I recall my mother mentioning that when she was a nurse at a large teaching hospital in the UK, they had a patient who acquired a post-operative wound infection; every time they brought it under control with antibiotics, it would flare up again, baffling the infection control team, who showed time and time again that there were no antibiotic resistant strains present in cultures taken from the patient - just regular run of the mill non-resistant Staph. But the antibiotics just didn't seem to work for more than a day or two, before the infection flared back up.
After several weeks, with increasing levels of staff/patient infection barriers in place, and after testing all of the nursing staff for the presence of the offending strain of bacterium, they caught the patient's elderly mother, who had been a regular visitor, sprinkling the wound with holy water brought from a local church. The water and the font from which it was taken were found to contain high levels of the exact strain of Staphylococcus found in the wound.
Of course, it's just her personal belief; What possible harm could it do?
