Antibacterial Influence of Silver Nanoparticles on Multi-Resistant Strains of K. Pneumoniae Isolated at Hospitals

Abstract

Introduction. Overuse and misuse of antibiotics in humans, animals, and agriculture has led to the widespread rise of antibiotic resistance and strengthened nosocomial pathogenes' impact. Klebsiella pneumoniae became an increasing threat to public health. Nanomaterials are promising alternatives to conventional antibiotics in the fight against multi-resistant germs. Silver nanoparticles are well-known metallic nanoparticles with antimicrobial activity. Our research aimed to evaluate the spreading of K. pneumonia resistant to antibiotics at hospital and assess the effectiveness of Ag NPs against multi-resistant clinical strains of K. pneumoniae. Material and methods. K. pneumoniae strains were isolated and identified with the use of conventional bacteriological techniques. Susceptibility of the microorganisms was assessed to inhibitors of β-lactamases, carbapenems, macrolides, oxazolidinones, and other groups of antibiotics with use Kirby-Bauer disk diffusion method. The capability of AgNPs to inhibit attachment and multiplication of the K. pneumoniae multi-resistant strains was tested with the use of serial microdilution method, resazurin assay, and SEM. Results. K. pneumoniae was isolated from 13.7% of samples predominantly at the microbial association (97.5%). The microorganisms were resistant to five or more antibiotics in 73.2% of cases. AgNPs possess antimicrobial activity against tested strains at concentrations varied from 1.25 µg/ml to 2.5 µg/ml and kill all germs in 3 hours of incubation. AgNPs inhibited biofilm formation at initial stages and destroyed the mature (2 days) biofilm with Ag NPs treatment at concentrations 20-40 µg/ml. The effectiveness of mature K. pneumoniae biofilm treatment with AgNPs depended on biofilm age. The SEM images of the two-days biofilm reveal lysis of the bacterial cells after the cocultivation with Ag NPs but SEM analysis detected the maintaining of the three-dimensional structure in the case of a five-day biofilm after cocultivation with AgNPs. Conclusions. The distribution of K. pneumonia among patients with laryngeal pathology and its sensitivity to eleven antibiotics were examined. There was revealed the high rate of K. pneumonia multi-resistant strains. Ag NPs have strong antibacterial and anti-biofilm potential against multi-resistant K. pneumoniae. Therefore, our results highlight that the Ag NPs have promising antimicrobial and anti-biofilm abilities against multi-resistant clinical strains of K. pneumoniae.