AUTHOR=Thummeepak Rapee , Kitti Thawatchai , Kunthalert Duangkamol , Sitthisak Sutthirat 

TITLE=Enhanced Antibacterial Activity of Acinetobacter baumannii Bacteriophage ØABP-01 Endolysin (LysABP-01) in Combination with Colistin

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01402

DOI=10.3389/fmicb.2016.01402

ISSN=1664-302X

ABSTRACT=<p>Endolysins are lytic enzymes produced by bacteriophages with their ability to degrade the cell wall of bacterial hosts. Endolysin (LysABP-01) from <italic>Acinetobacter baumannii</italic> bacteriophage ØABP-01 was cloned, overexpressed and characterized. Endolysin LysABP-01 has a globular structure consisting of lysozyme-like (<italic>N</italic>-acetyl-β-<sc>D</sc>-muramidase) catalytic domain. It contains 185 amino acids which correspond to a 21.1 kDa protein. The lytic activity of the recombinant endolysin protein was determined by a plate lysis assay for its ability to lyse the autoclaved cell (crude cell wall) of the different bacterial species. LysABP-01 can degrade the crude cell wall of <italic>A. baumannii</italic> strains, <italic>Escherichia coli</italic> and <italic>Pseudomonas aeruginosa</italic> but not of <italic>Staphylococcus aureus</italic>. The antibacterial activity of LysABP-01 and its synergism with various antibiotics were tested. The results exhibited elevated antibacterial activity in a combination of the sub-MIC LysABP-01 and colistin. The checkerboard assay for measuring antibiotic synergy of LysABP-01 and colistin was performed. This combination was synergistic against various drug-resistant strains of <italic>A. baumannii</italic> (FIC index &lt; 0.5). In summary, our study highlights the ability of LysABP-01 endolysin to hydrolyze the <italic>A. baumannii</italic> cell wall and its synergistic interaction with colistin.</p>