Gram-negative, capsulated bacteria with capsule, lactose-positive colonies. Isolated for the first time in pneumonia, but have more important role in urinary infections, otitis, meningitides, sepsis, nosocomial infections:
- A. Staphylococcus aureus
- B. Klebsiella pneumonia
- C. Streptococcus pneumoniae
- D. Mycobacterium tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Klebsiella pneumoniae. This bacterium is gram-negative, capsulated, and forms lactose-positive colonies. It was first isolated in pneumonia but is more commonly associated with urinary infections, otitis, meningitides, sepsis, and nosocomial infections. Klebsiella pneumoniae fits all the characteristics mentioned in the question, making it the correct choice.
Incorrect choices:
A: Staphylococcus aureus is gram-positive and does not have a capsule.
C: Streptococcus pneumoniae is also gram-positive and does not fit the description given.
D: Mycobacterium tuberculosis is an acid-fast bacterium associated with tuberculosis, but it is neither gram-negative nor lactose-positive.
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The enzyme required for replication of viral RNA is:
- A. Reverse transcriptase
- B. DNA polymerase
- C. RNA-dependent RNA polymerase
- D. Ligase
Correct Answer: C
Rationale: The correct answer is C: RNA-dependent RNA polymerase. This enzyme is required for replicating viral RNA due to its ability to catalyze the synthesis of RNA using an RNA template. Reverse transcriptase (A) is used to transcribe RNA into DNA, not replicate viral RNA. DNA polymerase (B) is used for replicating DNA, not RNA. Ligase (D) is involved in joining DNA fragments, not in replicating viral RNA. Therefore, RNA-dependent RNA polymerase is the only enzyme that specifically performs the function required for replicating viral RNA.
Which one is true about sexually transmitted infections?
- A. An example of sexually transmitted infection is the soft chancre
- B. Entry portal is only the mucus of the urogenital tract
- C. After the syphilis infection the developed immunity is life-lasting
- D. The sexually transmitted infections are typical for developing countries with low social status and low hygiene.
Correct Answer: A
Rationale: The correct answer is A because a soft chancre is a type of sexually transmitted infection caused by the bacterium Haemophilus ducreyi. It presents as a painless ulcer on the genitals. The other choices are incorrect. B is incorrect because STIs can enter the body through various routes, not only the urogenital tract mucosa. C is incorrect because immunity to syphilis is not lifelong; reinfection is possible. D is incorrect because STIs can occur in any country regardless of social status or hygiene levels.
At a bacteriological laboratory animal skins are analyzed by means of Ascoli precipitaion test. What is detected if the reaction is positive?
- A. Anthrax agent antigens
- B. Brucellosis agent
- C. Anaerobic infection toxin
- D. Plague agent
Correct Answer: A
Rationale: The Ascoli precipitation test is specifically used to detect anthrax agent antigens. The test involves mixing a patient's serum with a solution containing anthrax antigens, leading to precipitation if the antigens are present. Therefore, a positive reaction in this test indicates the presence of anthrax agent antigens. The other choices (B: Brucellosis agent, C: Anaerobic infection toxin, D: Plague agent) are incorrect because the Ascoli precipitation test is not designed to detect these specific agents or toxins.
In the South and Central America there can be found a species of trypanosomes that is the causative agent of Chagas disease. What animal is the infection carrier specific to this disease?
- A. Triatomine bug
- B. Mosquito
- C. Tsetse fly
- D. Cockroach
Correct Answer: A
Rationale: The correct answer is A: Triatomine bug. Triatomine bugs, also known as "kissing bugs," are the specific carrier of the trypanosomes that cause Chagas disease. These bugs transmit the parasite through their feces, which contain the infectious forms of the trypanosomes. When the bug bites a human or animal, it defecates near the bite wound, allowing the parasites to enter the bloodstream through the broken skin. Mosquitoes (B) transmit diseases like malaria and dengue fever, not Chagas disease. Tsetse flies (C) are known for transmitting African trypanosomiasis (sleeping sickness), not Chagas disease. Cockroaches (D) are not known to transmit Chagas disease.
A 32-year-old patient undergoing dental examination was found to have some rash-like lesions resembling secondary syphilis in the oral cavity. The patient was referred for the serological study with the purpose of diagnosis confirmation. In order to detect antibodies in the serum, living Treponema were used as diagnosticum. What serological test was performed?
- A. Immobilization
- B. Passive hemagglutination
- C. Precipitation
- D. Complement binding
Correct Answer: B
Rationale: The correct answer is B: Passive hemagglutination. In this test, red blood cells coated with Treponema antigens agglutinate in the presence of patient's serum antibodies. This indicates the presence of antibodies against Treponema, confirming the diagnosis.
A: Immobilization test uses live Treponema to detect specific antibodies, but it is not commonly used for syphilis diagnosis.
C: Precipitation test is not commonly used for syphilis diagnosis.
D: Complement binding test is not specific for syphilis and is used more for autoimmune diseases.
Therefore, passive hemagglutination is the most appropriate serological test in this case due to its specificity and relevance to the presentation of the patient.