Nokea
Salmonellosis is caused by:
- A. Salmonella typhi
- B. Salmonella enteritidis
- C. Shigella flexneri
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Salmonella enteritidis. Salmonellosis is typically caused by Salmonella species, with Salmonella enteritidis being one of the common culprits. Salmonella typhi causes typhoid fever, not salmonellosis. Shigella flexneri is responsible for causing shigellosis, a different bacterial infection. Choosing "None of the above" is incorrect as Salmonella enteritidis is a known cause of salmonellosis.
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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.
Which type of bacteria are capable of surviving in high salt concentrations?
- A. Acidophiles
- B. Thermophiles
- C. Halophiles
- D. Mesophiles
Correct Answer: C
Rationale: Correct Answer: C: Halophiles
Rationale:
1. Halophiles are bacteria adapted to high salt environments.
2. They have specific mechanisms to tolerate high salt concentrations.
3. Acidophiles thrive in acidic conditions.
4. Thermophiles prefer high temperature environments.
5. Mesophiles grow best at moderate temperatures.
A 25-year-old patient reports pain, burning at urination and scarce secretion in the morning. Urine samples are taken and cultivated on blood and MacConkey agar. After 24 hours of incubation, the culture are sterile. Which one of the following bacteria is the most probable cause of this disease?
- A. Escherichia coli
- B. Chlamydia trachomatis
- C. Streptococcus pneumoniae
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B: Chlamydia trachomatis. This is because Chlamydia trachomatis is an obligate intracellular bacterium that cannot be cultured on standard agar plates. The symptoms described by the patient, such as pain, burning at urination, and scarce secretion in the morning, are indicative of a possible chlamydial infection. Additionally, the fact that the urine cultures are sterile after 24 hours of incubation suggests that the causative agent is not a typical bacteria like Escherichia coli, Streptococcus pneumoniae, or Neisseria gonorrhoeae, which would normally grow on agar plates. Therefore, Chlamydia trachomatis is the most probable cause of this disease.
Summary:
A: Escherichia coli - Incorrect, as it is a common cause of urinary tract infections and would typically grow on agar plates.
C: Streptococcus pneumoniae - Incorrect, as it is
The organism that is responsible for the vast majority of cases of fungal vaginitis is:
- A. Escherichia coli
- B. Streptococcus agalactiae
- C. Klebsiella oxytoca
- D. Propionibacterium acnes
Correct Answer: D
Rationale: The correct answer is D: Propionibacterium acnes. This bacterium is not a fungus, but a common skin bacteria. Fungal vaginitis is typically caused by Candida albicans or other fungal species, not by bacteria like Escherichia coli, Streptococcus agalactiae, or Klebsiella oxytoca. Propionibacterium acnes is not associated with vaginal infections, making it the correct answer in this context.
The cell envelope of Gram-negative bacteria is composed of:
- A. Cytoplasmic membrane, a peptidoglycan layer and an outer membrane
- B. Cytoplasmic membrane and peptidoglycan layer
- C. Only peptidoglycan layer
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because Gram-negative bacteria have a unique cell envelope structure consisting of a cytoplasmic membrane, a peptidoglycan layer, and an outer membrane. The cytoplasmic membrane is the innermost layer that separates the cytoplasm from the external environment. The peptidoglycan layer provides structural support to the cell. The outer membrane acts as an additional protective barrier and contains lipopolysaccharides. Choice B is incorrect because Gram-negative bacteria have an outer membrane in addition to the cytoplasmic membrane and peptidoglycan layer. Choice C is incorrect because Gram-negative bacteria have more than just a peptidoglycan layer in their cell envelope. Choice D is incorrect as the cell envelope of Gram-negative bacteria does have specific components.