In this study, highly monodispersed, exceptionally stable, spherical silver nanoparticles (AgNPs) were successfully synthesized by the microwave assisted rapid and cost-effective green method. Aqueous extract of clammy cherry (Cordia obliqua Willd) fruit was used as the green reductant, and capping agent for the synthesis of AgNPs and the effect of different synthesis parameters on the optical properties of the synthesized AgNPs was also studied. The characterization of synthesized AgNPs by Fourier transform infrared spectroscopy, X-ray diffraction studies, UV-visible spectroscopy, scanning electron microscopy and transmission electron microscopy (TEM) revealed the formation of small AgNPs with narrow size distribution. TEM studies corroborated that the AgNPs are highly crystalline and spherical with an average diameter of 7.13 nm. The cyclic voltammetry profile of AgNPs modified electrode in NaOH depicted prominent redox peaks evidencing an impressive electrochemical response. The AgNPs manifested high catalytic activity towards reduction of methyl orange and rhodamine blue with apparent rate constant 0.3038 min −1 and 0.1542 min −1 respectively. Additionally, the prepared AgNPs exhibited strong antibacterial efficacy against the tested microbes.

BACKGROUND Acinetobacter species are important infectious agents worldwide especially in healthcare settings. It has the ability to develop various resistance mechanisms to various antibiotics. We wanted to study the role of tigecycline and minocycline in the treatment of multidrug resistant Acinetobacter species. METHODS 254 non-repetitive isolates of Acinetobacter species from various clinical samples like exudates, blood, sputum, urine were retrospectively studied. Antibiotic susceptibility testing was done by Vitek 2 compact system. Susceptibility of the carbapenem resistant isolates towards tigecycline and minocycline were analysed. RESULTS 205 (80.7 %) isolates were resistant to either of the carbapenem drugs and 49 (19.3 %) were sensitive to all the 3 carbapenems, namely imipenem, meropenem and doripenem. 54.1 % isolates were sensitive to tigecycline while sensitivity towards minocycline was 40.5 %. The degree of sensitive concordance in the susceptibility to minocycline and tigecycline against Acinetobacter species was 31.1 %, which indicated fair agreement statistically. 21.1 % isolates were resistant / intermediate to minocycline but sensitive to tigecycline. Only 9.4 % isolates which were resistant to tigecycline were sensitive to minocycline. CONCLUSIONS The results of the present study have demonstrated that minocycline and tigecycline are effective against the carbapenem resistant Acinetobacter species. Tigecycline can be considered as a therapeutic agent for the treatment of multidrug resistant Acinetobacter which are otherwise difficult to inhibit using other antibiotics. KEY WORDS Carbapenem Resistance, Tigecycline, Minocycline, Antimicrobial Resistance