Imipenem is the most efficient antibiotic against Acinetobacter baumannii infection, but new research has shown that the organism has also developed resistance to this agent. A. baumannii isolates from a total of 110 clinical samples were identified by multiplex PCR. The antibacterial activity of Syzygium aromaticum multiple extracts was assessed following the GC-Mass spectra analysis. The molecular docking study was performed to investigate the binding mode of interactions of guanosine (Ethanolic extract compound) against Penicillin- binding proteins 1 and 3 of A. baumannii. Ten isolates of A. baumannii were confirmed to carry recA and iutA genes. Isolates were multidrug-resistant containing blaTEM and BlaSHV. The concentrations (0.04 to 0.125 mg mL-1) of S. aromaticum ethanolic extract were very promising against A. baumannii isolates. Even though imipenem (0.02 mg mL-1) individually showed a great bactericidal efficacy against all isolates, the in-silico study of guanosine, apioline, eugenol, and elemicin showed acceptable fitting to the binding site of the A. baumannii PBP1 and/or PBP3 with highest binding energy for guanosine between -7.1 and -8.1 kcal/mol respectively. Moreover, it formed π-stacked interactions with the residue ARG76 at 4.14 and 5.6, Å respectively. These findings might support the in vitro study and show a substantial increase in binding affinity and enhanced physicochemical characteristics compared to imipenem.
Keywords: GC-Mass; antibiotic-resistant genes; docking; imipenem; penicillin-binding proteins; urine samples; virulence genes; wound swab.