Frequency of pili-based biofilm encoding csu gene among the multi-drug-resistant strains of Acinetobacter baumannii

Background: This study is aimed to isolate and molecularly characterize Acinetobacter baumannii from UTI and to evaluate its resistant and virulent profiles on the csu operon. Methods: Urine samples (N=100) were collected from Saveetha Medical College and Hospital, Chennai, between January to May 2024. Resistant traits of A. baumanni was assessed using the Vitek automated systems and the biofilm formation was assessed using the crystal violet assay. csu operon was characterized using PCR followed by sequencing. Results: Out of the 100 isolates, 13% were confirmed as A. baumannii and all the strains were resistant to all classes of antibiotics tested except tigecycline and colistin. Biofilm formation was observed, with 53.8% classified as strong biofilm producers, 30.8% as moderate, and 15. 4% as weak biofilm producers. The csu operon (csuA, csuB, csuC, and csuD) were detected in a high proportion of isolates, 61.54%, 84.62%, 92.31%, and 76.92% of isolates, respectively, highlighting their role in biofilm formation. Sanger sequencing revealed notable mutations, including nucleotide mismatches and deletions within the csuA, csuB, csuC, and csuD genes, suggesting potential impacts on biofilm structure and integrity. Conclusion: This study highlights the prevalence of antibiotic-resistant A. baumannii in UTIs and underscores the association between drug resistance and csu mediated biofilm formation. The identified mutations in the csu genes suggest genetic variability that may influence biofilm formation, warranting the need for targeted interventions to alleviate A. baumannii infectionsز