Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii
Acinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Its various intrinsic and acquired mechanisms of antibiotic resistance make the therapeutic challenge even more serious. One of the promising alternative treatments that is increasingly highlighted is phage the...
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Frontiers Media S.A.
2020-08-01
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| Series: | Frontiers in Medicine |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fmed.2020.00426/full |
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| author | Goran Vukotic Goran Vukotic Mina Obradovic Katarina Novovic Mariagrazia Di Luca Branko Jovcic Branko Jovcic Djordje Fira Horst Neve Milan Kojic Olivia McAuliffe |
| author_facet | Goran Vukotic Goran Vukotic Mina Obradovic Katarina Novovic Mariagrazia Di Luca Branko Jovcic Branko Jovcic Djordje Fira Horst Neve Milan Kojic Olivia McAuliffe |
| author_sort | Goran Vukotic |
| collection | DOAJ |
| description | Acinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Its various intrinsic and acquired mechanisms of antibiotic resistance make the therapeutic challenge even more serious. One of the promising alternative treatments that is increasingly highlighted is phage therapy, the therapeutic use of bacteriophages to treat bacterial infections. Two phages active against nosocomial carbapenem-resistant A. baumannii strain 6077/12, vB_AbaM_ISTD, and vB_AbaM_NOVI, were isolated from Belgrade wastewaters, purified, and concentrated using CsCl gradient ultracentrifugation. The phages were screened against 103 clinical isolates of A. baumannii from a laboratory collection and characterized based on plaque and virion morphology, host range, adsorption rate, and one-step growth curve. Given that phage ISTD showed a broader host range, better adsorption rate, shorter latent period, and larger burst size, its ability to lyse planktonic and biofilm-embedded cells was tested in detail. Phage ISTD yielded a 3.5- and 2-log reduction in planktonic and biofilm-associated viable bacterial cell count, respectively, but the effect was time-dependent. Both phages produced growing turbid halos around plaques indicating the synthesis of depolymerases, enzymes capable of degrading bacterial exopolysaccharides. Halos tested positive for presence of phages in the proximity of the plaque, but not further from the plaque, which indicates that the observed halo enlargement is a consequence of enzyme diffusion through the agar, independently of the phages. This notion was also supported by the growing halos induced by phage preparations applied on pregrown bacterial lawns, indicating that depolymerizing effect was achieved also on non-dividing sensitive cells. Overall, good rates of growth, fast adsorption rate, broad host range, and high depolymerizing activity, as well as antibacterial effectiveness against planktonic and biofilm-associated bacteria, make these phages good candidates for potential application in combating A. baumannii infections. |
| first_indexed | 2024-12-12T09:28:20Z |
| format | Article |
| id | doaj.art-950274f5623042a1b1ce050bb62dccf5 |
| institution | Directory Open Access Journal |
| issn | 2296-858X |
| language | English |
| last_indexed | 2024-12-12T09:28:20Z |
| publishDate | 2020-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Medicine |
| spelling | doaj.art-950274f5623042a1b1ce050bb62dccf52022-12-22T00:28:57ZengFrontiers Media S.A.Frontiers in Medicine2296-858X2020-08-01710.3389/fmed.2020.00426554897Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumanniiGoran Vukotic0Goran Vukotic1Mina Obradovic2Katarina Novovic3Mariagrazia Di Luca4Branko Jovcic5Branko Jovcic6Djordje Fira7Horst Neve8Milan Kojic9Olivia McAuliffe10Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, SerbiaChair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, SerbiaLaboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, SerbiaLaboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, SerbiaDepartment of Biology, University of Pisa, Pisa, ItalyLaboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, SerbiaChair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, SerbiaChair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, SerbiaDepartment of Microbiology and Biotechnology, Max Rubner-Institut, Kiel, GermanyLaboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, SerbiaDepartment of Food Biosciences, Teagasc Food Research Centre, Fermoy, IrelandAcinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Its various intrinsic and acquired mechanisms of antibiotic resistance make the therapeutic challenge even more serious. One of the promising alternative treatments that is increasingly highlighted is phage therapy, the therapeutic use of bacteriophages to treat bacterial infections. Two phages active against nosocomial carbapenem-resistant A. baumannii strain 6077/12, vB_AbaM_ISTD, and vB_AbaM_NOVI, were isolated from Belgrade wastewaters, purified, and concentrated using CsCl gradient ultracentrifugation. The phages were screened against 103 clinical isolates of A. baumannii from a laboratory collection and characterized based on plaque and virion morphology, host range, adsorption rate, and one-step growth curve. Given that phage ISTD showed a broader host range, better adsorption rate, shorter latent period, and larger burst size, its ability to lyse planktonic and biofilm-embedded cells was tested in detail. Phage ISTD yielded a 3.5- and 2-log reduction in planktonic and biofilm-associated viable bacterial cell count, respectively, but the effect was time-dependent. Both phages produced growing turbid halos around plaques indicating the synthesis of depolymerases, enzymes capable of degrading bacterial exopolysaccharides. Halos tested positive for presence of phages in the proximity of the plaque, but not further from the plaque, which indicates that the observed halo enlargement is a consequence of enzyme diffusion through the agar, independently of the phages. This notion was also supported by the growing halos induced by phage preparations applied on pregrown bacterial lawns, indicating that depolymerizing effect was achieved also on non-dividing sensitive cells. Overall, good rates of growth, fast adsorption rate, broad host range, and high depolymerizing activity, as well as antibacterial effectiveness against planktonic and biofilm-associated bacteria, make these phages good candidates for potential application in combating A. baumannii infections.https://www.frontiersin.org/article/10.3389/fmed.2020.00426/fullAcinetobacter baumanniicarbapenem resistancephagebiofilmdepolymerasehalo |
| spellingShingle | Goran Vukotic Goran Vukotic Mina Obradovic Katarina Novovic Mariagrazia Di Luca Branko Jovcic Branko Jovcic Djordje Fira Horst Neve Milan Kojic Olivia McAuliffe Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii Frontiers in Medicine Acinetobacter baumannii carbapenem resistance phage biofilm depolymerase halo |
| title | Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii |
| title_full | Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii |
| title_fullStr | Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii |
| title_full_unstemmed | Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii |
| title_short | Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii |
| title_sort | characterization antibiofilm and depolymerizing activity of two phages active on carbapenem resistant acinetobacter baumannii |
| topic | Acinetobacter baumannii carbapenem resistance phage biofilm depolymerase halo |
| url | https://www.frontiersin.org/article/10.3389/fmed.2020.00426/full |
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