ISOLATION OF LYTIC BACTERIOPHAGE AB72P AGAINST MULTI-DRUG RESISTANT ACINETOBACTER BAUMANNII ISOLATES OBTAINED FROM BURN INFECTION

Background & Aims: Acinetobacter baumannii is a gram-negative pathogen that causes a wide range of hospital-acquired infections. Due to its intrinsic traits and its remarkable abilities to quickly acquire resistance genes, it has become resistant to most antimicrobial agents and a major problem for hospitals. In recent years, application of lytic bacteriophages has been considered to eradicate multi-drug resistant (MDR) A. baumannii from the clinical setting. The purpose of this research was to isolate a lytic bacteriophage against MDR A. baumannii isolate obtained from an infected burn site. Materials & Methods: Different samples including lake, river and seawater, soil and municipal wastewater were tested for phage isolation by spot test and agar overlay method. Results: Lytic bacteriophage Ab72p against MDR A. baumannii isolate was isolated from municipal wastewater sample and classified as a member of Myoviridae family. The plaques formed by lytic phage Ab72p were completely clear plaque and had a diameter of 1-2 mm without halo. Phage Ab72p had an about 11 nm (in diameter) icosahedral head and a 17-22 nm (in length) contractile tail. The genome of phage Ab72p was double-stranded DNA with about 46 kb. Phage Ab72p was a very stable lytic phage in the high temperatures (up to 70 ºC) and wide range of pH (3 to 11), with an appropriate adsorption rate (99% adsorbed within 10 minutes), and large burst size (200 PFU per infected cell). Conclusion: Phage Ab72p could be appropriate choice to prepare phage cocktail against A. baumannii isolates.