1073. Sulbactam-Durlobactam Has Potent Activity Against Multidrug-Resistant Acinetobacter baumannii Clinical Isolates From Thai Patients With Chronic Infections

Background

Due to the increase in multi-drug resistance (MDR) of Acinetobacter baumannii chronic infections with accompanying considerable morbidity and mortality, it is imperative to find effective novel treatments. Durlobactam (DUR) is a potent broad-spectrum inhibitor of Ambler classes A, C and D serine β-lactamases that effectively restores sulbactam (SUL) activity against MDR A.baumannii isolates. SUL-DUR is currently in late-stage development for the treatment of infections caused by Acinetobacter spp., including drug resistant isolates. In this study, we sought to evaluate potency of SUL-DUR against MDR A. baumannii isolates collected from Thai patients with chronic infections.

Methods

Non-duplicative clinical strains were isolated during 2016–2019 from 200 chronically infected patients in different medical wards with a variety of different infections at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Susceptibility testing of SUL-DUR and comparator agents was performed according to CLSI guidelines. SUL-DUR was also tested on a background of imipenem (IPM) therapy (SUL-IPM titrated at a 1:1 ratio plus DUR fixed at 4 mg/L). Data analysis was performed using CLSI and EUCAST breakpoint criteria where available.

Results

This collection of isolates was 92% sulbactam-resistant (using a breakpoint of 4 mg/L), 91% carbapenem-resistant, 74% amikacin resistant and 8% colistin resistant. In contrast, the SUL-DUR MIC90 was 4 mg/L compared with 64 mg/L for sulbactam alone. SUL-DUR was equally potent across antibiotic-resistant subsets. Only 6 isolates (3%) had SUL-DUR MIC values >4 mg/L. Interestingly, addition of imipenem to SUL-DUR showed similar potency as SUL-DUR alone, with an MIC90 of 2 mg/L.

Conclusion

SUL-DUR showed potent in vitro activity against contemporary clinical isolates from a hospital in Bangkok, Thailand. If successfully developed, SUL-DUR may be an important new therapeutic option for the treatment of MDR Acinetobacter infections.

Disclosures

Alita Miller, PhD, Entasis Therapeutics (Employee)

Novel colistin-EDTA combination for successful eradication of colistin-resistant Klebsiella pneumoniae catheter-related biofilm infections

Development of an effective therapy to overcome colistin resistance in Klebsiella pneumoniae, a common pathogen causing catheter-related biofilm infections in vascular catheters, has become a serious therapeutic challenge that must be addressed urgently. Although colistin and EDTA have successful roles for eradicating biofilms, no in vitro and in vivo studies have investigated their efficacy in catheter-related biofilm infections of colistin-resistant K. pneumoniae. In this study, colistin resistance was significantly reversed in both planktonic and mature biofilms of colistin-resistant K. pneumoniae by a combination of colistin (0.25-1 µg/ml) with EDTA (12 mg/ml). This novel colistin-EDTA combination was also demonstrated to have potent efficacy in eradicating colistin-resistant K. pneumoniae catheter-related biofilm infections, and eliminating the risk of recurrence in vivo. Furthermore, this study revealed significant therapeutic efficacy of colistin-EDTA combination in reducing bacterial load in internal organs, lowering serum creatinine, and protecting treated mice from mortality. Altered in vivo expression of different virulence genes indicate bacterial adaptive responses to survive in hostile environments under different treatments. According to these data discovered in this study, a novel colistin-EDTA combination provides favorable efficacy and safety for successful eradication of colistin-resistant K. pneumonia catheter-related biofilm infections.