ATI RN
microbiology an evolving science test bank Questions
Question 1 of 9
Microscopic analysis of dental plaque revealed flagellated protozoa without a cyst stage. What microorganism is likely present?
Correct Answer: A
Rationale: The correct answer is A: Trichomonas tenax. Trichomonas tenax is a flagellated protozoan commonly found in the oral cavity and does not have a cyst stage. This organism typically inhabits the gingival crevices and can be identified in dental plaque samples. Entamoeba gingivalis (B) is an amoeba and does not have flagella. Balantidium coli (C) is a ciliated protozoan that infects the intestines, not the oral cavity. Giardia lamblia (D) is a flagellated protozoan that infects the intestines and has a distinct cyst stage. Therefore, the presence of flagellated protozoa without a cyst stage in dental plaque indicates Trichomonas tenax is likely present.
Question 2 of 9
Which one is an example of an immunomodulator:
Correct Answer: B
Rationale: Step-by-step rationale for why B (Gamma Interferon) is the correct answer: 1. Gamma Interferon is a type of immunomodulator that helps regulate the immune response. 2. It activates macrophages and enhances the immune system's ability to fight infections. 3. Rifampin is an antibiotic, not an immunomodulator. 4. Hexacima and Pentaxim are combination vaccines, not immunomodulators. In summary, Gamma Interferon is the correct answer as it directly influences the immune response, while the other choices are not immunomodulators.
Question 3 of 9
A 47-year-old male patient consulted a dentist about difficult mouth opening (lockjaw or trismus). The patient has a history of a stab wound of the lower extremity. What infection can be manifested by these symptoms?
Correct Answer: A
Rationale: The correct answer is A: Tetanus. Tetanus is caused by the bacterium Clostridium tetani, commonly found in soil, dust, and animal feces. The patient's history of a stab wound increases the risk of tetanus infection as the bacterium can enter the body through the wound. Tetanus infection can lead to symptoms such as lockjaw or trismus, which are characterized by muscle stiffness and difficulty opening the mouth. This is due to the neurotoxin produced by Clostridium tetani affecting the muscles. Summary of incorrect choices: B: Brucellosis is a bacterial infection transmitted from animals to humans through consumption of unpasteurized dairy products. It does not typically manifest with symptoms of lockjaw. C: Whooping cough (Pertussis) is a respiratory infection caused by Bordetella pertussis bacteria. It presents with severe coughing fits but does not cause lockjaw. D: Anaerobic wound infection
Question 4 of 9
A 40-year-old man developed skin redness and an swelling in the neck area, where eventually a small abscess appeared. The section the focus is dense and yellow-green colored. In the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthome cells, and macrophages detected. Specify the most correct etiological name of this pathological process?
Correct Answer: A
Rationale: The correct answer is A: Actinomycosis. This is a chronic bacterial infection caused by Actinomyces species. In this case, the description of dense yellow-green colored focus, white granules in purulent masses, and presence of fungal druses, plasma cells, xanthome cells, and macrophages all match the characteristics of actinomycosis. Actinomycosis typically presents with abscess formation containing sulfur granules, which are yellowish and granular. The other choices (B: Furuncle, C: Carbuncle, D: Syphilis) do not fit the clinical and histological features described in the question, making them incorrect options.
Question 5 of 9
Which of the following is true about plasmids?
Correct Answer: C
Rationale: Plasmids often carry antibiotic resistance genes, making choice C correct. Plasmids are circular DNA structures, not linear (A). They are found in both gram-positive and gram-negative bacteria, not exclusively in gram-positive bacteria (B). Plasmids are separate from the bacterial chromosome, not part of it (D). Therefore, choice C is the correct answer.
Question 6 of 9
Which bacteria is known for causing tuberculosis?
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacterium is known for causing tuberculosis, as it specifically infects the lungs and can lead to serious respiratory issues. Mycobacterium leprae (Choice B) causes leprosy, not tuberculosis. Escherichia coli (Choice C) is a common bacteria found in the intestines and is not associated with tuberculosis. Streptococcus pneumoniae (Choice D) causes pneumonia, but not tuberculosis. Therefore, the correct choice is A because Mycobacterium tuberculosis is the specific bacterium responsible for causing tuberculosis.
Question 7 of 9
While examining a blood smear taken form a patient and stained by Romanovsky's method a doctor revealed some protozoa and diagnozed the patient with Chagas disease. What protozoan is the causative agent of this disease?
Correct Answer: A
Rationale: Rationale: 1. Chagas disease is caused by Trypanosoma cruzi. 2. Trypanosoma cruzi is transmitted by triatomine bugs. 3. On a blood smear stained with Romanovsky's method, Trypanosoma cruzi appears as trypomastigotes. 4. Toxoplasma gondii causes toxoplasmosis, not Chagas disease. 5. Leishmania donovani and Leishmania tropica cause different forms of leishmaniasis, not Chagas disease.
Question 8 of 9
Drug of first choice for the treatment of syphilis is:
Correct Answer: B
Rationale: The correct answer is B: Penicillin. Penicillin is the drug of first choice for treating syphilis due to its effectiveness in eradicating the bacterium Treponema pallidum, which causes syphilis. It is the most reliable treatment with well-established efficacy. Gentamicin (A), ciprofloxacin (C), and chloramphenicol (D) are not recommended for treating syphilis as they are not effective against the specific bacteria causing the infection. Penicillin remains the gold standard for syphilis treatment.
Question 9 of 9
A patient had been provisionally diagnosed with syphilis. A laboratory assistant took the blood serum for an immunologic test based on the detection of antibodies preventing the movement of treponemas and causing their death. What reaction was used for the diagnosis?
Correct Answer: A
Rationale: The correct answer is A: Immobilization. This technique is called the Treponema pallidum immobilization (TPI) test, used to diagnose syphilis. The rationale is as follows: 1. TPI test detects antibodies that prevent the movement of treponemas, causing their death. 2. By immobilizing the treponemas, it indicates the presence of specific antibodies against syphilis. 3. This test is highly specific for syphilis diagnosis as it directly targets the causative agent. Other choices are incorrect: B: Complement binding - Not specific to syphilis, more commonly used for other diseases. C: Agglutination - Detects clumping of particles, not specific to treponemas or syphilis. D: Precipitation - Involves the formation of a solid, not directly related to treponema movement or death.