Nokea
A bacteriological analysis revealed spore-forming, Gram-positive rods in a wound smear. The bacteria were motile and produced gas in nutrient broth. What is the causative agent?
- A. Clostridium perfringens
- B. Bacillus anthracis
- C. Clostridium tetani
- D. Bacillus cereus
Correct Answer: A
Rationale: Rationale:
1. Spore-forming, Gram-positive rods: Characteristics shared by Clostridium and Bacillus.
2. Motile and gas production in nutrient broth: Clostridium perfringens is motile and produces gas, distinguishing it from Bacillus species.
3. Clostridium perfringens causes gas gangrene, correlating with gas production.
4. Bacillus anthracis causes anthrax, not related to wound infections.
5. Clostridium tetani causes tetanus, not associated with gas production.
6. Bacillus cereus causes food poisoning, not commonly associated with wound infections.
Summary:
- A is correct (Clostridium perfringens) due to motility, gas production, and wound infection correlation.
- B (Bacillus anthracis) causes anthrax, not wound infections.
- C (Clostridium tetani) causes tetanus, not gas production.
- D (B
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Which is the main mechanism of passing the infection with Listeria monocytogenes from man to man:
- A. alimentary mechanism
- B. transmission
- C. transplacental mechanism
- D. physical contact
Correct Answer: C
Rationale: The correct answer is C, transplacental mechanism. Listeria monocytogenes can cross the placenta, infecting the fetus during pregnancy. This mechanism allows the bacteria to be transmitted from mother to baby in utero. Alimentary mechanism (A) involves ingestion of contaminated food, not direct transfer between individuals. Transmission (B) is a broad term that doesn't specify the specific route of Listeria transmission. Physical contact (D) is not a common mode of Listeria transmission compared to transplacental transmission in the case of maternal-fetal infection.
The tool of choice to observe living microorganisms is the
- A. bright-field microscope
- B. phase-contrast microscope
- C. fluorescence microscope
- D. electron microscope
Correct Answer: B
Rationale: The correct answer is B: phase-contrast microscope. This type of microscope is ideal for observing living microorganisms because it enhances the contrast of transparent specimens without the need for staining or fixing, allowing for clear visualization of internal structures and movements. Bright-field microscopes (A) are suitable for observing fixed and stained specimens, not living organisms. Fluorescence microscopes (C) are used to detect specific cellular components tagged with fluorescent markers, not ideal for observing overall morphology. Electron microscopes (D) use electron beams and are best for viewing detailed structures at high magnification, but are not suitable for observing living organisms due to the need for vacuum conditions.
A 35-year-old patient has been admitted to a hospital for pain in the left sternoclavicular and knee joints, lumbar area. The disease has an acute character and is accompanied by fever up to 38oC. Objectively: the left sternoclavicular and knee joints are swollen and painful. In blood: WBCs - 9, 5x109/l, ESR - 40 mm/h, CRP - 1,5 millimole/l, fibrinogen - 4,8 g/l, uric acid - 0,28 millimole/l. Examination of the urethra scrapings reveals chlamydia. What is the most likely diagnosis?
- A. Reiter's syndrome
- B. Rheumatic arthritis
- C. Gout
- D. Bechterew's disease
Correct Answer: A
Rationale: The most likely diagnosis is Reiter's syndrome. This is suggested by the presence of joint pain, fever, elevated ESR and CRP levels, and chlamydia infection. Reiter's syndrome is a reactive arthritis triggered by an infection elsewhere in the body, such as chlamydia. The patient's symptoms of joint pain and swelling, along with the positive chlamydia test, support this diagnosis. Rheumatic arthritis (Choice B) is not associated with chlamydia infection, making it less likely. Gout (Choice C) typically presents with elevated uric acid levels, which are normal in this case. Bechterew's disease (Choice D) primarily affects the spine and sacroiliac joints, not the sternoclavicular and knee joints as seen in this patient.
A 4 year old child had Mantoux test. 60 hours after tuberculin introduction a focal skin hardening and redness 15 mm in diameter appeared. It was regarded as positive test. What type of hypersensitivity reaction is this test based upon?
- A. Delayed-type hypersensitivity
- B. Immune complex-mediated hypersensitivity
- C. Complement-mediated cytotoxic hypersensitivity
- D. Immediate hypersensitivity
Correct Answer: A
Rationale: The correct answer is A: Delayed-type hypersensitivity. The Mantoux test is a type IV hypersensitivity reaction, which is also known as delayed-type hypersensitivity. This reaction typically occurs 48-72 hours after exposure to an antigen, such as tuberculin in this case. The focal skin hardening and redness that appeared 60 hours after tuberculin introduction align with the timeline and characteristics of a delayed-type hypersensitivity reaction.
Summary:
- Choice A (Delayed-type hypersensitivity): Correct, as explained above.
- Choice B (Immune complex-mediated hypersensitivity): Incorrect, as this reaction involves immune complexes and typically presents with tissue damage and inflammation.
- Choice C (Complement-mediated cytotoxic hypersensitivity): Incorrect, as this reaction involves the activation of complement proteins leading to cell lysis.
- Choice D (Immediate hypersensitivity): Incorrect, as this reaction, such as in allergies, occurs within minutes to hours of exposure to an antigen and involves IgE-mediated mast
A vaginal yeast infection is typically caused by:
- A. Histoplasma capsulatum
- B. Candida albicans
- C. Aspergillus niger
- D. Saccharomyces cerevisiae
Correct Answer: B
Rationale: The correct answer is B: Candida albicans. Candida albicans is the most common cause of vaginal yeast infections due to its ability to overgrow in warm, moist environments like the vagina. It is a type of fungus that naturally resides in the body, but can cause infection when its growth is not regulated. Histoplasma capsulatum (A) causes a lung infection, Aspergillus niger (C) causes fungal sinusitis, and Saccharomyces cerevisiae (D) is a type of yeast used in baking and brewing, not typically associated with vaginal infections.