NY -- Standard & Poor's CreditWire 3/12/97 -- Standard & Poor's today has revised the rating outlook of Darden Restaurants Inc. to negative from stable. Standard & Poor's has affirmed its triple-`B' corporate credit and senior debt ratings, as well as its `A-2' commercial paper rating on the company. The outlook change is prompted by the company's reported second and third fiscal quarter operating results, which were below Standard & Poor's expectations. The moderate improvement in Red Lobster's customer traffic and average check amount in the third quarter of 1997 were mostly offset by higher-than-expected training and labor costs. As a result, Darden's third- quarter operating income fell 56% to $27.3 million from the same period the previous year. For