grades and characteristic actions of disinfectants.
High Level Disinfectants destroy all viruses and vegetative microorganisms but not endospores.
Intermediate Level Disinfectants destroy all vegetative cells including mycobacteria and most, but
not all, viruses.
Low Level Disinfectants have no activity on mycobacteria, non-enveloped viruses or endospores.__
11. What is a safer alternative to ethylene oxide sterilization?
Ozone_________________________________________________________
Week 23
What component of MacConkey agar selects for enteric bacteria?
a. phenol red
b. bile salts
c. lactose
d. agar
Which of the following is the best method for enumerating live bacterial cells?
a. Measurement of turbidity using a spectrophotometer
b. Direct counting using a cell counting chamber on a microscope slide
c. Viable counting of colonies that grow on agar plates
d. Polymerase chain reaction
Which of the following bacterial species is Gram positive?
a. Escherichia coli
b. Salmonella enterica
c. Staphylococcus aureus
d. Pseudomonas aeruginosa
How does an API strip identify bacterial species?
a. By collating the results of 20 biochemical tests
b. By antibiotic sensitivity profiling
c. By detecting catalase, oxidase and haemolysin activity
d. By differentiating the surface structures
If you have spread 0.1 ml of a diluted bacterial suspension onto 3 agar plates, how would you
calculate colony forming units per millilitre?
a. Total number of colonies x dilution factor
High Level Disinfectants destroy all viruses and vegetative microorganisms but not endospores.
Intermediate Level Disinfectants destroy all vegetative cells including mycobacteria and most, but
not all, viruses.
Low Level Disinfectants have no activity on mycobacteria, non-enveloped viruses or endospores.__
11. What is a safer alternative to ethylene oxide sterilization?
Ozone_________________________________________________________
Week 23
What component of MacConkey agar selects for enteric bacteria?
a. phenol red
b. bile salts
c. lactose
d. agar
Which of the following is the best method for enumerating live bacterial cells?
a. Measurement of turbidity using a spectrophotometer
b. Direct counting using a cell counting chamber on a microscope slide
c. Viable counting of colonies that grow on agar plates
d. Polymerase chain reaction
Which of the following bacterial species is Gram positive?
a. Escherichia coli
b. Salmonella enterica
c. Staphylococcus aureus
d. Pseudomonas aeruginosa
How does an API strip identify bacterial species?
a. By collating the results of 20 biochemical tests
b. By antibiotic sensitivity profiling
c. By detecting catalase, oxidase and haemolysin activity
d. By differentiating the surface structures
If you have spread 0.1 ml of a diluted bacterial suspension onto 3 agar plates, how would you
calculate colony forming units per millilitre?
a. Total number of colonies x dilution factor
