Nokea
A child with foul-smelling diarrhea had trophozoites with two nuclei and flagella identified in stool microscopy. What is the causative agent?
- A. Giardia lamblia
- B. Entamoeba histolytica
- C. Trichomonas vaginalis
- D. Balantidium coli
Correct Answer: A
Rationale: The correct answer is A: Giardia lamblia. Giardia lamblia is a protozoan parasite that causes foul-smelling diarrhea with trophozoites having two nuclei and flagella in stool microscopy. The presence of flagella and two nuclei is characteristic of Giardia lamblia. Entamoeba histolytica (Choice B) causes amoebic dysentery with trophozoites containing ingested RBCs. Trichomonas vaginalis (Choice C) is a sexually transmitted protozoan causing vaginitis with a distinctive pear-shaped trophozoite. Balantidium coli (Choice D) is a ciliated protozoan causing diarrhea with trophozoites containing a single nucleus.
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The immunity in syphilis is:
- A. Nonsterile (infectious)
- B. Antitoxic
- C. Humoral
- D. A + B + C
Correct Answer: A
Rationale: The correct answer is A because immunity in syphilis is nonsterile, meaning that individuals who have been infected may still carry the bacteria and be capable of transmitting the disease. This is due to the ability of the bacterium causing syphilis, Treponema pallidum, to evade the immune system by hiding within host cells.
Option B, antitoxic, is incorrect because syphilis is not caused by a toxin produced by the bacteria, but rather by the bacterium itself.
Option C, humoral, is also incorrect as syphilis immunity involves both humoral (antibody-mediated) and cell-mediated immune responses, not solely humoral immunity.
Option D is incorrect as it includes all three options, whereas in reality, the immunity in syphilis is primarily nonsterile.
The causative agent of bacterial dysentery belongs to which of the following genera?
- A. Genus Shigella
- B. Genus Salmonella
- C. Genus Klebsiella
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Genus Shigella. Shigella is known to be the causative agent of bacterial dysentery. It invades the intestinal lining, leading to symptoms like severe diarrhea and abdominal cramps. Salmonella (choice B) typically causes food poisoning, not dysentery. Klebsiella (choice C) is associated with pneumonia and urinary tract infections, not dysentery. "None of the above" (choice D) is incorrect as Shigella does belong to a specific genus responsible for bacterial dysentery.
The basic method for routine mumps diagnosis is;
- A. PCR
- B. Isolation on cell cultures
- C. ELISA
- D. Immunofluorescence method
Correct Answer: B
Rationale: The correct answer is B: Isolation on cell cultures. This method is the gold standard for routine mumps diagnosis as it involves isolating the virus in cell cultures to confirm the presence of the mumps virus. PCR (choice A) is used for detecting viral RNA, not for routine diagnosis. ELISA (choice C) detects antibodies, not the virus itself. Immunofluorescence method (choice D) is used for visualizing viral antigens but is not as reliable as isolating the virus in cell cultures for diagnosis.
A wound smear from a patient revealed Gram-positive cocci arranged in clusters. The culture was catalase-positive and coagulase-positive. What is the causative agent?
- A. Staphylococcus aureus
- B. Streptococcus pyogenes
- C. Micrococcus luteus
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus.
1. Gram-positive cocci in clusters suggest staphylococci.
2. Catalase-positive indicates staphylococci since streptococci are catalase-negative.
3. Coagulase-positive further confirms Staphylococcus aureus, distinguishing it from other staphylococci.
Summary: B is incorrect as Streptococcus pyogenes is catalase-negative. C is incorrect as Micrococcus luteus is catalase-negative and coagulase-negative. D is incorrect as Enterococcus faecalis is catalase-negative and coagulase-negative.
Which bacteria are responsible for causing pneumonia?
- A. Streptococcus pneumoniae
- B. Mycobacterium tuberculosis
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D (All of the above) because different bacteria can cause pneumonia. Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. Mycobacterium tuberculosis causes tuberculosis, which can lead to pneumonia. Pseudomonas aeruginosa is a common cause of hospital-acquired pneumonia. Therefore, all three bacteria can be responsible for causing pneumonia in different contexts. Choices A, B, and C are incorrect because each bacterium individually can cause pneumonia, so selecting only one option would not cover the full spectrum of bacterial causes of pneumonia.