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Which one of the following statements about Campylobacter fetus is NOT CORRECT?
- A. Gram-positive rod-shaped bacterium
- B. Optimal temperature for cultivation 35-37C
- C. Opportunistic pathogen causes infections usually in newborns, immunocompromised patients and cancer
- D. Fastidious, microaerophile
Correct Answer: A
Rationale: The correct answer is A: Gram-positive rod-shaped bacterium. Campylobacter fetus is actually a Gram-negative bacterium. This is because it has a thin peptidoglycan layer in its cell wall, which does not retain the crystal violet stain used in the Gram-staining technique. It appears red or pink under a microscope after counterstaining with safranin. Therefore, statement A is incorrect.
B: Optimal temperature for cultivation 35-37C - Correct, as Campylobacter fetus thrives at this temperature range.
C: Opportunistic pathogen causes infections usually in newborns, immunocompromised patients, and cancer - Correct, as Campylobacter fetus can cause infections in these populations.
D: Fastidious, microaerophile - Correct, as Campylobacter fetus is fastidious and requires specific growth conditions, including low oxygen levels.
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The bacteria that causes whooping cough is:
- A. Bordetella pertussis
- B. Haemophilus influenzae
- C. Pseudomonas aeruginosa
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Whooping cough is caused by this bacteria, which specifically infects the respiratory tract. Bordetella pertussis produces toxins that lead to the characteristic symptoms of the disease. Haemophilus influenzae, Pseudomonas aeruginosa, and Streptococcus pneumoniae are not the causative agents of whooping cough. Haemophilus influenzae can cause respiratory infections, Pseudomonas aeruginosa is associated with hospital-acquired infections, and Streptococcus pneumoniae is a common cause of pneumonia and other respiratory infections, but none of these bacteria are responsible for whooping cough.
Differentiating media are:
- A. Lowenstein-Jensen and Petraniani
- B. Apoholate-citrate aga and Brilliant-green phenol-red Lactose Agar
- C. Endo, Gassner and Levin
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because Endo, Gassner, and Levin are all examples of differential media used in microbiology. These media contain specific components that allow for the differentiation of different types of microorganisms based on their metabolic characteristics or biochemical reactions. Lowenstein-Jensen and Petraniani (choice A) are selective media for mycobacteria, not differential. Apoholate-citrate agar and Brilliant-green phenol-red Lactose agar (choice B) are selective media for Salmonella and E. coli, respectively, not differential. Therefore, the correct choice is C as it includes examples of differential media commonly used for microbial identification.
All is true for bacterial spores EXCEPT:
- A. They can deform the cell or not
- B. They can be terminal, subterminal and central
- C. They are used for cell division
- D. They are formed for 6-8h
Correct Answer: C
Rationale: The correct answer is C. Bacterial spores are NOT used for cell division. Bacterial spores are dormant, resistant forms of bacteria that are formed in response to harsh environmental conditions. They are not involved in cell division but rather serve as a survival mechanism for the bacteria.
A: They can deform the cell or not - This is true. Bacterial spores can deform the cell or not depending on the conditions.
B: They can be terminal, subterminal, and central - This is true. Bacterial spores can be located at different positions within the bacterial cell.
D: They are formed for 6-8h - This is incorrect. The formation of bacterial spores can take variable time periods depending on the species and environmental conditions.
Which of the following infections are typical for the upper respiratory tract?
- A. Psittacosis
- B. Mycoplasma bronchitis
- C. Chronic atrophic rhinitis
- D. Legionnaires disease
Correct Answer: C
Rationale: The correct answer is C: Chronic atrophic rhinitis. This infection is typical for the upper respiratory tract as it affects the nasal mucosa and sinuses. It is characterized by inflammation and atrophy of the nasal mucosa. Psittacosis (A) is a zoonotic infection transmitted from birds, affecting the lungs. Mycoplasma bronchitis (B) is a lower respiratory tract infection caused by Mycoplasma pneumoniae. Legionnaires disease (D) is a severe form of pneumonia caused by Legionella bacteria. Therefore, C is the correct answer as it specifically pertains to the upper respiratory tract.
Virulence
- A. Is the degree of pathogenicity
- B. Of the microorganism is not a constant characteristic
- C. Can be measured with LD50
- D. All the answers are true
Correct Answer: D
Rationale: The correct answer is D because virulence refers to the degree of pathogenicity of a microorganism, which can vary and is not a constant characteristic. It can be measured using LD50, which is the lethal dose that kills 50% of the test population. Therefore, all the statements in options A, B, and C are true and collectively provide a comprehensive understanding of virulence.