Characterization of clinical isolates of Acinetobacter baumannii and comparative proteomic profiling among strong and weak biofilm formers

ABSTRACT Acinetobacter baumannii , a critical priority pathogen, is also notable for its biofilm-forming abilities on medical devices like ventilators, catheters, and surgical drain tubes. The biofilm formation causes increased tolerance against antibiotics, making treatment difficult. The clinical isolates of A. baumannii present varied biofilm-forming capacity; hence, understanding the molecular determinants responsible for strong biofilm is crucial. The present study aims to characterize the antibiotic and biofilm-forming profile of 25 clinical isolates of A. baumannii and compare the proteome profiling of strong and weak biofilm-forming isolates to identify therapeutic targets. We observed n = 23 of the isolates as multidrug resistant, and n = 13 were forming strong biofilms. Comparative proteomic profiling revealed 42 differentially regulated proteins. In the strong biofilm-forming isolate new lipoprotein A (NLPA), uL16, DNA gyrase B, acetyl-CoA carboxylase, and purL were found to be upregulated, highlighting a dynamic reprogramming of cellular functions that promotes biofilm formation, stress adaptation, and immune evasion. In contrast, EF-Tu, ribosome hibernation factors, and T6SS components were downregulated, suggesting a lack of biosynthesis and cellular adaptability. These findings suggest a metabolic downshift and a possible energy conservation mechanism under conditions less favorable for strong biofilm development. Additionally, several uncharacterized proteins were identified, highlighting potential novel factors in biofilm regulation and virulence that warrant further investigation. The proteomics data correlated with qPCR findings, providing support for the unknown regulators of biofilm formation that were identified in this study. Key proteins, such as NLPA, 6,7-dimethyl-8-ribityllumazine synthase, and DNA gyrase B emerged as potential therapeutic targets that may be used for drug discovery. IMPORTANCE Acinetobacter baumannii has progressively evolved into a serious cause of both hospital and community-acquired infections. This bacterium’s resilience to harsh conditions, bacterial dormancy within biofilms, antibiotic resistance, and survival on inanimate surfaces contribute to its ability to cause chronic, hard-to-eradicate infections. The molecular determinants underlying variations in biofilm-forming capacity among clinical isolates remain insufficiently understood. This study addresses this gap by identifying key molecular adaptations associated with strong biofilm formation. By uncovering pathways linked to biofilm persistence, this work provides valuable insights into bacterial survival strategies and highlights potential avenues for therapeutic intervention. These findings lay the groundwork for the development of new anti-biofilm strategies aimed at improving treatment outcomes and combating antimicrobial resistance.