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Evaluation of photodynamic therapy effect along with colistin on pandrug-resistant <i>Acinetobacter baumannii</i>
摘要： Background and Aims: Pandrug-resistant Acinetobacter baumannii (PDRAB) are including colistin resistant starins (CoRAB) which cause infections potentially untreatable infections. Recently, incidence of these strains are increasing worldwide. Therefore, new approaches, methods and strategies are urgently needed for treatment and eradication of infections due to PDRAB. So the aim of this study was to evaluate the efficacy of photodynamic therapy (PDT) in combination treatment with colistin against PDRAB. Materials and Methods: PDRAB which was isolated from burn patients was used as a test strain. PDT carried out in which toluidine blue O (TBO) and light-emitting diode (LED) were used as photosensitizer and radiation source, respectively. Then, the effect of PDT plus colistin was evaluated on CoRAB and the colony-forming units of each tested groups calculated. Finally, confirmation of antibacterial activity of combination therapy was carried out using scanning electron microscope. Results: PDT declined bacterial count in comparing with control group by 83.7% of killing percentage, in other words, less than one log reduction. While PDT in combination with colistin showed high synergetic effect against A. baumannii in all concentrations of colistin tested by 100% of killing percentage with 9-log reduction. Conclusions: According to our results, PDT alone couldn’t eliminate all of the treated bacterial cells. But when combined with colistin, it killed all of the treated bacterial cells in all tested concentrations. Also PDT decreased the minimal inhibitory concentration of colistin against PDRAB by more than 11 fold.
关键词： colistin,Acinetobacter baumannii,wound infection,toluidine blue O,photodynamic therapy,pandrug resistance
更新于2025-09-23 15:21:21
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A surface-enhanced Raman scattering-based lateral flow immunosensor for colistin in raw milk
摘要： A surface-enhanced Raman scattering (SERS)-based lateral flow immunosensor was created to identify colistin in milk. The Raman reporter 5,5-dithiobis-2-nitrobenzoic acid (DTNB) was used to label gold nanoparticles, and then anti-colistin monoclonal antibody (mAb) was attached. The size of the gold nanoparticles in the SERS nanoprobe was optimized, and the amount of DTNB and mAb, the change in hydrodynamic size, zeta potential, and the surface plasmon resonance band were also monitored in the preparation process. The SERS nanoprobe was then applied to a lateral flow strip followed by Raman signal readout for the quantitative determination of colistin with high sensitivity. The limits of detection of this assay were 0.10 ng/mL for colistin in milk, which was far below the previously reported value that was obtained with the ELISA method and the maximum residue limit set by the European Union. The spiking experiment showed high accuracy for this SERS-based immunosensing assay, with a recovery of 88.1% to 112.7% and satisfactory assay precision with a standard deviation below 15%. Furthermore, this assay also has the advantage of rapidity, with an assay time less than 20 min. Therefore, these results demonstrate that this SERS-based lateral flow immunosensor is promising for use in the rapid monitoring of colistin in milk.
关键词： Surface enhanced Raman scattering,Immunoassay,Sensor,Milk,Colistin
更新于2025-09-09 09:28:46