In vitro efficacy of levonadifloxacin against methicillin-resistant Staphylococcus aureus (MRSA) including hVISA...

Vancomycin has been the preferred treatment for MRSA infections. However, newer drugs are necessary due to the increasing prevalence of MRSA isolates that are less susceptible to vancomycin. Levonadifloxacin and its prodrug alalevonadifloxacin, novel quinolones with broad spectrum anti-MRSA activity. They are approved in India for the treatment of skin and soft-tissue infections, bacteraemia, and diabetic foot infections.

A total of 456 MRSA (Methicillin-resistant Staphylococcus aureus) isolates, including 333 isolates from JIPMER and 123 isolates from other tertiary care centers collected between January to December 2022, underwent susceptibility testing to levonadifloxacin by disc diffusion method. The study isolates included 29 h-VISA. Fifty one blood isolates were also subjected to E-test and their results were compared to the gold standard, broth micro dilution (BMD).

All 456 isolates were found to be susceptible to levonadifloxacin by disc diffusion. Levonadifloxacin demonstrated potent activity against MRSA strains isolated from blood (n = 51) with an MIC₅₀ and MIC₉₀ of 0.38 and 0.5 μg/mL by E-test, respectively. Similarly, it demonstrated an MIC₅₀ and MIC₉₀ of 0.5 & 1 μg/ml by BMD.

The present study demonstrated 100 % susceptibility to levonadifloxacin among the tested isolates of MRSA, highlighting its promising clinical potential for treating infections caused by this organism. Furthermore, the study recorded a concordance of 100 % between disc diffusion and Etest method with BMD, indicating the reliability of these methods.