microbiology a systems approach test bank

Correct Answer: A

Rationale: Rationale: 1. Salmonella typhi causes typhoid fever, which can lead to intestinal infections. 2. Shigella flexneri causes dysentery, primarily affecting the colon. 3. Helicobacter pylori causes stomach ulcers, not intestine infections. Summary: A is correct as Salmonella typhi causes intestine infection. B and C are incorrect as they cause different gastrointestinal issues. D is incorrect as A is a valid choice.

Correct Answer: A

Rationale: The Ziehl-Neelsen stain is specific for acid-fast bacteria like Mycobacterium tuberculosis. The bright red bacilli seen in the smear indicate the presence of acid-fast organisms, which is characteristic of Mycobacterium tuberculosis. Staphylococcus aureus, Clostridium tetani, and Escherichia coli are not acid-fast bacteria and would not be stained red using the Ziehl-Neelsen method. Therefore, the correct answer is A: Mycobacterium tuberculosis.

Correct Answer: C

Rationale: The correct answer is C because coagulase helps bacteria like Staphylococcus aureus to form clots, allowing them to evade the host immune response. This mechanism helps the bacteria to hide from the immune system and establish infection. A. Adhesion to surfaces is usually facilitated by other factors like adhesins. B. Breaking down red blood cells is not a function of coagulase. D. Antibiotic resistance is typically mediated by other mechanisms like efflux pumps or enzymatic inactivation, not coagulase.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae are all bacteria associated with causing bacterial meningitis. Neisseria meningitidis commonly causes meningococcal meningitis, Haemophilus influenzae can cause H. influenzae type b meningitis, and Streptococcus pneumoniae is a common cause of pneumococcal meningitis. Therefore, all three bacteria are known to be causative agents of bacterial meningitis. The other choices are incorrect as they do not encompass all the bacteria associated with causing bacterial meningitis.

Correct Answer: A

Rationale: The correct answer is A: Psittacosis. This disease is transmitted via aerosols containing dried bird droppings or respiratory secretions from infected birds. When these aerosols are inhaled, the bacteria causing psittacosis enter the respiratory system and infect the individual. - B: Shigellosis is transmitted through contaminated food or water, not via aerosols. - C: Leptospirosis is transmitted through contact with water, soil, or food contaminated with the urine of infected animals, not via aerosols. - D: Giardiasis is transmitted through ingesting contaminated food or water, not via aerosols. Therefore, Psittacosis is the only disease in the list that is transmitted via aerosols, making it the correct answer.