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

Abstract

Acinetobacter baumannii is an opportunistic pathogen that exists in hospital environments. The emergence of multidrug resistant A. baumannii (MDRAB) has been reported worldwide. It is necessary to find a novel and effective treatment for MDRAB infection. In this study, three bacteriophages, designated as ØABP-01, ØABP-02 and ØABP-04 were selected for analysis. Transmission electron microscopy showed that bacteriophage ØABP-01 belonged to the Podoviridae family and bacteriophage ØABP-02 and ØABP-04 are classified into the family Myoviridae. ØABP-01 had the widest host range. ØABP-01, ØABP-02 and ØABP-04 exhibited a latent period of 15, 20 and 20 min. The burst sizes of the three bacteriophages were 110, 120 and 150 PFU/cell. DNA restriction analysis using EcoRI, HindIII, PstI, SphI, BamHI and SmaI showed different DNA fragment patterns between the three bacteriophages. ØABP-01 and ØABP-04 was positive for the endolysin gene as determined by PCR. In conclusion, bacteriophage ØABP-01 showed broad host-specificity, good lytic activity and a short latency period, making it an appropriate candidate for studying the control and diagnosis associated with MDRAB infections.

Investigating Bacteriophages Targeting the Opportunistic Pathogen Acinetobacter baumannii

“…Previous trials with purified A. baumannii bacteriophage endolysins showed broad range host activity and synergy with colistin [27]. The polymyxin colistin, with all its associated side effects, is one of the end line treatments for A. baumannii infection.…”

“…The five of these bacteriophages with the highest host range were carried forward for further investigation in this study (Table 1 and Figure 1). All five bacteriophages had been previously partially characterised and were all confirmed to belong to the lytic non-enveloped dsDNA Caudovirales order of viruses via electron microscopy [25][26][27][28][29] (Supplementary Figure S2). Bacteriophages vPhT2, 4, and 44 were all Myoviridaes, whereas vPhT29 and 39 were the smaller Podoviridaes.…”

“…Host strain A. baumannii AB183 was shown to be susceptible to colistin (EUCAST clinical breakpoint >2 µg/mL [38]) ( Supplementary Table S3 and Figure S4) with a measured MIC of 1 µg/mL. Previous studies have indicated that endolysins from A. baumannii bacteriophages can work synergistically with colistin [27]. When colistin and bacteriophage vPhT2 were tested in combination against AB183, a fractional inhibitory concentration index (FICI) value of 0.35 was calculated (Table 9), indicating synergy between this bacteriophage and colistin (where the FICI was interpreted as follows: FICI ≤ 0.5, synergy; <2 and >0.5, indifference; ≥2, antagonism [39]).…”

“…Seventeen bacteriophages were isolated from wastewater at Buddhachinaraj and Bang Rakam hospitals in Phitsanulok province, Thailand in 2010 and were screened against 150 MDR A. baumannii strains collected from five hospitals [11,22,27,29] using a spot test method as described previously [27]. For additional information on the chosen bacteriophages and MDR-AB, please refer to the supplement file: 'Selected-MDRAB-150-isolates'.…”

“…Bacteriophage families were classified as previously described, using electron microscopy [27,29,48].…”