Nokea
A smear of streptobacillus preparation stained by Ozheshko method has been studied microscopically with oil immersion. What structural feature of the bacteria has been studied?
- A. Spores
- B. Capsule
- C. Flagella
- D. Inclusions
Correct Answer: A
Rationale: The correct answer is A: Spores. The Ozheshko method is used to stain spores, which are resistant structures produced by certain bacterial species. By studying the smear of streptobacillus preparation under oil immersion, one can observe the presence of spores as distinct, oval bodies within the bacteria. Spores are important for bacterial survival in harsh conditions.
Summary:
B: Capsules are not typically stained using the Ozheshko method. Capsules are usually visualized using negative staining techniques.
C: Flagella are not stained by the Ozheshko method. Flagella are visualized using special staining techniques like the flagella stain.
D: Inclusions are not specifically stained by the Ozheshko method. Inclusions are often observed using techniques that highlight cellular structures or components.
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The key diagnostic feature of Corynebacterium diphtheriae is:
- A. formation of spores
- B. presence of metachromatic granules
- C. production of coagulase
- D. beta-hemolysis on blood agar
Correct Answer: B
Rationale: The correct answer is B: presence of metachromatic granules. This is because Corynebacterium diphtheriae is known for containing metachromatic granules, which are characteristic of this species. These granules can be observed under a microscope and aid in the identification of the bacteria.
Explanation of other choices:
A: formation of spores - Corynebacterium diphtheriae does not form spores. Spore formation is more commonly seen in bacteria such as Bacillus and Clostridium species.
C: production of coagulase - Coagulase production is a characteristic of Staphylococcus aureus, not Corynebacterium diphtheriae.
D: beta-hemolysis on blood agar - Corynebacterium diphtheriae does not exhibit beta-hemolysis on blood agar. This type of hemolysis is more typical of Streptococcus pyogenes.
Which of the following is a phase I reaction in biotransformation?
- A. Oxidation
- B. Conjugation
- C. Acetylation
- D. Glucuronidation
Correct Answer: A
Rationale: The correct answer is A: Oxidation. Phase I reactions in biotransformation involve introducing or unmasking functional groups through oxidation, reduction, or hydrolysis. Oxidation reactions typically involve the addition of an oxygen atom or removal of hydrogen atoms, making them common phase I reactions. In this process, enzymes like cytochrome P450 play a crucial role in catalyzing the oxidation reactions.
Conjugation (B), acetylation (C), and glucuronidation (D) are all examples of phase II reactions, which involve the conjugation of the drug or metabolite with endogenous compounds to increase water solubility for excretion. These reactions typically follow phase I reactions and are not classified as phase I reactions in biotransformation.
Which of the following diseases is not caused by enteroviruses?
- A. Myocarditis
- B. Infectious mononucleosis
- C. Herpangina
- D. Boston Exanthema
Correct Answer: B
Rationale: Answer B, Infectious mononucleosis, is not caused by enteroviruses. Infectious mononucleosis is primarily caused by the Epstein-Barr virus, a member of the herpesvirus family, not by enteroviruses. Enteroviruses are known to cause diseases such as myocarditis, herpangina, and Boston exanthema. Therefore, B is the correct answer. Myocarditis, herpangina, and Boston exanthema can all be caused by enteroviruses, making choices A, C, and D incorrect, respectively.
The sample used to proving epidemic meningitis is:
- A. CSF transported at 37°C (CSF sample, blood, nasopharyngeal secretion)
- B. Feces
- C. CSF transported at +4°C
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because CSF (Cerebrospinal fluid) is the sample used for proving epidemic meningitis. It should be transported at 37°C to maintain its integrity. Blood and nasopharyngeal secretions are not typically used for diagnosing meningitis. Choice B, feces, is unrelated to the diagnosis of meningitis. Choice C, CSF transported at +4°C, is incorrect as it should be transported at 37°C to prevent degradation of the sample. Therefore, A is the correct choice for proving epidemic meningitis due to the specificity of the sample and the proper transport conditions.
A 37-year-old male was admitted to a hospital complaining of abdominal pain, difficulty in swallowing and breathing, constipation, and nausea. He developed respiratory failure and required endotracheal intubation and ventilation. Two days before, the patient consumed dried salted fish bought from an artisanal producer. Laboratory investigation for infectious pathogen was performed using Kitt-Tarozzi's method. Observation under a bright field microscopy revealed the presence of typical microorganisms with tennis racket appearance. Which of the following is the most likely diagnosis?
- A. Botulism
- B. Cholera
- C. Nontyphoidal Salmonella infection
- D. Typhoid fever
Correct Answer: A
Rationale: The correct answer is A: Botulism. Botulism is caused by the toxin produced by Clostridium botulinum bacteria found in improperly preserved or canned foods. The symptoms described align with botulism, such as difficulty swallowing and breathing due to muscle paralysis. The tennis racket appearance seen under microscopy corresponds to the characteristic appearance of Clostridium botulinum spores. The other choices can be ruled out based on the clinical presentation and microscopy findings. Cholera typically presents with severe watery diarrhea, Nontyphoidal Salmonella infection with fever and gastrointestinal symptoms, and Typhoid fever with high fever and abdominal pain. Therefore, the most likely diagnosis in this case is botulism.