Nokea
A patient has a necrotizing phlegmon of his lower extremity. A doctor suspects a gas gangrene. Microscopy reveals grampositive bacilli. In order to confirm the diagnosis further bacteriological tests should include inoculation of the material into the following nutrient medium:
- A. Kitt-Tarozzi medium
- B. Endo agar
- C. Meat-peptone agar
- D. Levine agar
Correct Answer: A
Rationale: The correct answer is A: Kitt-Tarozzi medium. This medium is specifically designed to culture Clostridium species, the causative agents of gas gangrene. Clostridium species are gram-positive bacilli that produce gas during their metabolism. Inoculating the material into Kitt-Tarozzi medium allows for the selective growth of Clostridium species, aiding in the confirmation of a gas gangrene diagnosis.
Other choices are incorrect:
B: Endo agar is used for the isolation of gram-negative enteric bacteria.
C: Meat-peptone agar is a general-purpose medium and not specific for Clostridium species.
D: Levine agar is used for the isolation of Salmonella and Shigella species, not Clostridium.
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After the second abortion a 23 year old woman has been diagnosed with toxoplasmosis. Which drug should be used for toxoplasmosis treatment?
- A. Co-trimoxazole
- B. Itraconazole
- C. Mebendazole
- D. Azidothimidine
Correct Answer: A
Rationale: The correct answer is A: Co-trimoxazole. This drug combination is the first-line treatment for toxoplasmosis due to its efficacy against Toxoplasma gondii. Co-trimoxazole consists of sulfamethoxazole and trimethoprim, which work synergistically to inhibit bacterial and protozoal folate synthesis, effectively treating toxoplasmosis.
B: Itraconazole is an antifungal medication and not effective against toxoplasmosis.
C: Mebendazole is an anthelmintic drug used for treating parasitic worm infections, not toxoplasmosis.
D: Azidothimidine, also known as AZT, is used for treating HIV, not toxoplasmosis.
Which of the following is used to test for bacterial antibiotic susceptibility?
- A. Gram stain
- B. Catalase test
- C. Kirby-Bauer disk diffusion test
- D. Endospore stain
Correct Answer: C
Rationale: The correct answer is C: Kirby-Bauer disk diffusion test. This test is used to determine the antibiotic susceptibility of bacteria by measuring the zone of inhibition around antibiotic-soaked paper disks. It helps identify which antibiotics are effective against the bacteria being tested. This test is crucial in guiding antibiotic treatment decisions.
A: Gram stain is used to classify bacteria based on their cell wall composition and morphology, not for antibiotic susceptibility testing.
B: Catalase test is used to differentiate between catalase-positive and catalase-negative bacteria, not for antibiotic susceptibility testing.
D: Endospore stain is used to detect the presence of endospores in bacteria, not for antibiotic susceptibility testing.
Warts are commonly caused by the:
- A. human papillomavirus
- B. herpesvirus
- C. HIV
- D. varicella-zoster virus
Correct Answer: A
Rationale: Step-by-step rationale:
1. Warts are caused by human papillomavirus (HPV) due to its ability to infect the skin.
2. HPV infects the top layer of skin and causes the rapid growth of cells, leading to the formation of warts.
3. Herpesvirus (choice B) causes herpes, not warts.
4. HIV (choice C) weakens the immune system but does not directly cause warts.
5. Varicella-zoster virus (choice D) causes chickenpox and shingles, not warts.
Summary:
Choice A is correct as warts are primarily caused by HPV, which infects the skin cells. Choices B, C, and D are incorrect as they are associated with different viral infections that do not lead to the development of warts.
Which of the following statements about in vitro cultivation of viruses is true?
- A. Viral cultivation under laboratory conditions is impossible
- B. Viruses are cultured on hen embryos, cell cultures and experimental animals
- C. Viruses are cultivated on special nutrient media
- D. Viruses are cultured only in human embryonic cell cultures
Correct Answer: B
Rationale: The correct answer is B because viruses can indeed be cultured on hen embryos, cell cultures, and experimental animals in vitro. This method allows for the replication and study of viruses outside the host organism. Option A is incorrect as viral cultivation is possible in laboratory settings. Option C is incorrect because while viruses can be grown on nutrient media, it is not the only method. Option D is incorrect as viruses can be cultured in various types of cell cultures, not just human embryonic ones.
On the 5th day after a surgery for colon injury a patient complains of bursting pain in the postoperative wound, weakness, drowsiness, headache, fever up to 40oC. Objectively: the skin around the wound is swollen, there is gas crepitation. The wound discharges are scarce foul-smelling, of dark-gray color. What is the most likely diagnosis?
- A. Anaerobic clostridial wound infection
- B. Abscess
- C. Postoperative wound infection
- D. Erysipelas
Correct Answer: A
Rationale: The correct answer is A: Anaerobic clostridial wound infection. The symptoms and signs described (bursting pain, weakness, drowsiness, fever, swollen skin, gas crepitation, foul-smelling dark-gray discharge) are classic for gas gangrene, caused by Clostridium perfringens. Gas gangrene is an anaerobic infection that thrives in devitalized tissue, such as postoperative wounds. The gas crepitation is due to gas production by the bacteria. Abscess (B) typically presents with localized swelling and fluctuance, not gas crepitation. Postoperative wound infection (C) may present with redness, warmth, and increased wound discharge but not the specific features mentioned. Erysipelas (D) is a superficial bacterial skin infection, typically caused by Streptococcus pyogenes, presenting with well-defined raised borders and redness.