In Vitro Activities of Colistin and Sitafloxacin Combinations against Multidrug-, Carbapenem-, and Colistin-Resistant <i>Acinetobacter baumannii</i> Using the Broth Microdilution Checkerboard and Time-Kill Methods

• Main Authors: Vipavee Rodjun (Author), Jantana Houngsaitong (Author), Preecha Montakantikul (Author), Taniya Paiboonvong (Author), Piyatip Khuntayaporn (Author), Pattareeya Yanyongchaikit (Author), Pusana Sriyant (Author)
• Format: Book
• Published: MDPI AG, 2020-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics9080516; 2079-6382
• Keywords: polymyxin; fluoroquinolone; multidrug-resistant Gram-negative bacteria; carbapenem-resistant Gram-negative bacteria; colistin-resistant Gram-negative bacteria; combination; Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 9, Iss 8, p 516 (2020)

Drug-resistant <i>Acinetobacter baumannii (A. baumannii</i>) infections are a critical global problem, with limited treatment choices. This study aims to determine the in vitro activities of colistin-sitafloxacin combinations against multidrug-, carbapenem- and colistin-resistant <i>A. baumannii</i> (MDR-AB, CRAB, CoR-AB, respectively) clinical isolates from tertiary care hospitals. We used the broth microdilution checkerboard and time-kill methods in this study. Synergy was found using both methods. The colistin-sitafloxacin combination showed synergy in MDR-AB, CRAB, and CoR-AB isolates (3.4%, 3.1%, and 20.9%, respectively). No antagonism was found in any type of drug-resistant isolate. The majority of CoR-AB isolates became susceptible to colistin (95.4%). The time-kill method also showed that this combination could suppress regrowth back to the initial inocula of all representative isolates. Our results demonstrated that the colistin-sitafloxacin combination might be an interesting option for the treatment of drug-resistant <i>A. baumannii</i>. However, further in vivo and clinical studies are required.