Nokea
The causative agent of the disease gas gangrene Clostridium perfringens is:
- A. Gram-negative rod-shaped bacteria, fixed with capsule
- B. Gram-negative rod-shaped bacterium, motile, peritrichous without capsule
- C. Gram-positive rod-shaped bacterium, motile, peritrichous without capsule
- D. Gram-positive rod-shaped bacterium non-motile, with capsule
Correct Answer: C
Rationale: The correct answer is C because Clostridium perfringens is a Gram-positive rod-shaped bacterium, which matches the description provided. It is motile and peritrichous (having flagella all over the surface) without a capsule. This bacterium is known to cause gas gangrene due to its ability to produce toxins that destroy tissue.
Choice A is incorrect because Clostridium perfringens is Gram-positive, not Gram-negative, and it does not have a capsule. Choice B is incorrect because Clostridium perfringens is not motile and does not have flagella all over its surface. Choice D is incorrect because Clostridium perfringens is Gram-positive, not Gram-negative, and it is motile without a capsule.
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Penicillin-resistant, beta-lactamase-producing strains must be detected..
- A. After antibiotic therapy is begun
- B. Before antibiotic therapy is begun
- C. During the antibiotic therapy
- D. No importance for the time of detection
Correct Answer: B
Rationale: The correct answer is B: Before antibiotic therapy is begun. Detecting penicillin-resistant, beta-lactamase-producing strains before antibiotic therapy is crucial to ensure proper treatment. If detected after therapy (choice A), it may lead to treatment failure. Detection during therapy (choice C) may result in delayed or ineffective treatment. Choice D is incorrect as early detection is essential for successful management.
A 34 year old male patient consulted a doctor about face carbuncle. Objectively: a loose, painless edema of hypodermic tissue; black crust in the center of carbuncle, vesicular rash around it. Microbiological examination revealed static streptobacilli capable of capsule building. What microorganisms are the causative agents of this disease?
- A. Bacillus antracis
- B. Staptylococcus aureus
- C. Bacillus subtilis
- D. Bacillus anthracoides
Correct Answer: B
Rationale: The correct answer is B: Staphylococcus aureus. This bacterium is a common causative agent of skin infections like carbuncles. Staphylococcus aureus is known for its ability to produce pus-filled abscesses, which aligns with the symptoms described in the question. The presence of a vesicular rash around the carbuncle further supports this diagnosis, as Staphylococcus aureus can cause skin lesions. The other choices are not correct because:
A: Bacillus anthracis causes anthrax, which presents with different symptoms such as fever, malaise, and respiratory symptoms.
C: Bacillus subtilis is a harmless soil bacterium commonly used in research and not known to cause skin infections.
D: Bacillus anthracoides is not a known pathogen and is not associated with human infections.
Typhoid fever is caused by the bacterium:
- A. Escherichia coli
- B. Salmonella enterica
- C. Shigella flexneri
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B: Salmonella enterica. Typhoid fever is caused by the bacterium Salmonella enterica serotype Typhi. This specific strain of Salmonella is responsible for typhoid fever, a serious illness characterized by high fever, abdominal pain, and diarrhea. Escherichia coli (choice A) is not the causative agent of typhoid fever. Shigella flexneri (choice C) causes bacillary dysentery, not typhoid fever. Staphylococcus aureus (choice D) can cause food poisoning but is not associated with typhoid fever.
Treponemae are motile because of:
- A. axial filaments
- B. mans peritrichous filaments
- C. single monotrichous filament
- D. fimbriae
Correct Answer: A
Rationale: The correct answer is A: axial filaments. Treponemae are motile due to their unique structure of axial filaments, also known as endoflagella. These axial filaments are located within the periplasmic space of the organism and are responsible for the corkscrew-like motility of Treponemae. The other choices (B: mans peritrichous filaments, C: single monotrichous filament, D: fimbriae) do not play a role in the motility of Treponemae. Peritrichous filaments and single monotrichous filaments are not present in Treponemae, and fimbriae are primarily involved in adhesion rather than motility.
Microscopy of a wound abscess revealed Gram-negative rods producing blue-green pigment with a distinctive odor of jasmine. What is the likely causative agent?
- A. Pseudomonas aeruginosa
- B. Proteus vulgaris
- C. Escherichia coli
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (B) and Klebsiella pneumoniae (D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (C) typically does not produce blue-green pigment or have a jasmine-like odor.