Bacterial Infections and Mycoses Commons^™

Ecthyma Gangrenosum In An Immunocompromised Patient Without Detectable Bacteremia, Jonathan Miles, Alex Mari, Matthew Crabtree, Vinod Nambudiri, Jilian Sansbury

Dermatology

Ecthyma gangrenosum (EG) is typically pathognomonic of Pseudomonas aeruginosa bacteremia among immunocompromised patients, particularly with underlying malignancy. Recently, other pathogens and clinical histories have been implicated, challenging the classic picture of patients with EG. The cutaneous findings in patients follow a pattern of lesion progression from indurated pustules and hemorrhagic vesicles evolving to necrotic ulcers with central black eschar and surrounding erythema. While lesions typically occur on the perineum or lower extremities, their presence has also been described elsewhere. Herein, we describe a case of an immunocompromised man with chronic lymphocytic leukemia and multiple myeloma actively undergoing chemotherapy presenting with …

Azithromycin For Early Pseudomonas Infection In Cystic Fibrosis. The Optimize Randomized Trial., Nicole Mayer-Hamblett, George Retsch-Bogart, Margaret Kloster, Frank Accurso, Margaret Rosenfeld, Gary Albers, Philip Black, Perry Brown, Annemarie Cairns, Stephanie D. Davis, Gavin R. Graff, Gwendolyn S. Kerby, David Orenstein, Rachael Buckingham, Bonnie W. Ramsey, Optimize Study Group

Manuscripts, Articles, Book Chapters and Other Papers

RATIONALE: New isolation of Pseudomonas aeruginosa (Pa) is generally treated with inhaled antipseudomonal antibiotics such as tobramycin inhalation solution (TIS). A therapeutic approach that complements traditional antimicrobial therapy by reducing the risk of pulmonary exacerbation and inflammation may ultimately prolong the time to Pa recurrence.

OBJECTIVES: To test the hypothesis that the addition of azithromycin to TIS in children with cystic fibrosis and early Pa decreases the risk of pulmonary exacerbation and prolongs the time to Pa recurrence.

METHODS: The OPTIMIZE (Optimizing Treatment for Early Pseudomonas aeruginosa Infection in Cystic Fibrosis) trial was a multicenter, double-blind, randomized, placebo-controlled, 18-month trial …

The Impact Of Exos On Pseudomonas Aeruginosa Internalization By Epithelial Cells Is Independent Of Fleq And Correlates With Bistability Of Type Three Secretion System Gene Expression, Abby R. Kroken, Camille K. Chen, David J. Evans, Timothy L. Yahr, Suzanne M. J. Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

Pseudomonas aeruginosa is internalized into multiple types of epithelial cell in vitro and in vivo and yet is often regarded as an exclusively extracellular pathogen. Paradoxically, ExoS, a type three secretion system (T3SS) effector, has antiphagocytic activities but is required for intracellular survival of P. aeruginosaand its occupation of bleb niches in epithelial cells. Here, we addressed mechanisms for this dichotomy using invasive (ExoS-expressing) P. aeruginosaand corresponding effector-null isogenic T3SS mutants, effector-null mutants of cytotoxic P. aeruginosa with and without ExoS transformation, antibiotic exclusion assays, and imaging using a T3SS-GFP reporter. Except for effector-null PA103, all strains were internalized while …

Mucosal Fluid Glycoprotein Dmbt1 Suppresses Twitching Motility And Virulence Of The Opportunistic Pathogen Pseudomonas Aeruginosa, Jianfang Li, Matteo E. O. Metruccio, David J. Evans, Suzanne M. J. Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

It is generally thought that mucosal fluids protect underlying epithelial surfaces against opportunistic infection via their antimicrobial activity. However, our published data show that human tear fluid can protect against the major opportunistic pathogen Pseudomonas aeruginosa independently of bacteriostatic activity. Here, we explored the mechanisms for tear protection, focusing on impacts of tear fluid on bacterial virulence factor expression. Results showed that tear fluid suppressed twitching motility, a type of surface-associated movement conferred by pili. Previously, we showed that twitching is critical for P. aeruginosa traversal of corneal epithelia, exit from epithelial cells after internalization, and corneal virulence. Inhibition …

Human Tear Fluid Reduces Culturability Of Contact Lens-Associated Pseudomonas Aeruginosa Biofilms But Induces Expression Of The Virulence-Associated Type Iii Secretion System, Yvonne T. Wu, Connie Tam, Lucia S. Zhu, David J. Evans, Suzanne M. J. Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

Purpose

The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens(CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression.

Methods

P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured …

Pseudomonas Aeruginosa Outer Membrane Vesicles Triggered By Human Mucosal Fluid And Lysozyme Can Prime Host Tissue Surfaces For Bacterial Adhesion, Matteo M. E. Metruccio, David J. Evans, Manal M. Gabriel, Jagath L. Kadurugamuwa, Suzanne M. J. Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

Pseudomonas aeruginosa is a leading cause of human morbidity and mortality that often targets epithelial surfaces. Host immunocompromise, or the presence of indwelling medical devices, including contact lenses, can predispose to infection. While medical devices are known to accumulate bacterial biofilms, it is not well understood why resistant epithelial surfaces become susceptible to P. aeruginosa. Many bacteria, including P. aeruginosa, release outer membrane vesicles (OMVs) in response to stress that can fuse with host cells to alter their function. Here, we tested the hypothesis that mucosal fluid can trigger OMV release to compromise an epithelial barrier. This was tested using …

Pseudomonas Aeruginosa-Induced Bleb-Niche Formation In Epithelial Cells Is Independent Of Actinomyosin Contraction And Enhanced By Loss Of Cystic Fibrosis Transmembrane-Conductance Regulator Osmoregulatory Function, Amber L. Jolly, Desire Takawira, Olufolarin O. Oke, Sarah A. Whiteside, Stephanie W. Chang, Emily R. Wen, David J. Evans

Faculty Publications & Research of the TUC College of Pharmacy

The opportunistic pathogen Pseudomonas aeruginosa can infect almost any site in the body but most often targets epithelial cell-lined tissues such as the airways, skin, and the cornea of the eye. A common predisposing factor is cystic fibrosis (CF), caused by defects in the cystic fibrosis transmembrane-conductance regulator (CFTR). Previously, we showed that when P. aeruginosa enters epithelial cells it replicates intracellularly and occupies plasma membrane blebs. This phenotype is dependent on the type 3 secretion system (T3SS) effector ExoS, shown by others to induce host cell apoptosis. Here, we examined mechanisms for P. aeruginosa-induced bleb formation, focusing on its …

Bioengineered Lysozyme Reduces Bacterial Burden And Inflammation In A Murine Model Of Mucoid Pseudomonas Aeruginosa Lung Infection, Charlotte C. Teneback, Thomas C. Scanlon, Matthew J. Wargo, Jenna L. Bement, Karl E. Griswold, Laurie W. Leclair

Dartmouth Scholarship

The spread of drug-resistant bacterial pathogens is a growing global concern and has prompted an effort to explore potential adjuvant and alternative therapies derived from nature's repertoire of bactericidal proteins and peptides. In humans, the airway surface liquid layer is a rich source of antibiotics, and lysozyme represents one of the most abundant and effective antimicrobial components of airway secretions. Human lysozyme is active against both Gram-positive and Gram-negative bacteria, ac

Pseudomonas Aeruginosa Ampr Transcriptional Regulatory Network, Deepak Balasubramanian

FIU Electronic Theses and Dissertations

In Enterobacteriaceae, the transcriptional regulator AmpR, a member of the LysR family, regulates the expression of a chromosomal β-lactamase AmpC. The regulatory repertoire of AmpR is broader in Pseudomonas aeruginosa, an opportunistic pathogen responsible for numerous acute and chronic infections including cystic fibrosis. Previous studies showed that in addition to regulating ampC, P. aeruginosa AmpR regulates the sigma factor AlgT/U and production of some quorum sensing (QS)-regulated virulence factors. In order to better understand the ampR regulon, the transcriptional profiles generated using DNA microarrays and RNA-Seq of the prototypic P. aeruginosa PAO1 strain with its isogenic ampR deletion …

Polysorbate 80 Inhibition Of Pseudomonas Aeruginosa Biofilm Formation And Its Cleavage By The Secreted Lipase Lipa, C M. Toutain-Kidd, S C. Kadivar, C T. Bramante, S A. Bobin, Michael E. Zegans

Dartmouth Scholarship

Surface-associated bacterial communities known as biofilms are an important source of nosocomial infections. Microorganisms such as Pseudomonas aeruginosa can colonize the abiotic surfaces of medical implants, leading to chronic infections that are difficult to eradicate. Our study demonstrates that polysorbate 80 (PS80), a surfactant commonly added to food and medicines, is able to inhibit biofilm formation by P. aeruginosa on a variety of surfaces, including contact lenses.