In his criticism of scientists who find Koch's postulates obsolete,1 Todd Miller overlooks one important point. Recruiting volunteers to apply Koch's postulates to diseases such as Ebola fever and AIDS has been somewhat difficult of late. There was a time when prisoners would do, but we've outgrown that practice. Koch's postulates may or may not be obsolete, but they are not universal. David Carlberg, Ph.D. Professor Department of Biological Sciences California State University Long Beach,

At the expense of sounding a bit academic, I must object to the use of the word antibiotic by Donald R. Forsdyke in his commentary1 on the chemotherapy of AIDS. Forsdyke complains that other workers avoid using antibiotic when discussing HIV treatment. Perhaps they know something he doesn't know. An antibiotic is formally defined as a microbial product that kills or inhibits other microbes. AZT and most of the other agents used to treat HIV infections are synthetic molecules. They should rightly