*3.1.2 Sorbitol*

Another alcohol soluble sugar; **sorbitol**, act as a metabolic substrate for bacterial specific imaging. Gram negative bacterial strains (*Klebsiella pneumoniae*, *Escherichia coli*, Yersinia pestis, Enterobacter spp., etc.) show promising findings but limited detection in case of Gram-positive bacteria and mammalian cancer cells. Sorbitol was taken up by the bacterial surface membrane transporter, then phosphorylated and metabolized in the same manner as glucose. Initially 18F-FDG reduce to 18F-FDS (fluorodeoxysorbitol) as shown in **Figure 14** than transported to bacterial cell environment where analogous glucose metabolism begin next [47]. Interesting fact is that mammalian cells did not have transporter for this sugar [43]. Moreover, 18F-FDS act as promising agent in PET imaging for monitoring efficacy of antibacterial burden and proved to be safe for intravenous human use that determine radiation dosimetry and cell biodistribution [48].
