Acinetobacter baumannii—a multidrug-resistant (MDR) pathogen that causes, for example, skin and soft tissue wounds; urinary tract infections; pneumonia; bacteremia; and endocarditis, particularly due to its ability to form robust biofilms—poses a significant challenge in clinical settings. This structure protects the bacteria from immune responses and antibiotic treatments, making infections difficult to eradicate. Given the rise in antibiotic resistance, alternative therapeutic approaches are urgently needed. Bacteriophage-based strategies have emerged as a promising solution for combating A. baumannii biofilms. Phages, which are viruses that specifically infect bacteria, offer a targeted and effective means of disrupting biofilm and lysing bacterial cells. This review explores the current advancements in bacteriophage therapy, focusing on its potential for treating A. baumannii biofilm-related infections. We described the mechanisms by which phages interact with biofilms, the challenges in phage therapy implementation, and the strategies being developed to enhance its efficacy (phage cocktails, engineered phages, combination therapies with antibiotics). Understanding the role of bacteriophages in both biofilm disruption and in inhibition of its forming could pave the way for innovative treatments in combating MDR A. baumannii infections as well as the prevention of their development.

The Enterobacter cloacae complex (ECC) is a prevalent nosocomial pathogen associated with various human infections, which currently comprises several species, including Enterobacter cloacae and Enterobacter hormaechei . Strains capable of producing biofilm on various biotic and abiotic surfaces pose a particular threat. Therefore, we focused on three E. hormaechei strains in whose genomes the presence of the biofilm-related genes: fimA , csgA , csgD , and sdiA was confirmed. Kinetic of biofilm formation by these strains on urological catheters depended on the catheter material (silicon or latex), temperature (24 °C or 37 °C) and incubation time. The ability of phages to disrupt biofilm formation was assessed and found to be the most effective when phages were applied at an early stages of this process. Moreover, destruction of existing biofilm by bacteriophages and/or silver or copper nanoparticles was strain-dependent. Incubation with Enterobacter -specific bacteriophages enabled, in some cases, almost complete eradication of three-day biofilms attached to urological catheters. In genomes of two Enterobacter -specific bacteriophages the presence of regions encoding proteins with lytic activity were identified (6 regions in Entb_43 phage and 4 regions in Entb_45 phage genomes, respectively). These results highlight the threat of biofilm-related infections, but also indicate the multifaceted anti-biofilm activity of bacteriophages, which should be considered for useful in clinical practice.

Due to the rapidly increasing problem of pathogen resistance to drugs, including bacterial resistance to antibiotics, there is a growing need to explore new therapeutic solutions. One of the multidrug-resistant pathogens responsible for many difficult-to-treat infections is Acinetobacter baumannii. The clinical relevance of another species, A. johnsonii, is also increasingly being recognized. As the development pipeline for new antibiotics remains limited, alternative antimicrobial approaches are urgently required. Among these, the therapeutic use of bacteriophages against multidrug-resistant pathogens is currently gaining renewed interest. In this study, we describe the comprehensive characterization of three novel Acinetobacter-specific bacteriophages (Acba_19, Acjo_20 and Acba_21) isolated from sewage samples. The research were conducted using clinical strains obtained from various infection sites of patients in healthcare facilities in Poland. Genomic analysis revealed no markers of temperate phages in any of the isolates, allowing their classification as strictly lytic viruses. In addition to determining basic parameters of phages - such as lytic range, species specificity, virion morphology, adsorption dynamics and infection kinetics - we also conducted stability studies of phage preparations under various conditions. These studies included assessments of pH and temperature stability, evaluation of different cryoprotectants (such as trehalose, glycerol, and pluronic), as well as the effects of storage containers made of glass and plastic materials.

Newborns may suffer from dangerous bacterial infections caused by life-threatening multi-drug resistant pathogens. Thus, despite bactericidal capabilities of antibiotics, microorganisms are known to circumvent this therapy, and a new, more effective type of remedy is needed. An increasingly recognized strategy for addressing these challenges is the use of bacteriophages—viruses infecting bacteria—collectively referred to as phage therapy. Nonetheless, the research considering phage therapy amongst newborns is still at a pioneering stage, owing to the scarcity of systematic investigations and the prevalence of case-study data, leaving room for further discovery and analysis. This review summarizes the information needed to understand this complex issue, considering the description of pathogens causing infections affecting newborns, the formation of the early microbiota and phageome (defining its composition followed by an influence on immune system development), and the possible use of bacteriophages in the treatment, which may be complicated by ethical concerns.