Background: This study was carried out in the Iranian Tissue Bank Research and Preparation Center to evaluate the effectiveness of an antibiotic cocktail used for sterility of the cardiac valves and aseptic preparation method utilized for graft from March 2001 to February 2006.

Materials and Methods: This is a descriptive study of existing data on 848 cardiac valve specimens received and processed for graft at the Iranian Tissue Bank Research and Preparation Center. From two small pieces of cardiac valves dissected, one piece was directly cultured on blood agar and Methylene blue agar. The other was put in a test tube containing an antibiotic cocktail and then was cultured. The cultured media was incubated at 37 ^º c for 24 hours. The isolated bacteria were identified by standard biochemical tests. The results were analyzed statistically by the Chi square test.

Results: The overall contamination rate for cardiac valves in the intact and treatment groups was 37.7% (320 out of 848) and 5.4% (46 out of 848), respectively (P > 0.001). Gram negative bacilli were the predominant isolates. Enterobacter sp.�in 19. 4 % (62 out of 320), Streptococci in 17.2% (55 out of 320), and Klebsiella sp. in 14.1% (45 out of 320) were the most common isolated gram negative bacilli from the intact samples. Total of 46 samples from antibiotic treatment group were contaminated, and Klebsiella sp. isolated from previous sample was the most common i.e. 80.4% (37 out of 46).

Conclusion: Klebsiella sp. is the most common bacterial agent isolated from the treated cardiac valves then, further studies are necessary for antibacterial susceptibility tests and selection of the appropriate antibacterial components of the cocktail.