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Refining the Application of Microbial Lipids as Tracers of Staphylococcus aureus Growth Rates in Cystic Fibrosis Sputum

Neubauer, Cajetan and Kasi, Ajay S. and Grahl, Nora and Sessions, Alex L. and Kopf, Sebastian H. and Kato, Roberta M. and Hogan, Deborah A. and Newman, Dianne K. (2018) Refining the Application of Microbial Lipids as Tracers of Staphylococcus aureus Growth Rates in Cystic Fibrosis Sputum. Journal of Bacteriology, 200 (24). Art. No. e00365-18. ISSN 0021-9193. PMCID PMC6256016. http://resolver.caltech.edu/CaltechAUTHORS:20181004-081517527

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Abstract

Chronic lung infections in cystic fibrosis (CF) could be treated more effectively if the effects of antimicrobials on pathogens in situ were known. Here, we compared changes in the microbial community composition and pathogen growth rates in longitudinal studies of seven pediatric CF patients undergoing intravenous antibiotic administration during pulmonary exacerbations. The microbial community composition was determined by counting rRNA with NanoString DNA analysis, and growth rates were obtained by incubating CF sputum with heavy water and tracing incorporation of deuterium into two branched-chain (“anteiso”) fatty acids (a-C_(15:0) and a-C_(17:0)) using gas chromatography-mass spectrometry (GC/MS). Prior to this study, both lipids were thought to be specific for Staphylococcaceae; hence, their isotopic enrichment was interpreted as a growth proxy for Staphylococcus aureus. Our experiments revealed, however, that Prevotella is also a relevant microbial producer of a-C_(17:0) fatty acid in some CF patients; thus, deuterium incorporation into these lipids is better interpreted as a more general pathogen growth rate proxy. Even accounting for a small nonmicrobial background source detected in some patient samples, a-C_(15:0) fatty acid still appears to be a relatively robust proxy for CF pathogens, revealing a median generation time of ∼1.5 days, similar to prior observations. Contrary to our expectation, pathogen growth rates remained relatively stable throughout exacerbation treatment. We suggest two straightforward “best practices” for application of stable-isotope probing to CF sputum metabolites: (i) parallel determination of microbial community composition in CF sputum using culture-independent tools and (ii) assessing background levels of the diagnostic metabolite.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1128/jb.00365-18DOIArticle
https://doi.org/10.1101/348037DOIDiscussion Paper
https://doi.org/10.1128/JB.00540-18Featured InCommentary
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6256016/PubMed CentralArticle
ORCID:
AuthorORCID
Neubauer, Cajetan0000-0002-5348-5609
Sessions, Alex L.0000-0001-6120-2763
Hogan, Deborah A.0000-0002-6366-2971
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2018 American Society for Microbiology. Received 14 June 2018; Accepted 19 September 2018; Accepted manuscript posted online 24 September 2018. We thank Elise Cowley, Reto Wijker, and Fenfang Wu for helping with our study. We thank Dominique H. Limoli and George O'Toole for providing CFBE cells and Ram Balasubramanian for providing PMN and HL-60 cells. We thank Jennifer Dien Bard and Thomas G. Keens for their guidance with our study, the CHLA CF center team, and patients of the CHLA CF clinic for participating in this study. We thank the anonymous reviewers for their comments. This work was funded by grants from the National Institutes of Health (R01HL117328).
Funders:
Funding AgencyGrant Number
NIHR01HL117328
Subject Keywords:microbial growth rate; stable-isotope probing; heavy water; CF sputum; Staphylococcus aureus; Prevotella; respiratory pathogens
PubMed Central ID:PMC6256016
Record Number:CaltechAUTHORS:20181004-081517527
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181004-081517527
Official Citation:Refining the Application of Microbial Lipids as Tracers of Staphylococcus aureus Growth Rates in Cystic Fibrosis Sputum. Cajetan Neubauer, Ajay S. Kasi, Nora Grahl, Alex L. Sessions, Sebastian H. Kopf, Roberta Kato, Deborah A. Hogan, Dianne K. Newman. Journal of Bacteriology Nov 2018, 200 (24) e00365-18; DOI: 10.1128/JB.00365-18
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90127
Collection:CaltechAUTHORS
Deposited By: Donna Wrublewski
Deposited On:04 Oct 2018 16:09
Last Modified:02 Jan 2019 21:27

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