I am not sure what your definition of a parasite is? It may be a bacteria or a virus and the specifics need to be known before you can generally say probiotics kill parasites.

A very good probiotic can help eradicate harmful and even pathtogenic bacteria from the digestive system/GI tract. Probiotic essentially means "Lactic bacteria" and they do produce natural Antibiotics . Such Antibiotic are anti-septic to harmful bacteria and inhibits their growth further and under certain circumstances help the system expel the infection.

However, the probiotic must have multi-strains of lactic bacteria as different strains work in the different regions of the GI tract. It is also essential to distinguish between colonizing and transient. The colonizing strains can adhere to the epithelial walls of the GI tract and this prevents recurrence of the digestive problem or re-infection.

The number of lactic bacteria may be important to crowd out the harmful and pathogenic bacterium initially. They need to be replenished on a regular basis to maintain the healthy system. Probiotic assist in the system's assimilation of nutrients taken. They help break down food and absorb the required nutrients through a healthy GI tract. This in turn probably boosts the immune system of the a healthy body nutured with required nutrients.

For example there had been invitro studies with a particular lactic bacteria, Enterococcus faecalis TH 10. It has been shown by Prof. Dr. Lambert of the medical faculty of Monash University, Melbourne, Australia (1996 unpublished) that E faecalis TH10 does inhibit VRSA, MRSA, E Coli 0157 (all Antibiotic resistant bacteria) and H pylori (bacteria credited with causing peptic and oral ulcers).

I am not sure if you can consider coenzymeq10 as something that will affect living organisms. It is really a compound and I would quote:

"Coenzyme Q10 (also known as CoQ10, Q10, vitamin Q10, ubiquinone, or ubidecarenone) is a compound that is made naturally in the body. A coenzyme is a substance needed for the proper functioning of an enzyme, a protein that speeds up the rate at which chemical reactions take place in the body. The Q and the 10 in coenzyme Q10 refer to parts of the compound’s chemical structure."

You can find out more information at this link:
http://cis.nci.nih.gov/fact/9_16.htm
website of the National Cancer Institute.

Based on the above, I doubt if coenzymeq10 kills probiotics. It is more a compound within the body and not a living organism or an antibiotic?

I hope this in some way answers your question to some extent.

Take care

Our years of experience/results in permanent candida removal have proven that probiotics/acidophilus will NOT totally destroy a systemic Candida infestation. The idea behind taking any kind of acidophilus is to help replace the 'good flora' in your gut.
Common sense tells us that if you have a systemic Candida infection, the 'bad flora' must be destroyed first, in order for the 'good flora' to proliferate. The only thing proven to destroy 'systemic Candida infections' is a good quality Colloidal Silver , combined with our protocol for elimination.

Antifungal drugs such as Diflucan and Nystatin, works ONLY in the bowel, and is NOT absorbed 'systemically', thus, it's like putting a band-aid on the problem, creating a temporary solution. This is why so many people are frustrated about never getting rid of their Candida problem.
It also needs to be understood WHY people continue to create new candida infections for themselves. It's proven many times over the the "over use" of prescribed meds/ Antibiotics , alcohol, beer, and sugar, totally destroys the 'good flora', including the immune system, thus, allowing the candida to proliferate. Birth control pills, steroids, estrogens, will exacerbate the candida infestation. Many times some simple lifestyle changes will get you back on the road to optimal health.

Anti-candida nutritional supplements will help in preventing a new Candida infection, ONLY after the origional Systemic infection is eradicated.

Russ
Natural Healing Solutions
http://www.colloidalsilversolutions.com

Funny I was taking co-Q10 for about a year, a while before I got candida.