Browsing by Subject "Stenotrophomonas maltophilia"

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    Analysis of Polysaccharide and Biofilm Production of the Emerging Cystic Fibrosis Pathogen Stenotrophomonas maltophilia
    (Office of the Vice Chancellor for Research, 2016-04-08) Casiano-Rivera, Félix M.; Anderson, Gregory G.
    Stenotrophomonas maltophilia is an emerging Cystic Fibrosis (CF) lung pathogen, which displays high intrinsic resistance to a number of different antibiotics. Additionally, S. maltophilia is thought to increase antibiotic resistance by forming biofilms during infection. Biofilm disruption could promote clearance of the microorganism from CF-infected lungs. However, the genetic, biochemical and immunological mechanisms underlying S. maltophilia biofilm formation are not well understood. Secreted polysaccharides have been proven to form a vital component of the matrix that surrounds and protects biofilm bacteria. Hundreds of S. maltophilia mutants were generated by transposon mutagenesis and screened for strains with reduced polysaccharide secretion.. These strains were screened through the use of agar plates containing the polysaccharide-binding dye, Congo red. Experimental controls included a S. maltophilia wild-type strain (positive control) and a confirmed polysaccharide deficient mutant (negative control). A Congo red liquid binding assay was utilized to identify the amount of Congo red bound in the samples, which confirmed the amount of polysaccharide present in them. A total of 1,728 mutants were screened with 61 mutants showing reduced polysaccharide production. The mutants were further narrowed down to 8 samples showing the most consistent phenotype. Arbitrary-primed polymerase chain reactions (AP-PCR), followed by sequencing, will be performed on the selected samples in an effort to identify the genes mutated in polysaccharide deficient strains. We will also perform immunological assays in an effort to understand underlying immune responses to S. maltophilia. In order to determine the effects of the deletion of gpmA in S. maltophilia, we will be performing an in-vitro co-culture assay using the wild-type strain and the gpmA mutant strain. These studies will yield evidence to the molecular process involved in polysaccharide production, which could lead to mechanisms to disrupt biofilm formation in CF patients.
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    Evaluating Metabolic Pathways and Biofilm Formation in Stenotrophomonas maltophilia
    (American Society for Microbiology, 2022) Isom, Cierra M.; Fort, Blake; Anderson, Gregory G.; Biology, School of Science
    Stenotrophomonas maltophilia has recently arisen as a prominent nosocomial pathogen because of its high antimicrobial resistance and ability to cause chronic respiratory infections. Often the infections are worsened by biofilm formation which enhances antibiotic tolerance. We have previously found that mutation of the gpmA gene, encoding the glycolytic enzyme phosphoglycerate mutase, impacts the formation of this biofilm on biotic and abiotic surfaces at early time points. This finding, indicating an association between carbon source and biofilm formation, led us to hypothesize that metabolism would influence S. maltophilia biofilm formation and planktonic growth. In the present study, we tested the impact of various growth substrates on biofilm levels and growth kinetics to determine metabolic requirements for these processes. We found that S. maltophilia wild type preferred amino acids versus glucose for planktonic and biofilm growth and that gpmA deletion inhibited growth in amino acids. Furthermore, supplementation of the ΔgpmA strain by glucose or ribose phenotypically complemented growth defects. These results suggest that S. maltophilia shuttles amino acid carbon through gluconeogenesis to an undefined metabolic pathway supporting planktonic and biofilm growth. Further evaluation of these metabolic pathways might reveal novel metabolic activities of this pathogen. IMPORTANCE: Stenotrophomonas maltophilia is a prominent opportunistic pathogen that often forms biofilms during infection. However, the molecular mechanisms of virulence and biofilm formation are poorly understood. The glycolytic enzyme phosphoglycerate mutase appears to play a role in biofilm formation, and we used a mutant in its gene (gpmA) to probe the metabolic circuitry potentially involved in biofilm development. The results of our study indicate that S. maltophilia displays unique metabolic activities, which could be exploited for inhibiting growth and biofilm formation of this pathogen.
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    Phosphoglycerate mutase affects Stenotrophomonas maltophilia attachment to biotic and abiotic surfaces
    (Elsevier, 2020) Ramos-Hegazy, Layla; Chakravarty, Shubham; Anderson, Gregory G.; Biology, School of Science
    Stenotrophomonas maltophilia biofilm formation is of increasing medical concern, particularly for lung infections. However, the molecular mechanisms facilitating the biofilm lifestyle in S. maltophilia are poorly understood. We generated and screened a transposon mutant library for mutations that lead to altered biofilm formation compared to wild type. One of these mutations, in the gene for glycolytic enzyme phosphoglycerate mutase (gpmA), resulted in impaired attachment on abiotic and biotic surfaces. As adherence to a surface is the initial step in biofilm developmental processes, our results reveal a unique factor that could affect S. maltophilia biofilm initiation and, possibly, subsequent development.
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    Role of Stenotrophomonas Maltophilia Pili Iin Biofilm And Virulence
    (2024-08) Bhaumik, Radhika; Marrs, Kathleen; Anderson, Gregory; Berbari, Nicolas; Marrs, James A.; Gregory, Richard L.
    Stenotrophomonas maltophilia is an emerging multidrug-resistant, Gram-negative opportunistic pathogen. It causes many hospital-acquired infections such as sepsis, endocarditis, meningitis, and catheter-related urinary tract infections. It also affects individuals with cystic fibrosis, exacerbating their lung condition. S. maltophilia often causes pathogenesis through the formation of biofilms. However, the molecular mechanisms S. maltophilia uses to carry out these pathogenic steps are unclear. The SMF-1 chaperone/usher pilus has been thought to mediate S. maltophilia attachment. To confirm this role, we created an isogenic deletion of the smf-1 pilin gene and observed a defect in biofilm compared to wild type. We also discovered 2 additional chaperone/usher pilus operons, mutation of which also caused attenuation in biofilm levels. Analysis of S. maltophilia clinical strains and S. maltophilia complete genomes listed in NCBI showed that these three pili are prevalent and highly conserved, suggesting a vital role in infection. Intriguingly, through TEM studies, we found that the mutation of one pilus is not phenotypically compensated by another. Infection of Galleria mellonella larvae revealed increased virulence of the pilus mutants. Additionally, we also demonstrated a relationship between pilus and flagella contributing to the overall biofilm development of S. maltophilia. Understanding their activity may help identify therapeutic targets for this pathogen.