Effect of biofabricated gold nanoparticle-based antibiotic conjugates on minimum inhibitory concentration of bacterial isolates of clinical origin

Medical device related infections caused by coagulase-negative staphylococci (CoNS) are difficult to treat mainly because of the increased bacterial genetic tolerance to antibiotics and its notorious biofilm formation property which has been reported to be achieved through a wide range of mechanisms. Current study is the demonstration of persistent antibiotic delivering potential and broad spectrum of activity of nanoantibiotic combinations designed from gold nanoparticles in conjugation with known antimicrobial agents. Such formulations are of potential applications as surface engineering agents on medical devices to prevent device mediated infection caused by pathogens like CoNS. For this, highly stable gold nanoparticles fabricated by a Bacillus sp. were functionalized with ciprofloxacin, gentamycin, rifampicin, and vancomycin and these nanoparticle-antibiotic conjugates were studied for its effectiveness against selected CoNS like Staphylococcus epidermidis and Staphylococcus haemolyticus. Very interestingly, the designed conjugates were identified to have a profound antibacterial efficiency compared to pure antibiotic and AuNPs. Thus, the result of the study is with highly significant medical applications as the test organisms used are emerging opportunistic pathogens.