Nokea
The only way to get energy in haematrophic bacteria is:
- A. Heat production
- B. Biological oxidation
- C. In biosynthetic reactions
- D. Cultivation in culture media
Correct Answer: B
Rationale: The correct answer is B: Biological oxidation. Haematrophic bacteria obtain energy through biological oxidation, where they break down organic compounds to generate ATP for cellular processes. This process involves the transfer of electrons from the substrate to an electron transport chain to produce energy. Heat production (A) is a byproduct of metabolism, not the primary way to obtain energy. In biosynthetic reactions (C), energy is utilized rather than generated. Cultivation in culture media (D) is a method of growing bacteria but does not directly provide energy. Therefore, the correct answer is B as it aligns with the metabolic process of haematrophic bacteria.
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In an agar slant, bacterial colonies that appear separate or semiconfluent are referred to as:
- A. filiform
- B. echinulate
- C. beaded
- D. effuse
Correct Answer: C
Rationale: The correct answer is C: beaded. In an agar slant, beaded colonies appear as separate or semiconfluent, forming small, round colonies with gaps between them. This term accurately describes the appearance of the colonies in this context.
A: Filiform colonies are dense and opaque with smooth edges, not separate or semiconfluent.
B: Echinulate colonies have spiny projections, not the characteristic of separate or semiconfluent growth.
D: Effuse colonies spread out extensively and lack defined borders, unlike the distinct appearance of separate or semiconfluent colonies.
Which of the following bacteria is responsible for causing bacterial meningitis?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three bacteria (Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae) can cause bacterial meningitis. Neisseria meningitidis is a common cause of meningococcal meningitis, Haemophilus influenzae can cause H. influenzae meningitis, and Streptococcus pneumoniae is a leading cause of pneumococcal meningitis. Therefore, all of the above choices are correct. The other choices are incorrect because each of the bacteria listed can independently cause bacterial meningitis, so none of them alone can be the sole correct answer.
A child is presumably ill with diphtheria. A specimen of affected mucous membrane of his pharynx was taken for analysis. The smear was stained and microscopic examination revealed yellow rods with dark blue thickenings on their ends. What structural element of a germ cell was revealed in the detected microorganisms?
- A. Volutin granules
- B. Plasmids
- C. Capsule
- D. Spores
Correct Answer: A
Rationale: The correct answer is A: Volutin granules. Volutin granules are metachromatic granules that stain dark blue with methylene blue or Leishman stain. In diphtheria-causing bacteria, Corynebacterium diphtheriae, these granules are typically seen as yellow rods with dark blue thickenings on their ends when stained. Volutin granules are storage inclusions composed of polymetaphosphate that serve as an energy reserve for the bacteria. The presence of these granules in the detected microorganisms indicates the characteristic feature of Corynebacterium diphtheriae.
Summary of other choices:
B: Plasmids are extrachromosomal DNA molecules that are not typically visible on stained smears.
C: Capsules are outer protective layers that are not visible on stained smears.
D: Spores are reproductive structures formed by certain bacteria, not typically seen in Corynebacterium diphtheriae.
In order to accurately identify etiology of peptic ulcer disease, polymerase chain reaction (PCR) analysis was performed on gastric biopsy specimen taken from 47-year-old patient. Eventually, the test result was positive for H. pylori. Which of the following was most likely detected in PCR analysis?
- A. Bacterial DNA
- B. Bacterial toxin
- C. H. pylori bacterium itself
- D. Bacterial enzymes – urease and catalase
Correct Answer: A
Rationale: The correct answer is A: Bacterial DNA. PCR analysis detects specific DNA sequences, so a positive result for H. pylori indicates the presence of the bacterial DNA in the gastric biopsy specimen. This method identifies the genetic material of the bacterium, not the bacterium itself (choice C) or its toxins (choice B). Additionally, PCR does not directly detect bacterial enzymes (choice D) but rather focuses on genetic material for accurate identification. Therefore, in this case, the detection of H. pylori in the PCR analysis points to the presence of bacterial DNA, confirming the etiology of peptic ulcer disease.
A patient with pulmonary tuberculosis is prescribed the most effective antituberculosis antibiotic. Name this drug:
- A. Tetracycline
- B. Furasolidone
- C. Rifampicin
- D. Bactrim (Co-trimoxazole)
Correct Answer: C
Rationale: Rifampicin is the correct answer because it is a first-line antibiotic for treating pulmonary tuberculosis. It has excellent bactericidal activity and penetrates well into lung tissues where the infection is located. Rifampicin is also known for preventing the development of resistance. Tetracycline (A) and Furasolidone (B) are not commonly used for tuberculosis treatment. Bactrim (D) is a combination of sulfamethoxazole and trimethoprim, not effective for tuberculosis treatment.