LAC meaning in Medical ?

Lactobacillus acidophilus (New Latin 'acid-loving milk-bacillus') is a species of gram positive bacteria in the genus Lactobacillus. L. acidophilus is a homofermentative, microaerophilic species, fermenting sugars into lactic acid, and grows readily at rather low pH values (below pH 5.0) and has an optimum growth temperature of around 37 °C (99 °F). L. acidophilus is found in the human and animal gastrointestinal tract and mouth.Some strains of L. acidophilus may be considered to have probiotic characteristics. These strains are commercially used in many dairy products, sometimes together with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in the production of acidophilus-type yogurt, or acidophiline. Its genome has been sequenced.

L. acidophilus was found to lower serum cholesterol and raise cholesterol in fecal matter when fed to pigs. These pigs were fed the same amount of food, with the same nutritional content, but one group received saline solution with L. acidophilus while the other group received just the saline. The group given the saline with the bacteria had lowered serum cholesterol compared to the control group. Pigs were chosen because their digestive system is similar to that of humans.

L. acidophilus is also correlated with antagonistic actions upon growth for Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Clostridium perfringens. The S. aureus, out of the four organisms, was the most affected by L. acidophilus. However, along with S. aureus, the other gram positive bacteria C. perfringens, was affected more by L. acidophilus, than the two other bacteria that are gram negative.

L. acidophilus is found to also reduce oral plaque formation by Streptococcus mutans. Although some research has been done, more needs to be done to determine how strong the effect is on S. mutans, what the effect is, and how exactly the effect is executed on L. acidophilus. The research was performed in the lab, and not on animals.