ATI RN
microbiology an introduction 13th edition test bank Questions
Question 1 of 5
Which bacterial structure is involved in conjugation?
Correct Answer: C
Rationale: The correct answer is C: Pili. Pili are bacterial structures involved in conjugation, which is the process of transferring genetic material between bacterial cells. Pili facilitate the physical contact between donor and recipient cells, allowing for the transfer of plasmids or other genetic material. Capsules (choice A) are involved in protection and adherence, not conjugation. Flagella (choice B) are responsible for bacterial motility. Fimbriae (choice D) are also involved in adherence but not in conjugation. Therefore, the correct answer is C as pili specifically play a crucial role in the process of conjugation.
Question 2 of 5
A wound culture grew Gram-positive rods with central spores. The bacteria were catalase-positive and aerobic. Identify the microorganism.
Correct Answer: A
Rationale: The correct answer is A: Bacillus anthracis. The presence of Gram-positive rods with central spores, catalase-positive, and aerobic growth characteristics are indicative of Bacillus anthracis. Bacillus anthracis is known for its central spores and ability to grow aerobically. Summary of why other choices are incorrect: B: Clostridium tetani is a Gram-positive rod with terminal spores and is anaerobic. C: Streptococcus pyogenes is a Gram-positive cocci and catalase-negative. D: Klebsiella pneumoniae is a Gram-negative rod and catalase-positive, but is not associated with central spores.
Question 3 of 5
A Gram-stained smear from a urethral discharge revealed Gram-negative diplococci. The patient presented with dysuria and purulent discharge. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Neisseria gonorrhoeae. This bacterium is the likely causative agent of the patient's symptoms based on the presentation of dysuria and purulent discharge, which are classic signs of gonorrhea. Gram-negative diplococci are characteristic of Neisseria species. Neisseria gonorrhoeae is a sexually transmitted pathogen commonly associated with urethral infections. Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis are not typically associated with urethral discharge and are not Gram-negative diplococci.
Question 4 of 5
A Gram-negative, comma-shaped bacterium was isolated from a patient with cholera. What is the most likely microorganism?
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. 1. Vibrio cholerae is a Gram-negative, comma-shaped bacterium known to cause cholera. 2. Shigella dysenteriae causes dysentery, not cholera. 3. Salmonella typhi causes typhoid fever, not cholera. 4. Campylobacter jejuni causes gastroenteritis, not cholera. Therefore, based on the symptoms presented and the characteristics of the bacterium, Vibrio cholerae is the most likely microorganism.
Question 5 of 5
A Gram-stained smear from a wound infection revealed Gram-positive cocci arranged in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci arranged in clusters, catalase-positive, and coagulase-negative characteristics are indicative of Staphylococcus species. Staphylococcus epidermidis is a common skin commensal that causes wound infections. Staphylococcus aureus is coagulase-positive and often causes more aggressive infections. Streptococcus pyogenes is catalase-negative and typically forms chains, not clusters. Enterococcus faecalis is catalase-negative and commonly found in the GI tract, not a common cause of wound infections.