Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa
Phage therapy involves the application of lytic bacteriophages for treatment of clinical infections but bacterial resistance may develop over time. Isolated from nosocomial infections, small colony variants (SCVs) are morphologically distinct, highly virulent bacterial strains that are resistant to...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2016-03-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.00282/full |
| _version_ | 1818701382475055104 |
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| author | Wee Siang eLim Wee Siang eLim Kevin Kai Siang ePhang Andy Hee-Meng eTan Andy Hee-Meng eTan Sam Fong-Yau eLi Sam Fong-Yau eLi Sam Fong-Yau eLi Dave Siak-Wei eOw |
| author_facet | Wee Siang eLim Wee Siang eLim Kevin Kai Siang ePhang Andy Hee-Meng eTan Andy Hee-Meng eTan Sam Fong-Yau eLi Sam Fong-Yau eLi Sam Fong-Yau eLi Dave Siak-Wei eOw |
| author_sort | Wee Siang eLim |
| collection | DOAJ |
| description | Phage therapy involves the application of lytic bacteriophages for treatment of clinical infections but bacterial resistance may develop over time. Isolated from nosocomial infections, small colony variants (SCVs) are morphologically distinct, highly virulent bacterial strains that are resistant to conventional antibiotics. In this study, SCVs was derived from Pseudomonas aeruginosa exposed to the lytic bacteriophage PB1 and these cells were resistant to subsequent phage infection by PB1. To elucidate the mechanism of the SCV phage resistance, we performed phenotypic assays, DNA microarrays and whole-genome sequencing. Compared with wild type P. aeruginosa, the SCV isolate showed impaired biofilm formation, decreased twitching motility, reduced elastase and pyocyanin production. The SCV is also more susceptible to the antibiotic ciprofloxacin and exhibited higher syrface hydrophobicity than the wild type, indicative of changes to cell surface lipopolysaccharide (LPS) composition. Consistent with these results, transcriptomic studies of SCV revealed up-regulation of genes involved in O-specific antigen (OSA) biosynthesis, suggesting the regulation of surface moieties may account for phage resistance. Western blot analysis showed a difference in OSA distribution between the two strains. Simultaneously, genes involved in aromatic and branched chain amino acid catabolism were down-regulated. Whole genome sequencing of the SCV revealed multiple single nucleotide variations within the Pf1 prophage region, a genetic locus known to play a crucial role in biofilm formation and to provide survival advantage via gene transfer to a subpopulation of cells. Insights into phenotypic and genetic changes in SCV gained here should help direct future studies to elucidate mechanisms underpinning phage resistance, leading to novel counter resistance measures. |
| first_indexed | 2024-12-17T15:19:57Z |
| format | Article |
| id | doaj.art-d47442aab5f54142891e03b59dd377af |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-17T15:19:57Z |
| publishDate | 2016-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-d47442aab5f54142891e03b59dd377af2022-12-21T21:43:25ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2016-03-01710.3389/fmicb.2016.00282171225Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosaWee Siang eLim0Wee Siang eLim1Kevin Kai Siang ePhang2Andy Hee-Meng eTan3Andy Hee-Meng eTan4Sam Fong-Yau eLi5Sam Fong-Yau eLi6Sam Fong-Yau eLi7Dave Siak-Wei eOw8Bioprocessing Technology Institute, Agency for Science, Technology and ResearchNUS Graduate School for Integrative Sciences & Engineering, National University of SingaporeBioprocessing Technology Institute, Agency for Science, Technology and ResearchBioprocessing Technology Institute, Agency for Science, Technology and ResearchLee Kong Chian School of Medicine, Nanyang Technological UniversityNUS Graduate School for Integrative Sciences & Engineering, National University of SingaporeFaculty of Science, National University of SingaporeNUS Environmental Research Institute, National University of SingaporeBioprocessing Technology Institute, Agency for Science, Technology and ResearchPhage therapy involves the application of lytic bacteriophages for treatment of clinical infections but bacterial resistance may develop over time. Isolated from nosocomial infections, small colony variants (SCVs) are morphologically distinct, highly virulent bacterial strains that are resistant to conventional antibiotics. In this study, SCVs was derived from Pseudomonas aeruginosa exposed to the lytic bacteriophage PB1 and these cells were resistant to subsequent phage infection by PB1. To elucidate the mechanism of the SCV phage resistance, we performed phenotypic assays, DNA microarrays and whole-genome sequencing. Compared with wild type P. aeruginosa, the SCV isolate showed impaired biofilm formation, decreased twitching motility, reduced elastase and pyocyanin production. The SCV is also more susceptible to the antibiotic ciprofloxacin and exhibited higher syrface hydrophobicity than the wild type, indicative of changes to cell surface lipopolysaccharide (LPS) composition. Consistent with these results, transcriptomic studies of SCV revealed up-regulation of genes involved in O-specific antigen (OSA) biosynthesis, suggesting the regulation of surface moieties may account for phage resistance. Western blot analysis showed a difference in OSA distribution between the two strains. Simultaneously, genes involved in aromatic and branched chain amino acid catabolism were down-regulated. Whole genome sequencing of the SCV revealed multiple single nucleotide variations within the Pf1 prophage region, a genetic locus known to play a crucial role in biofilm formation and to provide survival advantage via gene transfer to a subpopulation of cells. Insights into phenotypic and genetic changes in SCV gained here should help direct future studies to elucidate mechanisms underpinning phage resistance, leading to novel counter resistance measures.http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.00282/fullPseudomonas aeruginosaphage therapysmall colony variantsphage resistancelipopolysaccharide (LPS)Pf1 region |
| spellingShingle | Wee Siang eLim Wee Siang eLim Kevin Kai Siang ePhang Andy Hee-Meng eTan Andy Hee-Meng eTan Sam Fong-Yau eLi Sam Fong-Yau eLi Sam Fong-Yau eLi Dave Siak-Wei eOw Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa Frontiers in Microbiology Pseudomonas aeruginosa phage therapy small colony variants phage resistance lipopolysaccharide (LPS) Pf1 region |
| title | Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa |
| title_full | Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa |
| title_fullStr | Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa |
| title_full_unstemmed | Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa |
| title_short | Small colony variants and single nucleotide variations in Pf1 region of PB1 phage-resistant Pseudomonas aeruginosa |
| title_sort | small colony variants and single nucleotide variations in pf1 region of pb1 phage resistant pseudomonas aeruginosa |
| topic | Pseudomonas aeruginosa phage therapy small colony variants phage resistance lipopolysaccharide (LPS) Pf1 region |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.00282/full |
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