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International Journal of Infectious... Mar 2024Pseudomonas fluorescens (P. fluorescens) is not generally considered a bacterial pathogen in humans; however, multiple culture-based and culture-independent studies have...
Pseudomonas fluorescens (P. fluorescens) is not generally considered a bacterial pathogen in humans; however, multiple culture-based and culture-independent studies have identified it in the indigenous microbiota of multiple body sites. We herein report a rare case of pneumonia caused by P. fluorescens. A man in his 80 s with chronic obstructive pulmonary disease and diabetes mellitus was diagnosed with stage II rectal cancer. He underwent laparoscopic surgery, and on the 6th postoperative day, he developed a high fever. Chest computed tomography revealed infiltration in the left lower lung. Gram staining of the sputum showed Gram-negative rods phagocytosed by neutrophils, suggesting postoperative nosocomial pneumonia. The patient was started on tazobactam/piperacillin, and his pneumonia quickly improved. Later, only P. fluorescens was detected in a sputum culture. It was susceptible to common antipseudomonal agents. Gram staining of P. fluorescens appears to show a slightly thicker and larger morphology in comparison to Pseudomonas aeruginosa. Although there have been reports of opportunistic infections caused by P. fluorescens in immunosuppressed patients, including those with advanced cancer, most have been bloodstream infections, with very few reports of pneumonia alone. Clinicians should be aware that patients, who are not necessarily immunosuppressed, may develop pneumonia caused by P. fluorescens.
Topics: Male; Humans; Pseudomonas fluorescens; Pseudomonas Infections; Pneumonia; Pneumonia, Bacterial; Piperacillin, Tazobactam Drug Combination; Pseudomonas aeruginosa; Anti-Bacterial Agents
PubMed: 38218379
DOI: 10.1016/j.ijid.2024.01.007 -
Nature Protocols Sep 2023A lack of generic and effective genetic manipulation methods for Pseudomonas has restricted fundamental research and utilization of this genus for biotechnology... (Review)
Review
A lack of generic and effective genetic manipulation methods for Pseudomonas has restricted fundamental research and utilization of this genus for biotechnology applications. Phage-encoded homologous recombination (PEHR) is an efficient tool for bacterial genome engineering. This PEHR system is based on a lambda Red-like operon (BAS) from Pseudomonas aeruginosa phage Ab31 and a Rac bacteriophage RecET-like operon (Rec-TE) from P. syringae pv. syringae B728a and also contains exogenous elements, including the RecBCD inhibitor (Redγ or Pluγ) or single-stranded DNA-binding protein (SSB), that were added to enhance the PEHR recombineering efficiency. To solve the problem of false positives in Pseudomonas editing with the PEHR system, the processive enzyme Cas3 with a minimal Type I-C Cascade-based system was combined with PEHR. This protocol describes the utilization of a Pseudomonas-specific PEHR-Cas3 system that was designed to universally and proficiently modify the genomes of Pseudomonas species. The pipeline uses standardized cassettes combined with the concerted use of SacB counterselection and Cre site-specific recombinase for markerless or seamless genome modification, in association with vectors that possess the selectively replicating template R6K to minimize recombineering background. Compared with the traditional allelic exchange editing method, the PEHR-Cas3 system does not need to construct suicide plasmids carrying long homologous arms, thus simplifying the experimental procedure and shortening the traceless editing period. Compared with general editing systems based on phage recombinases, the PEHR-Cas3 system can effectively improve the screening efficiency of mutants using the cutting ability of Cas3 protein. The entire procedure requires ~12 days.
Topics: Humans; Bacteriophages; Alleles; Homologous Recombination; Pseudomonas; CRISPR-Associated Proteins
PubMed: 37626246
DOI: 10.1038/s41596-023-00856-1 -
PLoS Pathogens Aug 2023Pseudomonas aeruginosa (P.a.) infection accounts for nearly 20% of all cases of hospital acquired pneumonia with mortality rates >30%. P.a. infection induces a robust...
Pseudomonas aeruginosa (P.a.) infection accounts for nearly 20% of all cases of hospital acquired pneumonia with mortality rates >30%. P.a. infection induces a robust inflammatory response, which ideally enhances bacterial clearance. Unfortunately, excessive inflammation can also have negative effects, and often leads to cardiac dysfunction with associated morbidity and mortality. However, it remains unclear how P.a. lung infection causes cardiac dysfunction. Using a murine pneumonia model, we found that P.a. infection of the lungs led to severe cardiac left ventricular dysfunction and electrical abnormalities. More specifically, we found that neutrophil recruitment and release of S100A8/A9 in the lungs activates the TLR4/RAGE signaling pathways, which in turn enhance systemic inflammation and subsequent cardiac dysfunction. Paradoxically, global deletion of S100A8/A9 did not improve but aggravated cardiac dysfunction and mortality likely due to uncontrolled bacterial burden in the lungs and heart. Our results indicate that P.a. infection induced release of S100A8/9 is double-edged, providing increased risk for cardiac dysfunction yet limiting P.a. growth.
Topics: Animals; Mice; Pseudomonas aeruginosa; Heart; Inflammation; Pseudomonas Infections; Lung; Heart Diseases
PubMed: 37624851
DOI: 10.1371/journal.ppat.1011573 -
International Journal of Biological... Jul 2023Alginates are natural polysaccharides widely participating in food, pharmaceutical, and environmental applications due to their excellent gelling capacity. Their... (Review)
Review
Alginates are natural polysaccharides widely participating in food, pharmaceutical, and environmental applications due to their excellent gelling capacity. Their excellent biocompatibility and biodegradability further extend their application to biomedical fields. The low consistency in molecular weight and composition of algae-based alginates may limit their performance in advanced biomedical applications. It makes microbial alginate production more attractive due to its potential for customizing alginate molecules with stable characteristics. Production costs remain the primary factor limiting the commercialization of microbial alginates. However, carbon-rich wastes from sugar, dairy, and biodiesel industries may serve as potential substitutes for pure sugars for microbial alginate production to reduce substrate costs. Fermentation parameter control and genetic engineering strategies may further improve the production efficiency and customize the molecular composition of microbial alginates. To meet the specific needs of biomedical applications, alginates may need functionalization, such as functional group modifications and crosslinking treatments, to achieve enhanced mechanical properties and biochemical activities. The development of alginate-based composites incorporated with other polysaccharides, gelatin, and bioactive factors can integrate the advantages of each component to meet multiple requirements in wound healing, drug delivery, and tissue engineering applications. This review provided a comprehensive insight into the sustainable production of high-value microbial alginates. It also discussed recent advances in alginate modification strategies and alginate-based composites for representative biomedical applications.
Topics: Alginates; Pseudomonas; Azotobacter; Wound Healing; Tissue Engineering; Drug Delivery Systems; Fermentation; Gene Expression Regulation, Bacterial; Humans
PubMed: 37236570
DOI: 10.1016/j.ijbiomac.2023.125048 -
Biometals : An International Journal on... Aug 2023Iron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its... (Review)
Review
Iron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its bioavailability is low in most habitats because ferric iron is largely insoluble under aerobic conditions and at neutral pH. Consequently, bacteria have evolved a plethora of mechanisms to solubilize and acquire iron from environmental and host stocks. In this review, I focus on Pseudomonas spp. and first present the main iron uptake mechanisms of this taxa, which involve the direct uptake of ferrous iron via importers, the production of iron-chelating siderophores, the exploitation of siderophores produced by other microbial species, and the use of iron-chelating compounds produced by plants and animals. In the second part of this review, I elaborate on how these mechanisms affect interactions between bacteria in microbial communities, and between bacteria and their hosts. This is important because Pseudomonas spp. live in diverse communities and certain iron-uptake strategies might have evolved not only to acquire this essential nutrient, but also to gain relative advantages over competitors in the race for iron. Thus, an integrative understanding of the mechanisms of iron acquisition and the eco-evolutionary dynamics they drive at the community level might prove most useful to understand why Pseudomonas spp., in particular, and many other bacterial species, in general, have evolved such diverse iron uptake repertoires.
Topics: Animals; Siderophores; Iron; Iron Chelating Agents; Pseudomonas; Bacteria
PubMed: 36508064
DOI: 10.1007/s10534-022-00480-8 -
Nature Chemical Biology Sep 2023Pseudomonas aeruginosa is an opportunistic pathogen that causes serious illness, especially in immunocompromised individuals. P. aeruginosa forms biofilms that...
Pseudomonas aeruginosa is an opportunistic pathogen that causes serious illness, especially in immunocompromised individuals. P. aeruginosa forms biofilms that contribute to growth and persistence in a wide range of environments. Here we investigated the aminopeptidase, P. aeruginosa aminopeptidase (PaAP) from P. aeruginosa, which is highly abundant in the biofilm matrix. PaAP is associated with biofilm development and contributes to nutrient recycling. We confirmed that post-translational processing was required for activation and PaAP is a promiscuous aminopeptidase acting on unstructured regions of peptides and proteins. Crystal structures of wild-type enzymes and variants revealed the mechanism of autoinhibition, whereby the C-terminal propeptide locks the protease-associated domain and the catalytic peptidase domain into a self-inhibited conformation. Inspired by this, we designed a highly potent small cyclic-peptide inhibitor that recapitulates the deleterious phenotype observed with a PaAP deletion variant in biofilm assays and present a path toward targeting secreted proteins in a biofilm context.
Topics: Aminopeptidases; Pseudomonas aeruginosa; Peptides, Cyclic; Biofilms; Peptide Hydrolases; Bacterial Proteins
PubMed: 37386135
DOI: 10.1038/s41589-023-01373-8 -
The Science of the Total Environment Aug 2023Rapid accumulation of end-of-life polyurethanes (PUR) in the environment is a global crisis. While biodegradation of PUR has been reported, the process is slow, and the...
Rapid accumulation of end-of-life polyurethanes (PUR) in the environment is a global crisis. While biodegradation of PUR has been reported, the process is slow, and the microbiology involved in PUR biodegradation is poorly understood. This study reported the microbial community involved in PUR biodegradation (designed as PUR-plastisphere) in estuary sediments, and isolation and characterization of two PUR-utilizing isolates. PUR foams were pretreated with oxygen plasma (referred as p-PUR foams) to mimic weathered conditions before embedded in microcosms containing estuary sediments. After 6 months of incubation, a substantial loss of ester/urethane bonds on the embedded p-PUR foams was observed, according to Fourier transform infrared (FTIR) spectroscopy. Analysis of PUR-plastisphere showed two dominant genera, Pseudomonas (2.7 %) and Hyphomicrobium (3.0 %), along with many unknown genera in Sphingomonadaceae (9.2 %), and predicted hydrolytic enzymes such as esterases and proteases. Purpureocillium sp., and Pseudomonas strain PHC1 (designated as strain PHC1 hereafter), isolated from the PUR plastisphere, can grow on Impranil (a commercial water-borne PUR) as a sole nitrogen or carbon source. High esterase activities were detected in the spent Impranil-containing media, and a significant loss of ester bonds of the spent Impranil was also observed. After 42 days of incubation, the strain PHC1-inoculated p-PUR foam showed a noticeable development of biofilm as observed via scanning electron microscopy (SEM), and disappearance of ester and urethane bonds of the PUR as detected by FTIR, supporting the role of strain PHC1 in biodegradation of the p-PUR foam. Also, the FTIR spectra observed for the sediment-embedded p-PUR foams was similar to those for the strain PHC1-inoculated p-PUR foams, suggesting the potential role of the dominant species of Pseudomonas in PUR-plastisphere. The results of this study showed the promise of rapid biodegradation of PUR foam through inoculating with a PUR-utilizing isolate, Pseudomonas strain PHC1.
Topics: Polyurethanes; Pseudomonas; Biodegradation, Environmental; Soil Microbiology; Esterases; Amides
PubMed: 37156380
DOI: 10.1016/j.scitotenv.2023.163932 -
Archives of Microbiology Dec 2023Two motile, rod-shaped, Gram-stain-negative bacterial strains, TNT11 and TNT19, were isolated from soil samples collected at Deception Island, Antarctica. According to...
Pseudomonas violetae sp. nov. and Pseudomonas emilianonis sp. nov., two new species with the ability to degrade TNT isolated from soil samples at Deception Island, maritime Antarctica.
Two motile, rod-shaped, Gram-stain-negative bacterial strains, TNT11 and TNT19, were isolated from soil samples collected at Deception Island, Antarctica. According to the 16S rRNA gene sequence similarity, both strains belong to the genus Pseudomonas. Further genomic analyses based on ANI and dDDH suggested that these strains were new species. Growth of strain TNT11 is observed at 0-30 ℃ (optimum, 20 ℃), pH 4.0-9.0 (optimum, pH 6.0) and in the presence of 0-5.0% NaCl (optimum, 1% NaCl), while for TNT19 is observed at 0-30 ℃ (optimum between 15 and 20 ℃), pH 5.0-9.0 (optimum, pH 6.0) and in the presence of 0-5.0% NaCl (optimum between 0 and 1% NaCl). The fatty acid profile consists of the major compounds; C and C for TNT11, and C and C for TNT19. Based on the draft genome sequences, the DNA G + C content for TNT11 is 60.43 mol% and 58.60 mol% for TNT19. Based on this polyphasic study, TNT11 and TNT19 represent two novel species of the genus Pseudomonas, for which the proposed names are Pseudomonas violetae sp. nov. and Pseudomonas emilianonis sp. nov., respectively. The type strains are Pseudomonas violetae TNT11 (= RGM 3443 = LMG 32959) and Pseudomonas emilianonis TNT19 (= RGM 3442 = LMG 32960). Strains TNT11 and TNT19 were deposited to CChRGM and BCCM/LMG with entry numbers RGM 3443/LMG 32959 and RGM 3442/LMG 32960, respectively.
Topics: Phospholipids; RNA, Ribosomal, 16S; Antarctic Regions; Pseudomonas; Sodium Chloride; DNA, Bacterial; Sequence Analysis, DNA; Nucleic Acid Hybridization; Phylogeny; Bacterial Typing Techniques; Fatty Acids; Deception; Soil
PubMed: 38142428
DOI: 10.1007/s00203-023-03768-6 -
Cell Reports. Medicine Oct 2023Nearly one-half of patients with cystic fibrosis (CF) carry the homozygous F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene but...
Nearly one-half of patients with cystic fibrosis (CF) carry the homozygous F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene but exhibit variable lung function phenotypes. How adaptive immunity influences their lung function remains unclear, particularly the serological antibody responses to antigens from mucoid Pseudomonas in sera from patients with CF with varying lung function. Sera from patients with CF with reduced lung function show higher anti-outer membrane protein I (OprI) immunoglobulin G1 (IgG1) titers and greater antibody-mediated complement deposition. Induction of anti-OprI antibody isotypes with complement activity enhances lung inflammation in preclinical mouse models. This enhanced inflammation is absent in immunized Rag2 mice and is transferrable to unimmunized mice through sera. In a CF cohort undergoing treatment with elexacaftor-tezacaftor-ivacaftor, the declination in anti-OprI IgG1 titers is associated with lung function improvement and reduced hospitalizations. These findings suggest that antibody responses to specific Pseudomonas aeruginosa (PA) antigens worsen lung function in patients with CF.
Topics: Humans; Animals; Mice; Cystic Fibrosis; Pseudomonas; Pseudomonas aeruginosa; Lung; Immunoglobulin G
PubMed: 37852181
DOI: 10.1016/j.xcrm.2023.101210 -
Journal of Bacteriology Aug 2023Pseudomonas aeruginosa is an opportunistic pathogen heavily implicated in chronic diseases. Immunocompromised patients that become infected with P. aeruginosa usually... (Review)
Review
Pseudomonas aeruginosa is an opportunistic pathogen heavily implicated in chronic diseases. Immunocompromised patients that become infected with P. aeruginosa usually are afflicted with a lifelong chronic infection, leading to worsened patient outcomes. The complement system is an integral piece of the first line of defense against invading microorganisms. Gram-negative bacteria are thought to be generally susceptible to attack from complement; however, P. aeruginosa can be an exception, with certain strains being serum resistant. Various molecular mechanisms have been described that confer P. aeruginosa unique resistance to numerous aspects of the complement response. In this review, we summarize the current published literature regarding the interactions of P. aeruginosa and complement, as well as the mechanisms used by P. aeruginosa to exploit various complement deficiencies and the strategies used to disrupt or hijack normal complement activities.
Topics: Humans; Pseudomonas aeruginosa; Pseudomonas Infections; Complement System Proteins
PubMed: 37436150
DOI: 10.1128/jb.00018-23