solution contains iodine, a halogen with antiseptic properties.
2. Iodine is effective against fungi, making it suitable for treating dermatomycosis.
3. Iodine solution is commonly used in dermatology for its fungicidal properties.
4. Formalin, methylene blue, and brilliant green do not contain halogens or have fungicidal properties.
Summary:
- Formalin is a disinfectant, not an antiseptic for dermatomycosis.
- Methylene blue is an antifungal dye, not used as an antiseptic.
- Brilliant green is an antiseptic, but does not contain halogens or have fungicidal properties.