Comparative Genome Study of Multidrug-resistant Serratia marcescens strain IU-BTGE-M-3 Isolated from a Diarrheal Patient Reveals Antibiotic Resistance Profile

Serratia marcescens is a notable pathogen known for its intrinsic and acquired antimicrobial resistance, posing challenges in healthcare. The study investigates the multidrug-resistant (MDR) Serratia marcescens strain BTGE-M-3, focusing on its genomic features and antibiotic resistance. The strain was identified using both morphological and molecular approaches, and its genome, which measured 4.97 Mbp and exhibited a GC content of 59.7%, was sequenced. The genome has 4,827 genes, including essential antibiotic resistance genes, such as tet (41) for tetracyclines, aac (6')-Ic for aminoglycosides, OqxB for fluoroquinolones, and blaSST-1 beta-lactam, alongside various virulence determinants. Comparative genomics revealed high similarity (98.06% ANI) to S. marcescens strain KS10, supporting its classification within the same species. Additionally, the genome analysis showed that S. marcescens strain IU-BTGE-M-3 comprises of 4390 gene clusters, 4564 genes, and 244 unique singleton genes. To summarize, the results showed that S. marcescens strain IU-BTGE-M-3 exhibited a high level of genomic diversity as well as diverse metabolic, cellular, and biological functions, and it is hypothesized that frequent strain exchanges resulted in the horizontal transfer of drug resistance genes. This study underscores the importance of genomic surveillance in understanding and combating antibiotic resistance in therapeutic settings.