Pseudomonas aeruginosaCan Inhibit Growth of Streptococcal Species via Siderophore Production

AbstractCystic Fibrosis (CF) is a genetic disease that causes patients to accumulate thick, dehydrated mucus in the lung and develop chronic, polymicrobial infections due to reduced mucociliary clearance. These chronic polymicrobial infections and subsequent decline in lung function are significant factors in the morbidity and mortality of CF.Pseudomonas aeruginosaandStreptococcusspp. are among the most prevalent organisms in the CF lung; the presence ofP. aeruginosacorrelates with lung function decline and theStreptococcus millerigroup (SMG), a subgroup of the viridans streptococci, is associated with exacerbations in patients with CF. Here we characterize the interspecies interactions that occur between these two genera. We demonstrated that multipleP. aeruginosalaboratory strains and clinical CF isolates promote the growth of multiple SMG strains and oral streptococci in anin vitrococulture system. We investigated the mechanism by whichP. aeruginosaenhances growth of streptococci by screening for mutants ofP. aeruginosaPA14 unable to enhanceStreptococcusgrowth, and we identified theP. aeruginosa pqsL::TnMmutant, which failed to promote growth ofS. constellatusandS. sanguinis. Characterization of theP. aeruginosaΔpqsLmutant revealed that this strain cannot promoteStreptococcusgrowth. Our genetic data and growth studies support a model whereby theP. aeruginosaΔpqsLmutant overproduces siderophores, and thus likely outcompetesStreptococcus sanguinisfor limited iron. We propose a model whereby competition for iron represents one important means of interaction betweenP. aeruginosaandStreptococcusspp.ImportanceCystic fibrosis (CF) lung infections are increasingly recognized for their polymicrobial nature. These polymicrobial infections may alter the biology of the organisms involved in CF-related infections, leading to changes in growth, virulence and/or antibiotic tolerance, and could thereby affect patient health and response to treatment. In this study, we demonstrate interactions betweenP. aeruginosaand streptococci using a coculture model, and show that one interaction between these microbes is likely competition for iron. Thus, these data indicate that one CF pathogen may influence the growth of another and add to our limited knowledge of polymicrobial interactions in the CF airway.

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Pseudomonas aeruginosa Can Inhibit Growth of Streptococcal Species via Siderophore Production

Journal of Bacteriology ◽

10.1128/jb.00014-19 ◽

2019 ◽

Vol 201 (8) ◽

Cited By ~ 6

Author(s):

Jessie E. Scott ◽

Kewei Li ◽

Laura M. Filkins ◽

Bin Zhu ◽

Sherry L. Kuchma ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Lung Function ◽

Response To Treatment ◽

Oral Streptococci ◽

Interspecies Interactions ◽

Viridans Streptococci ◽

Content Type ◽

Streptococcus Milleri ◽

Polymicrobial Infections

ABSTRACT Cystic fibrosis (CF) is a genetic disease that causes patients to accumulate thick, dehydrated mucus in the lung and develop chronic, polymicrobial infections due to reduced mucociliary clearance. These chronic polymicrobial infections and subsequent decline in lung function are significant factors in the morbidity and mortality of CF. Pseudomonas aeruginosa and Streptococcus spp. are among the most prevalent organisms in the CF lung; the presence of P. aeruginosa correlates with lung function decline, and the Streptococcus milleri group (SMG), a subgroup of the viridans streptococci, is associated with exacerbations in patients with CF. Here we characterized the interspecies interactions that occur between these two genera. We demonstrated that multiple P. aeruginosa laboratory strains and clinical CF isolates promote the growth of multiple SMG strains and oral streptococci in an in vitro coculture system. We investigated the mechanism by which P. aeruginosa enhances growth of streptococci by screening for mutants of P. aeruginosa PA14 that are unable to enhance Streptococcus growth, and we identified the P. aeruginosa pqsL::TnM mutant, which failed to promote growth of Streptococcus constellatus and S. sanguinis. Characterization of the P. aeruginosa ΔpqsL mutant revealed that this strain cannot promote Streptococcus growth. Our genetic data and growth studies support a model whereby the P. aeruginosa ΔpqsL mutant overproduces siderophores and thus likely outcompetes Streptococcus sanguinis for limited iron. We propose a model whereby competition for iron represents one important means of interaction between P. aeruginosa and Streptococcus spp. IMPORTANCE Cystic fibrosis (CF) lung infections are increasingly recognized for their polymicrobial nature. These polymicrobial infections may alter the biology of the organisms involved in CF-related infections, leading to changes in growth, virulence, and/or antibiotic tolerance, and could thereby affect patient health and response to treatment. In this study, we demonstrate interactions between P. aeruginosa and streptococci using a coculture model and show that one interaction between these microbes is likely competition for iron. Thus, these data indicate that one CF pathogen may influence the growth of another, and they add to our limited knowledge of polymicrobial interactions in the CF airway.

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Management of respiratory exacerbations

10.1093/med/9780198702948.003.0005 ◽

2015 ◽

Author(s):

Francis J Gilchrist ◽

Alex Horsley

Keyword(s):

Lung Function ◽

Response To Treatment ◽

Patient Treatment ◽

Lung Function Decline ◽

Duration Of Treatment ◽

Previous Response ◽

Cystic Fibrosis Lung Disease ◽

Intravenous Antibiotics ◽

Pseudomonas Aeruginosa Infection

Cystic fibrosis lung disease is characterized by chronic infection, inflammation and a progressive loss of lung function. Patients are also affected by recurrent episodes of increased respiratory symptoms, called exacerbations which have a detrimental effect on quality of life, the rate of lung function decline, and mortality. Early diagnosis and treatment is vital. Diagnosis relies on a combination of symptoms, examination findings, the results of laboratory tests, and lung function. Antibiotics are the mainstay of treatment but airway clearance, nutrition, and glucose homeostasis must also be optimized. Mild exacerbations are usually treated with oral antibiotics and more severe exacerbations with intravenous antibiotics. The choice of antibiotic is guided by the patient’s chronic pulmonary infections, the in-vitro antibiotic sensitivities, known antibiotic allergies, and the previous response to treatment. In patients with chronic Pseudomonas aeruginosa infection, antibiotic monotherapy is thought to increase the risk of resistance and treatment with 2 antibiotics is therefore suggested (usually a β‎-lactam and an aminoglycoside). Although there is a lack of evidence on the duration of treatment, most patients receive around 14 days. This can be altered according to the time taken for symptoms and lung function to return to pre-exacerbation levels. If patients are carefully selected and receive appropriate monitoring, home intravenous antibiotics can be as effective as in-patient treatment. They are also associated with decreased disruption to patients / family life, decreased risk of cross infection and decreased costs.

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Rapid cystic fibrosis lung-function decline and in-vitro CFTR modulation

Journal of Cystic Fibrosis ◽

10.1016/j.jcf.2021.04.001 ◽

2021 ◽

Author(s):

Emrah Gecili ◽

Weiji Su ◽

Cole Brokamp ◽

Eleni-Rosalina Andrinopoulou ◽

Francis J. LaRosa III ◽

...

Keyword(s):

Cystic Fibrosis ◽

Lung Function ◽

Cystic Fibrosis Lung ◽

Lung Function Decline

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Cystic Fibrosis Sputum Impairs the Ability of Neutrophils to Kill Staphylococcus aureus

Pathogens ◽

10.3390/pathogens10060703 ◽

2021 ◽

Vol 10 (6) ◽

pp. 703

Author(s):

Kayla Fantone ◽

Samantha L. Tucker ◽

Arthur Miller ◽

Ruchi Yadav ◽

Eryn E. Bernardy ◽

...

Keyword(s):

Cystic Fibrosis ◽

Staphylococcus Aureus ◽

Healthy Volunteers ◽

Airway Disease ◽

Neutrophil Extracellular Trap ◽

Lung Function Decline ◽

Bacterial Killing ◽

Cystic Fibrosis Sputum ◽

Microbial Infections

Cystic fibrosis (CF) airway disease is characterized by chronic microbial infections and infiltration of inflammatory polymorphonuclear (PMN) granulocytes. Staphylococcus aureus (S. aureus) is a major lung pathogen in CF that persists despite the presence of PMNs and has been associated with CF lung function decline. While PMNs represent the main mechanism of the immune system to kill S. aureus, it remains largely unknown why PMNs fail to eliminate S. aureus in CF. The goal of this study was to observe how the CF airway environment affects S. aureus killing by PMNs. PMNs were isolated from the blood of healthy volunteers and CF patients. Clinical isolates of S. aureus were obtained from the airways of CF patients. The results show that PMNs from healthy volunteers were able to kill all CF isolates and laboratory strains of S. aureus tested in vitro. The extent of killing varied among strains. When PMNs were pretreated with supernatants of CF sputum, S. aureus killing was significantly inhibited suggesting that the CF airway environment compromises PMN antibacterial functions. CF blood PMNs were capable of killing S. aureus. Although bacterial killing was inhibited with CF sputum, PMN binding and phagocytosis of S. aureus was not diminished. The S. aureus-induced respiratory burst and neutrophil extracellular trap release from PMNs also remained uninhibited by CF sputum. In summary, our data demonstrate that the CF airway environment limits killing of S. aureus by PMNs and provides a new in vitro experimental model to study this phenomenon and its mechanism.

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Correction: Pyrosequencing Unveils Cystic Fibrosis Lung Microbiome Differences Associated with a Severe Lung Function Decline

PLoS ONE ◽

10.1371/journal.pone.0160726 ◽

2016 ◽

Vol 11 (8) ◽

pp. e0160726 ◽

Cited By ~ 1

Author(s):

Giovanni Bacci ◽

Patrizia Paganin ◽

Loredana Lopez ◽

Chiara Vanni ◽

Claudia Dalmastri ◽

...

Keyword(s):

Cystic Fibrosis ◽

Lung Function ◽

Cystic Fibrosis Lung ◽

Lung Function Decline ◽

Lung Microbiome ◽

Severe Lung

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Increased rate of lung function decline in Australian adolescents with cystic fibrosis

Pediatric Pulmonology ◽

10.1002/ppul.22946 ◽

2013 ◽

Vol 49 (9) ◽

pp. 873-877 ◽

Cited By ~ 20

Author(s):

Liam Welsh ◽

Colin F. Robertson ◽

Sarath C. Ranganathan

Keyword(s):

Cystic Fibrosis ◽

Lung Function ◽

Lung Function Decline

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260 Predictors of lung function decline in cystic fibrosis

Journal of Cystic Fibrosis ◽

10.1016/s1569-1993(16)30498-2 ◽

2016 ◽

Vol 15 ◽

pp. S117-S118

Author(s):

F. Ferro ◽

F. Freitas ◽

C. Lopes ◽

R. Costa ◽

A. Pinto ◽

...

Keyword(s):

Cystic Fibrosis ◽

Lung Function ◽

Lung Function Decline

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Multi-Omics Study of Keystone Species in a Cystic Fibrosis Microbiome

International Journal of Molecular Sciences ◽

10.3390/ijms222112050 ◽

2021 ◽

Vol 22 (21) ◽

pp. 12050

Author(s):

Cynthia B. Silveira ◽

Ana G. Cobián-Güemes ◽

Carla Uranga ◽

Jonathon L. Baker ◽

Anna Edlund ◽

...

Keyword(s):

Cystic Fibrosis ◽

Lung Function ◽

Sequence Data ◽

Anaerobic Bacteria ◽

Keystone Species ◽

Clinical Diagnostics ◽

Epifluorescence Microscopy ◽

Fermentation Products ◽

Degrading Bacteria

Ecological networking and in vitro studies predict that anaerobic, mucus-degrading bacteria are keystone species in cystic fibrosis (CF) microbiomes. The metabolic byproducts from these bacteria facilitate the colonization and growth of CF pathogens like Pseudomonas aeruginosa. Here, a multi-omics study informed the control of putative anaerobic keystone species during a transition in antibiotic therapy of a CF patient. A quantitative metagenomics approach combining sequence data with epifluorescence microscopy showed that during periods of rapid lung function loss, the patient’s lung microbiome was dominated by the anaerobic, mucus-degrading bacteria belonging to Streptococcus, Veillonella, and Prevotella genera. Untargeted metabolomics and community cultures identified high rates of fermentation in these sputa, with the accumulation of lactic acid, citric acid, and acetic acid. P. aeruginosa utilized these fermentation products for growth, as indicated by quantitative transcriptomics data. Transcription levels of P. aeruginosa genes for the utilization of fermentation products were proportional to the abundance of anaerobic bacteria. Clindamycin therapy targeting Gram-positive anaerobes rapidly suppressed anaerobic bacteria and the accumulation of fermentation products. Clindamycin also lowered the abundance and transcription of P. aeruginosa, even though this patient’s strain was resistant to this antibiotic. The treatment stabilized the patient’s lung function and improved respiratory health for two months, lengthening by a factor of four the between-hospitalization time for this patient. Killing anaerobes indirectly limited the growth of P. aeruginosa by disrupting the cross-feeding of fermentation products. This case study supports the hypothesis that facultative anaerobes operated as keystone species in this CF microbiome. Personalized multi-omics may become a viable approach for routine clinical diagnostics in the future, providing critical information to inform treatment decisions.

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Prevalence and impact of oprD mutations in Pseudomonas aeruginosa strains in cystic fibrosis

10.1101/19013870 ◽

2019 ◽

Author(s):

Laura J. Sherrard ◽

Bryan A. Wee ◽

Christine Duplancic ◽

Kay A. Ramsay ◽

Keyur A. Dave ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Lung Function ◽

Hazard Rate ◽

Carbapenem Resistance ◽

Adverse Outcomes ◽

Nonsense Mutations ◽

Allelic Variants ◽

Novel Variants

ABSTRACTDefective OprD porins contribute to carbapenem resistance and may be important in Pseudomonas aeruginosa adaptation to cystic fibrosis airways. It is unclear whether oprD mutations are fixed in populations of shared strains that are transmitted between patients or whether novel variants arise during infection. We investigated oprD sequences and antimicrobial resistance of two common Australian shared strains, constructed P. aeruginosa mutants with the most common oprD allelic variants and compared characteristics between patients with or without evidence of infection with strains harbouring these variants. Our data show that three independently acquired nonsense mutations arising from a 1-base pair substitution are fixed in strain sub-lineages. These nonsense mutations are likely to contribute to reduced carbapenem susceptibility in the sub-lineages without compromising in vitro fitness. Not only was lung function worse among patients infected with strains harbouring the nonsense mutations than those without, but they also had an increased hazard rate of lung transplantation/death. Our findings further highlight that understanding adaptive changes may help to distinguish patients with greater adverse outcomes despite infection with the same strain.

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