I haven't tried Threelac, but was curious about your question so decided to look into it. This is what I found:
This is a quote from a website selling Threelac:
The live organisms in ThreeLac have been clinically proven to reduce candidiasis. Threelac are Lactobacillus Sporogenes, Bacillus Subtilis and Streptococcus Faecalis. In a delivery system which gets those bacteria into the intestines alive and unharmed.
Starting with the first: "lactobacillus sporogenes," this is what I found on Food-info.net:
Lactobacillus sporogenes ; this name is a fantasy name; no bacterial species with this name exist. It is claimed that this bacterium makes spores. By definition, lactobacilli can not make spores. It is unknown which species is used in the products with this ‘bacterium'. It has been mentioned (by the producer (!)) that it is actually a Bacillus coagulans strain. This is a soil bacterium, which is not present in the human intestine, and which has not been tested in human trials. It may also be a Clostridium sporogenes , a spore-forming organism, which is a human pathogen.
The second, "bacillus subtilis;" info obtained from wikipedia, but appears to be documented (I'm not going to look those up, though, suit yourself). I will add to the info below, that I don't know whether the strain QST713 is the same strain in Threelac.
B. subtilis is not considered a human pathogen; however it may contaminate food but rarely causes food poisoning. Its spores can survive the extreme heating that is often used to cook food, and it is responsible for causing ropiness in spoiled bread. Nevertheless, a strain of B. subtilis formerly known as Bacillus natto is used in the commercial production of the Japanese delicacy natto as well as the similar Korean food cheonggukjang. Other strains of B. subtilis also have commercial applications. For instance, B. subtilis strain QST 713 (marketed as QST 713 or Serenade™) has a natural fungicidal activity, and is employed as a biological control agent.,
The third, "Streptococcus Faecalis:" info from food-info.net:
Streptococcus faecium ; this name became obsolete in the early 1980s and may not be used since. The correct name is Enterococcus faecium . As this species is also a known pathogen, it is necessary that the strain number and name are properly used.
and from medinfo:
The enterococcus (previously Streptococcus faecalis), causes many of the same problems as other members of the intestinal flora. These include opportunistic urinary tract infections and wound infections. In contrast to the Enterobacteriaceae, enterococcal infection is often associated with bacteremia which can lead to endocarditis or colonization of previously damaged heart valves. Little is known about its pathogenesis. The D in an older name, group D strep, refers to the Lancefield classification which is based on the antigenicity of a carbohydrate which is soluble in dilute acid and called the C carbohydrate. Lancefield identified 13 types of C carbohydrate, designated A through O, that could be serologically differentiated. The organisms that most commonly infect humans are found in groups A, B, D, and G. Streptococci that do not contain the C carbohydrate substance are called viridans streptococci or non-typable streptococci.
OK, I'm still not an expert or anything, but if the product isn't helping you, and given that the above info raises concerns that it could harm you, I'd suggest that you reconsider using the product. I have a heart murmer, and wouldn't dare touch it!
Besides, if you are using a probiotic, well isn't that what Threelac is claiming to be? So it would be redundant anyways.
I'd suggest that you try reading on the board. There are some other approaches that may be more helpful to you than the Threelac has been. Now that I know a little more about it, I plan to bring this info to my health store and make sure they don't stock it. I know the owner doesn't want to harm anyone.
If you really have a problem with candida, you will need to follow a diet and also use some form of antifungals. That is the minimum that appears to be needed to get better. I found that I needed to do more, like P&B shakes, etc. Look around on the board some more!
Good luck and good health to you!