Wide-spectrum biomimetic antimicrobial systems

Antimicrobial peptides (AMPs) are effective components of the host immune response and are widely distributed throughout nature. Recently, nontoxic antimicrobial polymers that mimic the structures of naturally occurring AMPs have been designed and are under development commercially as novel therapeutics. These compounds have several potential advantages over natural AMPs, including greater stability and reduced immunogenicity compared to natural peptides, relatively simple and scalable syntheses and the ability to tailor or “fine tune” their activities through combinatorial approaches. In previous work, we demonstrated the utility of certain generally regarded as safe (GRAS) flavorant and aroma compounds as enhancers of uptake and activity of clinically important antibiotics (Brehm-Stecher & Johnson, 2003). Here, we have extended this approach to include enhancement of biomimetic antimicrobial polymers. Three low molecular weight (<1000 >D), broad-spectrum arylamide polymers (PolyMedix, Inc., Radnor, PA) were examined for their antimicrobial activities against gram-negative bacteria, gram-positive bacteria, yeast and filamentous fungi, both alone and when co-administered with sesquiterpenoid enhancers. Assay formats included disk diffusion, automated turbidimetry, time course (kinetic) plating of antimicrobial-treated cell suspensions, outer membrane assays with 1-N-phenylnaphthylamine (NPN) and transmission electron microscopy (TEM). Although results differed according to the polymer and test organism used, treatments containing sesquiterpenoids were marked by either increased ZOIs, decreased MICs or more rapid inactivation when compared with polymer-only treatments. Antimicrobial activity, expressed as decimal reduction times (D-value), showed that after 5 min, the combination of sesquiterpenoid and polymer was significantly different from the controls (p < 0.05) with a D-value of 3.92 min when incubated with Escherichia coli ATCC 25922. Collectively, our results indicate that the combination of sesquiterpenoidenhancing agents with biomimetic antimicrobial polymers shows promise for the development of new, fasteracting and more broadly effective antimicrobial therapies.

[1]  M. Vaara,et al.  Agents that increase the permeability of the outer membrane. , 1992, Microbiological reviews.

[2]  Clinical,et al.  Reference method for broth dilution antifungal susceptibility testing of yeasts : Approved standard , 2008 .

[3]  Eric A. Johnson,et al.  Sensitization of Staphylococcus aureus and Escherichia coli to Antibiotics by the Sesquiterpenoids Nerolidol, Farnesol, Bisabolol, and Apritone , 2003, Antimicrobial Agents and Chemotherapy.

[4]  J. Pemán,et al.  Antifungal Susceptibility Testing of Filamentous Fungi , 2012, Current Fungal Infection Reports.

[5]  Y. Shai,et al.  Mode of action of membrane active antimicrobial peptides. , 2002, Biopolymers.

[6]  Robert E W Hancock,et al.  Role of membranes in the activities of antimicrobial cationic peptides. , 2002, FEMS microbiology letters.

[7]  Clinical,et al.  Reference method for broth dilution antifungal susceptibility testing of filamentous fungi : Approved standard , 2008 .

[8]  W. DeGrado,et al.  Amphiphilic polymethacrylate derivatives as antimicrobial agents. , 2005, Journal of the American Chemical Society.

[9]  M. Gilmore,et al.  Simplified agar plate method for quantifying viable bacteria. , 1997, BioTechniques.

[10]  Simons,et al.  Disinfectant testing: use of the Bioscreen Microbiological Growth Analyser for laboratory biocide screening , 1998, Letters in applied microbiology.

[11]  Clinical,et al.  Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically : Approved standard , 2006 .

[12]  R. J. Doerksen,et al.  De novo design of biomimetic antimicrobial polymers , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Michael R. Yeaman,et al.  Mechanisms of Antimicrobial Peptide Action and Resistance , 2003, Pharmacological Reviews.

[14]  M. Zasloff.  Antimicrobial peptides of multicellular organisms , 2002, Nature.

[15]  J. Shimada,et al.  The antibacterial effects of terpene alcohols on Staphylococcus aureus and their mode of action. , 2004, FEMS microbiology letters.

[16]  Clinical,et al.  Performance standards for antimicrobial disk susceptibility tests : approved standard , 2006 .

[17]  P. Davidson,et al.  Enhancement of nisin, lysozyme, and monolaurin antimicrobial activities by ethylenediaminetetraacetic acid and lactoferrin. , 2004, International journal of food microbiology.

[18]  R. Hancock,et al.  Cationic peptides: effectors in innate immunity and novel antimicrobials. , 2001, The Lancet. Infectious diseases.

[19]  D. A. Santos,et al.  Establishing a Method of Inoculum Preparation for Susceptibility Testing of Trichophyton rubrum and Trichophyton mentagrophytes , 2006, Journal of Clinical Microbiology.