Antibacterial Activity of Some Nano-Antimicrobial Poly(amidoamine) (Pamam) Dendrimeric Products

Abstract

"Dendrimers are synthetic, branched macromolecules. Compared to linear polymers, dendrimers hold multiple advantages as potential carrier molecules: high capacity to incorporate pharmacologically active substances, chemical stability of micelles under physiological conditions, increased bioavailability of active substances covalently or noncovalently bound to dendrimers, due to increased dendrimers capacity to cross biological barriers. The carrier potential of dendrimers has been evaluated in combination with different antibiotics, as an alternative way to address the increasing resistance of Gram-positive and Gram-negative bacteria. This paper presents a study on the intrinsic antibacterial properties of the following poly(amidoamino) (PAMAM) ethylenediamine core dendrimers: PAMAM generation 3.5, PAMAM generation 4.0 and PAMAM-OH generation 4.0. The following bacterial strains were used: Staphylococcus aureus ATCC 29213, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 15442, Enterococcus faecalis ATCC 51299 and a multi-drug resistant (MDR) Acinetobacter baumannii clinical isolate. The dendrimers’ concentrations used in the experiment were established within the range of admissibility obtained following cytotoxicity testing on human cell cultures. The dendrimers’ antibacterial activity varied depending on the concentration and the bacterial species. The antibacterial efficacy was quantified by calculating the percentage and logarithmic reduction of the number of viable microorganisms. The logarithmic reduction varied between 0.06 and 1.10, corresponding to percentage reductions between 13% and 92%. The strongest antibacterial activity of all dendrimers used in this study was registered for the D3.5 dendrimer (50 μg/mL) against Acinetobacter baumannii and Pseudomonas aeruginosa ATCC 15442 reference strain. For A. baumannii, a logarithmic reduction of bacterial activity of 1.10 log10 (percentage reduction in the number of CFU of 92%) was registered, while for P. aeruginosa ATCC 15442 the logarithmic reduction was 0.75 log10 (percentage reduction of 82%)."