Mode of antibacterial activity of Eclalbasaponin isolated from Eclipta alba.

The present study was undertaken to evaluate the mode of antibacterial activity of Eclalbasaponin isolated from Eclipta alba, against selected Gram-positive and Gram-negative bacteria. The probable chemical structure was determined by using various spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. The antibacterial activity was evaluated by well diffusion technique, pH sensitivity, chemotaxis, and crystal violet assays. Eclalbasaponin showed clear zone of inhibition against both Bacillus subtilis and Pseudomonas aeruginosa and exhibited growth inhibition at the pH range of 5.5-9.0. The isolated saponin exhibited its positive chemoattractant property for both bacterial strains. Results of crystal violet assay and the presence of UV-sensitive materials in the cell-free supernatant confirmed the cellular damages caused by the treatment of Eclalbasaponin. The release of intracellular proteins due to the membrane damage was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Changes in the cell surface structure and membrane disruption were further revealed by FTIR and scanning electron microscopy analysis. The present study suggests that the isolated saponin from E. alba causes the disruption of the bacterial cell membrane which leads to the loss of bacterial cell viability.

Colloidal silver nanoparticles/rhamnolipid (SNPRL) composite as novel chemotactic antibacterial agent.

The antibacterial activity of silver nanoparticles and rhamnolipid are well known individually. In the present research, antibacterial and chemotactic activity due to colloidal silver nanoparticles (SNP), rhamnolipid (RL) and silver nanoparticles/rhamnolipid composite (SNPRL) were evaluated using Staphylococcus aureus (MTCC3160), Escherichia coli (MTCC40), Pseudomonas aeruginosa (MTCC8163) and Bacillus subtilis (MTCC441) as test strains. Further, the SNPRL nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The observation clearly indicates that SNPRL shows prominent antibacterial and chemotactic activity in comparison to all of its individual precursor components.

Rhamnolipid (RL) from Pseudomonas aeruginosa OBP1: a novel chemotaxis and antibacterial agent.

In the present study, the interaction of rhamnolipid produced by Pseudomonas aeruginosa OBP1 with the cell surfaces of Staphylococcus aureus (MTCC 3160) and Klebsiella pneumoniae (MTCC 618) were studied. Rhamnolipid concentration below critical micelle concentration (CMC) did not exhibit significant antibacterial activity. However, on increasing rhamnolipid concentration beyond CMC a prominent antibacterial activity was observed. The results demonstrated different degree of rhamnolipid interaction with both the bacteria. This might be due to the changes in their cell wall composition. The antibacterial activity determined by minimum inhibitory concentration (MIC). The antibacterial activity is prominent within 30 min of incubation. The antibacterial property of rhamnolipid was effective in all tested pH levels (5-9). The rhamnolipid was effective in almost all tested pH levels and showed better chemoattractant property against both the tested bacteria in comparison to glucose. The increase in the membrane permeability was evidenced by increase in the release of protein, enhancement in cell surface hydrophobicity and raises in the retention of crystal violet dye. Further, leakage of 260 nm absorbing intracellular materials, fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis confirmed the disruptive action of rhamnolipid. The above evidences support the idea that rhamnolipid significantly alters the cell membrane/envelop that leads to cell damage and enhances membrane permeability. Such activity of rhamnolipid could be used as an additive in the formulation of antibiotic and other antimicrobial agents for enhancing the effectiveness of chemotherapeutics.

Wound infection after cataract surgery: a report of two cases.

BACKGROUND: This is a report of 2 cases of fungal wound infection after cataract surgery (phacoemulsification). Both patients were noticed to have the fungal wound infection at the one-month follow-up after the surgery. OBSERVATIONS: Although both patients had been advised to taper steroid containing antibiotic eye drops, they failed to do so. Despite intensive treatment with antifungal eye drops and oral antifungal agents, visual outcome was poor. CONCLUSION: Fungal infection of the wound may occur in cataract patients in the post-operative period. This infection is probably more common in patients who have had a temporal incision and who are from an agricultural background living in a hot and humid climate.