I looked up the book called SOURCEBOOK OF BIOLOGICAL TERMS
by ED JAEGER and found that
iatr -> Greek for iatros meaning physician, healing, able to heal
nosocomial --> meaning hospital
My guess is iatrogenic infection comes form the fault of the doctor,
while nosocomial infection is the hospital aquired infection that
could come from patient-> patient, doctor -> patient, patient ->
health care workers etc.
This is just my guess, correct me if I am wrong.
I would like to know the true answer too.