Antibacterial activity and mechanism of moxifloxacin nanoparticles against drug-resistant Pseudomonas aeruginosa / 药学学报

We prepared moxifloxacin (MXF) loaded nanoparticles by nano-precipitation/self-assembly method, then compared the antibacterial activity of MXF and MXF loaded nanoparticles, and investigated the antibacterial mechanism of MXF loaded nanoparticles against Pseudomonas aeruginosa in vitro. The physicochemical properties such as particle size and zeta potential were investigated by laser particle size analyzer. The in vitro release characteristics were investigated by high performance liquid chromatography (HPLC). The effect of nanoparticles on HBE cells viability was investigated by CCK-8 assay. In addition, the in vitro antibacterial activity was investigated by minimum inhibitory concentration (MIC) assay, biofilm formation assays and transmission electron microscope (TEM) observation, then the antibacterial mechanism was initially explored. The particle size measurement showed that the nanoparticles had a size of 332.5 ± 2.7 nm, a polymer dispersion index (PDI) of 0.125 ± 0.053, a zeta potential of -24.3 ± 1.7 mV, and a uniform particle size distribution, drug loading content was (6.02 ± 1.27) %, encapsulation efficiency was (16.69 ± 1.17) %. The TEM results show that the nanoparticles have a spheroidal structure, and the particle size and distribution are consistent with the particle size measurement results. The nanoparticles can be effectively and rapidly released in phosphate buffer saline (PBS), releasing about 70% in 24 h, and releasing 87% in 72 h, and almost completely releasing the MXF at 120 h. At the same time, compared with moxifloxacin free drug, its MIC value is 8 μg·mL-1, which is 1/2 of MXF solution, and can significantly inhibit the formation of bacterial biofilms. It has well antibacterial activity in vitro and can be targeted to the surface of bacteria to exert its efficacy and improve the antibacterial effect. The moxifloxacin nanoparticles prepared in this study has a uniform particle size distribution, well drug release performance and antibacterial effect, and provides new ideas and strategies for the treatment of bacterial lung infection and the development of new antibacterial nanoformulations.

Biosurfactant production by Pseudomonas aeruginosain kefir and fish meal

The aim of this study was to increase rhamnolipid production by formulating media using kefir and fish meal for Pseudomonas aeruginosa strains isolated from different environmental resources. The strains, named as H1, SY1, and ST1, capable of rhamnolipid production were isolated from soil contaminated with wastes originating from olive and fish oil factories. Additionally, P. aeruginosa ATCC 9027 strain, which is known as rhamnolipid producer, was included in the study. Initially, rhamnolipid production by the strains was determined in Mineral Salt Medium (MSM) and then in media prepared by using kefir and fish meal. The obtained rhamnolipids were purified and quantified according to Dubois et al. (1956). The quantity of rhamnolipids of ATCC, H1 and SY1 strains in kefir media were determined as 11.7 g/L, 10.8 g/L and 3.2 g/L, respectively, and in fish meal media as 12.3 g/L, 9.3 g/L and 10.3 g/L, respectively. In addition, effect of UV light exposure on rhamnolipid production was also investigated but contrary a decrease was observed. The results indicate that P. aeruginosa strains isolated from various environmental resources used in this study can be important due to their rhamnolipid yield, and fish meal, which is obtained from waste of fish, can be an alternative source in low cost rhamnolipid production.

A comparative study of coastal and clinical isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous Gram-negative bacterium having a versatile metabolic potential and great ecological and clinical significance. The geographical distribution of P. aeruginosahas revealed the existence of an unbiased genetic arrangement in terrestrial isolates. In contrast, there are very few reports about P. aeruginosa strains from marine environments. The present work was aimed at studying the distribution of P. aeruginosa in coastal waters along the Indian Peninsula and understanding the environmental influence on genotypic, metabolic and phenotypic characteristics by comparing marine and clinical isolates. Of the 785 marine isolates obtained on selective media, only 32 (~4.1%) were identified as P. aeruginosa, based on their fatty acid methyl ester profiles. A low Euclidian distance value (< 2.5) obtained from chemotaxonomic analysis suggested that all the environmental (coastal and marine) isolates originated from a single species. While UPGMA analyses of AP-PCR and phenotypic profiles separated the environmental and clinical isolates, fatty acid biotyping showed overlapping between most clinical and environmental isolates. Our study revealed the genetic diversity among different environmental isolates of P. aeruginosa. While biogeographical separation was not evident based solely on phenotypic and metabolic typing, genomic and metatranscriptomic studies are more likely to show differences between these isolates. Thus, newer and more insightful methods are required to understand the ecological distribution of this complex group of bacteria.

Draft genome sequence of blaVeb-1, blaoxa-10producing multi-drug resistant (MDR) Pseudomonas aeruginosastrain VRFPA09 recovered from bloodstream infection

Pseudomonas aeruginosa (P. aeruginosa) bacteremia causes significant mortality rate due to emergence of multidrug resistant (MDR) nosocomial infections. We report the draft genome sequence of P. aeruginosa strain VRFPA09, a human bloodstream isolate, phenotypically proven as MDR strain. Whole genome sequencing on VRFPA09, deciphered betalactamase encoding bla_veb-1 and bla_OXA-10genes and multiple drug resistance, virulence factor encoding genes.