In order to prevent wound infection associated with surgical procedures a patient was given a synthetic antiprotozoan drug with a high activity against Helicobacter pylori. Specify this drug:

Correct Answer: A

Rationale: The correct answer is A: Metronidazole. Metronidazole is a synthetic antiprotozoan drug with high activity against Helicobacter pylori, a bacterium that can cause wound infections. Metronidazole specifically targets anaerobic bacteria like H. pylori, making it effective in preventing wound infections. Incorrect choices: B: Doxycycline hydrochloride - Doxycycline is primarily used for bacterial infections, not protozoan infections like H. pylori. C: Chingamin - Chingamin is not a commonly used drug for treating H. pylori infections or preventing wound infections. D: Acyclovir - Acyclovir is an antiviral drug used to treat herpes infections, not bacterial or protozoan infections like H. pylori.

Correct Answer: C

Rationale: The correct answer is C: Corynebacterium diphtheriae. This bacterium causes diphtheria, a disease characterized by a pseudomembrane in the throat. This pseudomembrane is a result of the bacterial exotoxins causing inflammation and necrosis of the throat tissues. Clostridium tetani (A) causes tetanus, characterized by muscle stiffness, not a pseudomembrane in the throat. Bordetella pertussis (B) causes whooping cough, with symptoms of severe coughing fits but no pseudomembrane. Streptococcus pyogenes (D) causes strep throat, but does not produce a pseudomembrane.

Correct Answer: D

Rationale: The correct answer is D because the catarrhal stage of whooping cough is characterized by mild respiratory symptoms such as mild coughing, sneezing, or a runny nose. During this stage, the cough may start to worsen but is not yet severe. A: Incorrect - Decrease in paroxysms of coughing is not seen in the catarrhal stage; it occurs later in the paroxysmal stage. B: Incorrect - Subsequent respiratory infection for many months after the onset of pertussis is not a characteristic of the catarrhal stage. C: Incorrect - Uncontrollable coughing followed by a high pitched 'whoop' sound is typical of the paroxysmal stage, not the catarrhal stage.

Correct Answer: C

Rationale: The correct answer is C: Bacillus anthracoides. 1. The patient's symptoms align with cutaneous anthrax, caused by Bacillus anthracis. 2. Presence of immobile streptobacilli able of capsulation matches the characteristics of Bacillus anthracis. 3. Symptoms such as black crust, peripheral vesicular rash, and non-painful edema are classic for cutaneous anthrax. 4. Choice A: Bacillus antracis is a misspelling, not a valid option. 5. Choice B: Staphylococcus aureus does not match the symptoms described in the scenario. 6. Choice D: Bacillus megaterium is not associated with cutaneous anthrax.

Correct Answer: A

Rationale: The correct answer is A: IgG. IgG is the most abundant class of immunoglobulins in the body, constituting about 75% of total immunoglobulins. IgG plays a crucial role in long-term immunity, neutralizing toxins, and enhancing phagocytosis. IgE is involved in allergic reactions, IgD is mainly found on B cells and functions as a receptor, and IgM is the first antibody produced in response to an infection but is less abundant compared to IgG. Therefore, IgG is the correct choice based on its abundance and diverse functions in the immune system.

Correct Answer: B

Rationale: The correct answer is B: Clostridium botulinum. This bacterium is capable of forming spores as a survival mechanism in harsh conditions. Spore formation allows it to remain dormant until conditions become favorable for growth again. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores and rely on other mechanisms for survival. Staphylococcus aureus is a common skin bacterium, Escherichia coli is a gut bacterium, and Neisseria gonorrhoeae is a sexually transmitted bacterium.

Correct Answer: D

Rationale: The correct answer is D because Streptococci are Gram-positive bacteria, typically spherical in shape, and range from 0.5-1 µm in size. A is incorrect as streptococci are not rod-shaped and are usually smaller in size. B is incorrect as they are not Gram-negative and are not typically of such small size. C is incorrect as streptococci are not Gram-negative and are not usually rod-shaped. Thus, based on their characteristics, the correct answer is D.

Correct Answer: A

Rationale: The correct answer is A: TRUE. The innate immune system is the body's first line of defense against infections and is always active, providing immediate protection without prior exposure to a specific pathogen. It includes physical barriers, such as skin and mucous membranes, and cellular components like phagocytes and natural killer cells. The innate immune response is nonspecific and rapid, providing a crucial initial defense against pathogens. Choice B is incorrect because the innate immune system is always active, even without any prior exposure to pathogens. Choice C is incorrect because the innate immune system is consistently functioning to protect the body, regardless of the situation. Choice D is incorrect as the correct answer is A.

Correct Answer: C

Rationale: Rationale for choice C (Strep. pneumoniae): 1. Strep. pneumoniae is a common cause of bacterial meningitis. 2. It is a leading pathogen responsible for meningitis in adults and children. 3. It can invade the bloodstream and reach the meninges, causing inflammation. 4. Treatment guidelines often include antibiotics effective against Strep. pneumoniae. Summary of why other choices are incorrect: A. Staph. aureus is not a common cause of meningitis. B. Strep. pyogenes typically causes streptococcal infections but not meningitis. D. "None of the above" is incorrect as Strep. pneumoniae can cause meningitis.