Nokea
Infection of several persons without any epidemiological link is
- A. epidemic
- B. sporadic disease
- C. endemic
- D. pandemic
Correct Answer: B
Rationale: The correct answer is B: sporadic disease. Infection of several persons without any epidemiological link is considered sporadic because it occurs in a random and isolated manner, with no clear pattern or connection between cases. It is not classified as an epidemic (A) because it does not involve a sudden increase in the number of cases within a specific population. It is also not endemic (C) as endemic diseases are constantly present in a particular region or population. Lastly, it is not a pandemic (D) which refers to a global outbreak affecting a large number of people across different countries.
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On the base of the clinical data a child was diagnosed with atypical pneumonia resistant to the effects of beta-lactam antibiotics. The patient's sputum was cultured and incubated in a special medium, which resulted in growth of microorganisms forming microscopic colonies with a dense center (looking like fried eggs). What microorganism caused the disease?
- A. Mycoplasma pneumoniae
- B. Klebsiella pneumoniae
- C. Str. pneumoniae
- D. L. pneumophila
Correct Answer: A
Rationale: The correct answer is A: Mycoplasma pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia and is known to be resistant to beta-lactam antibiotics. The description of microorganisms forming microscopic colonies with a dense center resembling fried eggs is characteristic of Mycoplasma pneumoniae colonies seen on special media.
Summary of other choices:
B: Klebsiella pneumoniae is not typically associated with atypical pneumonia and does not exhibit the described colony morphology.
C: Streptococcus pneumoniae is not resistant to beta-lactam antibiotics and does not produce colonies with the described appearance.
D: Legionella pneumophila is associated with Legionnaires' disease, not atypical pneumonia, and does not form colonies resembling fried eggs.
Gram (+) bacteria ... MG-ribonucleate and Mg. deoxyribonucleate in:
- A. Proportion 4:1
- B. Proportion 2:1
- C. Proportion 8:1
- D. Proportion 1:1
Correct Answer: A
Rationale: The correct answer is A, proportion 4:1. Gram (+) bacteria have a higher ratio of MG-ribonucleate to Mg. deoxyribonucleate because ribosomal RNA is more abundant in actively growing bacterial cells. This higher proportion of MG-ribonucleate to Mg. deoxyribonucleate is essential for protein synthesis and growth. The other choices are incorrect because they do not reflect the higher ratio of ribosomal RNA to DNA in Gram (+) bacteria, which is crucial for their metabolic activities and cellular functions.
A patient with abdominal pain had a stool culture revealing non-lactose-fermenting, Gram-negative rods that produced gas in a nutrient broth. What is the most likely causative agent?
- A. Salmonella typhi
- B. Shigella dysenteriae
- C. Escherichia coli
- D. Proteus vulgaris
Correct Answer: D
Rationale: The correct answer is D: Proteus vulgaris. This is because Proteus species are non-lactose-fermenting Gram-negative rods that are known to produce gas in nutrient broths. Proteus vulgaris is commonly associated with urinary tract infections and can also cause abdominal infections.
A: Salmonella typhi typically causes typhoid fever and is not known to produce gas in nutrient broths.
B: Shigella dysenteriae is a causative agent of dysentery and does not typically produce gas in nutrient broths.
C: Escherichia coli is a lactose-fermenting bacterium and does not fit the description of the organism in the stool culture.
Which toxin is specific for ETEC:
- A. TSST-1
- B. Shiga-like toxin
- C. Erythrogenic toxin
- D. LT enterotoxin
Correct Answer: D
Rationale: The correct answer is D: LT enterotoxin. This toxin is specific for Enterotoxigenic E. coli (ETEC) and is responsible for causing diarrhea by increasing cyclic AMP levels in intestinal cells. TSST-1 (choice A) is produced by Staphylococcus aureus, not ETEC. Shiga-like toxin (choice B) is produced by Shigella and EHEC, not ETEC. Erythrogenic toxin (choice C) is produced by Streptococcus pyogenes, not ETEC. Therefore, the LT enterotoxin is the specific toxin associated with ETEC.
A 10-year-old child had the mantoux tuberculin test administered. 48 hours later a papule up to 8 mm in diameter appeared on the site of the injection. What type of hypersensitivity reaction developed after the tuberculin injection?
- A. Type IV hypersensitivity reaction
- B. Arthus phenomenon
- C. Seroreaction
- D. Type II hypersensitivity reaction
Correct Answer: A
Rationale: The correct answer is A: Type IV hypersensitivity reaction. This type of reaction is characterized by a delayed response involving T cells. In this case, the appearance of a papule after 48 hours indicates a delayed hypersensitivity reaction, which is typical of a Type IV reaction. The other choices are incorrect because: B: Arthus phenomenon is a localized immune complex-mediated reaction, not seen in tuberculin tests. C: Seroreaction typically involves antibodies reacting with soluble antigens, not seen in this scenario. D: Type II hypersensitivity reactions involve antibodies targeting specific cells or tissues, which is not the mechanism at play in this case.