Waterborne Pathogen Detection Using Raman Spectroscopy

2008 ◽  
Vol 62 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Ashish Tripathi ◽  
Rabih E. Jabbour ◽  
Patrick J. Treado ◽  
Jason H. Neiss ◽  
Matthew P. Nelson ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Laser Power ◽  
Pathogen Detection ◽  
Species Level ◽  
Gram Positive ◽  
Gram Negative ◽  
Waterborne Pathogen ◽  
Water Matrix ◽  
The Impact ◽  
Power Densities

Raman spectroscopy is being evaluated as a candidate technology for waterborne pathogen detection. We have investigated the impact of key experimental and background interference parameters on the bacterial species level identification performance of Raman detection. These parameters include laser-induced photodamage threshold, composition of water matrix, and organism aging in water. The laser-induced photodamage may be minimized by operating a 532 nm continuous wave laser excitation at laser power densities below 2300 W/cm2 for Gram-positive Bacillus atrophaeus (formerly Bacillus globigii, BG) vegetative cells, 2800 W/cm2 for BG spores, and 3500 W/cm2 for Gram-negative E. coli (EC) organisms. In general, Bacillus spore microorganism preparations may be irradiated with higher laser power densities than the equivalent Bacillus vegetative preparations. In order to evaluate the impact of background interference and organism aging, we selected a biomaterials set comprising Gram-positive (anthrax simulants) organisms, Gram-negative (plague simulant) organisms, and proteins (toxin simulants) and constructed a Raman signature classifier that identifies at the species level. Subsequently, we evaluated the impact of tap water and storage time in water (aging) on the classifier performance when characterizing B. thuringiensis spores, BG spores, and EC cell preparations. In general, the measured Raman signatures of biological organisms exhibited minimal spectral variability with respect to the age of a resting suspension and water matrix composition. The observed signature variability did not substantially degrade discrimination performance at the genus and species levels. In addition, Raman chemical imaging spectroscopy was used to distinguish a mixture of BG spores and EC cells at the single cell level.

Impact of empirical antibiotic regimens on mortality in neutropenic patients with bloodstream infection presenting with septic shock

2021 ◽  
Author(s):  
Mariana Chumbita ◽  
Pedro Puerta-Alcalde ◽  
Carlota Gudiol ◽  
Nicole Garcia-Pouton ◽  
Júlia Laporte-Amargós ◽  
...  
Keyword(s):  
Risk Factors ◽  
Septic Shock ◽  
Kidney Injury ◽  
Bloodstream Infections ◽  
Gram Positive ◽  
Gram Negative ◽  
Neutropenic Patients ◽  
Prospective Cohorts ◽  
Independent Risk Factors ◽  
The Impact

Objectives: We analyzed risk factors for mortality in febrile neutropenic patients with bloodstream infections (BSI) presenting with septic shock and assessed the impact of empirical antibiotic regimens. Methods: Multicenter retrospective study (2010-2019) of two prospective cohorts comparing BSI episodes in patients with or without septic shock. Multivariate analysis was performed to identify independent risk factors for mortality in episodes with septic shock. Results: Of 1563 patients with BSI, 257 (16%) presented with septic shock. Those patients with septic shock had higher mortality than those without septic shock (55% vs 15%, p<0.001). Gram-negative bacilli caused 81% of episodes with septic shock; gram-positive cocci, 22%; and Candida species 5%. Inappropriate empirical antibiotic treatment (IEAT) was administered in 17.5% of septic shock episodes. Empirical β-lactam combined with other active antibiotics was associated with the lowest mortality observed. When amikacin was the only active antibiotic, mortality was 90%. Addition of empirical specific gram-positive coverage had no impact on mortality. Mortality was higher when IEAT was administered (76% vs 51%, p=0.002). Age >70 years (OR 2.3, 95% CI 1.2-4.7), IEAT for Candida spp. or gram-negative bacilli (OR 3.8, 1.3-11.1), acute kidney injury (OR 2.6, 1.4-4.9) and amikacin as the only active antibiotic (OR 15.2, 1.7-134.5) were independent risk factors for mortality, while combination of β-lactam and amikacin was protective (OR 0.32, 0.18-0.57). Conclusions: Septic shock in febrile neutropenic patients with BSI is associated with extremely high mortality, especially when IEAT is administered. Combination therapy including an active β-lactam and amikacin results in the best outcomes.

scholarly journals Facile fabrication of Tl4HgI6 nanostructures as a novel antibacterial and antibiofilm agents

2020 ◽  
Author(s):  
Maryam Karami ◽  
Mojgan Ghanbari ◽  
Omid Amiri ◽  
MASOUD SALAVATI-NIASARI ◽  
Somaye Rashki
Keyword(s):  
Raman Spectroscopy ◽  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Stoichiometric Ratio ◽  
Raman Spectrometry ◽  
Gram Negative ◽  
Biofilm Production ◽  
Facile Fabrication ◽  
Antibiofilm Agents ◽  
The Impact

Abstract In the present study, Tl4HgI6 nanostructures have been successfully fabricated through a simple precipitation route. The impact of TlI stoichiometric ratio to HgI2, and kind of surfactants was explored on purity, structure, and shape of samples. The as-fabricated Tl4HgI6 was characterized via XRD, EDX, FESEM, TEM, HRTEM, and Raman spectroscopy. Raman spectrometry corroborated the XRD outcomes, and revealed that the Tl4HgI6 nanoparticles were successfully fabricated. The structure, shape, and scale of the products were studied through FESEM images. It was observed that different factors have a notable aspect on the morphology and size of the products. The maximum antibacterial activity of Tl4HgI6 was perceived against S. aureus, E.coli and M. catarils. These outcomes demonstrate that Tl4HgI6 displays efficient bactericidal activity against Gram-positive and Gram-negative microorganisms. The anti-biofilm activity revealed that the best reduction of biofilm was recognized in higher Tl4HgI6 concentrations (2×MIC). Tl4HgI6 at 2×MIC concentration inhibits biofilm production by S. aureus and E. feacalis with an inhibition percentage of 95% and 90%, respectively.

Diversity profiling of xenic cultures of Dientamoeba fragilis following systematic antibiotic treatment and prospects for genome sequencing

Parasitology ◽  
2019 ◽  
Vol 147 (1) ◽  
pp. 29-38
Author(s):  
Rory Gough ◽  
Joel Barratt ◽  
Damien Stark ◽  
John Ellis
Keyword(s):  
Antibiotic Treatment ◽  
Genome Sequencing ◽  
Ribosomal Dna ◽  
Bacterial Species ◽  
Nutritional Requirement ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Dientamoeba Fragilis ◽  
The Impact

AbstractThe presence of bacterial DNA in Dientamoeba fragilis DNA extracts from culture poses a substantial challenge to sequencing the D. fragilis genome. However, elimination of bacteria from D. fragilis cultures has proven difficult in the past, presumably due to its dependence on some unknown prokaryote/s. This study explored options for removal of bacteria from D. fragilis cultures and for the generation of genome sequence data from D. fragilis. DNA was extracted from human faecal samples and xenic D. fragilis cultures. Extracts were subjected to 16S ribosomal DNA bacterial diversity profiling. Xenic D. fragilis cultures were then subject to antibiotic treatment regimens that systematically removed bacterial species depending on their membrane structure (Gram-positive or Gram-negative) and aerobic requirements. The impact of these treatments on cultures was assessed by 16S amplicon sequencing. Prior to antibiotic treatment, the cultures were dominated by Gram-negative bacteria. Addition of meropenem to cultures eliminated anaerobic Gram-negative bacteria, but it also led to protozoan death after 5 days incubation. The seeding of meropenem resistant Klebsiella pneumoniae strain KPC-2 into cultures before treatment by meropenem prevented death of D. fragilis cells beyond this 5 day period, suggesting that one or more species of Gram-negative bacteria may be an essential nutritional requirement for D. fragilis. Gram-positive cells were completely eliminated using vancomycin without affecting trophozoite growth. Finally, this study shows that genome sequencing of D. fragilis is feasible following bacterial elimination from cultures as the result of the major advances occurring in bioinformatics. We provide evidence on this fact by successfully sequencing the D. fragilis 28S large ribosomal DNA subunit gene using culture-derived DNA.

scholarly journals Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria

2010 ◽  
Vol 77 (1) ◽  
pp. 131-137 ◽  
Author(s):  
Sunil Palchaudhuri ◽  
Steven J. Rehse ◽  
Khozima Hamasha ◽  
Talha Syed ◽  
Eldar Kurtovic ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Preventive Therapy ◽  
Sugar Alcohol ◽  
Gram Positive ◽  
Prophylactic Measure ◽  
Gram Negative ◽  
E Coli ◽  
Viridans Group Streptococcus ◽  
K 12 ◽  
Uptake And Metabolism

ABSTRACTVisible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negativeEscherichia coli,E. coliC andE. coliK-12.E. coliC, but notE. coliK-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in theE. coliK-12. In both viridans group streptococcus and theE. coliC derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy.

Transcriptomic response of immune signalling pathways in intestinal epithelial cells exposed to lipopolysaccharides, Gram-negative bacteria or potentially probiotic microbes

2012 ◽  
Vol 3 (4) ◽  
pp. 273-286 ◽  
Author(s):  
J. Audy ◽  
O. Mathieu ◽  
J. Belvis ◽  
T.A. Tompkins
Keyword(s):  
Epithelial Cells ◽  
Host Response ◽  
Intestinal Epithelial Cells ◽  
Mitogen Activated Protein Kinase ◽  
Gram Negative Bacteria ◽  
Intestinal Epithelial ◽  
Gram Positive ◽  
Transcriptomic Response ◽  
Gram Negative ◽  
The Impact

In order to understand the appropriate use of potentially probiotic Gram-positive microbes through their introduction in the gut microbiome, it is necessary to understand the influence of individual bacteria on the host-response system at a cellular level. In the present study, we have shown that lipopolysaccharides, flagellated Gram-negative bacteria, potentially probiotic Gram-positive bacteria and yeast interact differently with human intestinal epithelial cells with a custom-designed expression microarray evaluating 17 specific host-response pathways. Only lipopolysaccharides and flagellated Gram-negative bacteria induced inflammatory response, while a subset of Gram-positive microbes had anti-inflammatory potential. The main outcome from the study was the differential regulation of the central mitogen-activated protein kinase signalling pathway by these Gram-positive microbes versus commensal/pathogenic Gram-negative bacteria. The microarray was efficient to highlight the impact of individual bacteria on the response of intestinal epithelial cells, but quantitative real-time polymerase chain reaction validation demonstrated some underestimation for down-regulated genes by the microarray. This immune array will allow us to better understand the mechanisms underlying microbe-induced host immune responses.

scholarly journals Structure-Guided Design of a Fluorescent Probe for the Visualization of FtsZ in Clinically Important Gram-Positive and Gram-Negative Bacterial Pathogens

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Edgar Ferrer-González ◽  
Junso Fujita ◽  
Takuya Yoshizawa ◽  
Julia M. Nelson ◽  
Alyssa J. Pilch ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Antibacterial Agents ◽  
Mechanisms Of Action ◽  
New Drugs ◽  
Gram Positive ◽  
Optimal Position ◽  
Gram Negative ◽  
High Affinity ◽  
Ftsz Inhibitors ◽  
The Impact

AbstractAddressing the growing problem of antibiotic resistance requires the development of new drugs with novel antibacterial targets. FtsZ has been identified as an appealing new target for antibacterial agents. Here, we describe the structure-guided design of a new fluorescent probe (BOFP) in which a BODIPY fluorophore has been conjugated to an oxazole-benzamide FtsZ inhibitor. Crystallographic studies have enabled us to identify the optimal position for tethering the fluorophore that facilitates the high-affinity FtsZ binding of BOFP. Fluorescence anisotropy studies demonstrate that BOFP binds the FtsZ proteins from the Gram-positive pathogens Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae with Kd values of 0.6–4.6 µM. Significantly, BOFP binds the FtsZ proteins from the Gram-negative pathogens Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii with an even higher affinity (Kd = 0.2–0.8 µM). Fluorescence microscopy studies reveal that BOFP can effectively label FtsZ in all the above Gram-positive and Gram-negative pathogens. In addition, BOFP is effective at monitoring the impact of non-fluorescent inhibitors on FtsZ localization in these target pathogens. Viewed as a whole, our results highlight the utility of BOFP as a powerful tool for identifying new broad-spectrum FtsZ inhibitors and understanding their mechanisms of action.

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