A Gram-negative bacterium producing a blue-green pigment and having a fruity odor was isolated from a patient's wound infection. What is the likely causative agent?

Correct Answer: A

Rationale: Step-by-step rationale: 1. Blue-green pigment + fruity odor are characteristic of Pseudomonas aeruginosa. 2. P. aeruginosa is a Gram-negative bacterium commonly associated with wound infections. 3. P. aeruginosa is known for its ability to produce pyocyanin (blue-green pigment) and a sweet, fruity odor. 4. Other choices like E. coli, K. pneumoniae, and P. mirabilis do not typically produce blue-green pigment or fruity odor. 5. Therefore, based on the characteristics observed, the likely causative agent is Pseudomonas aeruginosa. Summary of other choices: - Escherichia coli: Does not produce blue-green pigment or fruity odor. - Klebsiella pneumoniae: Does not typically produce blue-green pigment or fruity odor. - Proteus mirabilis: Does not produce blue-green pigment or fruity odor.

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.

Correct Answer: C

Rationale: The correct answer is C: urethra. Resident microflora refers to the normal, beneficial bacteria that inhabit a specific area of the body without causing harm. The urethra is one of the locations where resident microflora are commonly found. These bacteria play a vital role in maintaining a healthy balance and preventing harmful pathogens from colonizing the urethra. Blood (A), lung (B), and cerebro-spinal fluid (D) are not typical locations for resident microflora as these areas are usually sterile or have very limited microbial presence to prevent infections.

Correct Answer: B

Rationale: The correct answer is B because reinfection is indeed possible with rabies virus. Step 1: Reinfection occurs if a person is exposed to the virus again after initial infection. Step 2: Once infected, the virus can remain dormant in the body and become active upon re-exposure. Step 3: Therefore, it is essential to continue preventive measures even after initial immunization. Summary: Choices A, C, and D are incorrect because antibodies develop within 14-15 days post-immunization, HRIG is administered shortly after exposure, and a specific vaccination schedule is followed for rabies prophylaxis, respectively.

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.

Correct Answer: B

Rationale: The correct answer is B because live vaccines can potentially revert to a virulent form, although this is extremely rare. This is due to the live attenuated virus in the vaccine potentially mutating back to a more dangerous form. Live vaccines are designed to be weakened but there is a small risk of reversion. Therefore, statement B is not correct. A: This statement is correct as immunocompromised individuals may have adverse reactions to live vaccines due to their weakened immune system. C: This statement is correct as microbes with many serotypes can make it challenging to develop a vaccine that covers all variations. D: This statement is correct as side effects to vaccination, although usually mild and temporary, can occur in some individuals.

Correct Answer: A

Rationale: Exotoxins are proteins produced inside the microbe cell and then released outside the cell to exert their toxic effects on neighboring cells or tissues. This is why choice A is correct. Choices B and C are incorrect because exotoxins are not meant to act within the same cell they are produced in. Choice D is incorrect because exotoxins are usually released without causing cell lysis; they are secreted by the microbe actively rather than being leaked out due to cell damage.

Correct Answer: A

Rationale: The correct answer is A: Clostridium botulinum. Clostridium botulinum produces the neurotoxin that causes botulism. This bacterium thrives in anaerobic conditions and contaminated food. The neurotoxin blocks acetylcholine release at the neuromuscular junction, leading to muscle paralysis. Choices B, C, and D are incorrect because Clostridium tetani causes tetanus, Escherichia coli can cause food poisoning but not botulism, and Staphylococcus aureus produces enterotoxins causing food poisoning, not botulism.

Correct Answer: A

Rationale: The correct answer is A: BCG vaccination. The Mantoux test is used to detect tuberculosis infection. A negative reaction means the child is not infected. BCG vaccination is recommended for individuals without prior TB infection to prevent severe forms of the disease. Antitoxin and rabies vaccinations are not related to TB and are not indicated in this scenario. Repeating the Mantoux test is unnecessary since a negative result indicates absence of TB infection.