Sensitivity of Enterobacteriaceae strains to the third generation cephalosporins

The aim of this study was to evaluate the in vitro activity of cefotaxime, ceftriaxone, ceftazidime, ceftibuten and aztreonam against the clinical isolates of Enterobacteriaceae. MICROORGANISMS: A total of 973 enterobacteria isolated from clinical material (urine and faeces) were tested. Strains were collected during 1996-1998 period, in some centers of Eastern Romania. SENSITIVITY STUDY: MICs were performed using the agar dilution method following standardized techniques (NCCLS, 1994). Stock solutions of antibacterial agents were prepared from their respective powder forms, in concentrations ranging from 0.03 to 128 mg/ml. Our results show a good activity of the tested antimicrobials on Escherichia coli, Shigella spp and Klebsiella spp tested, and reveal a particular behaviour for Salmonella spp, characterized by a heterogenous susceptibility. In conclusion, cefotaxime, ceftriaxone, ceftazidime, ceftibuten and aztreonam were active at low concentrations against tested isolates. Against Salmonella spp, these agents were less active: percent of resistant strains by beta-lactamase production was significant.

Poly(vinylbenzyl chloride) microsphere synthesis and their chemical modifications

Vinylbenzyl chloride (VBC) was dispersion polymerized to give monodisperse microspheres in the presence of poly(vinylpyrrolidone) (PVP) as a steric stabilizer. The effect of PVP concentration on the size and on microsphere stability during the polymerization process was investigated. Microsphere size was examined when co-stabilizer molecules were employed with PVP during the polymerization reaction. The built-in reactive chloromethyl groups of the microspheres were the sites of the nucleophilic reaction of two amino-group model molecules, glucosamine (G), a hexosamine implicated in processes of molecular recognition, and also bovine serum albumin (BSA). Elemental analyses and Fourier transform infrared spectroscopy (FTIR) spectra showed that poly(vinylpyrrolidone) was associated with the microsphere network. Elemental analyses, attenuated total reflection infrared spectroscopy (ATR-FTIR), and zeta potential measurements confirmed G and BSA links at the microsphere surface.