Activity of imipenem-relebactam and meropenem-vaborbactam against carbapenem-resistant SME-producing Serratia marcescens

The Serratia marcescens enzyme (SME) is a chromosomally encoded carbapenemase with no known optimal treatment. Various beta-lactam/beta-lactamase inhibitors and comparators were evaluated against 8 SME producers via broth microdilution. Four isolates were subsequently tested via time-kill analyses. All isolates were resistant to imipenem, imipenem-relebactam, and meropenem but susceptible to ceftazidime, ceftazidime-avibactam, and meropenem-vaborbactam. Ceftazidime, imipenem-relebactam, and meropenem-vaborbactam were bactericidal against 3, 0, and 4 isolates, respectively. Meropenem-vaborbactam may be a potential option for severe SME-producing infections.