Convergence of Biofilm Formation and Antibiotic Resistance in Acinetobacter baumannii Infection

Abstract

Acinetobacter baumannii (A. baumannii) is a leading cause of nosocomial infections as this pathogen has certain attributes that facilitate the subversion of natural defenses of the human body. A. baumannii acquires antibiotic resistance determinants easily and can thrive on both biotic and abiotic surfaces. Different resistance mechanisms or determinants, both transmissible and non-transmissible, have aided in this victory over antibiotics. In addition, the propensity to form biofilms (communities of organism attached to a surface) allows the organism to persist in hospitals on various medical surfaces (cardiac valves, artificial joints, catheters, endotracheal tubes, and ventilators) and also evade antibiotics simply by shielding the bacteria and increasing its ability to acquire foreign genetic material through lateral gene transfer. The biofilm formation rate in A. baumannii is higher than in other species. Recent research has shown how A. baumannii biofilm-forming capacity exerts its effect on resistance phenotypes, development of resistome, and dissemination of resistance genes within biofilms by conjugation or transformation, thereby making biofilm a hotspot for genetic exchange. Various genes control the formation of A. baumannii biofilms and a beneficial relationship between biofilm formation and “antimicrobial resistance” (AMR) exists in the organism. This review discusses these various attributes of the organism that act independently or synergistically to cause hospital infections. Evolution of AMR in A. baumannii, resistance mechanisms including both transmissible (hydrolyzing enzymes) and non-transmissible (efflux pumps and chromosomal mutations) are presented. Intrinsic factors [biofilm-associated protein, outer membrane protein A, chaperon-usher pilus, iron uptake mechanism, poly-β-(1, 6)-N-acetyl glucosamine, BfmS/BfmR two-component system, PER-1, quorum sensing] involved in biofilm production, extrinsic factors (surface property, growth temperature, growth medium) associated with the process, the impact of biofilms on high antimicrobial tolerance and regulation of the process, gene transfer within the biofilm, are elaborated. The infections associated with colonization of A. baumannii on medical devices are discussed. Each important device-related infection is dealt with and both adult and pediatric studies are separately mentioned. Furthermore, the strategies of preventing A. baumannii biofilms with antibiotic combinations, quorum sensing quenchers, natural products, efflux pump inhibitors, antimicrobial peptides, nanoparticles, and phage therapy are enumerated.

Carbapenem-Resistant Acinetobacter baumannii: Biofilm-Associated Genes, Biofilm-Eradication Potential of Disinfectants, and Biofilm-Inhibitory Effects of Selenium Nanoparticles

“…Acinetobacter baumannii is an important opportunistic pathogen that causes a variety of infections in hospital settings, particularly in critically ill patients with predisposing risk factors such as an intensive care unit stay, assisted ventilation, surgical interventions, invasive procedures, and the presence of indwelling devices (catheters, drainage or endotracheal tubes, and artificial implants) [ 1 , 2 ]. Factors that contribute to an increasing trend of A. baumannii nosocomial infections worldwide sum up its persistence and growth in medical wards due to resistance to desiccation, disinfectants, and antibiotics, and ability to form biofilm on biotic and abiotic surfaces [ 1 ]. Until recently, carbapenems were the standard therapy for treating A. baumannii nosocomial infections.…”

Predictors of Occurrence and 30-Day Mortality for Co-Infection of Carbapenem-Resistant Klebsiella pneumoniae and Carbapenem-Resistant Acinetobacter baumannii

“…Bronchoscopy is one of the standard methods to diagnose respiratory diseases. Studies have shown that A. baumannii and K. pneumoniae readily colonizes the surfaces of medical devices, especially tracheal tubes, by forming biofilms ( Chung, 2016 ; Roy et al., 2022 ). Bringing colonized bacteria into the lesion during the examination and subsequently causing infection ( Sato et al., 2020 ).…”

Biological Control of Acinetobacter baumannii: In Vitro and In Vivo Activity, Limitations, and Combination Therapies

“…Biofilm formation and maintenance have also been associated with intracellular communication, mediated by 3′,5′-cyclic diguanylic acid and quorum sensing, which is facilitated by AtaI autoinducer synthase and the AbaR cognate receptor [ 50 ] ( Figure 1 ). Additionally, the association or correlation between biofilm formation and antibiotic resistance has been extensively investigated [ 54 , 55 , 56 ]. For example, Thummeepak et al [ 54 ] investigated the association between biofilm formation, antibiotic resistance phenotype, and virulence genes in clinical A. baumannii ( n = 225) isolates, with 86.2% of the strains characterised as MDR, of which 76.9% were biofilm producers.…”