Need a fact checker

Our church went to plastic communion cups years ago, not for sanitation but because there weren't enough ladies left in the altar guild to wash them when the congregation grew. Some congregations/denominations are doing away with the common cup due to fear of disease transmission. Somewhere years ago when I first started serving communion (and we do occasionally have common cup in small services), I heard that someone had tested a common cup against the individual glass cup, and found more germs on the glass due to inadequate washing and storing. Anyone know more about this? I would think the alcohol will kill some germs, although not handling the bread so much would make sense.