Antimicrobial activity of omadacycline in vitro against bacteria isolated from 2014 to 2017 in China, a multi-center study
Meng Xiao, Jingjing Huang, Ge Zhang, Wen-hang Yang, Fanrong Kong, Timothy Kudinha, Ying-Chun Xu
Abstract
Abstract Background Omadacycline (ZL-2401) is a semi-synthetic derivative of minocycline. It has a broadspectrum activity against Gram-positive and Gram-negative bacteria, and atypical pathogens. The objective of this study was to evaluate the antibacterial activity of omadacycline against recently collected bacterial isolates from Chinese patients. Results Omadacycline showed potent activity against all Gram-positive pathogens: S. aureus MICs were low regardless of susceptibility to methicillin (methicillin-resistant Staphylococcus aureus , MRSA: N = 97, MIC 50/90 0.12/0.25 mg/L, 98.5% susceptible; methicillin-sensitive Staphylococcus aureus , MSSA: N = 100, MIC 50/90 0.12/0.12 mg/L, 100.0% susceptible). Omadacycline was also very effective against β-haemolytic streptococci (MIC 50/90 , 0.06/0.12 mg/L), viridans group streptococci (MIC 50/90 ,<0.03/0. 06 mg/L), and enterococci (MIC 50/90 , 0.03/0.12 mg/L). Against S. pneumoniae , omadacycline was highly active regardless of penicillin-resistance (MIC 90 0.06 mg/L) and despite the fact that less than 10.0% of these strains were susceptible to tetracycline. Omadacycline exhibited good in vitro activity against Enterobacterales isolates (MIC 50/90 , 2/8 mg/L), inhibiting 81.7% of the isolates at ≤4 mg/L. M. catarrhalis isolates (MIC 50/90 , 0.12/0.25 mg/L) were fully susceptible to omadacycline at ≤0.5 mg/L. Conclusions Omadacycline showed potent in vitro activity against most common bacterial pathogens, and even against highly resistant problem pathogens, such as MRSA, penicillin-R and tetracycline-R S. pneumoniae and enterococci. The susceptibility rate of Chinese isolates was similar to those reported in other countries, but the decreased activity against K. pneumoniae isolates in the present study should be noted.