microbiology basic and clinical principles test bank

Correct Answer: B

Rationale: The correct answer is B: biofilms. Biofilms refer to complex communities of microorganisms that adhere to surfaces. They are characterized by a protective matrix that allows the microorganisms to communicate and cooperate. Colonies (A) typically refer to groups of a single species, not diverse communities. Biospheres (C) refer to the regions of the Earth where life exists, not specific microbial communities. Flora (D) generally refers to the plant life in a particular region, not microbial communities on surfaces.

Correct Answer: B

Rationale: The correct answer is B. Immunity after a single tetanus vaccination is of limited duration, usually around 10 years. Booster vaccinations are needed to maintain protection due to waning immunity over time. Choice A is incorrect as immunity is not usually lifelong. Choice C is incorrect as tetanus toxoid is a sterile vaccine and does not cause infection. Choice D is also incorrect as there is a correct answer, which is B.

Correct Answer: A

Rationale: The correct answer is A: Sabouraud. Sabouraud agar is specifically designed for the cultivation of fungi and yeasts, making it ideal for identifying Candida species causing candidosis. It contains antibiotics to inhibit bacterial growth, promoting the growth of fungi. Endo, Loewenstein-Jensen, and Roux are not suitable for fungal cultures and are used for different purposes like bacterial isolation or mycobacterial cultures. Sabouraud agar is the best choice for confirming candidosis due to its fungal-selective properties.

Correct Answer: B

Rationale: The correct answer is B: Chlamydia trachomatis. This is because Chlamydia trachomatis is an obligate intracellular bacterium that cannot be cultured on standard agar plates. The symptoms described by the patient, such as pain, burning at urination, and scarce secretion in the morning, are indicative of a possible chlamydial infection. Additionally, the fact that the urine cultures are sterile after 24 hours of incubation suggests that the causative agent is not a typical bacteria like Escherichia coli, Streptococcus pneumoniae, or Neisseria gonorrhoeae, which would normally grow on agar plates. Therefore, Chlamydia trachomatis is the most probable cause of this disease. Summary: A: Escherichia coli - Incorrect, as it is a common cause of urinary tract infections and would typically grow on agar plates. C: Streptococcus pneumoniae - Incorrect, as it is

Correct Answer: D

Rationale: The correct answer is D because bacteremia can be caused by a variety of bacteria including S.epidermidis, E.coli, S.aureus, P.aeruginosa, K.pneumoniae, and resident skin diphtheroids. Bacteremia refers to the presence of bacteria in the bloodstream, which can occur due to infections from various sources. Choices A and B include common bacteria known to cause bacteremia, while choice C refers to resident skin diphtheroids that can also enter the bloodstream under certain conditions. Therefore, the correct answer is D as it encompasses all the possible etiological causes of bacteremia.