Nokea
Which of the following is characteristic of Gram-negative bacteria?
- A. Thick peptidoglycan layer
- B. Outer membrane containing lipopolysaccharides
- C. Presence of teichoic acids
- D. Absence of a cell wall
Correct Answer: B
Rationale: The correct answer is B: Outer membrane containing lipopolysaccharides. Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which are important for protection and pathogenicity. This outer membrane is a unique feature of Gram-negative bacteria and is not present in Gram-positive bacteria, making it a key characteristic.
A: Incorrect because Gram-negative bacteria have a thin peptidoglycan layer compared to Gram-positive bacteria.
C: Incorrect because teichoic acids are a characteristic of Gram-positive bacteria, not Gram-negative bacteria.
D: Incorrect because all bacteria, including Gram-negative bacteria, have a cell wall.
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Which of the following diseases is considered to fall in the group II category?
- A. Anthrax
- B. Lyme disease
- C. Mumps
- D. Smallpox
Correct Answer: C
Rationale: The correct answer is C: Mumps. Group II diseases are vaccine-preventable diseases that are communicable and can cause outbreaks. Mumps fits this criteria as it is preventable through vaccination, easily transmitted through respiratory droplets, and can lead to outbreaks in communities. Anthrax (A) is a zoonotic disease, Lyme disease (B) is transmitted by ticks, and Smallpox (D) has been eradicated.
A patient with severe pneumonia had a sputum culture revealing Gram-negative rods that are non-lactose fermenters. What is the most likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Enterobacter cloacae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas aeruginosa is a common Gram-negative rod that is a non-lactose fermenter and a common cause of severe pneumonia, especially in immunocompromised individuals. It is also known for its resistance to many antibiotics, making it difficult to treat.
Summary of other choices:
B: Escherichia coli is a lactose fermenter and is not commonly associated with severe pneumonia.
C: Klebsiella pneumoniae is a lactose fermenter and is more commonly associated with pneumonia in alcoholics or debilitated patients.
D: Enterobacter cloacae is a lactose fermenter and is not a common cause of severe pneumonia.
Disinfection with chemicals acting on cell surface:
- A. Soaps
- B. Phenols
- C. Amines
- D. Polymyxin
Correct Answer: B
Rationale: The correct answer is B: Phenols. Phenols act on the cell surface by disrupting cell membranes and denaturing proteins, leading to cell death. Soaps (A) work by lifting dirt and microbes off surfaces, not directly acting on cell surfaces. Amines (C) are typically used as disinfectants targeting specific enzymes in microbes, not cell surfaces. Polymyxin (D) is an antibiotic that works by disrupting cell membranes internally, not on the cell surface.
Elementary and reticular bodies are morphological?
- A. Mycoplasma genitalium
- B. Chlamydia trachomatis
- C. Rickettsia prowazekii
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Chlamydia trachomatis. Elementary bodies (EBs) and reticular bodies (RBs) are two distinct forms of Chlamydia trachomatis, a bacterium causing various infections. EBs are the infectious form, while RBs are the replicative form within host cells. Mycoplasma genitalium (choice A) lacks a cell wall and does not have these specific morphological forms. Rickettsia prowazekii (choice C) is an obligate intracellular bacterium but does not exhibit the elementary and reticular body forms characteristic of Chlamydia trachomatis. Therefore, the correct answer is B, as only Chlamydia trachomatis exhibits the elementary and reticular bodies.
An 18-year-old patient has developed candidiasis after the case of pneumonia treated with β-lactam antibiotic. What antimycotic agent should be prescribed?
- A. Fluconazole
- B. Streptomycin
- C. Phthalylsulfathiazole
- D. Ampicillin
Correct Answer: A
Rationale: The correct answer is A: Fluconazole.
1. Fluconazole is an antifungal agent effective against Candida species commonly causing candidiasis.
2. Streptomycin (B) is an antibiotic used for bacterial infections, not fungal.
3. Phthalylsulfathiazole (C) is an antibacterial agent, not antifungal.
4. Ampicillin (D) is a β-lactam antibiotic, which can actually contribute to fungal infections like candidiasis.