microbiology chapter 12 test bank

Correct Answer: A

Rationale: The likely diagnosis is Meningococcal meningitis (Choice A) due to the presence of Gram-negative diplococci in the cerebrospinal fluid. Neisseria meningitidis is a Gram-negative diplococcus commonly associated with meningococcal meningitis. Fever, chills, and neck stiffness are classic symptoms of bacterial meningitis, and Neisseria meningitidis often presents with these symptoms. Pneumococcal meningitis (Choice B) is caused by Streptococcus pneumoniae, a Gram-positive organism. Haemophilus influenzae (Choice C) is also a Gram-negative organism but typically presents with a different clinical picture. Listeria monocytogenes (Choice D) is a Gram-positive rod and is more commonly associated with meningitis in neonates, elderly, and immunocompromised individuals.

Correct Answer: A

Rationale: The correct answer is A: Smooth S colonies. Bacteria with long O-specific chains are known as smooth strains, and when cultured on solid growth media, they form smooth colonies due to the presence of the O antigen. This gives them a glossy appearance. Rough R colonies (Choice B) lack O antigen and appear rough. Mucoid -M colonies (Choice C) are associated with capsules, not O-specific chains. H colonies (Choice D) are not relevant to the O-specific chains. Smooth S colonies are the characteristic phenotype of bacteria with long O-specific chains when cultured on solid media.

Correct Answer: C

Rationale: The correct answer is C because Parvovirus B19 causes erythema infectiosum, also known as fifth disease. This virus primarily affects children and causes a distinctive red rash on the cheeks, arms, and legs. It is not associated with causing HBV (Hepatitis B Virus), AIDS, or measles. Parvovirus B19 specifically targets red blood cell precursors, leading to anemia in some cases. Understanding the characteristic clinical presentation and pathophysiology of the virus helps in selecting the correct answer.

Correct Answer: D

Rationale: The correct answer is D because the treatment for Anthrax involves using antibiotics such as penicillins, tetracyclines, and macrolides to target the bacteria. Anti-anthrax gamma-globulins and immune-serum are used to provide passive immunity, but they are not the primary treatment. Therefore, options A, B, and C are incorrect as they do not encompass all the necessary components for treating Anthrax. Overall, using a combination of antibiotics and immune-based treatments like gamma-globulins and immune-serum provides a comprehensive approach to managing Anthrax infection.

Correct Answer: A

Rationale: The correct answer is A: Mycoplasma pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia and is known to be resistant to beta-lactam antibiotics. The description of microorganisms forming microscopic colonies with a dense center resembling fried eggs is characteristic of Mycoplasma pneumoniae colonies seen on special media. Summary of other choices: B: Klebsiella pneumoniae is not typically associated with atypical pneumonia and does not exhibit the described colony morphology. C: Streptococcus pneumoniae is not resistant to beta-lactam antibiotics and does not produce colonies with the described appearance. D: Legionella pneumophila is associated with Legionnaires' disease, not atypical pneumonia, and does not form colonies resembling fried eggs.