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microbiology chapter 13 test bank Questions
Question 1 of 5
For isolating Rickettsia, the sample is investigated via:
Correct Answer: C
Rationale: The correct answer is C because Rickettsia requires living cells for growth and replication. Chick embryos, cell cultures, and lab animals provide a suitable environment for Rickettsia isolation. Skin-allergy tests (A) and serological methods for proving antibodies (B) are not directly used for isolating Rickettsia as they do not support the growth of the bacteria. "None of the above" (D) is incorrect as option C involves the appropriate methods for isolating Rickettsia.
Question 2 of 5
A 25-year-old patient was delivered to an infectious diseases unit on the 3rd day of illness with complaints of headache, pain in lumbar spine and gastrocnemius muscles, high fever, chill. Objectively: condition of moderate severity. Scleras are icteric. Pharynx is hyperemic. Tongue is dry with dry brown coating. Abdomen is distended. Liver is enlarged by 2 cm. Spleen is not enlarged. Palpation of muscles, especially gastrocnemius muscles, is painful. Urine is dark in color. Stool is normal in color. The most likely diagnosis is:
Correct Answer: A
Rationale: The correct diagnosis is Leptospirosis. Leptospirosis presents with headache, fever, muscle pain, jaundice, and kidney involvement. The patient's symptoms of headache, lumbar and muscle pain, high fever, icteric scleras, and dark urine are classic for Leptospirosis. The enlarged liver could be due to liver involvement in the disease. The absence of splenic enlargement and normal stool color rule out malaria. Infectious mononucleosis typically presents with sore throat and lymphadenopathy, which are absent in this case. Viral hepatitis A may present with similar symptoms, but the presence of muscle pain and dark urine is more indicative of Leptospirosis. Therefore, based on the patient's symptoms and clinical findings, Leptospirosis is the most likely diagnosis.
Question 3 of 5
How the prepared immunofluorescence slide should be examined?
Correct Answer: A
Rationale: The correct answer is A because immunofluorescence slides are examined under a fluorescence microscope with a x100 oil immersion objective. This is because immunofluorescence relies on the detection of fluorescently labeled antibodies, which emit light when excited by a specific wavelength. Using a fluorescence microscope allows for visualization of these labeled antibodies at high magnification and resolution, enabling precise examination of cellular structures and protein localization. Choice B is incorrect as light microscopes are not suitable for visualizing fluorescence. Choice C is incorrect as electron microscopes use electrons, not light, for imaging, which is not compatible with immunofluorescence. Choice D is incorrect as there is a specific method for examining immunofluorescence slides.
Question 4 of 5
A patient with a productive cough and fever had a sputum smear revealing Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is the most likely causative agent based on the description of Gram-positive cocci in pairs with a capsule. S. pneumoniae is known for its characteristic morphology and the presence of a capsule, which helps in evading the immune system. It commonly causes pneumonia, especially in patients with a productive cough and fever. Incorrect choices: B: Klebsiella pneumoniae typically presents with a mucoid capsule and is associated with pneumonia in immunocompromised individuals. C: Neisseria meningitidis is a Gram-negative diplococcus and is more commonly associated with meningitis and septicemia. D: Staphylococcus aureus is a Gram-positive cocci, but it does not typically present in pairs with a capsule and is more commonly associated with skin and soft tissue infections.
Question 5 of 5
While studying a microslide obtained from the punctuate of a regional lymph node and stained by Romanovsky-Giemsa method a physician revealed some light pink thin microorganisms with 12-14 regular spiral coils and pointed ends, up to 10-13 micrometer long. This might be the causative agent of the following disease:
Correct Answer: D
Rationale: The correct answer is D: Relapsing fever. The description matches Borrelia species, the causative agent of relapsing fever. The thin, spiral-shaped microorganisms with pointed ends and specific length are characteristic of Borrelia. The number of coils and size mentioned also align with Borrelia morphology. Relapsing fever is transmitted by tick bites and manifests as recurring febrile episodes. Incorrect choices: A: Syphilis - Syphilis is caused by Treponema pallidum, which is not spiral-shaped. B: Trypanosomiasis - Trypanosomiasis is caused by Trypanosoma species, which are not spiral-shaped. C: Leptospirosis - Leptospirosis is caused by Leptospira species, which are not spiral-shaped and do not match the specific description provided.