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Which type of bacteria can survive in extreme salty environments?
- A. Psychrophiles
- B. Halophiles
- C. Thermophiles
- D. Mesophiles
Correct Answer: B
Rationale: The correct answer is B: Halophiles. Halophiles are bacteria that can survive in extreme salty environments. They have adapted to thrive in high salt concentrations. Psychrophiles (A) thrive in cold temperatures, Thermophiles (C) thrive in high temperatures, and Mesophiles (D) thrive in moderate temperatures. Therefore, they are not adapted to survive in extreme salty environments like Halophiles.
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A 14-year-old patient was diagnosed with Hutchinson's triad: barrel-shaped incisors, parenchymatous keratitis and deafness. The revealed presentations are consistent with the following disease:
- A. Syphilis
- B. Toxoplasmosis
- C. Lepra
- D. Tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Syphilis. Hutchinson's triad is a classic presentation of congenital syphilis in children. Barrel-shaped incisors, parenchymatous keratitis, and deafness are key manifestations. Barrel-shaped incisors result from mulberry molars, a type of abnormal tooth. Parenchymatous keratitis is an inflammation of the cornea, a common ocular sign in congenital syphilis. Deafness can occur due to damage to the auditory nerve caused by the infection. Choices B, C, and D are incorrect as they do not typically present with the specific triad of symptoms seen in congenital syphilis.
Listeria monocytogenes are:
- A. Gram-negative rod-shaped bacteria
- B. Gram-positive spherical bacteria
- C. Gram-positive rod-shaped bacteria
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Gram-positive rod-shaped bacteria. Listeria monocytogenes is a Gram-positive bacterium, as it retains the crystal violet stain during the Gram staining process. The bacteria are rod-shaped, not spherical. Choice A is incorrect as Listeria monocytogenes is not Gram-negative. Choice D is incorrect as Listeria monocytogenes does fall under the category of Gram-positive bacteria. The key is to remember the characteristics of Listeria monocytogenes, which are Gram-positive and rod-shaped.
Family Reoviridae does not include:
- A. Orthoreovirus type 3
- B. Orthomyxovirus type 1
- C. Orthoreovirus type 1
- D. Orthoreovirus type 2
Correct Answer: B
Rationale: The correct answer is B: Orthomyxovirus type 1. Family Reoviridae includes Orthoreovirus types 1, 2, and 3. Orthomyxovirus belongs to a different family, Orthomyxoviridae. Therefore, B is the correct answer. Orthoreovirus types 1, 2, and 3 are part of the Reoviridae family. Choice A, C, and D are incorrect because they are all part of the Reoviridae family which includes Orthoreoviruses.
Microscopy of a smear obtained from a patient with acute purulent periostitis revealed gram-positive bacteria arranged in clusters resembling bunch of grapes. What microorganisms is this morphology typical for?
- A. Staphylococci
- B. Sarcina
- C. Tetracocci
- D. Candida fungi
Correct Answer: A
Rationale: Rationale:
Staphylococci are gram-positive bacteria that typically arrange in clusters resembling a bunch of grapes. This characteristic morphology is specific to staphylococci due to their division pattern. Sarcina, Tetracocci, and Candida fungi do not exhibit this clustering pattern. Staphylococci are commonly associated with purulent infections, making them the most likely microorganisms in this scenario.
A 47-year-old patient came to see a doctor on the 7th day of disease. The disease developed very fast: after the chill body temperature rose to 40oC and lasted up to 7 hours, then dropped abruptly, which caused profuse sweat. There were three such attacks occur in once in two days. Two days ago the patient arrived from Africa. Objectively: pale skin, subicteric sclera, significantly enlarged liver and spleen. What is the cause of fever attacks in this disease?
- A. Erythrocytic schizogony
- B. Tissue schizogony
- C. Exotoxin of a causative agent
- D. Gametocytes
Correct Answer: A
Rationale: The correct answer is A: Erythrocytic schizogony. In this case, the patient most likely has malaria, specifically caused by Plasmodium falciparum. The fever attacks every 2 days (tertian fever) are characteristic of P. falciparum infection. The cycle of erythrocytic schizogony in P. falciparum is around 48 hours, leading to the recurring fever pattern. Choices B, C, and D are incorrect as tissue schizogony does not cause the characteristic fever pattern, exotoxins are not typically involved in malaria fever, and gametocytes do not directly cause fever attacks.