The nation's top epidemiological societies have joined with the American Hospital Association and the Joint Commission to issue a compendium of guidelines for preventing six lethal conditions. The recommended practices do not vary in significant ways from the encyclopedic guidelines issued and revised over the last two decades by a government advisory panel. But their authors said they had been written more clearly and concisely, with advice not only on what hospitals should do, but also on what they should not, and on secondary approaches to try if first-line measures do not lower infection rates.