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Rajar P, Dhariwal A, Salvadori G, Junges R, Åmdal HA, Berild D, Fugelseth D, Saugstad OD, Lausten-Thomsen U, Greisen G, Haaland K, Petersen FC. Microbial DNA extraction of high-host content and low biomass samples: Optimized protocol for nasopharynx metagenomic studies. Front Microbiol 2022; 13:1038120. [PMID: 36620054 PMCID: PMC9811202 DOI: 10.3389/fmicb.2022.1038120] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction Low microbial biomass and high human DNA content in nasopharyngeal aspirate samples hinder comprehensive characterization of microbiota and resistome. We obtained samples from premature infants, a group with increased risk of developing respiratory disorders and infections, and consequently frequent exposure to antibiotics. Our aim was to devise an optimal protocol for handling nasopharyngeal aspirate samples from premature infants, focusing on host DNA depletion and microbiome and resistome characterization. Methods Three depletion and three DNA extraction protocols were compared, using RT-PCR and whole metagenome sequencing to determine the efficiency of human DNA removal, taxonomic profiling and assignment of antibiotic resistance genes. Protocols were tested using mock communities, as well as pooled and individual patient samples. Results The only extraction protocol to retrieve the expected DNA yield from mock community samples was based on a lytic method to improve Gram positive recovery (MasterPure™). Host DNA content in non-depleted aliquots from pooled patient samples was 99%. Only samples depleted with MolYsis™ showed satisfactory, but varied reduction in host DNA content, in both pooled and individual patient samples, allowing for microbiome and resistome characterisation (host DNA content from 15% to 98%). Other depletion protocols either retrieved too low total DNA yields, preventing further analysis, or failed to reduce host DNA content. By using Mol_MasterPure protocol on aliquots from pooled patient samples, we increased the number of bacterial reads by 7.6 to 1,725.8-fold compared to non-depleted reference samples. PCR results were indicative of achieved microbial enrichment. Individual patient samples processed with Mol_MasterPure protocol varied greatly in total DNA yield, host DNA content (from 40% to 98%), species and antibiotic resistance gene richness. Discussion Despite high human DNA and low microbial biomass content in nasopharynx aspirates of preterm infants, we were able to reduce host DNA content to levels compatible with downstream shotgun metagenomic analysis, including bacterial species identification and coverage of antibiotic resistance genes. Whole metagenomic sequencing of microbes colonizing the nasopharynx may contribute to explaining the possible role of airway microbiota in respiratory conditions and reveal carriage of antibiotic resistance genes.
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Affiliation(s)
- Polona Rajar
- Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Oslo University Hospital Ullevål, Oslo, Norway,Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Achal Dhariwal
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Gabriela Salvadori
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Roger Junges
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Heidi Aarø Åmdal
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Dag Berild
- Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway,Institute of Clinical Medicine, Faculty of Medicine, Oslo University, Oslo, Norway
| | - Drude Fugelseth
- Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Oslo University Hospital Ullevål, Oslo, Norway,Institute of Clinical Medicine, Faculty of Medicine, Oslo University, Oslo, Norway
| | | | - Ulrik Lausten-Thomsen
- Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Gorm Greisen
- Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Kirsti Haaland
- Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Oslo University Hospital Ullevål, Oslo, Norway
| | - Fernanda Cristina Petersen
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway,*Correspondence: Fernanda Cristina Petersen,
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Dorn ES, Tress B, Suchodolski JS, Nisar T, Ravindran P, Weber K, Hartmann K, Schulz BS. Bacterial microbiome in the nose of healthy cats and in cats with nasal disease. PLoS One 2017; 12:e0180299. [PMID: 28662139 PMCID: PMC5491177 DOI: 10.1371/journal.pone.0180299] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 06/13/2017] [Indexed: 12/22/2022] Open
Abstract
Background Traditionally, changes in the microbial population of the nose have been assessed using conventional culture techniques. Sequencing of bacterial 16S rRNA genes demonstrated that the human nose is inhabited by a rich and diverse bacterial microbiome that cannot be detected using culture-based methods. The goal of this study was to describe the nasal microbiome of healthy cats, cats with nasal neoplasia, and cats with feline upper respiratory tract disease (FURTD). Methodology/Principal findings DNA was extracted from nasal swabs of healthy cats (n = 28), cats with nasal neoplasia (n = 16), and cats with FURTD (n = 15), and 16S rRNA genes were sequenced. High species richness was observed in all samples. Rarefaction analysis revealed that healthy cats living indoors had greater species richness (observed species p = 0.042) and Shannon diversity (p = 0.003) compared with healthy cats living outdoors. Higher species richness (observed species p = 0.001) and Shannon diversity (p<0.001) were found in middle-aged cats in comparison to healthy cats in different age groups. Principal coordinate analysis revealed separate clustering based on similarities in bacterial molecular phylogenetic trees of 16S rRNA genes for indoor and outdoor cats. In all groups examined, the most abundant phyla identified were Proteobacteria, Firmicutes, and Bacteroidetes. At the genus level, 375 operational taxonomic units (OTUs) were identified. In healthy cats and cats with FURTD, Moraxella spp. was the most common genus, while it was unclassified Bradyrhizobiaceae in cats with nasal neoplasia. High individual variability was observed. Conclusion This study demonstrates that the nose of cats is inhabited by much more variable and diverse microbial communities than previously shown. Future research in this field might help to develop new diagnostic tools to easily identify nasal microbial changes, relate them to certain disease processes, and help clinicians in the decision process of antibiotic selection for individual patients.
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Affiliation(s)
- Elisabeth S. Dorn
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany
| | - Barbara Tress
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany
| | - Jan S. Suchodolski
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Tariq Nisar
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Prajesh Ravindran
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Karin Weber
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany
| | - Katrin Hartmann
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany
| | - Bianka S. Schulz
- Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany
- * E-mail:
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Affiliation(s)
- Tara F Carr
- Department of Internal Medicine, University of Arizona College of Medicine, Tucson, Arizona
| | - Monica Kraft
- Department of Internal Medicine, University of Arizona College of Medicine, Tucson, Arizona
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