Nokea
A patient with pneumonia had sputum cultured, revealing Gram-negative rods. The bacteria were lactose fermenters and produced green colonies on MacConkey agar. What is the most likely causative agent?
- A. Escherichia coli
- B. Klebsiella pneumoniae
- C. Pseudomonas aeruginosa
- D. Proteus mirabilis
Correct Answer: A
Rationale: Rationale:
1. Gram-negative rods suggest Enterobacteriaceae family.
2. Lactose fermenters narrow down to E. coli.
3. Green colonies on MacConkey agar indicate acid production.
4. E. coli is a common cause of pneumonia.
Therefore, the most likely causative agent is Escherichia coli. Other choices are incorrect as Klebsiella is non-lactose fermenter, Pseudomonas is oxidase-positive, and Proteus is non-lactose fermenter.
You may also like to solve these questions
The structures that can move fluid, mucus, or cells over the surface of a cell are:
- A. cilia
- B. fimbriae
- C. flagella
- D. microvilli
Correct Answer: C
Rationale: The correct answer is C: flagella. Flagella are whip-like structures that move fluid, mucus, or cells over the surface of a cell. They are longer and fewer in number compared to cilia, which are shorter and more numerous. Fimbriae are small, bristle-like structures that help bacteria attach to surfaces but do not move fluid. Microvilli are tiny projections that increase the surface area for absorption but do not have a role in moving fluid or cells. Therefore, flagella is the correct answer as it specifically fits the function described in the question.
During the skill-building session in microbiology the students need to stain the prepared and fixed sputum smears obtained from a tuberculosis patient. What staining technique should be used in this case?
- A. Gram
- B. Giemsa
- C. Ziehl-Neelsen
- D. Burri
Correct Answer: C
Rationale: The correct staining technique for sputum smears obtained from a tuberculosis patient is Ziehl-Neelsen staining. This technique uses carbol fuchsin dye to stain the acid-fast bacteria, such as Mycobacterium tuberculosis, red. Here's a step-by-step rationale:
1. Ziehl-Neelsen staining is specifically designed to detect acid-fast bacteria like Mycobacterium tuberculosis.
2. Carbol fuchsin dye is used to penetrate the mycolic acid layer in the cell wall of the bacteria, making them resistant to decolorization.
3. Acid-alcohol is used as a decolorizer to remove the stain from non-acid-fast bacteria.
4. Methylene blue is used as a counterstain to visualize non-acid-fast bacteria in blue.
Therefore, Ziehl-Neelsen staining is the most appropriate technique for identifying Mycobacterium tuberculosis in sputum smears.
Other choices like Gram, Giemsa, and
A Gram-negative, comma-shaped bacterium was isolated from a patient with cholera. What is the most likely causative agent?
- A. Vibrio cholerae
- B. Shigella dysenteriae
- C. Salmonella typhi
- D. Campylobacter jejuni
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This is because Vibrio cholerae is a Gram-negative, comma-shaped bacterium known to cause cholera. The characteristic shape and the association with cholera make it the most likely causative agent in this case.
Explanation for incorrect choices:
B: Shigella dysenteriae - Shigella dysenteriae is a Gram-negative bacterium that causes bacillary dysentery, not cholera.
C: Salmonella typhi - Salmonella typhi is a Gram-negative bacterium that causes typhoid fever, not cholera.
D: Campylobacter jejuni - Campylobacter jejuni is a Gram-negative bacterium that commonly causes foodborne gastroenteritis, not cholera.
A 28 y.o. patient without permanent residence was admitted to the hospital with the preliminary diagnosis influenza. On the fith day of illness he got a maculopapular petechial rash on his body and internal surfaces of extremities. Body temperature is 410 C, euphoria, face hyperemia, sclera reddening, tongue tremor, tachycardia, splenomegaly, excitement. What is the most probable diagnosis?
- A. Epidemic typhus
- B. Delirium alcoholicum
- C. Leptospirosis
- D. Measles
Correct Answer: A
Rationale: Step 1: Initial diagnosis of influenza suggests a viral illness.
Step 2: Presence of maculopapular petechial rash and high fever indicates a systemic infection.
Step 3: Symptoms like euphoria, hyperemia, tachycardia, splenomegaly, and excitement are characteristic of epidemic typhus.
Step 4: Face hyperemia, sclera reddening, and tongue tremor are specific to epidemic typhus.
Step 5: Epidemic typhus is transmitted by body lice, which fits the scenario of a patient without permanent residence.
Summary:
- Delirium alcoholicum is unlikely due to the specific symptoms and lack of history of alcohol abuse.
- Leptospirosis typically presents with jaundice and renal symptoms, not seen in this case.
- Measles rash is different from the maculopapular petechial rash described.
A 40-year-old man developed skin redness and swelling in the neck area, where eventually a small abscess appeared. On section the focus is dense and yellow-green colored, in the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthoma cells, and macrophages detected. Specify the most correct etiological name of this pathological process:
- A. Syphilis
- B. Carbuncle
- C. Actinomycosis
- D. Leprosy
Correct Answer: C
Rationale: The correct answer is C: Actinomycosis. Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species, which form sulfur granules in purulent masses surrounded by dense fibrous tissue. In this case, the presence of fungal druses, plasma cells, xanthoma cells, and macrophages in the histological examination is characteristic of actinomycosis. The clinical presentation of skin redness, swelling, and abscess formation in the neck area also aligns with actinomycosis.
Choice A: Syphilis is caused by Treponema pallidum, presenting with a painless chancre at the site of infection, not skin redness and swelling in the neck area.
Choice B: Carbuncle is a bacterial skin infection involving a group of hair follicles, typically on the back of the neck, not characterized by fungal druses or sulfur granules.
Choice D: Leprosy