Gram-negative Moraxella Catarrhalis Research Articles

Characterization and Antibacterial Activity of Biosynthesized Silver Nanoparticles Using the Ethanolic Extract of Pelargonium sidoides DC

Development of cost-effective and eco-friendly methods of nanoparticle synthesis could play a crucial role in integrating nanotechnology and phytomedicine for biological applications. In this study, biogenic silver nanoparticles (AgNPs) were synthesized using the ethanolic extract of Pelargonium sidoides DC at 60°C. Formation of nanoparticles was monitored using UV-Visible spectroscopy at different time intervals. A maximum absorption at 456 nm was observed as the reaction time increased, resulting in a red shift of the surface plasmon band (SPB). Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR) revealed the reducing and stabilizing activity of flavonoids, coumarins, tannins, and phenols. Size and morphology of the AgNPs were analysed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which indicated the spherical nature of the nanoparticles with sizes ranging from 11 to 90 nm. Further characterization of the AgNPs was carried out using EDS, XRD, and Raman spectroscopy, respectively. Additionally, the AgNPs had a marginally higher antimicrobial activity when compared to the plant extract against Gram-positive Streptococcus pneumoniae (ATCC 27336) and Bacillus cereus (ATCC 10876) and Gram-negative Moraxella catarrhalis (ATCC 25240), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853).

Purification and identification of antibacterial compounds from Euclea crispa subsp. crispa (Ebenaceae) leaves

The isolation, purification and identification of antibacterial compounds from Euclea crispa subsp. crispa reported here, is a continuation of earlier work. Most of the antimicrobial activity was located in an ethyl acetate fraction obtained by means of liquid–liquid extraction. Subsequent purification of this fraction, by means of multiple preparative thin layer chromatography using different solvent systems, revealed the presence of essential oils, bitter principles and saponins, all terpenoid derivatives, as well as alkaloids and phenolic compounds. A terpenoid that tested positive for bitter principles and for saponins, and possessed a steroidlike structure, was isolated and purified from the ethyl acetate fraction. This compound was active against the Gram-negative Moraxella catarrhalis. Also isolated from the ethyl acetate fraction, and showing antimicrobial activity as individual compounds, were five flavonoids identified as catechin, epicatechin, gallocatechin, hyperoside and quercitrin. Of these epicatechin and hyperoside were most active in inhibiting the growth of M. catarrhalis (−), Streptococcus pneumoniae (+) and Haemophilus influenza (−). The isolated flavonoids seemed, in general, to have less activity than the entire ethyl acetate fraction, suggesting that these compounds function in synergy.

Identification of the conjugative mef gene in clinical Acinetobacter junii and Neisseria gonorrhoeae isolates.

The mef gene, originally described for gram-positive organisms and coding for an efflux pump, has been identified in clinical isolates of Acinetobacter junii and Neisseria gonorrhoeae. These strains could transfer the mef gene at frequencies ranging from 10(-6) to 10(-9) into one or more of the following recipients: gram-negative Moraxella catarrhalis, Neisseria perflava/sicca and Neisseria mucosa and gram-positive Enterococcus faecalis. Three Streptococcus pneumoniae strains could transfer the mef gene into Eikenella corrodens, Haemophilus influenzae, Kingella denitrificans, M. catarrhalis, Neisseria meningitidis, N. perflava/sicca, and N. mucosa at similar frequencies. The mef gene can thus be transferred to and expressed in a variety of gram-negative recipients.