-
Journal of Ophthalmic Inflammation and... Feb 2024To describe a puzzling case of endophthalmitis caused by three unusual bacteria after intravitreal injection, its outcome, and underlying questions.
PURPOSE
To describe a puzzling case of endophthalmitis caused by three unusual bacteria after intravitreal injection, its outcome, and underlying questions.
FINDINGS
A 70-year-old female patient was diagnosed with acute endophthalmitis following intravitreal aflibercept injection for age-related macular degeneration. A standard tap and inject procedure was performed. Microbiological analyses on the anterior chamber and vitreous samples yielded the presence of three non-fermenting Gram-negative rods: Pseudomonas stutzeri, Stenotrophomonas maltophilia, and Ochrobactrum anthropi. The outcome was favorable after intravitreal injections of vancomycin and ceftazidime, with an almost complete recovery of the visual acuity to its baseline level. No potential source of infection was identified.
CONCLUSION
Endophthalmitis following intravitreal injection can be caused by a wide variety of bacteria, including some rare Gram-negative species. They can sometimes co-exist in a single patient, but their virulence may vary greatly. Due to the variable antibiotic susceptibility and frequent multiresistance associated with non-fermenting Gram-negative rods, a prompt microbiological approach is required. Favorable outcome can be achieved with standard management.
PubMed: 38334879
DOI: 10.1186/s12348-023-00376-9 -
Marine Drugs Jul 2017273 is a marine bacterium producing exopolysaccharide 273 (EPS273) with high anti-biofilm activity against PAO1. Here, the complete genome of 273 was sequenced and...
273 is a marine bacterium producing exopolysaccharide 273 (EPS273) with high anti-biofilm activity against PAO1. Here, the complete genome of 273 was sequenced and the genome contained a circular 5.03 Mb chromosome. With extensive analysis of the genome, a genetic locus containing 18 genes was predicted to be involved in the biosynthesis of EPS273. In order to confirm this prediction, two adjacent genes ( and ) encoding glycosyltransferases and one gene () encoding tyrosine protein kinase within the genetic locus were deleted and biosynthesis of EPS273 was checked in parallel. The molecular weight profile of EPS purified from the mutant Δ was obviously different from that purified from wild-type 273, while the corresponding EPS was hardly detected from the mutant Δ, which indicated the involvement of the proposed 18-gene cluster in the biosynthesis of EPS273. Moreover, the mutant Δ had the biofilm formed earlier compared with the wild type, and the mutant Δ almost completely lost the ability of biofilm formation. Therefore, EPS273 might facilitate the biofilm formation for its producing strain 273 while inhibiting the biofilm formation of PAO1. This study can contribute to better understanding of the biosynthesis of EPS273 and disclose the biological function of EPS273 for its producing strain 273.
Topics: Bacterial Proteins; Biofilms; Genes, Bacterial; Genome, Bacterial; Multigene Family; Polysaccharides, Bacterial; Pseudomonas aeruginosa; Pseudomonas stutzeri; Sequence Analysis
PubMed: 28698510
DOI: 10.3390/md15070218 -
BMC Microbiology May 2022Pseudomonas stutzeri S116 is a sulfur-oxidizing bacteria isolated from marine sludge. It exhibited excellent electricity generation as bioanode and biocathode applied in...
BACKGROUND
Pseudomonas stutzeri S116 is a sulfur-oxidizing bacteria isolated from marine sludge. It exhibited excellent electricity generation as bioanode and biocathode applied in microbial fuel cells (MFCs). Complete genome sequencing of P. stutzeri and cyclic voltammetry method were performed to reveal its mechanism in microbial fuel cells system.
RESULTS
This study indicated that the MFCs generated a maximum output voltage of 254.2 mV and 226.0 mV, and maximum power density of 765 mW/m and 656.6 mW/m respectively. Complete genome sequencing of P. stutzeri S116 was performed to indicate that most function genes showed high similarities with P. stutzeri, and its primary annotations were associated with energy production and conversion (6.84%), amino acid transport and metabolism (6.82%) and inorganic ion transport and metabolism (6.77%). Homology of 36 genes involved in oxidative phosphorylation was detected, which suggests the strain S116 possesses an integrated electron transport chain. Additionally, many genes encoding pilus-assembly proteins and redox mediators (riboflavin and phenazine) were detected in the databases. Thiosulfate oxidization and dissimilatory nitrate reduction were annotated in the sulfur metabolism pathway and nitrogen metabolism pathway, respectively. Gene function analysis and cyclic voltammetry indicated that P. stutzeri probably possesses cellular machinery such as cytochrome c and redox mediators and can perform extracellular electron transfer and produce electricity in MFCs.
CONCLUSION
The redox mediators secreted by P. stutzeri S116 were probably responsible for performance of MFCs. The critical genes and metabolic pathways involved in thiosulfate oxide and nitrate reduction were detected, which indicated that the strain can treat wastewater containing sulfide and nitrite efficiently.
Topics: Bioelectric Energy Sources; Catalysis; Electricity; Electrodes; Nitrates; Pseudomonas stutzeri; Sulfur; Thiosulfates
PubMed: 35590268
DOI: 10.1186/s12866-022-02552-8 -
Indian Journal of Ophthalmology Jun 2022To report clinical features, antibiotic susceptibility profile, management, and outcomes of a cluster outbreak of post-cataract surgery Pseudomonas stutzeri...
PURPOSE
To report clinical features, antibiotic susceptibility profile, management, and outcomes of a cluster outbreak of post-cataract surgery Pseudomonas stutzeri endophthalmitis.
METHODS
This was a hospital-based case series in which 14 patients with acute postoperative endophthalmitis who underwent cataract surgery on the same day were included. Based on severity of presentation, they either underwent pars plana vitrectomy (PPV) with intraocular antibiotics (IOAB) or vitreous tap with IOAB. Vitreous aspirates and environmental surveillance samples were inoculated on culture media and further processed by MALDI-TOF MS for identification and Vitek3 for susceptibility profile.
RESULTS
There were 8 females and 6 males with a mean age of 62.14 ± 8.08 years. Presenting signs included corneal folds (100%), hypopyon (57.1%) and fibrin (50%). Ten patients with mild presentation underwent vitreous tap with IOAB. Four patients with severe presentation underwent PPV with IOAB. Pseudomonas stutzeri was isolated from the vitreous samples and was pan-sensitive. Six eyes required multiple interventions. Favorable outcome was obtained in 12 eyes, one eye developed phthisis, and one patient was lost to follow-up.
CONCLUSION
We report the first ever cluster outbreak of Pseudomonas stutzeri endophthalmitis following phacoemulsification with IOL implantation in a single surgeon setting. Majority of the patients had a mild presentation and responded well to targeted anti-microbial treatment.
Topics: Acute Disease; Aged; Anti-Bacterial Agents; Cataract; Disease Outbreaks; Endophthalmitis; Eye Infections, Bacterial; Female; Humans; Male; Middle Aged; Phacoemulsification; Pseudomonas Infections; Pseudomonas stutzeri
PubMed: 35647987
DOI: 10.4103/ijo.IJO_3096_21 -
Frontiers in Microbiology 2019The threat of antibiotic resistance has attracted strong interest during the last two decades, thus stimulating stewardship programs and research on alternative... (Review)
Review
The threat of antibiotic resistance has attracted strong interest during the last two decades, thus stimulating stewardship programs and research on alternative antimicrobial therapies. Conversely, much less attention has been given to the directly related problem of resistance toward antiseptics and biocides. While bacterial resistances toward triclosan or quaternary ammonium compounds have been considered in this context, the bis-biguanide chlorhexidine (CHX) has been put into focus only very recently when its use was associated with emergence of stable resistance to the last-resort antibiotic colistin. The antimicrobial effect of CHX is based on damaging the bacterial cytoplasmic membrane and subsequent leakage of cytoplasmic material. Consequently, mechanisms conferring resistance toward CHX include multidrug efflux pumps and cell membrane changes. For instance, in staphylococci it has been shown that plasmid-borne ("quaternary ammonium compound") genes encode Qac efflux proteins that recognize cationic antiseptics as substrates. In , changes in the outer membrane protein and lipopolysaccharide profiles have been implicated in CHX resistance. However, little is known about the risk of resistance toward CHX in oral bacteria and potential mechanisms conferring this resistance or even cross-resistances toward antibiotics. Interestingly, there is also little awareness about the risk of CHX resistance in the dental community even though CHX has been widely used in dental practice as the gold-standard antiseptic for more than 40 years and is also included in a wide range of oral care consumer products. This review provides an overview of general resistance mechanisms toward CHX and the evidence for CHX resistance in oral bacteria. Furthermore, this work aims to raise awareness among the dental community about the risk of resistance toward CHX and accompanying cross-resistance to antibiotics. We propose new research directions related to the effects of CHX on bacteria in oral biofilms.
PubMed: 30967854
DOI: 10.3389/fmicb.2019.00587 -
Microbial Cell Factories Sep 2017Studies on membrane proteins are often hampered by insufficient yields of the protein of interest. Several prokaryotic hosts have been tested for their applicability as...
BACKGROUND
Studies on membrane proteins are often hampered by insufficient yields of the protein of interest. Several prokaryotic hosts have been tested for their applicability as production platform but still Escherichia coli by far is the one most commonly used. Nevertheless, it has been demonstrated that in some cases hosts other than E. coli are more appropriate for certain target proteins.
RESULTS
Here we have developed an expression system for the heterologous production of membrane proteins using a single plasmid-based approach. The gammaproteobacterium Pseudomonas stutzeri was employed as a new production host. We investigated several basic microbiological features crucial for its handling in the laboratory. The organism belonging to bio-safety level one is a close relative of the human pathogen Pseudomonas aeruginosa. Pseudomonas stutzeri is comparable to E. coli regarding its growth and cultivation conditions. Several effective antibiotics were identified and a protocol for plasmid transformation was established. We present a workflow including cloning of the target proteins, small-scale screening for the best production conditions and finally large-scale production in the milligram range. The GFP folding assay was used for the rapid analysis of protein folding states. In summary, out of 36 heterologous target proteins, 20 were produced at high yields. Additionally, eight transporters derived from P. aeruginosa could be obtained with high yields. Upscaling of protein production and purification of a Gluconate:H Symporter (GntP) family transporter (STM2913) from Salmonella enterica to high purity was demonstrated.
CONCLUSIONS
Pseudomonas stutzeri is an alternative production host for membrane proteins with success rates comparable to E. coli. However, some proteins were produced with high yields in P. stutzeri but not in E. coli and vice versa. Therefore, P. stutzeri extends the spectrum of useful production hosts for membrane proteins and increases the success rate for highly produced proteins. Using the new pL2020 vector no additional cloning is required to test both hosts in parallel.
Topics: Bacterial Proteins; Cloning, Molecular; Membrane Proteins; Membrane Transport Proteins; Plasmids; Pseudomonas aeruginosa; Pseudomonas stutzeri; Recombinant Proteins
PubMed: 28931397
DOI: 10.1186/s12934-017-0771-0 -
MSphere Apr 2018encodes a master regulator protein conserved across pseudomonads, which can be either a positive or negative regulator of swimming motility depending on the species...
encodes a master regulator protein conserved across pseudomonads, which can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for two different motility-related phenotypes in As in , AmrZ functions as a positive regulator of swimming motility within , which suggests that the functions of this protein with regard to swimming motility have switched at least twice across pseudomonads. Shifts in mode of regulation cannot be explained by changes in AmrZ sequence alone. We further show that AmrZ acts as a positive regulator of colony spreading within this strain and that this regulation is at least partially independent of swimming motility. Closer investigation of mechanistic shifts in dual-function regulators like AmrZ could provide unique insights into how transcriptional pathways are rewired between closely related species. Microbes often display finely tuned patterns of gene regulation across different environments, with major regulatory changes controlled by a small group of "master" regulators within each cell. AmrZ is a master regulator of gene expression across pseudomonads and can be either a positive or negative regulator for a variety of pathways depending on the strain and genomic context. Here, we demonstrate that the phenotypic outcomes of regulation of swimming motility by AmrZ have switched at least twice independently in pseudomonads, so that AmrZ promotes increased swimming motility in and but represses this phenotype in and Since examples of switches in regulatory mode are relatively rare, further investigation into the mechanisms underlying shifts in regulator function for AmrZ could provide unique insights into the evolution of bacterial regulatory proteins.
Topics: Bacterial Proteins; Evolution, Molecular; Gene Expression Regulation, Bacterial; Genes, Regulator; Promoter Regions, Genetic; Protein Binding; Pseudomonas; Transcription Factors
PubMed: 29669886
DOI: 10.1128/mSphere.00132-18 -
Microorganisms Jun 2024Enhanced denitrification has been reported under weak electric fields. However, it is difficult to investigate the mechanism of enhanced denitrification due to the...
Enhanced denitrification has been reported under weak electric fields. However, it is difficult to investigate the mechanism of enhanced denitrification due to the complex interspecific interactions of mixed-culture systems. In this study, , capable of denitrification under anaerobic conditions, was selected for treating low COD/N (2.0, ratio between concentration of chemical oxygen demand and NO-N) artificial wastewater under constant external voltages of 0.2, 0.4, and 0.6 V. The results revealed that exhibited the highest efficiency in nitrate reduction at 0.2 V. Moreover, the maximum nitrate removal rate was 15.96 mg/(L·h) among the closed-circuit groups, 19.39% higher than that under the open-circuit group. Additionally, a notable reduction in nitrite accumulation was observed under weak electric fields. Enzyme activity analysis showed that the nitrate reductase activities were significantly increased among the closed-circuit groups, while nitrite reductase activities were inhibited. Transcriptomic analysis indicated that amino acid metabolism, carbohydrate metabolism, and energy metabolism were increased, enhancing the resistance of to environmental stress and the efficiency of carbon source utilization for denitrification. The current study examined the impacts of weak electric fields on enzyme activities and microbial metabolic pathways and offers valuable insights into the mechanism by which denitrification is enhanced by weak electric fields.
PubMed: 38930600
DOI: 10.3390/microorganisms12061218 -
Acta Biologica Hungarica Sep 2016An alginate lyase with high specific enzyme activity was purified from Pseudomonas stutzeri MSEA04, isolated from marine brown algae. The alginate lyase was purified by...
An alginate lyase with high specific enzyme activity was purified from Pseudomonas stutzeri MSEA04, isolated from marine brown algae. The alginate lyase was purified by precipitation with ammonium sulphate, acetone and ethanol individually. 70% ethanol fraction showed maximum specific activity (133.3 U/mg). This fraction was re-purified by anion exchange chromatography DEAE- Cellulose A-52. The loaded protein was separated into 3 peaks. The second protein peak was the major one which contained 48.2% of the total protein recovered and 79.4% of the total recovered activity. The collected fractions of this peak were subjected to further purification by re-chromatography on Sephadex G-100. Alginate lyase activity was fractionated in the Sephadex column into one major peak, and the specific activity of this fraction reached 116 U/mg. The optimal substrate concentration, pH and temperature for alginate lyase activity were 8 mg/ml, pH 7.5 and 37 °C, respectively. While, Km and Vmax values were 1.07 mg alginate/ ml and 128.2 U/mg protein, respectively. The enzyme was partially stable below 50 °C, and the activity of the enzyme was strongly enhanced by K(+), and strongly inhibited by Ba(+2), Cd(+2), Fe(+2) and Zn(+2). The purified enzyme yielded a single band on SDS-PAGE with molecular weight (40.0 kDa).
Topics: Alginates; Bacterial Proteins; Chromatography, DEAE-Cellulose; Chromatography, Gel; DEAE-Cellulose; Dextrans; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Glucuronic Acid; Hexuronic Acids; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Polysaccharide-Lyases; Protein Denaturation; Pseudomonas stutzeri; Temperature; Water Microbiology
PubMed: 27630053
DOI: 10.1556/018.67.2016.3.8 -
Microorganisms Nov 2021Integrative and conjugative elements (ICEs) are chromosomally integrated self-transmissible mobile genetic elements. Although some ICEs are known to carry genes for the...
A New ICE Subfamily Integrative and Conjugative Element Responsible for Horizontal Transfer of Biphenyl and Salicylic Acid Catabolic Pathway in the PCB-Degrading Strain KF716.
Integrative and conjugative elements (ICEs) are chromosomally integrated self-transmissible mobile genetic elements. Although some ICEs are known to carry genes for the degradation of aromatic compounds, information on their genetic features is limited. We identified a new member of the ICE family carrying biphenyl catabolic genes and salicylic acid catabolic genes from the PCB-degrading strain KF716. The 117-kb ICEKF716 contains common core regions exhibiting homology with those of degradative ICE from B13 and ICE from sp. CIB. A comparison of the gene loci collected from the public database revealed that several putative ICEs from B6-2 JAB1, AN10 and 2A20 had highly conserved core regions with those of ICEKF716, along with the variable region that encodes the catabolic genes for biphenyl, naphthalene, toluene, or phenol. These data indicate that this type of ICE subfamily is ubiquitously distributed within aromatic compound-degrading bacteria. ICEKF716 was transferred from KF716 to PAO1 via a circular extrachromosomal intermediate form. In this study, we describe the structure and genetic features of ICEKF716 compared to other catabolic ICEs.
PubMed: 34946064
DOI: 10.3390/microorganisms9122462