Evaluation of antibacterial activity of silver nanoparticles against multidrug-resistant gram negative bacilli clinical isolates from Zagazig University Hospitals

Background: The growing incidence of multidrug resistant (MDR) bacterial infections has become a public health crisis. This work aims to evaluate the in-vitro activity of silver nanoparticles (AgNPs), alone and in combination with the antimicrobials amikacin and ceftazidime, against MDR Gram-negative bacilli (GNB) isolated from clinical cases in Zagazig University Hospitals. Methods: In a cross sectional study, MDR GNB were isolated from different clinical specimens and were tested to determine the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and bactericidal activity of AgNPs using broth microdilution method. The effect of combining subMIC levels of AgNPs (MIC/2 and MIC/4) with amikacin and ceftazidime, was also determined by broth microdilution. Results: A total of 63 MDR GNB was obtained during the study period (22 E. coli, 17 Klebsiella, 15 Pseudomonas aeruginosa and 9 Acinetobacter isolates). AgNPs demonstrated a bactericidal effect on all tested isolates with an MBC/MIC ratio of less than 4. When combined with amikacin, a synergistic effect was demonstrated on all tested E.coli and Klebsiella isolates at AgNPs MIC/2 and on 45.4%, 40% and 77.8% of E.coli, P.aeruginosa and Acinetobacter isolates, respectively at MIC/4. In combination with ceftazidime, AgNPs exhibited a synergistic effect on 100% of E. coli and 88.2% Klebsiella at both MIC/2 and MIC/4 and on 40% of P. aeruginosa isolates at AgNPs MIC/4. Conclusions: AgNPs exert a bactericidal activity on MDR GNB as well as a synergistic effect when combined with amikacin and ceftazidime suggesting them as a new weapon in the war against MDR GNB

Silver nanoparticles: A potential antibacterial and antibiofilm agent against biofilm forming multidrug resistant bacteria

Background: Multi-drug resistant (MDR) bacteria are seriously endangering the antibiotics. Different alternative strategies are needed to reinforce antibiotics, of, these; nanostructured materials may play a fruitful role. This study aimed to investigate the antibacterial and antibiofilm activity of silver nanoparticles (AgNPs) against MDR bacteria. Methods: In a cross-sectional study, a total of 33 methicillin resistant Staphylococcus aureus (MRSA) and 52 MDR Pseudomonas aeruginosa (P. aeruginosa) isolates were recovered from intensive care units' (ICUs) admitted patients over a period of 9 months, from December 2017 to August 2018. The antibacterial activity of AgNPs on the clinical isolates of MRSA and MDR P. aeruginosa was assessed by minimum inhibitory concentrations (MICs) using broth microdilution method. The minimum bactericidal concentrations (MBCs) were determined as the lowest concentrations required to kill 99.9% of the initial inoculum. Tissue culture plate method was used to evaluate the antibiofilm activity. Results: The MIC and MBC values ranged from 1 to 16 µg/ml and 2 to 64 µg/ml, respectively. Silver nanoparticles exerted a significant antibiofilm activity against MRSA and MDR P.aeruginosa at all tested concentrations, recording a maximum inhibition value of (82%) and (91%), respectively. Conclusions: AgNPs exhibited a considerable antibacterial and antibiofilm, effect; it could represent a promising weapon in the fight against biofilm forming MDR organisms

Phytochemical composition and comparative evaluation of antimicrobial activities of the juice extract of citrus aurantifolia and its silver nanoparticles

Background: Citrus aurantifolia juice has been useful for the treatment of various infections and green synthesis of silver nanoparticle using lime juice may offer added advantages.Objective: The phytochemical composition and comparative evaluation of antimicrobial activities of the crude juice extract and biosynthesized Silver nanoparticle (SNPs) from Citrus aurantifolia juice was investigated.Materials and methods: Phytochemical, antimicrobial evaluation (agar well diffusion) and biosynthesis of SNPs was done using Crude extract of Citrus aurantifolia. The SNPs were characterized by colour changes, spectroscopy and Fourier-Transform Infrared (FTIR) Spectroscopy.Results: The juice extract contained bioactive compounds such as flavonoids (710mg/100g), tannins (525mg/100g), phenols (65mg/100g) and terpenes (56mg/100g). Changes in colour, UV-Vis Spectroscopy at 300-550nm ranges and FTIR revealed the functional groups present in the biosynthesized SNPs. The crude extract and SNPs exhibited varying antimicrobial activities against some selected pathogens including Streptococcus pyogenes ATCC 19615, Klebsiella pneumoniae ATCC 10031, Bacillus sp, Actinobacillus sp., Pseudomonas aeruginosa and Staphylococcus aureus. The crude extract has more antibacterial potential against the tested pathogens than the biosynthesized SNPs. The crude extract also had higher antimicrobial activities against Streptococcus pyogenes which were resistant to ciprofloxacin. The result revealed that the crude extract was more effective than the SNPs produced and the Minimum Inhibitory concentration (MIC) also showed increasing activities with an increase in the concentration of the juice extract and SNPs.Conclusion: Crude extract of Citrus aurantifolia contain bioactive compound with potent antimicrobial potential and the extract was more effective than the biosythesized SNPs