Title : Assessment of in vitro activity of levonadifloxacin against clinical bacterial isolates from ICU patients in a tertiary care hospital

Abstract:

Background: Levonadifloxacin is a novel benzoquinolizine fluoroquinolone with potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and other resistant Gram-positive pathogens. While its efficacy against Gram-positive cocci is well documented, limited data exist regarding its activity against Gram-negative bacilli. This study aimed to evaluate the in vitro activity of levonadifloxacin against clinical bacterial isolates obtained from ICU patients.

Methodology: This descriptive study was conducted at a tertiary care hospital between March 2025 to May 2025. A total of 135 non-duplicate clinical isolates from ICU patients were included. Identification was performed using conventional methods and MALDI-TOF MS. Antimicrobial susceptibility testing was done by Kirby–Bauer disk diffusion. Minimum inhibitory concentrations (MICs) of levonadifloxacin were determined using broth microdilution as per CLSI 2025 guidelines. Interpretation was based on proposed PK/PD breakpoints (≤4 µg/mL).

Results: Among 135 isolates, 50 (37.0%) were Gram-positive cocci and 85 (63.0%) were Gram-negative bacilli. Methicillin resistance was observed in 47% of S. aureus and 79.1% of coagulase-negative staphylococci. Overall, 76.3% isolates were levofloxacin-resistant. All Gram-positive isolates, including MRSA, MRCONS, and VRE, were susceptible to levonadifloxacin (MIC₉₀ ≤1 µg/mL). In contrast, Gram-negative bacilli demonstrated limited susceptibility, with activity mainly observed in levofloxacin-sensitive strains.

Conclusion: Levonadifloxacin exhibited excellent in vitro activity against multidrug-resistant Gram-positive cocci, supporting its role in the management of ICU-acquired infections. However, its limited efficacy against Gram-negative bacilli warrants further clinical investigation.

Biography:

Dr. Sangram Singh Patel is an Additional Professor in the Department of Microbiology at Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGIMS), Lucknow, India. He obtained his MBBS from MLN Medical College, Allahabad (2006), and MD in Microbiology from SGPGIMS, Lucknow (2011). With over a decade of academic and clinical experience, he has authored more than 60 peer-reviewed publications and co-authored a textbook on Applied Microbiology. His research interests include antimicrobial resistance, ICU infections, and novel antimicrobial agents. He is a Life Member of the Indian Association of Medical Microbiologists and a Member of the European Society for Clinical Microbiology and Infectious Diseases.