Antibacterial and Antifungal Activities from Siamese Crocodile Blood
Ratree Leelawongtawon PhD*, Jindawan Siruntawineti PhD**, Win Chaeychomsri PhD**, Chisanucha Sattaponpan BSc***
Affiliation : * Division of Microbiology and Immunology, Preclinical Science Institute, Faculty of Medicine, Thammasat University, Pathumthani, Thailand ** Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand *** Research Office, Faculty of Medicine, Thammasat University, Pathumthani, Thailand
Objective : To evaluate the in vitro antimicrobial activity of the Siamese crocodile blood against bacteria and fungi.
Material and Method: Thirty Siamese crocodile blood samples including freeze dried whole blood (FDWB), fresh serum
(FS), and freeze dried serum (FDS) were evaluated for antimicrobial susceptibility and MIC values against ATCC-registered
strains of nine bacterial species and two fungal species and one fungus isolated from a clinical specimen, by using the
standard broth microdilution method and a modified resazurin microtiter plate assay.
Results : The result showed that FS (80 mg/ml) and FDS (100 mg/ml) inhibited Gram negative bacteria including Enterobacter
aerogenes ATCC 13048, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 27736, Salmonella typhimurium
ATCC 13311 and Pseudomonas aeruginosa ATCC 27853 with the susceptibility rate at 23.30%, 10.00%, 40.00%, 70.00%,
and 86.67%, respectively for FS, and 30.00%, 10.00%, 43.33%, 76.67% and 90.00%, respectively for FDS. The MIC and
MBC were in the range of 12.50-100.00 mg/ml and 25.00-100.00 mg/ml, respectively. FS and FDS also inhibited Cryptococcus
neoformans 250309 and Aspergillus niger with the susceptibility rate at 90.00% and 80.00%, respectively for FS and
100.00% and 83.33%, respectively for FDS. The MIC was in the range of 25.00-100.00 mg/ml. However, FS and FDS did
not inhibit Gram positive bacteria and did not kill fungi. FDWB (100 mg/ml) could neither inhibit bacteria nor fungi.
Conclusion : FS and FDS from Siamese crocodile exhibited potential antibacterial and antifungal activities.
Keywords : Antimicrobial susceptibility test, Siamese crocodile blood, MIC, MBC
