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The process of development of reliable and eco-friendly metallic nanoparticles is an important step in the field of nanotechnology. To achieve this, use of natural sources like biological systems becomes essential. In the present work, extracellular biosynthesis of gold nanoparticles using Padina gymnospora has been attempted and achieved rapid formation of gold nanoparticles in a short duration. The UV-vis spectrum of the aqueous medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. Scanning electron microscopy showed the formation of welldispersed gold nanoparticles. FTIR spectra of brown alga confirmed that hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. AFM analysis showed the results of particle sizes (53-67 nm) and average height of the particle roughness (60.0 nm). X-ray diffraction (XRD) spectrum of the gold nanoparticles exhibited Bragg reflections corresponding to gold nanoparticles. This environment-friendly method of biological gold nanoparticle synthesis can be applied potentially in various products that directly come in contact with the human body, such as cosmetics, and foods and consumer goods, besides medical applications.

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Silver nanoparticles (Ag-NPs) are known to have inhibitory and fungicidal effects. Resistance against fungal infection has emerged as a major health problem in recent years, which needs great and immediate concern. Here, we report the extracellular biological synthesis of silver nanoparticles through a simple green route approach using a marine mangrove (Rhizophora mucronata) and silver nitrate. Aqueous extract of marine mangrove helped in reduction and was used as capping agent in biological synthesis. Nanoparticles were characterized using microscopy and spectroscopy techniques such as HRTEM, UV-Vis absorption spectroscopy and FTIR spectroscopy. X-ray diffraction analysis showed that the nanoparticles had face centered cubic structure with crystalline nature. FTIR spectroscopy showed the presence of different functional groups, such as hydroxyl and carbonyl, involved in the synthesis of nanoparticles. The antifungal activity of fluconazole and itraconazole was enhanced against the tested pathogenic fungi in the presence of Ag-NP and confirmed from increase in fold area of inhibition. This environmentally friendly method of biological synthesis can be easily integrated for various medical applications.

The molecular epidemiology and carbapenem resistance mechanisms of clinical isolates of Acinetobacter baumannii obtained from a south Indian tertiary care hospital were investigated by repetitive extragenic palindromic sequence PCR (REP-PCR) and multi-locus sequence typing (MLST). Analysis of resistant determinants was achieved by PCR screening for the presence of genes encoding OXA-carbapenemases, metallo-b-lactamases (MBLs) and efflux pumps. REP-PCR generated around eight clusters of high heterogeneity; of these, two major clusters (I and V) appeared to be clonal in origin. Analysis of representative isolates from different clusters by MLST revealed that most of the isolates belonged to sequence type 103 of CC103 B . Second most prevalent ST belonged to clonal complex (CC) 92 B which is also referred to as international clone II. Most of the isolates were multi-drug resistant, being susceptible only to polymyxin-B and newer quinolones. Class D b-lactamases such as bla OXA-51-like (100%), bla OXA-23-like (56.8%) and bla OXA-24-like (14.8%) were found to be predominant, followed by a class B b-lactamase, namely bla IMP-1 (40.7%); none of the isolates had bla OXA-58 like, bla NDM-1 or bla SIM-1 . Genes of efflux-pump adeABC were predominant, most of isolates being biofilm producers that were PCR-positive for autoinducer synthase gene (>94%). Carbapenem non-susceptible isolates were highly diverse and present throughout the hospital irrespective of type of ward or intensive care unit. Although previous reports have documented diverse resistant mechanisms in A. baumannii, production of MBL and OXA-type of carbapenamases were found to be the predominant mechanism(s) of carbapenem resistance identified in strains isolated from Southern India.