Question

95. Dry heat kills by oxidation while moist heat kills by denaturation of proteins.               

A. True                

B. False

                                                                                          

96. Any medium can be used for antibiotic susceptibility testing by the disk agar diffusion method.                                                                                                                                                                         

A. True                  

B. False

97. Pseudomonas aeruginosa is an obligate aerobe and is a nonfermenter.                                                                   

A. True                

B. False

Answer 1

95. True.

Sterilization by moist heat destroys microorganisms due to irreversible denaturation of structural proteins and enzymes. The temperature applied for sterilization varies and is inversely proportional with the amount of water present. Moist heat sterilization requires perfect control of time, pressure and temperature.

96. False.

The most commonly used media for antibiotic susceptibility testing is Mueller Hinton Agar. The advantage of using this media is its acceptable batch-to-batch reproducibility and also satisfactory growth of most non-fastidious pathogens.MH agar has low concentration of sulfonamide, trimethoprim, and tetracycline inhibitors which avoids wrong results. However, depending on the pathogen very rarely selective media and supplemets are used for antibiotic susceptibility testing.

97. True

Pseudomonas aeruginosa is a gram-negative rod shaped bacteria. It is an obligate aerobe which follows aerobic respiration using oxygen for its optimal metabolism. P. aeruginosa can oxidize a wide range of organic molecules such aas glucose and xylose but it does not ferment lactose or other carbohydrates and is thus non-fermenter.