Antimicrobial compositions and methods

A method to treat a microbial infection in an animal comprising:

• administering to an animal in need of such treatment an effective antimicrobial amount of a composition that includes polyanhydride nanoparticles that encapsulate a plurality of antimicrobial agents;
• wherein the polyanhydride nanoparticles comprise copolymers of (a) 1,8-bis(carboxyphenoxy)-3,6-dioxaoctane (CPTEG) anhydrides, and (b) 1,6-bis-(p-carboxyphenoxy)hexane (CPH) anhydride in a ratio of about 20:80 to about 50:50;
• wherein the nanoparticles are substantially spherical in shape and have an average diameter of about 100 nm to about 900 nm;
• and
• wherein the nanoparticles accumulate in infected monocytes, dendritic cells, or both, and degrade by surface erosion over a period of time to release the antimicrobial agents into the infected monocytes or dendritic cells;
• thereby treating the microbial infection.

A method to deliver antimicrobial agents to cells infected with microbes comprising:

• contacting cells infected by microbes with an effective amount of a composition that includes polyanhydride nanoparticles;
• wherein the polyanhydride nanoparticles comprise copolymers of (a) 1,8-bis(carboxyphenoxy)-3,6-dioxaoctane (CPTEG) anhydrides, and (b) 1,6-bis-(p-carboxyphenoxy)hexane (CPH) anhydride in a ratio of about 20:80 to about 50:50;
• wherein the nanoparticles are substantially spherical in shape and have an average diameter of about 100 nm to about 900 nm;
• the copolymers of the polyanhydride particles form a matrix around a plurality of antimicrobial agents within the particles;
• and
• the nanoparticles accumulate in the cells infected by microbes, and degrade by surface erosion over a period of time to release the antimicrobial agents, thereby delivering the antimicrobial agents to the microbes.