Nokea
Enzymes used in ELISA are those except:
- A. Î’-lactamase
- B. Alkaline phosphatase
- C. Horseradish peroxidase
- D. Î’- galactosidase
Correct Answer: A
Rationale: The correct answer is A: Β-lactamase. In ELISA, enzymes like alkaline phosphatase, horseradish peroxidase, and Β-galactosidase are commonly used as labels to detect the presence of specific molecules. Β-lactamase is not typically used in ELISA as it is an enzyme used to hydrolyze β-lactam antibiotics. Therefore, it does not serve the purpose of detecting specific molecules in ELISA. Alkaline phosphatase, horseradish peroxidase, and Β-galactosidase are preferred enzymes in ELISA due to their ability to produce a detectable signal when bound to specific molecules.
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Examination of duodenal contents revealed some pyriform protozoa with twin nuclei and four pairs of flagella. There were two supporting filaments between the nuclei and a suctorial disc on the ventral side. What representative of protozoa was revealed in this patient?
- A. Lamblia
- B. Toxoplasma
- C. Leishmania
- D. Intestinal trichomonad
Correct Answer: A
Rationale: Rationale for Correct Answer A (Lamblia):
1. Pyriform protozoa with twin nuclei, four pairs of flagella, and a suctorial disc match the characteristics of Giardia lamblia.
2. The presence of two supporting filaments between the nuclei is a unique feature of Giardia lamblia.
3. Giardia lamblia is known to infect the duodenum and cause symptoms such as diarrhea and abdominal pain.
Summary of Incorrect Choices:
B: Toxoplasma - Toxoplasma gondii is not characterized by four pairs of flagella or supporting filaments in the nuclei.
C: Leishmania - Leishmania species do not typically have the described morphology or location in the duodenum.
D: Intestinal trichomonad - Intestinal trichomonads do not exhibit the specific features mentioned in the question, such as twin nuclei and supporting filaments.
Gram (-) bacteria have basal structure consisting of:
- A. 20-25% of all materials building the cell wall
- B. 1-4% of all materials building the cell wall
- C. 4-10% of all materials building the cell wall
- D. 10-20% of all materials building the cell wall
Correct Answer: C
Rationale: The correct answer is C: 4-10% of all materials building the cell wall. Gram (-) bacteria have a thin peptidoglycan layer making up 4-10% of the cell wall. This is in contrast to Gram (+) bacteria which have a thicker peptidoglycan layer. Choice A is too high a percentage for Gram (-) bacteria. Choice B is too low as it would not provide enough structural support. Choice D is also too high and would not accurately reflect the composition of Gram (-) bacteria.
Which of the following media is often used to grow Mycobacterium tuberculosis?
- A. Middlebrook’s medium
- B. Heart infusion broth
- C. MacConkey agar
- D. Middlebrook’s medium
Correct Answer: D
Rationale: The correct answer is D: Middlebrook's medium. This medium is specifically designed for the growth of Mycobacterium tuberculosis due to its low concentration of malachite green, which inhibits the growth of other bacteria but not Mycobacterium species. Middlebrook's medium also contains various nutrients that support the growth of Mycobacterium tuberculosis.
A: Middlebrook's medium is the correct answer, not incorrect.
B: Heart infusion broth is a general-purpose medium, not specific for Mycobacterium tuberculosis.
C: MacConkey agar is selective for gram-negative bacteria and would not support the growth of Mycobacterium tuberculosis.
In summary, Middlebrook's medium is the ideal choice for cultivating Mycobacterium tuberculosis due to its specific formulation that promotes the growth of this pathogen while inhibiting other bacteria.
A patient was admitted to the hospital on the 7th day of the disease with complaints of high temperature, headache, pain in the muscles, especially in calf muscles. Dermal integuments and scleras are icteric. There is hemorrhagic rash on the skin. Urine is bloody. The patient was fishing two weeks ago. What is the most likely diagnosis?
- A. Leptospirosis
- B. Yersiniosis
- C. Salmonellosis
- D. Brucellosis
Correct Answer: A
Rationale: The most likely diagnosis is A: Leptospirosis. Leptospirosis is caused by the spirochete Leptospira interrogans and is commonly transmitted through contact with water contaminated by animal urine, such as in this case of fishing. The symptoms described match those of leptospirosis, including high fever, headache, muscle pain, jaundice, hemorrhagic rash, and bloody urine. The calf muscle pain is a characteristic symptom of leptospirosis known as "Weil's disease." Yersiniosis (B) typically presents with abdominal symptoms, Salmonellosis (C) with gastrointestinal symptoms, and Brucellosis (D) with flu-like symptoms. Therefore, based on the symptoms and history provided, Leptospirosis is the most likely diagnosis.
A sputum smear from a patient with pneumonia revealed Gram-positive diplococci with a capsule. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Klebsiella pneumoniae
- C. Neisseria meningitidis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is a common cause of pneumonia and is characterized by Gram-positive diplococci with a capsule. The presence of a capsule helps the bacterium evade the immune system and contributes to its virulence. Klebsiella pneumoniae (B) is a Gram-negative bacterium and does not typically have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus and is associated with meningitis, not pneumonia. Staphylococcus aureus (D) is a Gram-positive bacterium, but it does not typically present as diplococci with a capsule in a sputum smear from a pneumonia patient.