Dataset Information

Isolation and Characterisation of Bacteriophage Selective for Key Acinetobacter baumannii Capsule Chemotypes.

ABSTRACT: Nineteen bacteriophages against five main capsular types of multidrug-resistant Acinetobacter baumannii were isolated from tertiary care hospital sewage. Eight representative phages from each capsular type were characterized and tested for their biological properties. The biological features revealed that phages T1245, T444, and T515 had a large burst size of more than 420 pfu/mL, together with a short latent period lasting less than 6 min, and were readily adsorbed to a bacterial host within 10 min. Moreover, these phages demonstrated host specificity and stability over a broad range of temperatures (-20 to 60 °C) and pH (5.0-9.0). A whole-genome analysis of six lytic and two temperate phages revealed high genomic similarity with double-stranded DNA between 40 and 50 kb and G + C content of 38-39%. The protein compositions disclosed the absence of toxin-coding genes. The phylogenic results, together with morphological micrographs, confirmed that three selected phages (T1245, T444, and T515) belong to the Podoviridae family within the order Caudovirales. The biological data and bioinformatics analysis indicated that these novel A. baumannii phages possess important enzymes, including depolymerase and endolysin, which could be further developed as promising alternative antibacterial agents to control A. baumannii infections.

SUBMITTER: Soontarach R

PROVIDER: S-EPMC9027227 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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Isolation and Characterisation of Bacteriophage Selective for Key <i>Acinetobacter baumannii</i> Capsule Chemotypes.

Soontarach Rosesathorn R Srimanote Potjanee P Enright Mark C MC Blundell-Hunter George G Dorman Matthew J MJ Thomson Nicholas R NR Taylor Peter W PW Voravuthikunchai Supayang P SP

Pharmaceuticals (Basel, Switzerland) 20220402 4

Nineteen bacteriophages against five main capsular types of multidrug-resistant <i>Acinetobacter baumannii</i> were isolated from tertiary care hospital sewage. Eight representative phages from each capsular type were characterized and tested for their biological properties. The biological features revealed that phages T1245, T444, and T515 had a large burst size of more than 420 pfu/mL, together with a short latent period lasting less than 6 min, and were readily adsorbed to a bacterial host wi ...[more]

PMID: 35455440

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Project description: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 degrees 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.

Project description:Capsular polysaccharides enable clinically important clones of Klebsiella pneumoniae to cause severe systemic infections in susceptible hosts. Phage-encoded capsule depolymerases have the potential to provide an alternative treatment paradigm in patients when multiple drug resistance has eroded the efficacy of conventional antibiotic chemotherapy. An investigation of 164 K. pneumoniae from intensive care patients in Thailand revealed a large number of distinct K types in low abundance but four (K2, K51, K1, K10) with a frequency of at least 5%. To identify depolymerases with the capacity to degrade capsules associated with these common K-types, 62 lytic phage were isolated from Thai hospital sewage water using K1, K2 and K51 isolates as hosts; phage plaques, without exception, displayed halos indicative of the presence of capsule-degrading enzymes. Phage genomes ranged in size from 41-348 kb with between 50 and 535 predicted coding sequences (CDSs). Using a custom phage protein database we were successful in applying annotation to 30 - 70% (mean = 58%) of these CDSs. The largest genomes, of so-called jumbo phage, carried multiple tRNAs as well as CRISPR repeat and spacer sequences. One of the smaller phage genomes was found to contain a putative Cas type 1E gene, indicating a history of host DNA acquisition in these obligate lytic phage. Whole-genome sequencing (WGS) indicated that some phage displayed an extended host range due to the presence of multiple depolymerase genes; in total, 42 candidate depolymerase genes were identified with up to eight in a single genome. Seven distinct virions were selected for further investigation on the basis of host range, phage morphology and WGS. Candidate genes for K1, K2 and K51 depolymerases were expressed and purified as his6-tagged soluble protein and enzymatic activity demonstrated against K. pneumoniae capsular polysaccharides by gel electrophoresis and Anton-Paar rolling ball viscometry. Depolymerases completely removed the capsule in K-type-specific fashion from K. pneumoniae cells. We conclude that broad-host range phage carry multiple enzymes, each with the capacity to degrade a single K-type, and any future use of these enzymes as therapeutic agents will require enzyme cocktails for utility against a range of K. pneumoniae infections.

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Isolation and Characterisation of Bacteriophage Selective for Key Acinetobacter baumannii Capsule Chemotypes.

Publications

Isolation and Characterisation of Bacteriophage Selective for Key <i>Acinetobacter baumannii</i> Capsule Chemotypes.

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Isolation and Characterisation of Bacteriophage Selective for Key Acinetobacter baumannii Capsule Chemotypes.

Publications

Isolation and Characterisation of Bacteriophage Selective for Key &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; Capsule Chemotypes.

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Isolation and Characterisation of Bacteriophage Selective for Key <i>Acinetobacter baumannii</i> Capsule Chemotypes.