Nokea
The cytopathic effect caused by viruses of family paramyxoviridae looks like:
- A. Fine grained degeneration
- B. Giant multinucleated cells syncytia
- C. Large cell degeneration with grape clustering of cells
- D. Do not provoke a cytopathic effect on cell cultures
Correct Answer: B
Rationale: Rationale: The correct answer is B. Viruses of the family Paramyxoviridae cause the formation of giant multinucleated cells called syncytia. This occurs when infected cells fuse together, resulting in large, multinucleated structures. This is a characteristic cytopathic effect of paramyxoviruses.
Summary:
A: Fine grained degeneration is not typically seen in paramyxovirus infections.
C: Large cell degeneration with grape clustering of cells is not a typical cytopathic effect of paramyxoviruses.
D: Paramyxoviruses do provoke a cytopathic effect, so this statement is incorrect.
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The generation time of Escherichia coli is
- A. 20 min
- B. 60 min
- C. 20 hours
- D. 24 hours
Correct Answer: A
Rationale: The correct answer is A (20 min) because Escherichia coli typically has a generation time of around 20 minutes, meaning the time it takes for a bacterial population to double. This rapid reproduction rate is a key characteristic of E. coli. Option B (60 min) is incorrect as it is longer than the usual generation time. Option C (20 hours) is too long for E. coli's generation time. Option D (24 hours) is also incorrect as it is much longer than the typical generation time of E. coli.
A woman who was infected with toxoplasmosis during the pregnancy has a child with multiple congenital defects. This is a result of:
- A. Teratogenesis
- B. Cancerogenesis
- C. Recombination
- D. Chemical mutogenesis
Correct Answer: A
Rationale: The correct answer is A: Teratogenesis. Teratogenesis refers to the process of abnormal development of the fetus leading to congenital defects due to exposure to harmful agents during pregnancy. In this case, toxoplasmosis infection during pregnancy can lead to teratogenesis, causing multiple congenital defects in the child. Other choices are incorrect because B: Cancerogenesis refers to the process of cancer formation, C: Recombination is a genetic process unrelated to congenital defects, and D: Chemical mutagenesis refers to mutations caused by chemical agents, not necessarily congenital defects.
A patient with pneumonia had a sputum culture revealing Gram-positive diplococci. The bacteria were catalase-negative and alpha-hemolytic. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Neisseria meningitidis
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: Step 1: Gram-positive diplococci suggest a pneumococcal infection.
Step 2: Catalase-negative indicates Streptococcus.
Step 3: Alpha-hemolysis matches S. pneumoniae's characteristics.
Therefore, Streptococcus pneumoniae is the most likely causative agent. Staphylococcus aureus (B) is catalase-positive, Neisseria meningitidis (C) is Gram-negative, and Klebsiella pneumoniae (D) is not diplococci or alpha-hemolytic.
Your patient is a 22-year-old man. The patient reports that two weeks after unprotected sexual contact, a small ulcer appeared on its penis. The local inguinal lymph nodes are enlarged. Dark field microscopic examination of the ulcer secretions was performed. The test reveals presence of motile, curved spirochete. The most common causative agent of the disease is:
- A. Chlamydia trachoma's
- B. Treponema pallidum
- C. Neisseria gonorrhoeae
- D. Herpes simplex virus, type 2
Correct Answer: B
Rationale: The correct answer is B: Treponema pallidum. The scenario describes symptoms of primary syphilis, which is caused by Treponema pallidum. The presence of a painless ulcer (chancre) and enlarged inguinal lymph nodes are characteristic of syphilis. Dark field microscopic examination showing motile, curved spirochetes is highly specific for Treponema pallidum.
Incorrect explanations:
A: Chlamydia trachomatis typically causes urethritis or cervicitis, not painless ulcers.
C: Neisseria gonorrhoeae causes gonorrhea, which presents with purulent discharge, not painless ulcers.
D: Herpes simplex virus type 2 causes genital herpes, leading to painful ulcers and vesicles, not painless ulcers seen in syphilis.
Which of the following statements for measles is NOT true?
- A. It is a childhood infection manifested with exanthema
- B. A characteristic clinical signs are the spots of Koplik
- C. Finding negris bodies is important for diagnosis
- D. Prophylaxis is done via live attenuated vaccine
Correct Answer: C
Rationale: The correct answer is C. Negri bodies are not associated with measles but with rabies. Step 1: Measles is a childhood infection with a rash (A). Step 2: Koplik spots are small white spots on a red base found inside the mouth and are characteristic of measles (B). Step 3: Negri bodies are eosinophilic cytoplasmic inclusions found in neurons infected with rabies virus, not measles (C). Step 4: Prophylaxis for measles is through the MMR vaccine, which is a live attenuated vaccine (D). Therefore, choice C is incorrect as it does not pertain to measles.