Evaluating the Efficacy of Eravacycline and Omadacycline against Extensively Drug-Resistant Acinetobacter baumannii Patient Isolates

For decades, the spread of multidrug-resistant (MDR) Acinetobacter baumannii has been rampant in critically ill, hospitalized patients. Traditional antibiotic therapies against this pathogen have been failing, leading to rising concerns over management options for patients. Two new antibiotics, eravacycline and omadacycline, were introduced to the market and have shown promising results in the treatment of Gram-negative infections. Since these drugs are newly available, there is limited in vitro data about their effectiveness against MDR A. baumannii or even susceptible strains. Here, we examined the effectiveness of 22 standard-of-care antibiotics, eravacycline, and omadacycline against susceptible and extensively drug-resistant (XDR) A. baumannii patient isolates from Cooper University Hospital. Furthermore, we examined selected combinations of eravacycline or omadacycline with other antibiotics against an XDR strain. We demonstrated that this collection of strains is largely resistant to monotherapies of carbapenems, fluoroquinolones, folate pathway antagonists, cephalosporins, and most tetracyclines. While clinical breakpoint data are not available for eravacycline or omadacycline, based on minimum inhibitory concentrations, eravacycline was highly effective against these strains. The aminoglycoside amikacin alone and in combination with eravacycline or omadacycline yielded the most promising results. Our comprehensive characterization offers direction in the treatment of this deadly infection in hospitalized patients.

Automated summary

The spread of multidrug-resistant Acinetobacter baumannii in critically ill, hospitalized patients has been a serious concern for decades. Traditional antibiotic therapies have failed to effectively treat this pathogen, prompting the introduction of new antibiotics such as eravacycline and omadacycline. In this study, the effectiveness of various antibiotics, including eravacycline and omadacycline, against susceptible and extensively drug-resistant A. baumannii strains was examined. The results showed that while monotherapies with certain antibiotics were largely ineffective, eravacycline showed high efficacy against these strains. Combination therapy with eravacycline or omadacycline and the aminoglycoside amikacin yielded the most promising results. This comprehensive characterization provides valuable guidance for the treatment of this deadly infection in hospitalized patients.