Nokea
Method for rapid diagnosis of some viral infections is
- A. immunofluorescence method
- B. demonstration of antibodies by viral neutralization reaction
- C. electron microscopic method for detection of specific antibodies
- D. all three answers are correct
Correct Answer: D
Rationale: The correct answer is D because utilizing all three methods—immunofluorescence, viral neutralization reaction, and electron microscopy—provides a comprehensive and rapid diagnosis of various viral infections. Immunofluorescence detects viral antigens directly, viral neutralization reaction demonstrates the presence of specific antibodies, and electron microscopy visualizes viral particles. This combination ensures accurate and quick identification of different viruses. Choices A, B, and C alone may not cover all aspects of viral diagnosis, making them less effective compared to the comprehensive approach of using all three methods.
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A patient with a painful ulcer had a wound culture revealing Gram-negative rods with a characteristic 'safety pin' appearance. What is the most likely causative agent?
- A. Yersinia pestis
- B. Francisella tularensis
- C. Brucella abortus
- D. Clostridium botulinum
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis is a Gram-negative rod that exhibits a 'safety pin' appearance on staining due to bipolar staining. This bacterium is the causative agent of plague, which can present as painful ulcers known as buboes. Y. pestis is transmitted by fleas and can cause outbreaks in humans.
Summary:
- B: Francisella tularensis causes tularemia, not typically associated with painful ulcers.
- C: Brucella abortus causes brucellosis, which does not typically present with painful ulcers.
- D: Clostridium botulinum causes botulism, characterized by muscle weakness and paralysis, not painful ulcers.
Examination of a man revealed a protozoan disease that affected brain and caused vision loss. Blood analysis revealed unicellular half-moon-shaped organisms with pointed end. The causative agent of this disease is:
- A. Toxoplasma B.Leishmania C.Lamblia D.Amoeba E.Trichmonad
Correct Answer: A
Rationale: The correct answer is A: Toxoplasma. Toxoplasma gondii is a protozoan parasite that can infect the brain and cause vision loss. The description of half-moon-shaped organisms with a pointed end matches the appearance of Toxoplasma under the microscope. Toxoplasma is known to cause a condition called toxoplasmosis, which can lead to neurological symptoms such as vision loss. Leishmania, Lamblia, Amoeba, and Trichomonad are not known to cause brain infections or vision loss, making them incorrect choices.
The protozoan that lacks a cyst stage and therefore must be transferred quickly from host to host is:
- A. Molds
- B. Protozoans
- C. Helminths
- D. Viruses
Correct Answer: B
Rationale: The correct answer is B: Protozoans. Protozoans lack a cyst stage, which is a protective, dormant stage that allows them to survive in harsh conditions outside the host. Without a cyst stage, protozoans must be transferred quickly between hosts to avoid exposure to unfavorable environments. Molds (A) are fungi that reproduce through spores and do not have a cyst stage like protozoans. Helminths (C) are parasitic worms that have complex life cycles involving different hosts but do not rely on a cyst stage for survival. Viruses (D) are not considered protozoans and do not have a cyst stage, but they are not classified as protozoans.
Which one of the following growth media is used to cultivate Mycobacterium tuberculosis?
- A. Lowestein-Jensen
- B. Loefllers's
- C. All of the above
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Lowestein-Jensen. This is because Lowestein-Jensen medium is specifically designed to cultivate Mycobacterium tuberculosis, providing necessary nutrients and conditions for its growth. Loefller's medium is not optimal for cultivating M. tuberculosis. Choice C (All of the above) is incorrect as not all the options listed are suitable for cultivating M. tuberculosis. Choice D (None of the above) is also incorrect as Lowestein-Jensen is indeed the recommended growth medium for this bacterium.
A patient has severe catarrhal symptoms. Material growth on Bordet-Gengou agar showed mercury- drop like colonies. Examination of the blood smears revealed some small ovoid gram-negative bacilli sized 1-3 microns. What microorganisms were isolated?
- A. Bordetella
- B. Corynebacteria
- C. Mycobacteria
- D. Meningococcus
Correct Answer: A
Rationale: The correct answer is A: Bordetella. The presence of mercury-drop like colonies on Bordet-Gengou agar indicates Bordetella pertussis. The small ovoid gram-negative bacilli sized 1-3 microns are characteristic of Bordetella species. Catarrhal symptoms are typical of pertussis caused by Bordetella pertussis.
Summary of other choices:
B: Corynebacteria do not typically exhibit mercury-drop like colonies or small ovoid shapes.
C: Mycobacteria are acid-fast bacilli and do not grow on Bordet-Gengou agar.
D: Meningococcus is a gram-negative diplococcus and does not match the description provided.