Browsing by Subject "Pseudomonas"

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    Filamentous bacteriophage delays healing of Pseudomonas-infected wounds
    (Elsevier, 2022) Bach, Michelle S.; de Vries, Christiaan R.; Khosravi, Arya; Sweere, Johanna M.; Popescu, Medeea C.; Chen, Qingquan; Demirdjian, Sally; Hargil, Aviv; Van Belleghem, Jonas D.; Kaber, Gernot; Hajfathalian, Maryam; Burgener, Elizabeth B.; Liu, Dan; Tran, Quynh-Lam; Dharmaraj, Tejas; Birukova, Maria; Sunkari, Vivekananda; Balaji, Swathi; Ghosh, Nandini; Mathew-Steiner, Shomita S.; El Masry, Mohamed S.; Keswani, Sundeep G.; Banaei, Niaz; Nedelec, Laurence; Sen, Chandan K.; Chandra, Venita; Secor, Patrick R.; Suh, Gina A.; Bollyky, Paul L.; Surgery, School of Medicine
    Chronic wounds infected by Pseudomonas aeruginosa (Pa) are characterized by disease progression and increased mortality. We reveal Pf, a bacteriophage produced by Pa that delays healing of chronically infected wounds in human subjects and animal models of disease. Interestingly, impairment of wound closure by Pf is independent of its effects on Pa pathogenesis. Rather, Pf impedes keratinocyte migration, which is essential for wound healing, through direct inhibition of CXCL1 signaling. In support of these findings, a prospective cohort study of 36 human patients with chronic Pa wound infections reveals that wounds infected with Pf-positive strains of Pa are more likely to progress in size compared with wounds infected with Pf-negative strains. Together, these data implicate Pf phage in the delayed wound healing associated with Pa infection through direct manipulation of mammalian cells. These findings suggest Pf may have potential as a biomarker and therapeutic target in chronic wounds.
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    The Immune Response to Chronic Pseudomonas aeruginosa Wound Infection in Immunocompetent Mice
    (Mary Ann Liebert, Inc., 2019-12-18) Sweere, Johanna M.; Ishak, Heather; Sunkari, Vivekananda; Bach, Michelle S.; Manasherob, Robert; Yadava, Koshika; Ruppert, Shannon M.; Sen, Chandan K.; Balaji, Swathi; Keswani, Sundeep G.; Secor, Patrick R.; Bollyky, Paul L.; Surgery, School of Medicine
    Objective: Our goal was to develop a chronic wound model in mice that avoids implantation of foreign material or impaired immunity and to use this to characterize the local and systemic immune response associated with Pseudomonas aeruginosa infection. Approach: We generated bilateral full-thickness dermal wounds in healthy 10–12-week-old C57Bl6 mice. We waited 24 h to inoculate the developing wound eschar at these sites. We performed careful titration experiments with luminescent strains of P. aeruginosa to identify bacterial inoculation concentrations that consistently established stable infections in these animals. We performed flow cytometry-based immunophenotyping of immune cell infiltrates at the wound site, spleen, and draining lymph nodes over time. Finally, we compared inflammatory responses seen in wound inoculation with planktonic bacteria, preformed biofilm, and heat-killed (HK) P. aeruginosa. Results: Using this delayed inoculation model and 7.5 ± 2.5 × 102 CFU/mL of PAO1 we consistently established stable infections that lasted at 10 days in duration. During early infection, we detected a strong upregulation of inflammatory cytokines and neutrophil infiltration at the wound site, while natural killer (NK) cells and dendritic cells (DCs) were reduced. At the systemic level, only plasmacytoid DCs were increased early in infection. During later stages, there was systemic upregulation of B cells, T cells, and macrophages, whereas NK cells and interferon killer DCs were reduced. Infections with P. aeruginosa biofilms were not more virulent than infections with planktonic P. aeruginosa, whereas treatment with HK P. aeruginosa only induces a short-term inflammatory state. Innovation: We describe a versatile wound model of chronic P. aeruginosa infection that lasts 10 days without causing sepsis or other excessive morbidity. Conclusion: This model may facilitate the study of chronic wound infections in immunocompetent mice. Our findings also highlight the induction of early innate immune cell populations during P. aeruginosa infection.
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    Multicenter Evaluation of Ceftazidime-Avibactam Susceptibility Testing of Enterobacterales and Pseudomonas aeruginosa on the Vitek 2 System
    (American Society for Microbiology, 2021-02-18) Humphries, Romney; Campeau, Shelley; Davis, Thomas E.; Nagaro, Kristin J.; LaBombardi, Vincent J.; Franklin, Simone; Heimbach, Lisa; Dwivedi, Hari P.; Pathology and Laboratory Medicine, School of Medicine
    In this multisite study, Vitek 2 AST-Gram-Negative Ceftazidime/Avibactam test results for 1,073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa) were compared to the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (sensitive [S], ≤8/4 μg/ml; resistant [R], ≥16/4 μg/ml). The overall EA was 94.5% (1,014/1,073) and CA was 98.7% (1,059/1,073). No very major errors were reported. The major error rate was 1.4% (14/998). Out of 14 major errors, 9 were within EA. Based on the EA and lack of an intermediate category for ceftazidime-avibactam (CZA), the adjusted major error rate for FDA criteria was 0.5% (5/998). The performance for ISO criteria after error resolutions included EA of 94.5% (1,014/1,073), CA of 98.9% (1,061/1,073), major error of 1.2% (12/998), and no very major error. Vitek 2 met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. Vitek 2 overall performance for Enterobacterales and P. aeruginosa met or exceeded the FDA and ISO performance criteria; thus, it is a reliable alternative to the BMD reference method for routine CZA susceptibility testing.