The article discusses the global challenge of multidrug-resistant Acinetobacter baumannii, a bacterium that has become a major nosocomial pathogen due to its ability to resist many antibiotics. It highlights the increasing prevalence of multidrug-resistant (MDR) A. baumannii worldwide, with outbreaks occurring in various regions, including Europe, North America, and Asia. The bacterium's resistance mechanisms include the production of various beta-lactamases, such as class A, B, and C enzymes, as well as the presence of mobile genetic elements that facilitate the acquisition of resistance genes. The article also discusses the genetic basis of antibiotic resistance in A. baumannii, including the presence of resistance islands and the role of mobile genetic elements in the dissemination of resistance genes. The mechanisms of resistance to selected antibiotics include the hydrolysis of beta-lactams by beta-lactamases, changes in penicillin-binding proteins, alterations in porin proteins that reduce antibiotic permeability, and the activity of efflux pumps that decrease antibiotic concentration within the bacterial cell. Resistance to aminoglycosides is mediated by aminoglycoside-modifying enzymes, while resistance to quinolones is often due to mutations in the quinolone resistance-determining regions of the gyrA and parC genes. Resistance to tetracyclines is mediated by efflux pumps and ribosomal protection proteins. Resistance to polymyxins is often due to modifications in the lipopolysaccharide of the bacterium. The article also discusses the implications for diagnosis and treatment of infections caused by A. baumannii, emphasizing the importance of in vitro antimicrobial susceptibility assays. It highlights the challenges in interpreting these results and the need for accurate susceptibility testing. The article reviews the use of various antibiotics, including tigecycline, doripenem, and colistin, in the treatment of MDR A. baumannii. It also discusses the potential for combination therapy, including the use of colistin with rifampin and imipenem, and the role of efflux pumps in resistance. The article concludes with perspectives on the control of MDR A. baumannii, emphasizing the need for infection control measures, the restriction of antibiotic use, and the development of new antimicrobial agents and vaccines. It highlights the importance of molecular tools in the investigation of outbreaks and the need for genomic and proteomic techniques in the discovery of new antimicrobials and vaccines. The article also discusses the potential for the use of antimicrobial peptides in the treatment of A. baumannii infections. Overall, the article underscores the urgent need for new strategies to combat the growing threat of multidrug-resistant Acinetobacter baumannii.The article discusses the global challenge of multidrug-resistant Acinetobacter baumannii, a bacterium that has become a major nosocomial pathogen due to its ability to resist many antibiotics. It highlights the increasing prevalence of multidrug-resistant (MDR) A. baumannii worldwide, with outbreaks occurring in various regions, including Europe, North America, and Asia. The bacterium's resistance mechanisms include the production of various beta-lactamases, such as class A, B, and C enzymes, as well as the presence of mobile genetic elements that facilitate the acquisition of resistance genes. The article also discusses the genetic basis of antibiotic resistance in A. baumannii, including the presence of resistance islands and the role of mobile genetic elements in the dissemination of resistance genes. The mechanisms of resistance to selected antibiotics include the hydrolysis of beta-lactams by beta-lactamases, changes in penicillin-binding proteins, alterations in porin proteins that reduce antibiotic permeability, and the activity of efflux pumps that decrease antibiotic concentration within the bacterial cell. Resistance to aminoglycosides is mediated by aminoglycoside-modifying enzymes, while resistance to quinolones is often due to mutations in the quinolone resistance-determining regions of the gyrA and parC genes. Resistance to tetracyclines is mediated by efflux pumps and ribosomal protection proteins. Resistance to polymyxins is often due to modifications in the lipopolysaccharide of the bacterium. The article also discusses the implications for diagnosis and treatment of infections caused by A. baumannii, emphasizing the importance of in vitro antimicrobial susceptibility assays. It highlights the challenges in interpreting these results and the need for accurate susceptibility testing. The article reviews the use of various antibiotics, including tigecycline, doripenem, and colistin, in the treatment of MDR A. baumannii. It also discusses the potential for combination therapy, including the use of colistin with rifampin and imipenem, and the role of efflux pumps in resistance. The article concludes with perspectives on the control of MDR A. baumannii, emphasizing the need for infection control measures, the restriction of antibiotic use, and the development of new antimicrobial agents and vaccines. It highlights the importance of molecular tools in the investigation of outbreaks and the need for genomic and proteomic techniques in the discovery of new antimicrobials and vaccines. The article also discusses the potential for the use of antimicrobial peptides in the treatment of A. baumannii infections. Overall, the article underscores the urgent need for new strategies to combat the growing threat of multidrug-resistant Acinetobacter baumannii.