lec 1: controlling microbial growth in vitro

Question 1

microbes that have a high degree of resistance to disinfection and sterilization

Answer 1

• prions (the most resistant to heat)
• bacterial spores
• protozoal cysts
• mycobacteria

Question 2

microbes that have a low degree of resistance to disinfection and sterilization

Answer 2

vegetative bacteria
enveloped (lipid) or medium-sized viruses

Question 3

what is lyophilization

Answer 3

a process combining the effects of cold and drying to preserve a wide variety of objects

Question 4

dry heat is usually performed at

Answer 4

160-165 c for 2 hours or 170-180 for 1 hour

Question 5

moist heat (autoclaving) is performed at

Answer 5

121.5 c and 15 psi for 20 minutes

Question 6

properties of an ideal disinfectant

Answer 6

1- Easy to prepare and apply (soluble in water) , fast-acting
2- Broad antimicrobial spectrum
3- Leave a residual antimicrobial film
4- Not affected by organic matter (feces, blood, vomitus, pus)
5- Nontoxic to human tissue and Non-destructive to inanimate objects
6- Stable, Odorless, and Inexpensive