The combination of sitafloxacin and sulbactam was found to have synergistic effect and enhanced in vitro antimicrobial activity against extensively drug-resistant (XDR) Acinetobacter baumannii.

Multidrug-resistant (MDR) A. baumannii refers to strains that are resistant to at least three different classes of the following antimicrobial agents: aminoglycosides, antipseudomonal penicillins, carbapenems, cephalosporins, and quinolones; XDR includes resistance to tigecycline and polymyxins – in addition to the mentioned antimicrobials.¹ The emergence of XDR-A. baumannii has resulted in limited treatment options in clinical practice.

The current study conducted by a team of researchers from Shandong University aimed to identify the antimicrobial activity of a sitafloxacin/sulbactam combination against XDR-A. baumannii. Previously, sitafloxacin has been demonstrated to have acceptable antimicrobial activity against carbapenem-resistant A. baumannii despite their resistance to other fluoroquinolones.² Sulbactam, on the other hand, has been shown to have synergistic effects with other antimicrobials and is used for A. baumannii infections.²

A total of 50 XDR-A. baumannii strains were isolated from sputum, lavages, blood, skin wounds, cerebrospinal fluid, and urine specimens.² The minimum inhibitory concentration (MIC) for sulbactam and sitafloxacin was determined using broth microdilution assay; the in vitro antimicrobial activity was determined using the microdilution checkerboard method; and time-kill study was conducted for four strains of XDR-A. baumannii with different susceptibilities to determine the bactericidal activities of sitafloxacin and sulbactam.²

The sitafloxacin/sulbactam combination had an increased inhibitory effect on XDR-A. baumannii strains compared to the use of sitafloxacin or sulbactam alone. A susceptibility rate of 96% was reported with the sitafloxacin/sulbactam combination.² The combination also induced a synergistic or partial synergistic effect on the majority of the 50 strains; none of the strains exhibited antagonistic effects.² Time-kill studies of the combination of sitafloxacin/sulbactam showed bactericidal activity and synergistic effect against all four selected XDR-A. baumannii isolates.²

The researchers concluded that the sitafloxacin/sulbactam combination could be an alternative treatment of XDR-A. baumannii infections – which are on the rise particularly in hospitals and other care facilities.

Source

Sulbactam enhances the in vitro activity of sitafloxacin against extensively-drug resistant Acinetobacter baumannii.

PMID: 30233699

DOI: 10.3892/etm.2018.6630

Link: https://www.ncbi.nlm.nih.gov/pubmed/30233699

References

1. Lee K, et al. Yonsei Med J 2011;52:879-891.
2. Xu N, et al. Exp Ther Med 2018;16:3485-3491.