Browsing by Subject "Bacterial infection"

Now showing 1 - 6 of 6
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    Association of Antibiotics, Airway Microbiome, and Inflammation in Infants with Cystic Fibrosis
    (American Thoracic Society, 2017-10) Pittman, Jessica E.; Wylie, Kristine M.; Akers, Kathryn; Storch, Gregory A.; Hatch, Joseph; Quante, Jane; Frayman, Katherine B.; Clarke, Nadeene; Davis, Miriam; Stick, Stephen M.; Hall, Graham L.; Montgomery, Gregory; Ranganathan, Sarath; Davis, Stephanie D.; Ferkol, Thomas W.; Pediatrics, School of Medicine
    RATIONALE: The underlying defect in the cystic fibrosis (CF) airway leads to defective mucociliary clearance and impaired bacterial killing, resulting in endobronchial infection and inflammation that contributes to progressive lung disease. Little is known about the respiratory microbiota in the early CF airway and its relationship to inflammation. OBJECTIVES: To examine the bacterial microbiota and inflammatory profiles in bronchoalveolar lavage fluid and oropharyngeal secretions in infants with CF. METHODS: Infants with CF from U.S. and Australian centers were enrolled in a prospective, observational study examining the bacterial microbiota and inflammatory profiles of the respiratory tract. Bacterial diversity and density (load) were measured. Lavage samples were analyzed for inflammatory markers (interleukin 8, unbound neutrophil elastase, and absolute neutrophil count) in the epithelial lining fluid. RESULTS: Thirty-two infants (mean age, 4.7 months) underwent bronchoalveolar lavage and oropharyngeal sampling. Shannon diversity strongly correlated between upper and lower airway samples from a given subject, although community compositions differed. Microbial diversity was lower in younger subjects and in those receiving daily antistaphylococcal antibiotic prophylaxis. In lavage samples, reduced diversity correlated with lower interleukin 8 concentration and absolute neutrophil count. CONCLUSIONS: In infants with CF, reduced bacterial diversity in the upper and lower airways was strongly associated with the use of prophylactic antibiotics and younger age at the time of sampling; less diversity in the lower airway correlated with lower inflammation on bronchoalveolar lavage. Our findings suggest modification of the respiratory microbiome in infants with CF may influence airway inflammation.
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    Host inflammatory dynamics reveal placental immune modulation by Group B Streptococcus during pregnancy
    (EMBO Press, 2023) Kuperwaser, Felicia; Avital, Gal; Vaz, Michelle J.; Noble, Kristen N.; Dammann, Allison N.; Randis, Tara M.; Aronoff, David M.; Ratner, Adam J.; Yanai, Itai; Medicine, School of Medicine
    Group B Streptococcus (GBS) is a pathobiont that can ascend to the placenta and cause adverse pregnancy outcomes, in part through production of the toxin β‐hemolysin/cytolysin (β‐h/c). Innate immune cells have been implicated in the response to GBS infection, but the impact of β‐h/c on their response is poorly defined. We show that GBS modulates innate immune cell states by subversion of host inflammation through β‐h/c, allowing worse outcomes. We used an ascending mouse model of GBS infection to measure placental cell state changes over time following infection with a β‐h/c‐deficient and isogenic wild type GBS strain. Transcriptomic analysis suggests that β‐h/c‐producing GBS elicit a worse phenotype through suppression of host inflammatory signaling in placental macrophages and neutrophils, and comparison of human placental macrophages infected with the same strains recapitulates these results. Our findings have implications for identification of new targets in GBS disease to support host defense against pathogenic challenge.
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    Modulation of MRSA virulence gene expression by the wall teichoic acid enzyme TarO
    (Springer Nature, 2023-03-22) Lu, Yunfu; Chen, Feifei; Zhao, Qingmin; Cao, Qiao; Chen, Rongrong; Pan, Huiwen; Wang, Yanhui; Huang, Haixin; Huang, Ruimin; Liu, Qian; Li, Min; Bae, Taeok; Liang, Haihua; Lan, Lefu; Microbiology and Immunology, School of Medicine
    Phenol-soluble modulins (PSMs) and Staphylococcal protein A (SpA) are key virulence determinants for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), an important human pathogen that causes a wide range of diseases. Here, using chemical and genetic approaches, we show that inhibition of TarO, the first enzyme in the wall teichoic acid (WTA) biosynthetic pathway, decreases the expression of genes encoding PSMs and SpA in the prototypical CA-MRSA strain USA300 LAC. Mechanistically, these effects are linked to the activation of VraRS two-component system that directly represses the expression of accessory gene regulator (agr) locus and spa. The activation of VraRS was due in part to the loss of the functional integrity of penicillin-binding protein 2 (PBP2) in a PBP2a-dependent manner. TarO inhibition can also activate VraRS in a manner independent of PBP2a. We provide multiple lines of evidence that accumulation of lipid-linked peptidoglycan precursors is a trigger for the activation of VraRS. In sum, our results reveal that WTA biosynthesis plays an important role in the regulation of virulence gene expression in CA-MRSA, underlining TarO as an attractive target for anti-virulence therapy. Our data also suggest that acquisition of PBP2a-encoding mecA gene can impart an additional regulatory layer for the modulation of key signaling pathways in S. aureus.
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    Self-derived structure-disrupting peptides targeting methionine aminopeptidase in pathogenic bacteria: a new strategy to generate antimicrobial peptides
    (Federation of American Society of Experimental Biology (FASEB), 2019-02) Zhan, Jian; Jia, Husen; Semchenko, Evgeny A.; Bian, Yunqiang; Zhou, Amy M.; Li, Zhixiu; Yang, Yuedong; Wang, Jihua; Sarkar, Sohinee; Totsika, Makrina; Blanchard, Helen; Jen, Freda E.-C.; Ye, Qizhuang; Haselhorst, Thomas; Jennings, Michael P.; Seib, Kate L.; Zhou, Yaoqi; Biochemistry and Molecular Biology, School of Medicine
    Bacterial infection is one of the leading causes of death in young, elderly, and immune-compromised patients. The rapid spread of multi-drug-resistant (MDR) bacteria is a global health emergency and there is a lack of new drugs to control MDR pathogens. We describe a heretofore-unexplored discovery pathway for novel antibiotics that is based on self-targeting, structure-disrupting peptides. We show that a helical peptide, KFF- EcH3, derived from the Escherichia coli methionine aminopeptidase can disrupt secondary and tertiary structure of this essential enzyme, thereby killing the bacterium (including MDR strains). Significantly, no detectable resistance developed against this peptide. Based on a computational analysis, our study predicted that peptide KFF- EcH3 has the strongest interaction with the structural core of the methionine aminopeptidase. We further used our approach to identify peptide KFF- NgH1 to target the same enzyme from Neisseria gonorrhoeae. This peptide inhibited bacterial growth and was able to treat a gonococcal infection in a human cervical epithelial cell model. These findings present an exciting new paradigm in antibiotic discovery using self-derived peptides that can be developed to target the structures of any essential bacterial proteins.
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    Testing the effects of combining azithromycin with inhaled tobramycin for P. aeruginosa in cystic fibrosis: a randomised, controlled clinical trial
    (BMJ, 2022) Nichols, David P.; Singh, Pradeep K.; Baines, Arthur; Caverly, Lindsay J.; Chmiel, James F.; Glbson, Ronald L.; Lascano, Jorge; Morgan, Sarah J.; Retsch-Bogart, George; Saiman, Lisa; Sadeghi, Hossein; Billings, Joanne L.; Heltshe, Sonya L.; Kirby, Shannon; Kong, Ada; Nick, Jerry A.; Mayer-Hamblett, Nicole; TEACH Study Group; Pediatrics, School of Medicine
    Rationale: Inhaled tobramycin and oral azithromycin are common chronic therapies in people with cystic fibrosis and Pseudomonas aeruginosa airway infection. Some studies have shown that azithromycin can reduce the ability of tobramycin to kill P. aeruginosa. This trial was done to test the effects of combining azithromycin with inhaled tobramycin on clinical and microbiological outcomes in people already using inhaled tobramycin. We theorised that those randomised to placebo (no azithromycin) would have greater improvement in forced expiratory volume in one second (FEV1) and greater reduction in P. aeruginosa sputum in response to tobramycin. Methods: A 6-week prospective, randomised, placebo-controlled, double-blind trial testing oral azithromycin versus placebo combined with clinically prescribed inhaled tobramycin in individuals with cystic fibrosis and P. aeruginosa airway infection. Results: Over a 6-week period, including 4 weeks of inhaled tobramycin, the relative change in FEV1 did not statistically significantly differ between groups (azithromycin (n=56) minus placebo (n=52) difference: 3.44%; 95% CI: -0.48 to 7.35; p=0.085). Differences in secondary clinical outcomes, including patient-reported symptom scores, weight and need for additional antibiotics, did not significantly differ. Among the 29 azithromycin and 35 placebo participants providing paired sputum samples, the 6-week change in P. aeruginosa density differed in favour of the placebo group (difference: 0.75 log10 CFU/mL; 95% CI: 0.03 to 1.47; p=0.043). Conclusions: Despite having greater reduction in P. aeruginosa density in participants able to provide sputum samples, participants randomised to placebo with inhaled tobramycin did not experience significantly greater improvements in lung function or other clinical outcomes compared with those randomised to azithromycin with tobramycin.
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    Treponema pallidum, the syphilis spirochete: making a living as a stealth pathogen
    (Springer Nature, 2016-12) Radolf, Justin D.; Deka, Ranjit K.; Anand, Arvind; Šmajs, David; Norgard, Michael V.; Yang, X. Frank; Microbiology and Immunology, School of Medicine
    The past two decades have seen a worldwide resurgence in infections caused by Treponema pallidum subsp. pallidum, the syphilis spirochete. The well-recognized capacity of the syphilis spirochete for early dissemination and immune evasion has earned it the designation 'the stealth pathogen'. Despite the many hurdles to studying syphilis pathogenesis, most notably the inability to culture and to genetically manipulate T. pallidum, in recent years, considerable progress has been made in elucidating the structural, physiological, and regulatory facets of T. pallidum pathogenicity. In this Review, we integrate this eclectic body of information to garner fresh insights into the highly successful parasitic lifestyles of the syphilis spirochete and related pathogenic treponemes.