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Which bacteria are responsible for causing the disease known as leprosy?
- A. Mycobacterium leprae
- B. Escherichia coli
- C. Clostridium botulinum
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium leprae. This bacterium is responsible for causing leprosy because it has a unique ability to infect the skin, nerves, and mucous membranes. It is an acid-fast bacillus that multiplies very slowly, leading to a chronic infection. Clostridium botulinum (choice C) causes botulism, Escherichia coli (choice B) causes various gastrointestinal infections, and Staphylococcus aureus (choice D) causes skin infections and other diseases, but none of these bacteria are associated with leprosy.
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A 35-year-old patient has been admitted to a hospital for pain in the left sternoclavicular and knee joints, lumbar area. The disease has an acute character and is accompanied by fever up to 38oC. Objectively: the left sternoclavicular and knee joints are swollen and painful. In blood: WBCs - 9, 5x109/l, ESR - 40 mm/h, CRP - 1,5 millimole/l, fibrinogen - 4,8 g/l, uric acid - 0,28 millimole/l. Examination of the urethra scrapings reveals chlamydia. What is the most likely diagnosis?
- A. Reiter's syndrome
- B. Rheumatic arthritis
- C. Gout
- D. Bechterew's disease
Correct Answer: A
Rationale: The most likely diagnosis is Reiter's syndrome. This is suggested by the presence of joint pain, fever, elevated ESR and CRP levels, and chlamydia infection. Reiter's syndrome is a reactive arthritis triggered by an infection elsewhere in the body, such as chlamydia. The patient's symptoms of joint pain and swelling, along with the positive chlamydia test, support this diagnosis. Rheumatic arthritis (Choice B) is not associated with chlamydia infection, making it less likely. Gout (Choice C) typically presents with elevated uric acid levels, which are normal in this case. Bechterew's disease (Choice D) primarily affects the spine and sacroiliac joints, not the sternoclavicular and knee joints as seen in this patient.
Which of the following is a host-dependent bacterium?
- A. Mycoplasma
- B. Ureaplasma
- C. Rickettsia
- D. Micrococcus
Correct Answer: C
Rationale: The correct answer is C: Rickettsia. Rickettsia is a host-dependent bacterium because it requires living cells of a host organism to survive and replicate. This bacterium is an obligate intracellular pathogen, meaning it cannot grow outside of a host cell.
A: Mycoplasma and B: Ureaplasma are not host-dependent as they can grow and reproduce in cell-free environments due to possessing their own unique cell wall structures.
D: Micrococcus is a free-living bacterium that can survive and reproduce independently without relying on a host organism.
During bacteriological examination of sputum of a child with choking cough and fever there were revealed glossy smooth colonies growing on casein-charcoal agar and reminding of mercury drops. Microscopic examination revealed short Gram-negative bacteria. What microorganism was secured from the sputum?
- A. Bordetella pertussis
- B. Haemophylus influenzae
- C. Corynebacterium dyphtheriae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Glossy smooth colonies growing on casein-charcoal agar resembling mercury drops indicate Bordetella pertussis, the causative agent of whooping cough. The presence of short Gram-negative bacteria further supports this identification. Option B, Haemophilus influenzae, typically grows as small, round, translucent colonies on chocolate agar. Option C, Corynebacterium diphtheriae, forms gray colonies on tellurite agar. Option D, Klebsiella pneumoniae, appears as mucoid colonies on MacConkey agar.
Which statement about leptospirosis is INCORRECT:
- A. Leptospirosis is acute infectious disease with typical geographic distribution
- B. Reservoirs of leptospira are different wild and domestic animals-mainly rodents
- C. Leptospira can be cultivated on blood and chocolate agar
- D. doxycycline and penicillins are drugs of choice for treatment of leptospirosis
Correct Answer: C
Rationale: The correct answer is C because Leptospira cannot be cultivated on blood and chocolate agar. The bacterium requires specialized media such as Ellinghausen-McCullough-Johnson-Harris (EMJH) medium for growth. Blood and chocolate agar do not provide the necessary nutrients for the bacterium's growth. Leptospira is a fastidious organism that has unique culture requirements. Therefore, the statement that Leptospira can be cultivated on blood and chocolate agar is incorrect. The other choices are correct: A - Leptospirosis is an acute infectious disease with a typical geographic distribution, B - Reservoirs of leptospira are different wild and domestic animals, mainly rodents, and D - Doxycycline and penicillins are drugs of choice for the treatment of leptospirosis.
Transduction is:
- A. Transformation
- B. Transfer of genetic material between donor and recipient bacterial cells with the help of latent phage
- C. Transfer of large plasmids from a donor cell to a recipient cell
- D. None of the above
Correct Answer: B
Rationale: Transduction is the transfer of genetic material between bacterial cells with the help of a phage (virus). This process involves a phage infecting a bacterial cell, replicating inside it, and then transferring bacterial DNA along with phage DNA to another bacterial cell. This is different from transformation (choice A) which involves the uptake of naked DNA by a bacterial cell and plasmid transfer (choice C) which involves the transfer of small, circular DNA molecules. Therefore, the correct answer is B because it specifically describes the process of transduction in bacteria, while choices A and C describe different mechanisms of genetic transfer.