1. Exercise 33: Effectiveness of Alcohol as an Antiseptic
Lab 27 Goals and Objectives:
Exercise 33: Effectiveness of Alcohol as an Antiseptic
Calculate percent reduction for control, dip and swab
Exercise 34: Antimicrobial Sensitivity Testing
Measure zones of inhibition (total diameter in mm)
Record millimeter diameter on class data chart
Determine if organism is resistant, sensitive, or intermediate
Exercise 35: Evaluation of Antiseptics
Note different effects Gram + vs Gram – for some agents

2. Exercise 33: Effectiveness of Alcohol as an Antiseptic
Calculate percent reduction for control, dip and swab page 231
%reduction =
(#colonies 1st) – (#colonies 2nd)
(#colonies 1st)
X100

3. Exercise 35: Evaluation of Antiseptics and Disinfectants
Anything effective against only S. aureus?
Only P. aeruginosa?
Not effective on either?
Highly effective on both?
The only way to know if an agent will stop/kill a particular organism is to test it against that particular organism!

4. Exercise 34: Antimicrobial Sensitivity Testing
Measure zones of inhibition in mm
Score according to chart: S, I, R
S- sensitive; is effective for this organism
I- intermediate; is effective, but not the best
(so why use it then?)
R- resistant; is not effective for this organism
Share data on class chart

5. Pg 237
Enterobacteriaceae = many Gram negatives: Escherichia, Proteus, Enterobacter, Klebsiella, Salmonella, Shigella…

6. Exercise 33: Effectiveness of Alcohol as an Antiseptic
Lab 27 Goals and Objectives:
Exercise 33: Effectiveness of Alcohol as an Antiseptic
Calculate percent reduction for control, dip and swab
Exercise 34: Antimicrobial Sensitivity Testing
Measure zones of inhibition (total diameter in mm)
Record millimeter diameter on class data chart
Determine if organism is resistant, sensitive, or intermediate
Exercise 35: Evaluation of Antiseptics
Note different effects Gram + vs Gram – for some agents