Antibacterial and wound healing potential of biosynthesized zinc oxide nanoparticles against carbapenem-resistant Acinetobacter baumannii: an in vitro and in vivo study

Carbapenem-resistant Acinetobacter baumannii denotes a significant menace to public health, and it mandates an urgent development of new effective medications. Here, we aimed to estimate the efficiency of the zinc oxide nanoparticles (ZnO NP) biosynthesized from Arthrospira maxima (Spirulina) both in vitro and in vivo. Carbapenem-resistant A. baumannii isolates were collected, identified, tested for their antibiotic susceptibility, and then subjected to PCR to detect carbapenemase-producing genes. The most predominant carbapenemase resistance gene was bla_KPC. The biosynthesized ZnO NP were characterized using UV, FTIR, XRD, SEM, and TEM. The prepared ZnO NP was then tested against A. baumannii isolates to determine the minimum inhibitory concentration (MIC), which ranged from 250 to 1000 μg/ml. Burn wound was persuaded in twenty rats and inoculated with carbapenem-resistant A. baumannii isolate. Rats were allocated into four groups: a negative control group, a positive control group treated with topical 0.9% saline, a test treatment group that received topical ZnO NP, and a standard treatment group. All groups received treatment for 15 consecutive days and then euthanized. Skin samples were harvested and then subjected to histopathological and immunochemical investigations. ZnO NP revealed a comparable antibacterial activity to colistin as it revealed a lower level of fibrosis, mature surface epithelization with keratinization, and restoration of the normal skin architecture. In addition, it significantly decreased the immunoreactivity of the studied inflammatory markers. Thus, ZnO NP synthesized by A. maxima could be considered a promising, safe, and biocompatible alternative to traditional antibiotics in the therapy of carbapenem-resistant A. baumannii infections.