A New Spectrophotometric Reagent for Fe(III): 2-(2,3-Dihydroxy-4-oxocyclobut-2-enylidene) Hydrozinecarbothiamide and Its Application in Real Samples

A new reagent 2-(2,3-dihydroxy-4-oxocyclobut-2-enylidene) hydrozinecarbothiamide has been synthesized and used for developing a simple spectrophotometric method for the determination of Fe(III) which is based on a 2 : 1 complex formation between Fe(III) and new reagent in aqueous solution. The method is optimized in terms of the pH value, amount of reagent required, ionic strength, and stability of the complex, sensitivity, linearity, and tolerance limits of various foreign ions. The complex is a red-brown chelate, with max=465 nm at pH = 3 (=1.95×103 L⋅mol−1⋅cm−1). The ionic strength was kept constant at 0.02 by adding appropriate amounts of NaCl solution. The calibration curve is linear in the concentration range from 0.27–33.50 μg⋅mL−1. The effects of foreign ions on the determination of Fe(III) were investigated in order to assess the selectivity of the method. The method was applied in determination of Fe(III) in tap water, cow milk, and human serum

Clonal dissemination of high-level gentamicin-resistant isolates of Enterococcus faecalis within a university hospital in southeastern Iran Klonale Verbreitung von hochgradig gentamicinresistenten Isolaten von Enterococcus faecalis in einem Universitätsklinikum im Südosten des Iran

Background: Combination of a cell wall-active antibiotic with an aminoglycoside confers a synergistic effect in the treatment of some severe enterococcal infections. Unfortunately, with the emergence of enterococci with high-level resistance to aminoglycosides, particularly to gentamicin, the efficacy of the synergistic combinations has decreased. In this study, high-level gentamicin-resistant (HLGR) isolates of enterococci and the diversity of the genes encoding aminoglycoside-modifying enzymes (AMEs) as well as putative clonal dissemination of HLGR isolates were investigated in a university hospital in southeastern Iran. Methods: The minimum inhibitory concentration of gentamicin was determined and HLGR isolates were investigated for AME genes. Genetic similarity between isolates was analyzed using repetitive extragenic palindromic (rep)-Polymerase Chain Reaction (PCR) assay. Results: Of 150 Enterococcus isolates, 62 isolates including Enterococcus faecalis (n�= 46) and E. faecium (n�= 16) were identified as HLGR. The most prevalent AME genes in both species were as follows: aph(3�)-IIIa (n�= 44), aac(6�)-Ie-aph(2�)-Ia (n�= 36), and ant(4�)-Ia (n�= 15). The rep-PCR analysis showed clonality among E. faecalis isolates, so that 27 isolates were grouped in seven clusters representing similarity greater than 95. Conclusions: No link between AME determinants and clusters was found. Clonal spread of HLGR isolates of E. faecalis was found within our hospital. More rigorous recommendations are required to avoid dissemination of such resistant microorganisms in the hospital setting. © 2019, Springer-Verlag GmbH Austria, ein Teil von Springer Nature