Geocillin, a trade name is the sodium salt of the indanyl ester of carbenicillin disodium, which used to treat acute and chronic infections of the upper and lower urinary tract and in asymptomatic bacteriuria due to susceptible strains of bacteria. In addition, Geocillin was also indicated in the treatment of prostatitis due to susceptible strains of the following organisms: Escherichia coli; Enterococcus (S. faecalis); Proteus mirabilis; Enterobacter sp. Free carbenicillin is the predominant pharmacologically active fraction of Geocillin. After absorption, Geocillin is rapidly converted to carbenicillin by hydrolysis of the ester linkage. Carbenicillin exerts its antibacterial activity by interference with final cell wall synthesis of susceptible bacteria. Penicillins acylate the penicillin-sensitive transpeptidase C-terminal domain by opening the lactam ring. This inactivation of the enzyme prevents the formation of a cross-link of two linear peptidoglycan strands, inhibiting the third and last stage of bacterial cell wall synthesis. In 2008 Pfizer has decided to discontinue the manufacturing of Geocillin (carbenicillin indanyl sodium)