Accuracy of in vitro susceptibility tests for carbapenemase-producing Gram-negative bacteria

Abstract

Accurate susceptibility results on antibiotic-resistant bacteria are essential for proper treatment of infections. In this study, 100 metallo-b-lactamase (MBL)-producing strains and 95 isolates with Klebsiella pneumoniae carbapenemase (KPC) were tested for carbapenem susceptibility using two automated platforms, the Phoenix and Vitek-2 systems, and a manual Etest. Phoenix showed higher categorical agreements (97 % for imipenem and 94 % for meropenem) compared with those from Vitek-2 (92 and 74 %) and Etest (89 and 96 %), respectively, when testing MBL strains. Categorical agreement for imipenem tests with KPC-producing strains was 88.4 % with the Phoenix system, 83.2 % with the Vitek 2 system and 90.5 % with the Etest. Categorical agreement was 100 % for all tests with ertapenem. In conclusion, the Phoenix system demonstrated a higher accuracy than Vitek-2 in testing carbapenemase-producing strains, particularly in MBL strains.

Comparison of Carbapenem Resistance Detected by the BD Phoenix Automated System in Enterobacteriaceae Isolates with E-Test Method

“…In another study [28], metallo-b-lactamase (MBL) producing strains and Carbapenem resistance K. pneumoniae isolates were compared in terms of Carbapenem susceptibility with Vitek-2 and Phoenix automated systems and E-test methods. Phoenix showed higher categorical agreement (97% for imipenem and 94% for meropenem) compared to Vitek-2 (92% vs. 74%) and E-test (89% vs. 96%) in detecting MBL strains.…”

<p>Epidemiology of Febrile Neutropenia Episodes with Gram-Negative Bacteria Infection in Patients Who Have Undergone Chemotherapy for Hematologic Malignancies: A Retrospective Study of 10 Years’ Data from a Single Center</p>

“…More detailed methods have been described in our previous studies. 13,14 Definition of IIAT and Data Collection Empirical antibiotic treatment was classified as being appropriate if direct sensitivity of the identified pathogen to the initially prescribed antibiotic regimen was confirmed based on in vitro susceptibility testing, while confirmed antibiotic resistance and no direct testing of prescribed antibiotics were considered IIAT. Baseline patient characteristics and clinical data collected included age, sex, comorbidities, such as diabetes and manifestations of neutropenia and/or fever, and complications (including liver damage, respiratory failure, renal insufficiency, bleeding, heart failure, and requirement of ventilator support).…”