In vitro susceptibility of Omadacycline against extensively drug resistant (XDR) Acinetobacter baumannii and Klebsiella pneumoniae clinical isolates from bloodstream infections and bacterial meningitis.

BACKGROUND

Antimicrobial resistance among Acinetobacter baumannii and Klebsiella pneumoniae has significantly increased which has reduced available treatment options. Omadacycline, a novel tetracycline, has shown in vitro activity against multidrug-resistant pathogens; however, in vitro susceptibility of Omadacycline has not been previously studied against the extensively drug-resistant (XDR) isolates in Indian setting.

METHODS

This prospective observational study evaluated the in vitro activity of Omadacycline against extensively drug-resistant (XDR) A. baumannii and K. pneumoniae isolates obtained from bloodstream infections and bacterial meningitis. Minimum inhibitory concentrations (MICs) of Omadacycline were determined using broth microdilution method. MIC50 and MIC90 values were calculated, and results were also compared with Tigecycline.

RESULTS

Overall, 30.58% of isolates demonstrated MIC values ≤ 2 μg/mL. Omadacycline exhibited better in vitro activity against A. baumannii than K. pneumoniae. Lower MICs were observed in bloodstream isolates than meningitis isolates. Comparative analysis with Tigecycline showed no statistically significant difference in vitro susceptibility.

CONCLUSION

Omadacycline demonstrated favorable in vitro activity against XDR A. baumannii, particularly bloodstream isolates, with lower activity against K. pneumoniae. No statistically significant difference in vitro susceptibility was observed compared with Tigecycline. These findings support further evaluation of Omadacycline as a potential therapeutic option and further clinical and pharmacokinetic studies are required to define the role in management of XDR infections in Indian setting.