Acinetobacter baumannii Virulence Factors, Resistance Mechanisms, and New Insights on Infection Treatment

Acinetobacter baumannii is an alarming pathogen that threatens human health around the world and most of the antibiotics have become unable to cope with it. It has been classified by the World Health Organization (WHO) as a member of the most dangerous ESKAPE organisms “ Enterococcus faecium , Staphylococcus aureus , Klebsiella pneumoniae, A. baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae ” which show high resistance rates toward antibacterial agents. A. baumannii causes life-threatening infections with limited treatment options that include pneumonia, bacteremia, meningitis, urinary tract infection, and wound infection, and numerous reports have documented A. baumannii infection after SARS-CoV-2 infections in multiple publications through the COVID-19 catastrophe. Many virulence factors such as efflux pumps, outer membrane proteins (OMPs), phospholipase, lipopolysaccharide, capsule, protein secretion systems, nutrient-acquisition systems, biofilm production, and quorum sensing account for the pathological and lethal effects of A. baumannii . The present review concentrates on highlighting the major mechanisms of antibiotic resistance declared in A. baumannii , the virulence factors of A. baumannii, and the novel therapeutic strategies. These strategies include novel antibiotics, drug repurposing, antimicrobial peptides (AMPs), nanoparticles, bacteriophage therapy, monoclonal antibodies of humans (Hu-mAbs), and gene amendment in an attempt to help the scientific research society.