The effectiveness of Antibacterial soap
The hypothesis that antibacterial soap will kill more bacteria than normal soap is proven to be true. However the antibacterial soap was effective only if the contaminated object (chopstick) was washed with antibacterial soap for more than 2 minutes.
Many diseases, such as influenza, are caused by viruses and not bacteria. These diseases are not prevented by the use of antibacterial soaps. Washing our hands with warm water and regular soap is sufficient to ward of infections provided that we thoroughly wash our hands, soaping them properly.
The experiment can be repeated by touching the petri plate with a finger instead of using saliva.
Try to repeat the experiment under different room temperatures and/or lighting conditions to ascertain if there is any impact on the rate of growth of the bacteria colonies.
Also consider repeating the experiment with anti-bacterial sprays/hand-rubs.
The bacteria should be destroyed before disposal. Pour some bleach into the petri dishes to kill all the bacteria before disposing.