Antibacterial activity of silver nanoparticles against carbapenem-resistant Acinetobacter baumannii clinical isolates

Carbapenem-resistant Acinetobacter baumannii (CRAB) produce resistance to various classes of antibiotics and left limited options for treatment. This study was designed to determine antibacterial activity of AgNPs against CRAB. Total 100 A. baumannii were collected from a tertiary care hospital, Lahore. Isolates were subcultured on blood and MacConkey agar. Preliminary identification was carried out by morphological and biochemical tests. Antibiogram was done by Kirby-Bauer disc diffusion method. Antibacterial activity of AgNPs was performed by agar well diffusion method, while minimum inhibitory concentration and minimum bactericidal concentration were determined by micro broth dilution assay. Of 100 A. baumannii, 24 were confirmed as carbapenem-resistant. These isolates were mainly recovered from tracheal secretion (8; 33%), CSF (5; 20.8%), and urine (4; 16.8%). Antibacterial activity of AgNPs revealed a maximum zone of inhibition, 22mm at 50mg/mL and 18mm at 40mg/mL by agar well diffusion method. MIC of AgNPs determined that 14 CRAB were inhibited at 12.5mg/mL and 7 at 25mg/mL. However, MBC revealed that 13 CRAB were killed at 25mg/mL and 7 at 50mg/mL. This study concluded that most of the CRAB were inhibited and killed at 12.5mg/mL and 25mg/mL, respectively. AgNPs can be used as an alternative therapeutic agent followed by their pharmacokinetics and pharmacognosy.