Nokea
Which of the following diseases is transmitted by the fecal–oral route?
- A. Ehrlichiosis
- B. Peptic ulcer
- C. Lyme disease
- D. Tularemia
Correct Answer: B
Rationale: The correct answer is B: Peptic ulcer. Peptic ulcers are commonly caused by Helicobacter pylori bacteria, which can be transmitted through the fecal-oral route. This means that the bacteria from infected feces can be ingested through contaminated food or water, leading to the development of peptic ulcers in the gastrointestinal tract.
Incorrect choices:
A: Ehrlichiosis - Ehrlichiosis is a tick-borne disease transmitted through the bite of an infected tick, not through the fecal-oral route.
C: Lyme disease - Lyme disease is also transmitted through the bite of an infected tick, specifically the black-legged tick.
D: Tularemia - Tularemia is a bacterial disease typically transmitted through insect bites, handling of infected animals, or ingestion of contaminated water, not through the fecal-oral route.
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While examining the feces of a patient with diarrhea, cysts with four nuclei were found. What protozoan is most likely causing the condition?
- A. Entamoeba histolytica
- B. Lamblia
- C. Trichomonas
- D. Balantidium
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This protozoan causes amoebiasis, which presents with symptoms like diarrhea. The cysts with four nuclei found in the feces are characteristic of Entamoeba histolytica. This protozoan is known to cause invasive infection, leading to tissue destruction and ulcers in the intestines. Lamblia (choice B) typically presents with cysts containing two nuclei. Trichomonas (choice C) is a sexually transmitted parasite and does not form cysts. Balantidium (choice D) is a ciliated protozoan that does not have four nuclei in its cyst form.
Which of the following is a feature of Gram-negative bacteria?
- A. Thick peptidoglycan layer
- B. Outer membrane with lipopolysaccharides
- C. Presence of teichoic acids
- D. Absence of a cell wall
Correct Answer: B
Rationale: The correct answer is B: Outer membrane with lipopolysaccharides. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS), which are important in pathogenesis and immune response. This feature is unique to Gram-negative bacteria, distinguishing them from Gram-positive bacteria (choice A). Teichoic acids (choice C) are found in the cell walls of Gram-positive bacteria, not Gram-negative. The statement in choice D, absence of a cell wall, is incorrect as all bacteria have a cell wall, although the composition may vary between Gram-negative and Gram-positive bacteria.
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.
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.
A scientist identifies a strand of RNA that can be directly used to code for important viral proteins during viral replication. What have they found?
- A. RNA major
- B. -RNA
- C. (+RNA)
- D. RNA minor
Correct Answer: C
Rationale: The correct answer is C: (+RNA). This indicates that the scientist found a positive-sense RNA strand that can be directly translated by host cell machinery to produce viral proteins. Positive-sense RNA can act as messenger RNA, allowing immediate protein synthesis during viral replication. Choice A (RNA major) and D (RNA minor) are not standard terms used to describe RNA strands in virology. Choice B (-RNA) indicates a negative-sense RNA strand, which requires transcription to form a complementary positive-sense strand before protein synthesis. Thus, the identification of a strand of RNA that directly codes for viral proteins aligns with the characteristics of a positive-sense RNA strand.