Rheumatic fever is an inflammatory disease and rare complication of:

Correct Answer: A

Rationale: Rheumatic fever is caused by untreated strep throat. Step 1: Strep throat is caused by Streptococcus bacteria. Step 2: If strep throat is not treated with antibiotics, it may lead to rheumatic fever due to the body's immune response attacking its own tissues. Summary: Gangrene, brucellosis, and tularemia are not associated with rheumatic fever.

Correct Answer: B

Rationale: The correct answer is B: Yersinia pestis. Yersinia pestis is the bacterium responsible for causing the plague, specifically the bubonic plague. It is transmitted through fleas and rodents. Escherichia coli (A) is a common gut bacterium, Clostridium difficile (C) causes antibiotic-associated diarrhea, and Staphylococcus aureus (D) is associated with skin infections, but they are not responsible for causing the plague.

Correct Answer: B

Rationale: During latency, HSV1 exists as episomes in neurons. This is because HSV1 establishes a lifelong latent infection in sensory neurons, where the viral genome remains as a circular episome in the nucleus. This form allows the virus to persist in a dormant state, avoiding detection by the immune system. Choice A is incorrect as HSV1 does not integrate into the host chromosome. Choice C is incorrect as latency is a well-documented phenomenon for HSV1. Choice D is incorrect as the correct answer is B.

Correct Answer: A

Rationale: The correct answer is A: Metronidazole. Rationale: 1. Metronidazole is the drug of choice for amebic dysentery due to its effectiveness against the causative agent, Entamoeba histolytica. 2. Metronidazole has good tissue penetration and is able to reach the site of infection in the gut. 3. It is a bactericidal drug that acts by disrupting the DNA structure of the parasite. 4. Metronidazole is well-absorbed orally and has minimal side effects. Summary of other choices: B: Furazolidonum - Not the drug of choice for amebic dysentery. It is primarily used for treating bacterial diarrhea. C: Levomycetin - Not effective against Entamoeba histolytica and not recommended for amebic dysentery. D: Phthalazol - Not commonly used for amebic dysentery treatment. Metronidazole is preferred due

Correct Answer: B

Rationale: The correct answer is B: Clostridium botulinum. This bacterium belongs to the Clostridium genus, known for its ability to produce endospores. Endospores are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not produce endospores. Staphylococcus aureus is a gram-positive bacterium known for causing various infections, but it does not form endospores. Escherichia coli is a gram-negative bacterium commonly found in the intestines of humans and animals, but it does not produce endospores. Neisseria gonorrhoeae is a gram-negative bacterium that causes the sexually transmitted infection gonorrhea, but it also does not form endospores.

Correct Answer: B

Rationale: The correct answer is B: Staphylococcus aureus. This bacterium is commonly found in hospital environments due to its ability to colonize human skin and mucous membranes. It is a leading cause of hospital-acquired infections. Borrelia burgdorferi is mainly associated with Lyme disease transmitted by ticks, not commonly found in hospitals. Bacillus cereus is a foodborne pathogen, not typically prevalent in hospital settings. Staphylococcus haemolyticus is a coagulase-negative staphylococcus species, less pathogenic and less common in hospitals compared to Staphylococcus aureus.

Correct Answer: A

Rationale: The correct answer is A: Tetanus. The symptoms of tonic tension of the masticatory muscles following a dog bite are indicative of tetanus, caused by the bacterium Clostridium tetani. The incubation period of tetanus is usually 3-21 days, consistent with the patient's history of being bitten 12 days ago. Tetanus toxin causes muscle stiffness and spasms, leading to the inability to open the mouth. Rabies (B) presents with hydrophobia and neurological symptoms. Hysteria (C) is a psychological condition. Trigeminal neuralgia (D) is characterized by severe facial pain, not muscle stiffness.

Correct Answer: C

Rationale: The correct answer is C: young adults. Young adults are at a higher risk for sexually transmitted infections (STIs) due to factors such as engaging in risky sexual behaviors, lack of awareness, and inconsistent condom use. They are more likely to have multiple sexual partners and are less likely to seek regular STI screenings. Adolescents, while also at risk, may not make up almost half of all STI cases in the U.S. The elderly, on the other hand, are generally at a lower risk due to lower levels of sexual activity compared to young adults.

Correct Answer: A

Rationale: The correct answer is A: Neisseria meningitidis. Step 1: Gram-negative diplococci - characteristic of Neisseria species. Step 2: Oxidase-positive - Neisseria species are oxidase-positive. Step 3: Fermentative - Neisseria meningitidis is a fermentative bacterium. Therefore, Neisseria meningitidis is the most likely causative agent. Summary: - B: Neisseria gonorrhoeae is also a Neisseria species but is not fermentative. - C: Moraxella catarrhalis is oxidase-positive but not fermentative. - D: Haemophilus influenzae is not a Neisseria species and is not typically fermentative.