Nokea
When using gram staining method fungi stain:
- A. Blue-purple
- B. Red
- C. Silver
- D. Do not stain
Correct Answer: D
Rationale: The correct answer is D: Fungi do not stain in the gram staining method because they have a unique cell wall composition different from bacteria. Fungi have chitin in their cell walls, which is not easily stained by the gram staining process. This method primarily targets the peptidoglycan layer present in bacterial cell walls. Therefore, fungi will not take up the stain and will remain colorless. The other choices (A: Blue-purple, B: Red, C: Silver) are incorrect because they describe colors that are associated with staining results for bacteria, not fungi.
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Allergy to penicillin is an example of:
- A. Type I hypersensitivity reaction
- B. Type II hypersensitivity reaction
- C. Type III hypersensitivity reaction
- D. Type IV hypersensitivity reaction
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Penicillin allergy involves IgE antibodies binding to penicillin.
2. This triggers mast cell degranulation, releasing histamine.
3. Histamine causes allergic symptoms like rash, swelling.
4. This immune response characterizes Type I hypersensitivity reactions.
Summary of other choices:
B: Type II reactions involve antibody-mediated cell destruction, not seen in penicillin allergy.
C: Type III reactions involve immune complex deposition, not typical in penicillin allergy.
D: Type IV reactions are delayed hypersensitivity reactions, not immediate like penicillin allergy.
During sanitary and bacteriological testing of water with the membrane filter technique there were revealed two red colonies on a membrane filter (Endo agar) through which 500 ml of water was filtred. Calculate the coli index and coli titer of the analyzed water:
- A. 4 and 250
- B. 2 and 500
- C. 250 and 4
- D. 500 and 2
Correct Answer: C
Rationale: The correct answer is C (coli index of 250 and coli titer of 4). The coli index is calculated by multiplying the number of colonies by the reciprocal of the volume filtered, which gives 2 colonies x (1/0.5 L) = 4. The coli titer is obtained by dividing the volume filtered by the number of colonies, which gives 0.5 L / 2 colonies = 0.25 L or 250 ml. This indicates the concentration of coliform bacteria in the water sample.
Choice A (4 and 250) is incorrect because it has the correct coli index but the values are reversed for coli index and coli titer. Choice B (2 and 500) is incorrect as it provides the correct coli titer value but the values are reversed for coli index and coli titer. Choice D (500 and 2) is incorrect because it reverses the values for both coli index and coli titer.
After consumption some tinned meat a patient had diplopia, acute headache, deglutition disorder, hard breathing, muscle weakness. The diagnosis was botulism. What factor of pathogenicity are the clinic presentations of this disease connected with?
- A. Exotoxin B.Hemolysin C.Endotoxin D.Plasmocoagulase E.Fibrinolysin
Correct Answer: A
Rationale: The correct answer is A, Exotoxin. Botulism is caused by the exotoxin produced by Clostridium botulinum bacteria. The symptoms described - diplopia, acute headache, deglutition disorder, hard breathing, muscle weakness - are all consistent with botulism due to the neurotoxic effects of the exotoxin. The exotoxin interferes with neurotransmission at the neuromuscular junction, leading to muscle paralysis and the symptoms mentioned. The other choices (B, C, D, E) are incorrect as they do not correspond to the pathogenic mechanism of botulism and do not explain the specific clinical manifestations observed in this case.
A 60-year-old patient was hospitalized to the surgical department because of infection caused by blue pus bacillus (Pseudomonas aeruginosa) which is sensative to penicillin antibiotics. Indicate which of the given penicillins has marked activity to the Pseudomonas aeruginosa?
- A. Carbenicillin disodium
- B. Benzylpenicillin
- C. Methicillin
- D. Oxacillin
Correct Answer: A
Rationale: The correct answer is A: Carbenicillin disodium. Carbenicillin is a semisynthetic penicillin that has marked activity against Pseudomonas aeruginosa. This is due to its extended spectrum of activity and increased stability against beta-lactamases produced by Pseudomonas aeruginosa. Carbenicillin is commonly used to treat infections caused by this bacterium.
Choice B: Benzylpenicillin (Penicillin G) has limited activity against Pseudomonas aeruginosa.
Choice C: Methicillin is not effective against Pseudomonas aeruginosa.
Choice D: Oxacillin also has limited activity against Pseudomonas aeruginosa.
In summary, Carbenicillin is the correct choice due to its marked activity against Pseudomonas aeruginosa compared to the other penicillins listed.
The causative agent of plague is:
- A. Bordetella pertussis
- B. Yersinia pestis
- C. Rickettsia prowazekii
- D. Treponema pallidum
Correct Answer: B
Rationale: The correct answer is B: Yersinia pestis. Y. pestis is the causative agent of plague, a serious infectious disease transmitted through fleas. It causes bubonic, pneumonic, and septicemic plague. Bordetella pertussis causes whooping cough, Rickettsia prowazekii causes epidemic typhus, and Treponema pallidum causes syphilis. Y. pestis is the correct answer because it is specifically associated with plague, making the other options incorrect.