Antimicrobial and anti-biofilm activity of hexadentated macrocyclic complex of copper (II) derived from thiosemicarbazide against Staphylococcus aureus

Abstract

Multidrug-resistant pathogens causing nosocomial and community acquired infections delineate a significant threat to public health. It had urged to identify new antimicrobials and thus, generated interest in studying macrocyclic metal complex, which has been studied in the past for their antimicrobial activity. Hence, in the present study, we have evaluated the antimicrobial activity of the hexadentated macrocyclic complex of copper (II) (Cu Complex) derived from thiosemicarbazide against Gram-positive and Gram-negative bacteria. We observed increased susceptibility against standard isolates of Staphylococcus aureus with a minimum inhibitory concentration (MIC) range of 6.25 to 12.5 μg/mL. Similar activity was also observed towards methicillin resistant and sensitive clinical isolates of S. aureus from human (n = 20) and animal (n = 20) infections. The compound has rapid bactericidal activity, and we did not observe any resistant mutant of S. aureus. The compound also exhibited antibiofilm activity and was able to disrupt pre-formed biofilms. Cu complex showed increased susceptibility towards intracellular S. aureus and was able to reduce more than 95% of the bacterial load at 10 μg/mL. Overall, our results suggest that Cu complex with its potent anti-microbial and anti-biofilm activity can be used to treat MRSA infections and evaluated further clinically.