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Combinations of Antibiotics Effective against Extensively- and Pandrug-Resistant Acinetobacter baumannii Patient
Justin Halim1, Rachel A Carr1, Rebecca Fliorent2
1Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ 08103, USA.
Abstract:
Infections due to drug-resistant Acinetobacter baumannii strains are increasing and cause significant morbidity and mortality, especially in hospitalized and critically ill patients. A. baumannii rapidly develops resistance to numerous antibiotics, and antibiotics traditionally used against this deadly pathogen have been failing in recent years, highlighting the need to identify new treatment strategies. Treatment options that have shown promise include revisiting common antibiotics not typically used against A. baumannii, evaluating new antibiotics recently introduced to market, and identifying combinations of antibiotics that display synergistic interactions. In this study, we characterized the antibiotic susceptibility profiles of extensively (XDR) and pandrug-resistant (PDR) A. baumannii patient isolates. We examined the potency of 22 standard-of-care antibiotics and the newer antibiotics eravacycline, omadacycline, and plazomicin against these strains. Furthermore, we examined combinations of these antibiotics against our collection to identify synergistic effects. We found that this collection is highly resistant to most or all standard-of-care antibiotics, except for minocycline and rifampin. We show that eravacycline and omadacycline are effective against these strains based on minimum inhibitory concentrations. We also identified two highly effective combinations, cefepime and amikacin and cefepime and ampicillin-sulbactam, which exhibited high rates of synergy against this collection. This information is valuable in our battle against highly drug resistant and virtually untreatable A. baumannii infections.
Insights
Drug-resistant Acinetobacter baumannii infections are a growing threat. New antibiotics like eravacycline and omadacycline show promise, alongside synergistic combinations of cefepime with amikacin or ampicillin-sulbactam.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Rising incidence of multidrug-resistant *Acinetobacter baumannii* infections, particularly in hospital settings.
- Limited treatment options due to rapid development of antibiotic resistance.
- Urgent need for novel therapeutic strategies against extensively drug-resistant (XDR) and pandrug-resistant (PDR) strains.
Purpose of the Study:
- To characterize antibiotic susceptibility profiles of XDR and PDR *A. baumannii* patient isolates.
- To evaluate the efficacy of standard-of-care and newer antibiotics, including eravacycline, omadacycline, and plazomicin.
- To identify synergistic antibiotic combinations against these resistant strains.
Main Methods:
- Testing the susceptibility of *A. baumannii* isolates to 22 standard antibiotics and 3 newer agents.
- Determining minimum inhibitory concentrations (MICs) for effective agents.
- Evaluating synergistic interactions between antibiotic combinations.
Main Results:
- Isolates demonstrated high resistance to most standard antibiotics, with minocycline and rifampin showing some activity.
- Eravacycline and omadacycline were found to be effective against the tested strains.
- Synergistic activity was observed with combinations of cefepime and amikacin, and cefepime and ampicillin-sulbactam.
Conclusions:
- Minocycline, rifampin, eravacycline, and omadacycline represent potential treatment options for XDR/PDR *A. baumannii* infections.
- Specific antibiotic combinations, notably cefepime with amikacin or ampicillin-sulbactam, show significant synergistic potential.
- Findings provide valuable insights for combating difficult-to-treat *A. baumannii* infections.
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