Introduction
The bacteriostatic activity of "Proteque Skin Protectant Lotion" (containing 0.3% Irgasan DP 300) have been determined under in-vivo fingerprint test conditions against gram-positive and gram-negative bacteria. The results have been compared to the placebo "Proteque Skin Protectant Lotion" and a hand lotion containing 0.3% lrgasan DP 300 from the market.

Conclusion

• The Irgasan DP300 containing "Proteque Skin Protectant Lotion" as well as the hand lotion containing 0.3% Irgasan DP 300 from the market show excellent long term bacteriostatic effects up to 6 hours after application on the skin.
• After two washing cycles with a placebo bar soap still good antibacterial effects on the treated skin have been shown.
• The "Proteque Skin Protectant Lotion" without Irgasan DP 300 shows absolutely no antibacterial effects on the treated skin.

Realization time: 12 hours.

"Proteque Skin Protectant Lotion" (containing 0.3% Irgasan DP 300)
	Staphylococcus aureus ATCC 9144	Escherichia coli NCTC 8196
	VR	VR
Placebo	0/0	0/0
Immediately after application	4/4	4/4
After 4 hours	2/2	2/2
After 6 hours	2/2	2/2
After 6 hours and two washings with placebo soap	2/2	2/2

"Proteque Skin Protectant Lotion" (without Irgasan DP 300)
	Staphylococcus aureus ATCC 9144	Escherichia coli NCTC 8196
	VR	VR
Placebo	0/0	0/0
Immediately after application	0/0	0/0
After 4 hours	0/0	0/0
After 6 hours	0/0	0/0
After 6 hours and two washings with placebo soap	0/0	0/0

• Each test was performed twice and both results are given in the table.
• VR = Vinson rating
  • 0 = strong growth (no activity)
  • 2 = moderate growth (good activity)
  • 4 = no growth (very good activity)

Microbiological test methods.

Fingerprint test (Ciba method No. 139).

Samples:

• "Proteque Skin Protectant Lotion"
  Lab Ref#: l IM086D/B#l 2801 (containing 0.3% Irgasan DP 300).
• "Proteque Skin Protectant Lotion"
  Lab Ref#: l IM086D-Placebo/Ol 30 (without Irgasan DP 300).
• Anti-bacterial hand lotion (containing 0.3% Irgasan DP 300).

Test bacteria: Staphylococcus aureus ATCC 9144, Escherichia coli NCTC 8196.

Nutrient medium: Casein soy meal pepton agar.

Incubation: 24 hours at 37°C.

Principle:

• The hands were wetted for 15 sec. under running tap water.
• Hands were washed with a placebo soap, rinsed and dried.
• Finger tips were pressed lightly on the solidified agar medium containing test bacteria. For preparation of the agar plates, 3.5 ml of a 1:1000 diluted overnight culture was added to 500 ml agar for Escherichia coli, and a 1:100 diluted overnight culture for Staphylococcus aureus.
• Subsequently hands were rubbed with 3 ml test formulation and dried.
• The finger tips were pressed lightly on the prepared plates for 30 sec.
• During the incubation phase, the antimicrobial substance is allowed to diffuse into the agar resulting in clear zones due to inhibition of the bacterial growth. For testing the remnant effect, step 5 was repeated 4 and 6 hours after application of the product. After the 6 hours print has been performed, the hands have been washed twice with placebo soap for 30 seconds under running tap water. Between both washing cycles, the finger tips were again pressed lightly on the prepared plates for 30 sec.