I've found an [old paper][1] using radioactively labeled bacteria to track its fate in macrophages. According to the data, both C$^{14}$ and P$^{32}$ are reutilized in the host cell. [COHN ZA. (1963)][1]. The fate of bacteria within phagocytic cells. I. The degradation of isotopically labeled bacteria by polymorphonuclear leucocytes and macrophages. J Exp Med. Jan 1;117:27-42. [1]: http://www.ncbi.nlm.nih.gov/pubmed/14022146?dopt=Abstract