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Bacterioscopic examination of chancre material revealed some mobile, long, convoluted microorganisms with 8-12 regular coils. These features are typical for:
- A. Treponema
- B. Borrellia
- C. Leptospira
- D. Vibrios
Correct Answer: A
Rationale: The correct answer is A: Treponema. Treponema pallidum is a spirochete bacterium that appears as long, thin, and spiral-shaped microorganisms with 8-12 regular coils under the microscope. This characteristic morphology is specific to Treponema species, making it the correct choice. Borrelia, Leptospira, and Vibrios have different shapes and arrangements under the microscope, making them incorrect choices in this scenario.
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The most common test for the diagnosis of Lyme borreliosis is:
- A. Widal agglutination test
- B. Cultivation on blood and chocolate agar
- C. ELISA, Western blot
- D. Ascoli thermoprecipitation test
Correct Answer: C
Rationale: The correct answer is C: ELISA, Western blot. These tests are commonly used for diagnosing Lyme borreliosis due to their high sensitivity and specificity in detecting antibodies against Borrelia burgdorferi, the causative agent. ELISA is the initial screening test, while Western blot is used for confirmation. Widal agglutination test (A) is used for diagnosing typhoid fever, not Lyme disease. Cultivation on blood and chocolate agar (B) is not commonly used for diagnosing Lyme borreliosis as Borrelia species are difficult to culture. Ascoli thermoprecipitation test (D) is used for diagnosing pneumonia caused by Streptococcus pneumoniae, not Lyme disease.
Extrachromosomal carriers of the genetic information in bacteria are:
- A. Mesosomes
- B. Plasmids
- C. Ribosomes
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Plasmids. Plasmids are extrachromosomal DNA molecules found in bacteria that can replicate independently of the bacterial chromosome. They carry additional genetic information, such as antibiotic resistance genes or virulence factors. Mesosomes (choice A) are not involved in carrying genetic information; they are infoldings of the cell membrane. Ribosomes (choice C) are cellular organelles responsible for protein synthesis, not carriers of genetic information. Choice D is incorrect as plasmids are indeed extrachromosomal carriers of genetic information in bacteria.
In a bacteriology lab, bacteria cultured from fecal samples produced red colonies on Endo agar. What is the most likely microorganism?
- A. Escherichia coli
- B. Salmonella
- C. Shigella
- D. Proteus vulgaris
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. E. coli typically produces red colonies on Endo agar due to its ability to ferment lactose. This results in the production of acid, causing the colonies to appear red. Salmonella and Shigella are non-lactose fermenters, so they would appear colorless or transparent on Endo agar. Proteus vulgaris is not commonly associated with red colonies on Endo agar. Therefore, based on the characteristic lactose fermentation pattern, E. coli is the most likely microorganism in this scenario.
Sanitary bacteriological research on water by the membrane filter method revealed two red colonies on a membrane filter (Endo agar) through which 500 ml of analyzed water were passed. Calculate the coli index and coli titer of the analyzed water:
- A. 4 and 250
- B. 2 and 500
- C. 250 and 4
- D. 500 and 2
Correct Answer: A
Rationale: The correct answer is A: 4 and 250. Coli index is calculated by dividing the number of red colonies by the volume of water analyzed, which gives 2 red colonies / 500 ml = 4. Coli titer is the reciprocal of the coli index, so it is 1 / 4 = 250. This indicates the concentration of coliform bacteria in the water sample. Choices B, C, and D are incorrect as they do not follow the correct calculation steps for determining the coli index and coli titer. B has the correct coli index but incorrect coli titer. C and D have the values reversed, leading to incorrect results.
Which one of the following microbiological diagnostic methods is the most suitable for detection of genitourinary chlamydiosis
- A. cultural diagnostic
- B. ELISA
- C. CFT
- D. PCR
Correct Answer: D
Rationale: The correct answer is D: PCR. PCR (Polymerase Chain Reaction) is the most suitable method for detecting genitourinary chlamydiosis due to its high sensitivity and specificity in detecting the genetic material of Chlamydia trachomatis. PCR can detect even low levels of the pathogen, providing accurate results.
A: Cultural diagnostic is not as sensitive as PCR and may take longer to produce results.
B: ELISA detects antibodies, which may not be present in early stages of infection, leading to false-negative results.
C: CFT (Complement Fixation Test) is an older method with lower sensitivity compared to PCR for detecting chlamydiosis.