Detection of acquired carbapenemase genes among Acinetobacter baumannii isolated from blood culture in patients with hematological malignancies

Abstract

Objective. To evaluate the prevalence of acquired carbapenemase genes among A. baumannii isolates collected from blood culture in patients with hematological malignancies. Materials and Methods. This prospective multicenter study included A. baumannii isolated from blood culture in hematological patients in 7 Russian hospitals (2003–2015). Minimum inhibitory concentrations (MICs) of meropenem and imipenem were determined by broth microdilution method (CLSI, 2017). All A. baumannii isolates were tested by multiplex real-time PCR for presence of acquired carbapenemase genes (blaOXA-23-like, blaOXA-24/40-like, blaOXA-58-like, blaNDM-like, blaVIM-like and blaIMP-like). Results. A total of 74 A. baumannii isolates were studied, of them 55 (74.3%) were non-susceptible to meropenem and/or imipenem. Genes of acquired OXA-carbapenemases were detected in 70.9% (39/55) of carbapenem non-susceptible isolates. Metallo-beta-lactamase genes (blaNDM-like, blaVIM-like and blaIMP-like) were not detected. The most prevalent carbapenemase genes were blaOXA-24/40-like (51.3%), followed by blaOXA-23-like (38.5%) and blaOXA-58-like (10.3%). The MIC50/90 values of meropenem and imipenem were higher in carbapenem non-susceptible A. baumannii harboring carbapenemase genes compared to isolates without acquired carbapenemase genes. A. baumannii isolates carrying blaOXA-24/40-like demonstrated the highest MIC50/90 values of carbapenems. Conclusions. The majority of carbapenem non-susceptible A. baumannii isolates (70.9%) carried acquired carbapenemase genes, of which blaOXA-24/40-like were predominant. The highest MIC50/90 values of carbapenems were detected in A. baumannii harboring blaOXA-24/40-like.

Keywords

• acinetobacter baumannii
• blood culture
• hematological malignancies
• carbapenems
• resistance
• oxa-carbapenemases