Antibiotic delivery using gold nanoparticles

Antibiotic resistance is set to become one of the greatest threats to human existence and new treatments or more effective ways of treating infections have to be developed. Colistin is considered a last line of defence antibiotic which has decreased usage due to undesirable side effects and thus has reduced resistance. Due to the rise of pathogens that are resistant to all common antibacterial drugs, Colistin is once again being considered as a treatment option. As Colistin’s side effects are dose dependent; it is therefore desirable to be able to treat infections using Colistin with the same therapeutic effect but at a lower dosage. Gold nanoparticles have been used as a vehicle for Colistin delivery, with a Colistin coating on both negatively charged and positively charged gold nanoparticles. This study demonstrated that by delivering Colistin on an anionic gold nanoparticle, the minimum inhibitory concentration of E. coli was reduced sixfold compared to antibiotic alone. The addition of Colistin coated gold nanoparticles (both positive and negatively charged) significantly reduced the growth of E. coli in nutrient broth over a 24 h period, with 10,000 times lower CFU per mL at 8 h compared to the control. It has also been shown that both anionic and cationic 5 nm diameter gold nanoparticles are not inherently antibacterial and do not affect bacterial growth. The anionic Colistin coated gold nanoparticles therefore show great promise for delivery of Colistin at a lower dosage with improved efficacy.