Effects of Leukocyte Extract from the American Alligator (Alligator mississippiensis) on Antibiotic-Resistant Bacteria

Treatment of clinical isolates of human pathogenic bacteria, which were known to be resistant to multiple commonly-used antibiotics, with refined leukocyte extracts from the American alligator (Alligator mississippiensis) resulted in a time- and concentration-dependent inhibition of bacterial proliferation. The alligator leukocyte extract exhibited the strongest antibacterial effect on Pseudomonas aeruginosa followed by Enterococcus faecium and then Klebsiella pneumonia. The antibacterial activities were acid-soluble, heat-stable at 70oC for one h, sensitive to protease treatment, and did not require divalent metal ions for antibacterial activity. Collectively, these data strongly suggest that the molecule(s) responsible for the observed antibacterial activities are small, cationic antimicrobial peptides.