1. Lab 28 Goals and Objectives: Read results Exercise 31: Lethal Effect of UV Light Exercise 33: Effectiveness of Alcohol as an Antiseptic Exercise 36: Effectiveness of Hand Scrubbing Exercise 34: Antimicrobial Sensitivity Testing Exercise 35: Evaluation of Antiseptics

2. Read results Exercise 31: Lethal Effect of UV Light Score plates (+++, ++, +, -) for growth using control side of each plate as +++ for comparison; record on class sheet

3. Cover half with paper card UV Exposed side Control (was covered) Read results Exercise 31: Lethal Effect of UV Light Score plates (+++, ++, +, -) for growth using control side of each plate as +++ for comparison; record on class sheet

4. Exercise 33: Effectiveness of Alcohol as an Antiseptic Calculate percent reduction for control, dip and swab Colony count 1 st press = 100% Colony count 1 st press – Colony count 2 nd press = reduced number of bacteria (Colony count 1st press – Colony count 2nd press) Percent reduction = x 100 Colony count 1st press Exercise 38: Effectiveness of Hand Scrubbing Calculate CFU/ml for each scrubbing round: don’t forget to multiply by dilution factors: 0.1ml → x 10 (0.1ml is 1/10 of 1ml) 0.2ml → x 5 (0.2ml is 1/5 of 1ml) 0.4 ml → x 2.5 (0.4ml is 2/5 of 1ml)

5. Exercise 34: Antimicrobial Sensitivity Testing Figure 20.17 Disk-Diffusion Test (Kirby-Bauer test) is used in determining what treatment of antibiotics should be used when treating an infection –to determine the inhibition of bacterial growth measured under standard conditions –a culture medium - the Mueller-Hinton agar –plate lawn of bacteria and place disks of known antimicrobials on the lawn –measure zones of inhibition (total diameter in mm) Record millimeter diameter on class data chart compare to a standard table for that drug –Sensitive –Intermediate –Resistant Determine if organism is resistant, sensitive, or intermediate

6. Exercise 35: Evaluation of Antiseptics Note different effects Gram + vs Gram – for some agents