Effect of Silver nanoParticles on Carbapenem Resistant Gram-negative Bacteria

Abstract

Background: Gram-negative bacteria are common causes of both community-acquired and hospital-acquired infections. β-Lactam drugs are often the primary therapeutic option for serious infections, and carbapenems in particular are often considered agents of last resort. Thus, the emergence and spread of carbapenem-resistant (CR) bacteria are a significant public health concern. Infections with these resistant bacteria are associated with higher mortality rates than those for infections caused by carbapenem susceptible organisms. There have been considerable efforts to develop new antimicrobials drug against this type of resistant bacteria. Silver Nanoparticles (AgNPs) have emerged as promising weapons in the anti-microbial arsenal. Their anti-microbial efficacy is attributable to multiple mechanism of action. Objective: The aim of this study was to evaluate effect of AgNPs on CR Gram-negative bacteria. Materials and Methods: Effect of AgNPs on CR Gram-negative bacteria alone and in combination with carbapenems. 50 CR Gram-negative bacterial samples were included in this study. They were divided into 4 types; Acinetobacter, E. coli, klebseilla and P. aeruginosa. Each type was divided into (subtypes) metalo and non metalo carbapenemase producers. Results: There was statistically significant difference between all types of CR Gram-negative bacteria with AgNPs alone and some of them with AgNPs plus antibiotic (P-value < 0.05). A comparison of the effect of AgNPs alone between different types of detected CR Gram-negative bacteria showed different levels of response. Lowest response was observed with klebsiella (metalo), while highest was remarked with P. aeruginosa (metalo). Highest synergy with highly statistically significant difference (P-value < 0.001) occurred with Meropenem in P. aeruginosa Conclusion: AgNPs showed anti-microbial effect against CR Gram-negative bacteria alone and synergistic effect against some of detected CR Gram-negative bacteria with certain antibiotics.