Nokea
A smear of pus from an abscess revealed Gram-positive cocci in clusters. The culture was catalase-positive and coagulase-positive. What microorganism was isolated?
- A. Staphylococcus aureus
- B. Streptococcus pyogenes
- C. Micrococcus luteus
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. This bacterium is Gram-positive cocci in clusters, catalase-positive, and coagulase-positive. Staphylococcus aureus is a common pathogen causing abscesses. Streptococcus pyogenes (B) is Gram-positive cocci in chains, not clusters. Micrococcus luteus (C) is catalase-positive but coagulase-negative. Enterococcus faecalis (D) is catalase-negative and coagulase-negative.
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Mesophylic bacteria are with temperature optimum:
- A. 25-37 °C
- B. 55-65 °C
- C. 15-18 °C
- D. 38-45 °C
Correct Answer: A
Rationale: The correct answer is A (25-37 °C) because mesophilic bacteria thrive best at moderate temperatures typical of most environments, making 25-37 °C their optimum range. This range allows for optimal enzyme activity and growth. Choice B (55-65 °C) is incorrect as it is more suitable for thermophilic bacteria. Choice C (15-18 °C) is too low for mesophiles to thrive efficiently. Choice D (38-45 °C) is too high and is more suitable for thermophiles. Ultimately, the correct answer aligns with the typical temperature range where mesophilic bacteria are most active and abundant.
In serologic reactions used in virology, a diagnostic antibody response should be taken into account if:
- A. A threshold increase in the titer in the second serum sample is observed
- B. The increase of the titer has no diagnostic significance for viral infections
- C. Two fold increase in the titer in the second serum sample is observed
- D. A fourfold increase in the titer in the second serum sample is observed
Correct Answer: D
Rationale: The correct answer is D because a fourfold increase in titer in the second serum sample indicates a significant rise in specific antibodies, which is crucial for diagnosing viral infections accurately. This increase is considered significant in serologic reactions as it shows a strong antibody response to the virus.
A: A threshold increase may not be substantial enough to confirm a diagnostic antibody response.
B: Dismissing the increase in titer would overlook important diagnostic information.
C: A twofold increase may not be as indicative of a strong antibody response compared to a fourfold increase.
Which one of the following statements about Campylobacter fetus is NOT CORRECT?
- A. Gram-positive rod-shaped bacterium
- B. Optimal temperature for cultivation 35-37C
- C. Opportunistic pathogen causes infections usually in newborns, immunocompromised patients and cancer
- D. Fastidious, microaerophile
Correct Answer: A
Rationale: The correct answer is A: Gram-positive rod-shaped bacterium. Campylobacter fetus is actually a Gram-negative bacterium. This is because it has a thin peptidoglycan layer in its cell wall, which does not retain the crystal violet stain used in the Gram-staining technique. It appears red or pink under a microscope after counterstaining with safranin. Therefore, statement A is incorrect.
B: Optimal temperature for cultivation 35-37C - Correct, as Campylobacter fetus thrives at this temperature range.
C: Opportunistic pathogen causes infections usually in newborns, immunocompromised patients, and cancer - Correct, as Campylobacter fetus can cause infections in these populations.
D: Fastidious, microaerophile - Correct, as Campylobacter fetus is fastidious and requires specific growth conditions, including low oxygen levels.
The discipline addressing issues associated with the choice and application of drugs to be used for disease prevention, treatment, and/or diagnosis is:
- A. pharmacotherapeutics
- B. toxicology
- C. pharmacokinetics
- D. pharmacy
Correct Answer: A
Rationale: The correct answer is A: pharmacotherapeutics. Pharmacotherapeutics focuses on the selection and use of drugs for disease prevention, treatment, and diagnosis. It involves determining the most effective and safe medications for specific conditions based on patient factors. Toxicology (B) is the study of the adverse effects of chemicals, including drugs. Pharmacokinetics (C) focuses on drug absorption, distribution, metabolism, and excretion in the body. Pharmacy (D) involves the preparation and dispensing of medications, but does not specifically address drug selection and application for disease management. Therefore, pharmacotherapeutics is the most suitable discipline for addressing the use of drugs in disease management.
A smear of a patient's sputum suspected for tuberculosis was prepared and stained. The smear showed red bacilli against a blue background. What staining method was used?
- A. Ziehl-Neelsen
- B. Gram
- C. Giemsa
- D. Neisser
Correct Answer: A
Rationale: The correct answer is A: Ziehl-Neelsen staining method. This method is used to detect acid-fast bacteria like Mycobacterium tuberculosis. Step-by-step rationale: 1. Acid-fast bacteria resist decolorization with acid-alcohol. 2. The red bacilli seen in the smear indicate acid-fast bacteria. 3. Ziehl-Neelsen stain uses carbol fuchsin to stain acid-fast bacteria red. 4. The blue background is likely the counterstain methylene blue. Incorrect choices: B: Gram stain is for categorizing bacteria into Gram-positive or Gram-negative, not specific for acid-fast bacteria. C: Giemsa stain is used for blood films and detecting parasites, not acid-fast bacteria. D: Neisser stain is not a standard microbiological staining method.