WASHINGTON (AP) _ A test that can rapidly detect bacteria in beef, pork and poultry has been proven effective, the Agriculture Department said Thursday.

While the government urged companies to adopt the test, it was vague on just how they should use it. The department also said it will have to study the best way to incorporate the test in new meat safety regulations and legislation being developed.

Bacteria testing is widely practiced in the meat industry but it is not required.

Agriculture Secretary Mike Espy said the Food Safety and Inspection Service and the Agricultural Research Service, which adapted the test to animal carcasses, would work to determine how the test could be applied.

''This test will provide inspectors with microvision, not just 20/20 vision,'' Espy said at a briefing on the test, which was developed at the U.S. Meat Animal Research Center in Clay Center, Neb.

Although Espy implied that inspectors would be using the test as a supplement to their visual inspection of each carcass, it is unlikely that the test would be applied to each of the billions of carcasses that pass by inspectors each day.

Department officials said the test would be useful in quality control programs to make sure that sanitation measures are working. Current tests can now do that, but at a slower pace.

The test involves using a sponge to take a swab from a carcass, squeezing out the bacteria into a solution, extracting the cells from the solution, and reading the glow of the bacteria with a special meter.

The test has been used to some degree in the food processing and pharmaceutical industry.

Currently available tests can give a reading of general bacterial levels after 48 hours. Neither that test nor the rapid test can distinguish harmful from harmless bacteria.

And although the rapid test is able to detect only relatively high levels of bacteria, the department considers it useful.

Also, scientists are working on a version that will quickly detect harmful bacteria such as E. coli O157:H7 and salmonella. Even small levels of O157:H7 can be deadly to young children and people with weakened immune systems.

Testing for specific pathogens now takes three days.

Dan Laster, who directed the research, said the test can determine whether a carcass has been contaminated with feces, which bear both harmful and harmless bacteria. A high general bacteria count would indicate the presence of harmful ones, he said.

Michael R. Taylor, the new head of the inspection service, said that finding an application for the test will be difficult.

''There are a number of issues to be resolved,'' he said, adding that the agency will work with the inspectors' union, outside scientists and industry.