Bacterial biofilm infections are difficult to eradicate because of antibiotic insusceptibility and high recurrence rates. Biofilm formation by Pseudomonas aeruginosa, a leading cause of bacterial ...keratitis, is facilitated by the bacterial Psl exopolysaccharide and associated with heightened virulence. Using intravital microscopy, we observed that neutrophilic recruitment to corneal infections limits P. aeruginosa biofilms to the outer eye surface, preventing bacterial dissemination. Neutrophils moved to the base of forming biofilms, where they underwent neutrophil extracellular trap formation (NETosis) in response to high expression of the bacterial type-3 secretion system (T3SS). NETs formed a barrier “dead zone,” confining bacteria to the external corneal environment and inhibiting bacterial dissemination into the brain. Once formed, ocular biofilms were resistant to antibiotics and neutrophil killing, advancing eye pathology. However, blocking both Psl and T3SS together with antibiotic treatment broke down the biofilm and reversed keratitis, suggesting future therapeutic strategies for this intractable infection.
Display omitted
•P. aeruginosa keratitis infections result in biofilm formation on the cornea•NETs form at the base of the biofilm, triggered by the type-3 secretion system (T3SS)•NETs stop bacterial dissemination into the brain but promote antibiotic resistance•Blocking exopolysaccharide Psl and the T3SS allowed neutrophils to break down the biofilm
Thanabalasuriar et al. characterize the interplay between neutrophils and Pseudomonas biofilms on the cornea. At the base of the biofilm, neutrophils encountered expression of the type-3 secretion system, leading to an expansive deposition of neutrophil extracellular traps (NETs). NET formation impeded bacterial dissemination into the brain yet promoted antibiotic resistance.
The recent increase in outbreaks of pathogenic bacteria and antimicrobial resistance represent major public health problems. Being the leading cause of death in humans, the bacterial infections need ...to be accurately and quickly diagnosed. Hence, the development of fast, cost-effective, sensitive and specific strategies for the detection of the targeted bacterium is of utmost importance.
This review presents a systematic, critical evaluation of the recent analytical methods for the characterization and diagnosis of infections caused by Pseudomonas aeruginosa. The clinical manifestations, incidence and treatment of the P. aeruginosa infection and the associated quorum sensing, biofilm formation and virulence factors are also discussed. An overview of a variety of analytical methods for the detection of P. aeruginosa is provided, including whole-cell detection (microbiological methods, biosensors), antigens, DNA, and relevant markers (quorum sensing molecules, virulence factors) detection. The latest trends in analytical methods, especially sensors, are the orientation towards portability and on-site detection. The efforts made so far to achieve these goals in the detection of P. aeruginosa and its markers are also presented and discussed in this review. The strengths and weaknesses of the current detection methods are evaluated, while exploring potential routes for further development.
Display omitted
•Comprehensive description of analytical methods for Pseudomonas aeruginosa detection as whole bacterium.•The methods via some well-known metabolites and virulence factors were also described.•The main purpose was for diagnosis and to find the most effective treatment schemes.•The development of biofilms was also investigated with analytical methods.
The rapid detection of the pathogenic bacteria in patient samples is crucial to expedient patient care. The proposed approach reports the development of a novel lab-on-a-chip device for the rapid ...detection of P. aeruginosa based on immunomagnetic separation, optical scattering, and machine learning. The immunomagnetic particles with a diameter of 5 μm were synthesized for isolating P. aeruginosa from the test sample. A microfluidic chip was fabricated, and three optical fibers were embedded for connecting a laser light and two photodetectors. The laser light was pointed towards the channel to pass light through the sample. A pair of photodetectors via optical fibers were arranged symmetrically at 45° to the channel. The photodetectors acquired scattered light from the flowing sample and converted the light to an electrical signal. The sample containing immunomagnetic beads linked with bacteria was injected into the microfluidic chip. The optimized conditions for performing the experiments were characterized for real-time detection of P. aeruginosa. The data acquisition system recorded the real-time light scattering from the test sample. After removing noise from the output waveform, five different time-domain statistical features were extracted from each waveform: standard mean, standard variance, skewness, kurtosis, and coefficient of variation. The pathogens classification was performed by training the discrimination model using extracted features based on machine learning algorithms. The support vector machines (SVM) with a sigmoid function kernel showed superior classification performance with 97.9% accuracy among other classifiers, including k-nearest neighbors (KNN), logistic regression (LR), and naïve Bayes (NB). The method can detect P. aeruginosa specifically and quantitatively with a limit of detection of 102 CFU/mL. The device can classify P. aeruginosa within 10 min with a total assay time of 25 min. The device was used to test its ability to detect pathogen from the serum and sputum specimens spiked with 105 CFU/mL concentration of P. aeruginosa. The results indicate that light scattering combined with machine learning can be used to detect P. aeruginosa. The proposed technique is anticipated to be helpful as a rapid device for diagnosing P. aeruginosa related infections.
Display omitted
•On-chip detection of P. aeruginosa using immunomagnetic separation, light scattering, and machine learning approach.•P. aeruginosa was isolated using immunomagnetic separation.•Embedded optical fibers for coupling laser device and photosensors.•Time domain features were evaluated and SVM was trained for classification.•P.aeruginosa was detected specifically and quantitatively with a classification accuracy of 97.9% and a limit of detection of 102 CFU/mL.
This study investigates the effectiveness of non-activated peroxymonosulfate (PMS) as oxidative agent for water purification in the presence and absence of natural solar radiation. The inactivation ...of three pathogens (Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa) and degradation of three Contaminants of Emerging Concern (CECs) (Trimethoprim-TMP, Sulfamethoxazole-SMX and Diclofenac-DCF) was simultaneously assessed in isotonic water (IW) by testing a wide range of PMS concentrations (from 0.0001 to 0.01 mM). A significant oxidative effect of PMS in darkness was obtained for both bacteria and CEC abatement, but when irradiated with solar light, results demonstrated a great enhancement on all bacterial kinetic rates, reaching >5 Log reduction in 30 min (1.5 kJL−1 of QUV) with 0.005 mM of oxidant as the best concentration. For CECs, higher degradation performance was obtained with 0.01 mM, 80% removal of DCF, SMX and TMP was achieved in 16 min (1.5 kJL−1), 27 min (9.4 kJL−1) and 150 min (16.8 kJL−1), respectively. Besides, the influence of inorganic species on the global PMS/solar system performance was assessed by testing its effectiveness in distilled water (DW), natural well water (WeW) and diluted well water (d-WeW) at 0.01 mM. Results revealed that (i) high chloride concentration (IW) has an important positive effect, (ii) the presence of a complex inorganic chemical water composition reduced the system efficiency (WeW), and (iii) no differences were obtained from the presence of low or high contents of carbonates/bicarbonates (WeW versus d-WeW), obtaining the following global PMS/solar efficiency performance order: IW > DW > WeW = d-WeW.
Display omitted
•Simultaneous abatement of CECs and bacteria by PMS direct oxidation was proved.•Best PMS concentration to disinfect and decontaminated water was 0.01 mML-1.•A synergistic effect on bacterial inactivation by PMS and sunlight was obtained.•Presence of inorganic species in water strongly affect the process efficiency.
Due to the increasing resistance of Pseudomonas aeruginosa to most clinically relevant antimicrobials, it is challenging to treat bacterial infection with traditional antibiotics. Quorum sensing can ...regulate the production of biofilms and virulence factors which are closely related to bacterial resistance. Previously we synthesized a series of oxazolidinone compounds targeting the quorum-sensing transcriptional regulatory protein CviR and ZS-12 showed good activity against Chromobacterium violaceum CV026 quorum-sensing. In this study, eighteen 3-amino-2-oxazolidinone compounds were designed and synthesized using ZS-12 as the lead compound. We initially evaluated the inhibitory activities of novel oxazolidinone compounds against QS using C. violaceum CV026 as a reporter strain. Thirteen compounds showed good activities (IC50 range 3.69–63.58 μM) and YXL-13 inhibition was the most significant (IC50 = 3.686 ± 0.5790 μM) against biofilm formation and virulence factors determination of P. aeruginosa PAO1. In vitro, YXL-13 significantly inhibited the formation of PAO1 biofilm (range 42.98%–17.67%), the production of virulence factors (pyocyanin, elastase, rhamnolipid, and protease), and bacterial motility. Moreover, the combination of YXL-13 with an antibiotic (meropenem trihydrate) could significantly improve the antibiotic susceptibility of biofilm P. aeruginosa PAO1 cells. In vivo, YXL-13 significantly prolonged the lifespan of wildtype Caenorhabditis elegans N2 infected by P. aeruginosa PAO1. In conclusion, YXL-13 is a candidate agent for antibiotic-resistant P. aeruginosa PAO1and provides a method for finding new antibacterial drugs.
A series of 3-amino-2-oxazolidinone compounds targeting the quorum-sensing were synthesized and YXL-13 showed significant activity against Chromobacterium violaceum CV026 quorum-sensing. In vivo and in vitro studies have shown that it was a good candidate for the study of novel antibiotic strategies. Display omitted
•Eighteen novel 3-amino-2-oxazolidinone compounds as quorum-sensing inhibitors were designed, synthesized and characterized.•In vitro, YXL-13 strongly inhibited P. aeruginosa PAO1 biofilm, virulence factors and bacterial motility.•In vivo, YXL-13 significantly prolonged the lifespan of wildtype C. elegans N2 infected by P. aeruginosa PAO1.
The high incidence of persistent multidrug resistant bacterial infections is a worldwide public health burden. Alternative strategies are required to deal with such issue including the use of drugs ...with anti-virulence activity. The application of nanotechnology to develop advanced Nano-materials that target quorum sensing regulated virulence factors is an attractive approach. Synthesis of ascorbic acid Nano-emulsion (ASC-NEs) and assessment of its activity in vitro against the virulence factors and its protective ability against pathogenesis as well as the effect against expression of quorum sensing genes of Pseudomonas aeruginosa and Staphylococcus aureus isolates. Ascorbic acid Nano-emulsion was characterized by DLS Zetasizer Technique, Zeta potential; Transmission Electron Microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The antibacterial activity of ASC-NEs was tested by the broth microdilution method and the activity of their sub-MIC against the expression of quorum sensing controlled virulence was investigated using phenotypic experiments and RT-PCR. The protective activity of ASC-NEs against P. aeruginosa as well as S. aureus pathogenesis was tested in vivo. Phenotypically, ASC-NEs had strong virulence inhibitory activity against the tested bacteria. The RT-PCR experiment showed that it exhibited significant QS inhibitory activity. The in vivo results showed that ASC-NEs protected against staphylococcal infection, however, it failed to protect mice against Pseudomonal infection. These results suggest the promising use of nanoformulations against virulence factors in multidrug resistant P. aeruginosa and S. aureus. However, further studies are required concerning the potential toxicity, clearance and phamacokinetics of the nanoformulations.
The purpose of this research is synthesis of photoluminescence nanoparticles for detection of Pseudomonas aeruginosa that is feasible for bio medial applications. Carbon nano-templates were prepared ...from soot by burning of almond as a green precursor. Then NiFe2O4 nanoparticles were synthesized on the carbon templates. For preparation of hollow structures, the product was calcinated for removing of carbon templates. Finally, carbon dots were synthesized on the hollow nickel ferrite cores by applying ethylene diamine and citric acid. Phase of the products was approved by X-ray diffraction (XRD), scanning electron microscopy (SEM) depict the morphology and transmission electron microscopy (TEM) probe the grain size and hollow structures of the nickel ferrite, carbon dot and nanocomposites. Fourier transform infrared (FT-IR) spectroscopy approved the purity of the nanostructures. Ultraviolet–visible (UV–Vis) absorption and photo-luminescence (PL) spectroscopy confirmed appropriate photo-luminescence under ultraviolet irradiation. Vibrating sample magnetometer (VSM) shows ferromagnetic property of the both hollow NiFe2O4 and nickel ferrite-carbon nanocomposite. This work presents a new nanostructure as green prepared photoluminescence sensor for detecting of Pseudomonas aeruginosa bacteria, lead and mercury ions. Outcomes confirm decreasing in photoluminescence intensity of the nanocomposite by enhancing of Pseudomonas aeruginosa, Pb(II) and Hg(II) ions. Antibacterial effect of NiFe2O4-carbon dot on the degradation of Pseudomonas aeruginosa bacteria was also examined.
Display omitted
•Carbon nano-templates were prepared from soot by burning of almond.•NiFe2O4 nanoparticles were synthesized on the carbon templates.•Carbon dots were synthesized on the hollow magnetic nickel ferrite cores.•New photoluminescence sensor for detecting of bacteria was introduced.
PDF
