[Studies on beta-lactam antibiotics for medicinal purpose. XI. Studies on the metabolism of sodium 7-(D(-)-alpha-(4-ethyl-2,3-dioxo-1-piperazinecarboxamido)-alpha-(4-hydroxyphenyl)acetamido)-3-((1-methyl-1H-tetrazole-5-yl)thiomethyl)-3-cephem-4-carboxylate (T-1551) (author's transl)]