Nokea
Which of the following is a primary function of bacterial capsules?
- A. Energy production
- B. Protection from desiccation
- C. Adhesion and immune evasion
- D. DNA replication
Correct Answer: C
Rationale: The correct answer is C: Adhesion and immune evasion. Bacterial capsules serve as a protective layer that aids in adhesion to surfaces and host cells, allowing bacteria to colonize and evade the immune system. This function is crucial for bacterial survival and pathogenicity. Choices A and D are incorrect because energy production and DNA replication are not primary functions of bacterial capsules. Choice B is incorrect because while bacterial capsules do provide some protection from desiccation, their primary function lies in adhesion and immune evasion.
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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.
A patient of surgical department complains about pain in the small of her back and in the lower part of her belly; painful and frequent urination. Bacteriological examination of urine revealed gram-negative oxidase-positive rod-like bacteria forming greenish mucoid colonies with specific smell. What causative agent can it be?
- A. Pseudomonas aeruginosa
- B. Proteus mirabilis
- C. E.coli
- D. Str.pyogenes
Correct Answer: B
Rationale: The correct answer is B: Proteus mirabilis. This bacterium is known to cause urinary tract infections (UTIs) and matches the description given in the question. Proteus mirabilis is a gram-negative rod-like bacterium that forms greenish mucoid colonies with a specific smell due to its production of urease enzyme. This enzyme leads to the formation of struvite crystals, which can cause painful and frequent urination. Pseudomonas aeruginosa (A) is not typically associated with UTIs. E.coli (C) is the most common cause of UTIs but does not match the specific description provided. Str.pyogenes (D) is a gram-positive bacterium and is not typically associated with UTIs.
Production of RNA from DNA is called
- A. Transposition
- B. Translation
- C. Transcription
- D. RNA splicing
Correct Answer: C
Rationale: The correct answer is C: Transcription. Transcription is the process of synthesizing RNA from a DNA template. During transcription, RNA polymerase binds to the DNA and produces a complementary RNA strand. This process is essential for gene expression.
Explanation for why other choices are incorrect:
A: Transposition involves the movement of genetic elements within a genome, not the production of RNA from DNA.
B: Translation is the process of synthesizing proteins from mRNA, not the production of RNA from DNA.
D: RNA splicing is the process of removing introns and joining exons in pre-mRNA to produce mature mRNA, not the initial production of RNA from DNA.
Which bacteria produces an enterotoxin that causes diarrhea?
- A. Vibrio cholerae
- B. Clostridium botulinum
- C. Escherichia coli
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium produces the cholera toxin, an enterotoxin that causes profuse watery diarrhea by disrupting the normal function of the intestines. Vibrio cholerae is specifically known for causing cholera, a severe diarrheal disease. Clostridium botulinum (B) produces botulinum toxin, causing botulism (paralysis, not diarrhea). Escherichia coli (C) can produce enterotoxins, but the question specifies a specific enterotoxin causing diarrhea, which is not a characteristic of all strains of E. coli. Streptococcus pneumoniae (D) is a common cause of respiratory infections but does not produce an enterotoxin causing diarrhea.
Acute hemorrhagic cystitis may be due to:
- A. Parvovirus B19
- B. CMV
- C. Adenovirus
- D. Herpesvirus type 2
Correct Answer: C
Rationale: Rationale for choice C (Adenovirus) being correct:
1. Adenovirus is a common cause of acute hemorrhagic cystitis.
2. Adenovirus infects the bladder epithelium, leading to inflammation and bleeding.
3. Symptoms include hematuria and bladder pain.
4. Diagnosis is confirmed through viral culture or PCR testing.
Summary of why other choices are incorrect:
A: Parvovirus B19 - More commonly associated with erythema infectiosum (fifth disease) and aplastic anemia.
B: CMV - Known to cause congenital infections, mononucleosis, and retinitis, not typically associated with hemorrhagic cystitis.
D: Herpesvirus type 2 - Commonly causes genital herpes, but not typically associated with acute hemorrhagic cystitis.