Nokea
The bacterium that shows swarming on blood agar
- A. providencia stuartii
- B. providencia rettgeri
- C. Proteus mirabilis
- D. morganella morganii
Correct Answer: C
Rationale: The correct answer is C: Proteus mirabilis. This bacterium shows swarming on blood agar due to its ability to produce flagella and exhibit rapid and coordinated movement. Providencia stuartii and Providencia rettgeri are not known for swarming behavior on blood agar. Morganella morganii can exhibit swarming motility, but it is not as commonly associated with this characteristic compared to Proteus mirabilis, making C the most appropriate choice.
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A 43-year-old cattle farm worker is brought to the surgeon with fever, malaise, and inflamed lesions on his hands and arms. He reports that about 2 weeks before his presentation at the hospital he noticed small, painless, pruritic papules that quickly enlarged and developed a central vesicle. The vesicles developed into erosion and left painless necrotic ulcers with black, depressed eschar. Gram's staining of the ulcer reveals gram-positive spore-forming bacilli. Which of the following diseases is the most likely cause of these findings?
- A. Anthrax
- B. Chickenpox
- C. Syphilis
- D. Tularemia
Correct Answer: A
Rationale: The correct answer is A: Anthrax. The clinical presentation of painless necrotic ulcers with black eschar, along with the gram-positive spore-forming bacilli seen on Gram's staining, is classic for cutaneous anthrax. Anthrax is caused by Bacillus anthracis, which produces spores and can lead to skin lesions in individuals working with animals or animal products. Choice B, Chickenpox, typically presents with vesicular rash all over the body. Choice C, Syphilis, is caused by Treponema pallidum and does not present with the characteristic eschar seen in the patient. Choice D, Tularemia, caused by Francisella tularensis, presents with ulceroglandular lesions but lacks the black eschar characteristic of anthrax.
A 23-year-old man developed a perforation in his hard palate, a dense formation with clear margins was detected in this area. After a surgery, microscopy of excised formation shows there a large focus of caseous necrosis surrounded with a granulation tissue with endovasculitis and a cellular infiltration consisting of lymphocytes and epithelioid cells with predominance of plasma cells. What is the most likely disease in this case?
- A. Syphilis
- B. Tuberculosis
- C. Leprosy
- D. Scleroma
Correct Answer: B
Rationale: The correct answer is B: Tuberculosis. The case describes a man with a perforation in the hard palate and features of caseous necrosis with granulation tissue, endovasculitis, and a cellular infiltration mainly of lymphocytes, epithelioid cells, and plasma cells. These findings are classic for tuberculosis infection, commonly seen in extrapulmonary sites like the oral cavity. Syphilis (choice A) typically presents with a painless ulcer and different histopathological features. Leprosy (choice C) presents with granulomas containing foamy macrophages. Scleroma (choice D) is caused by Klebsiella rhinoscleromatis and presents with chronic granulomatous inflammation.
Which of the following viruses can cause hemorrhagic cystitis?
- A. BK virus
- B. Enteroviruses
- C. Flaviviruses
- D. Coronaviruses
Correct Answer: A
Rationale: The correct answer is A: BK virus. BK virus is a common cause of hemorrhagic cystitis, especially in immunocompromised individuals. It infects the urinary tract, leading to inflammation and bleeding in the bladder. Enteroviruses, Flaviviruses, and Coronaviruses do not typically cause hemorrhagic cystitis. Enteroviruses usually cause respiratory and gastrointestinal infections, Flaviviruses are commonly associated with diseases like dengue fever and Zika virus, and Coronaviruses are known for causing respiratory illnesses such as COVID-19. Hence, the correct answer is A as it is the only virus among the options known to cause hemorrhagic cystitis.
A bacterial colony is:
- A. Visible formation, formed by clustering of cells, belonging to different bacterial species
- B. Formed only on a liquid nutrient medium
- C. Both are incorrect
- D. None of the above
Correct Answer: A
Rationale: Step 1: A bacterial colony is a visible formation: Correct as colonies are visible to the naked eye.
Step 2: Formed by clustering of cells: Correct as colonies are made up of numerous bacterial cells.
Step 3: Belonging to different bacterial species: Correct as colonies can consist of one or multiple species.
Summary:
Choice A is correct as it accurately describes a bacterial colony. Choice B is incorrect as colonies can also form on solid nutrient mediums. Choice C is incorrect as choice A is correct. Choice D is incorrect as there is a correct option provided.
A patient with fever and enlarged lymph nodes had a blood smear examined under the microscope. Spiral microorganisms with pointed ends were detected. What is the likely diagnosis?
- A. Syphilis
- B. Leptospirosis
- C. Lyme disease
- D. Relapsing fever
Correct Answer: A
Rationale: Rationale: The correct answer is A: Syphilis. Spiral microorganisms with pointed ends are characteristic of Treponema pallidum, the causative agent of syphilis. This bacterium is known for its corkscrew shape. Other choices are incorrect because Leptospirosis, Lyme disease, and Relapsing fever are caused by different pathogens and do not exhibit spiral microorganisms on blood smears. Syphilis should be suspected in the presence of these specific spiral microorganisms.