Isolation and Characterization of a Virulent Bacteriophage AB1 of Acinetobacter baumannii

Abstract

BackgroundAcinetobacter baumannii is an emerging nosocomial pathogen worldwide with increasing prevalence of multi-drug and pan-drug resistance. A. baumannii exists widely in natural environment, especially in health care settings, and has been shown difficult to be eradicated. Bacteriophages are often considered alternative agent for controlling bacterial infection and contamination. In this study, we described the isolation and characterization of one virulent bacteriophage AB1 capable of specifically infecting A. baumannii.ResultsA virulent bacteriophage AB1, specific for infecting a clinical strain A. baumannii KD311, was first isolated from marine sediment sample. Restriction analysis indicated that phage AB1 was a dsDNA virus with an approximate genome size of 45.2 kb to 46.9 kb. Transmission electron microscopy showed that phage AB1 had an icosahedral head with a non-contractile tail and collar or whisker structures, and might be tentatively classified as a member of the Siphoviridae family. Proteomic pattern of phage AB1, generated by SDS-PAGE using purified phage particles, revealed five major bands and six minor bands with molecular weight ranging from 14 to 80 kilo-dalton. Also determined was the adsorption rate of phage AB1 to the host bacterium, which was significantly enhanced by addition of 10 mM CaCl2. In a single step growth test, phage AB1 was shown having a latent period of 18 minutes and a burst size of 409. Moreover, pH and thermal stability of phage AB1 were also investigated. At the optimal pH 6.0, 73.2% of phages survived after 60 min incubation at 50°C. When phage AB1 was used to infect four additional clinical isolates of A. baumannii, one clinical isolate of Stenotrophomonas maltophilia, and Pseudomonas aeruginosa lab strains PAK and PAO1, none of the tested strains was found susceptible, indicating a relatively narrow host range for phage AB1.ConclusionPhage AB1 was capable of eliciting efficient lysis of A. baumannii, revealing its potential as a non-toxic sanitizer for controlling A. baumannii infection and contamination in both hospital and other public environments.

Isolation and characterization of lytic phages TSE1-3 against Enterobacter cloacae

“…The best temperature for phage stability was determined as 37°C, which is also reported for other bacteriophages against Enterobacter cloacae [8,18]. The TSE phages survived at all the tested temperatures from 28°C to 60°C, however the phage titer decreased when treated at 37°C to 60°C ( Figure 4 and Figure 5).…”

Characterization of Siphoviridae phage Z and studying its efficacy against multidrug-resistant Klebsiella pneumoniae planktonic cells and biofilm

“…It is also postulated that Ca 2+ ions may increase the concentration of phage particles at the host surface or alter the structure of a cell surface receptor so as to increase accessibility to the receptor molecules or transfer of phage nucleic acids (Russel et al, 1988;Watanabe & Takesue, 1972). Yang et al (2010) have described a burst size and duration of the latent phase that nearly correlate with our results (latent period 24 min; burst size 320 virions per cell), while Sillankorva et al (2004) found a smaller burst size and shorter duration of the latent phase. Thus, variations have been reported in the literature regarding latent time and burst size of bacteriophages.…”

Characterization and Detection of Endolysin Gene from Three Acinetobacter baumannii Bacteriophages Isolated from Sewage Water

“…Phage endolysins have been studied in a variety of pathogenic bacteria including A. baumannii for theirs antibacterial activity [11][12][13]. In the past three years, A. baumannii bacteriophages and endolysin have been isolated and characterized [14][15][16][17][18][19][20][21][22][23][24]. However, there are geographic differences in A. baumannii host strains.…”