I found these papers will be most useful for your questions
Arunachalam K.D., Gill H.S., and Chandra R.K. “Enhancement of natural immune function by dietary consumption of Bificlobacterium lactis”, European journal of Clinical Nutrition 2000, Vol. 54, No: 3, PP: 263-267.
Well, many studies showed that most probiotic strains are GRAS. Hence, administrating them to elders will not be a problem. However, it is really important that what method you choose for doing it. Whether you want to use supplementation or food carriers. On the other hand, it is important which strains do you choose. I recommend food products with probiotics to my elder patients all the time and it works well. I consider products with Lactobacillus acidophilus and/or Bifidobacterium lactis, since they are the most safe and common strains.
Patrick, permitt me present for you some books edited for me. I hope that they be useful for you. Its address is http://www.intechopen.com/profiles/39553/Everlon-Rigobelo
Obrigado por seu retorno Everlon. Estamos elaborando nossa dissertação de mestrado na FMB envolvendo o tema e o uso de probióticos em idosos institucionalizados, agradeço seu contato e a indicação de suas referências.
We use probiotics in all our nursing home residents who receive antibiotics for over 10 years. We rarely see Clostridium difficile diarrhea in nursing home residents treated this way. A recent meta-analysis supports this viewpoint.
Comparative effectiveness of Clostridium difficile treatments: a systematic review.
Drekonja DM, Butler M, MacDonald R, Bliss D, Filice GA, Rector TS, Wilt TJ.