1. A patient with a history of diabetes mellitus and peripheral vascular

disease presents with a chronic ulcer on his left foot. The wound

culture reveals the presence of Pseudomonas aeruginosa, a

gram-negative rod that produces a greenish pigment and a fruity

odor. Which of the following statements is true about this

organism?

a) It is an obligate anaerobe that can cause gas gangrene.

b) It is a facultative intracellular parasite that can survive inside

macrophages.

c) It is an opportunistic pathogen that can form biofilms and resist

antibiotics.

d) It is a strict aerobe that can produce exotoxins and endotoxins.

*Answer: c) It is an opportunistic pathogen that can form biofilms and

resist antibiotics.

Rationale: Pseudomonas aeruginosa is a common cause of nosocomial

infections, especially in immunocompromised patients and those

with chronic wounds. It can adhere to surfaces and form

biofilms, which protect it from host defenses and antimicrobial

agents. It can also produce various virulence factors, such as

enzymes, siderophores, and quorum sensing molecules, that

enhance its pathogenicity and resistance.

2. A 25-year-old woman visits her gynecologist with complaints of

vaginal itching, burning, and discharge. She admits to having

unprotected sex with a new partner two weeks ago. The

gynecologist performs a wet mount of the vaginal discharge and

observes clue cells under the microscope. Which of the

following organisms is most likely responsible for this

condition?

a) Candida albicans

b) Gardnerella vaginalis

c) Neisseria gonorrhoeae

d) Trichomonas vaginalis

*Answer: b) Gardnerella vaginalis

Rationale: Gardnerella vaginalis is a gram-variable rod that can cause

bacterial vaginosis, a condition characterized by a thin, grayishwhite, fishy-smelling discharge and vaginal pH above 4.5. Clue

cells are epithelial cells covered with adherent bacteria, which

are diagnostic of bacterial vaginosis. Candida albicans is a

fungus that causes vulvovaginal candidiasis, which manifests as

a thick, white, curdy discharge and vaginal pH below 4.5.

Neisseria gonorrhoeae is a gram-negative diplococcus that

causes gonorrhea, which may present as a purulent discharge