Activity of imipenem-relebactam against multi-drug and extensively-drug resistant
Burkholderia cepacia complex
and
Burkholderia gladioli
The Burkholderia cepacia complex (Bcc) and Burkholderia gladioli are opportunistic pathogens that most commonly infect persons with cystic fibrosis or compromised immune systems. Members of the Burkholderia genus are intrinsically multidrug resistant (MDR), possessing both a PenA carbapenemase and an AmpC β-lactamase, which renders treatment of infection due to these species problematic. Here, we tested the β-lactam-β-lactamase inhibitor combination, imipenem-relebactam, against a panel of MDR Bcc and B. gladioli . The addition of relebactam to imipenem dramatically lowered the MICs for Bcc and B . gladioli with only 16% of isolates testing susceptible to imipenem vs. 71.3% being susceptible to the imipenem-relebactam combination. While ceftazidime-avibactam remained the most potent combination drug against this panel of Bcc and B. gladioli , imipenem-relebactam was active against 71.4% of the ceftazidime-avibactam-resistant isolates. Relebactam demonstrated potent inactivation of the Burkholderia multivorans PenA1 with a K i app value of 3.2 μM. Timed mass spectrometry revealed that PenA1 formed a very stable adduct with relebactam, without any detectable desulfation up to 24 hours. Based on our results, imipenem-relebactam may represent an alternative salvage therapy for Bcc and B . gladioli infection, especially in cases where the isolates are resistant to ceftazidime-avibactam.