Quantification of airborne road-side pollution carbon nanoparticles

Roadside diesel particulate matter (DPM) has been collected using a P-Trak particle counter with modified inlet filter. The P-Trak monitor assesses ultrafine particle number in real-time rather than accumulated PM mass over a period of time, which is important for DPM where the particles are often <100nm in size. Collected pollution particulate matter was analysed by SEM and TEM, quantifying particle size, morphology and size distribution. The primary carbon nanoparticles form complex fractal aggregates with open porous morphologies and evidence of secondary carbon deposition. For the chosen collection sites, occasional but significantly larger mineral and fibrous particles were identified. The assessment of airborne particles by mass collection (TEOM), particle-number (P-Trak) and TEM methods is discussed

Characterization of ocular clinical isolates of Pseudomonas aeruginosa from non-contact lens related keratitis patients from south India

P. aeruginosa is the most common Gram-negative organism causing bacterial keratitis. Pseudomonas utilizes various virulence mechanisms to adhere and colonize in the host tissue. In the present study, we examined virulence factors associated with thirty-four clinical P. aeruginosa isolates collected from keratitis patients seeking care at L V Prasad Eye Institute, Hyderabad. The virulence-associated genes in all the isolates were genotyped and characteristics such as antibiotic susceptibility, biofilm formation, swarming motility, pyoverdine production and cell cytotoxicity were analyzed. All the isolates showed the presence of genes related to biofilm formation, alkaline proteases and elastases; however, there was a difference in the presence of genes related to the type III secretion system (T3SS). A higher prevalence of exoU+ genotype was noted in the drug-resistant isolates. All the isolates were capable of forming biofilms and more than 70% of the isolates showed good swarming motility. Pyoverdine production was not associated with the T3SS genotype. In the cytotoxicity assay, the presence of exoS, exoU or both resulted in higher cytotoxicity compared to the absence of both the genes. Overall, our results suggest that the T3SS profile is a good indicator of P. aeruginosa virulence characteristics and the isolates lacking the effector genes may have evolved alternate mechanisms of colonization in the host