Isolation and Characterization of Lytic Bacteriophages Infecting Acinetobacter baumannii

Abstract

This study was carried out during the period from October 2015 to March 2016. It included the isolation of 42 isolates were identified asAcinetobacterbaumannii. All Isolates showed wide range of resistance to antibiotics. Two types of lytic bacteriophages primarily named Phage 1 and Phage 2 were isolated from sewage water. Phage 1 exhibited broad host spectrum it was lytic against all Acinetobacter baumannii isolates included for the study. Conversely,phage 2 have narrow host range as they could inhibit only 30 isolates,None of these phages inhibited a bacterium other than staphylococci species. The adsorption rate of Phage 1 was 3.1×10-10 ml min-1while Phage 2 was 1.7×10-10 ml min-1. Eclipse and Latent periods of Phage 1 were 6,17 minutes and for phage 2 were 7,14 minutes respectively,the burst size of Phage 1 and Phage 2 were 73±16 pfu\cell and 38±11 pfu\cell respectively. Complete lysis time of Phage 1 particles was 4.30 hours while the complete lysis time of Phage 2 particles was 6 hours. Phages passaging results showed a remarkable increment in PFU which were reached its maximal elevation at six passage in Phage 1 and fourth passage in Phage 2. Fitness of Phage 1 and Phage 2 were 24 ±5 pfu\cell and 26 ±4 pfu\cellrespectively through six generations. The Phage 1 and Phage 2 particles were stabled at a wide range of pH (6-10) and temperatures (30-50°C),the optimal temperature of two phages were 37°C.