Extended-Spectrum Beta-Lactamase Detection with Different Panels for Automated Susceptibility Testing and with a Chromogenic Medium

Abstract

Infections caused by extended-spectrum beta-lactamase (ESBL)-and ampC beta-lactamase-producing gramnegative bacteria complicate therapy and limit treatment options. Several different panels for ESBL detection with automated systems exist. In addition, a chromogenic agar medium is available for ESBL screening. We compared two automated identification and susceptibility testing systems with regard to their effectiveness in detecting ESBL production in Enterobacteriaceae: the BD Phoenix system (BD Diagnostic Systems, Sparks, MD) and the Vitek 2 system (bioMerieux, Marcy l'Etoile, France). We tested 114 strains using the Etest as the standard, various available panels for both automated systems (for BD Phoenix, the NMIC/ID-50 and NMIC/ ID-70 GN Combo panels for combined identification and susceptibility testing of gram-negative bacilli, and for Vitek 2, the ID-GNB panel for identification of gram-negative bacilli and the AST-N020, AST-N041, and AST-N062 panels for susceptibility testing), and a chromogenic agar medium (bioMérieux, Marcy l'Etoile, France). PCR for common ESBL gene families (encoding TEM, SHV, OXA, and CTX-M) and for chromosomal or plasmid-mediated ampC beta-lactamase genes was conducted to complete the study design. For the tested specimens overall, the chromID ESBL agar showed the highest sensitivity (95.8%) but the lowest specificity (10.5%) compared to the sensitivity and specificity of the Etest (chosen as reference by the authors) for the detection of ESBL-producing strains. The BD Phoenix system showed sensitivities of 77.1% and 84.2% and specificities of 61.5% and 75.0%, respectively, for the NMIC/ID-50 andNMIC/ID-70 panels. The sensitivity of the Vitek 2 system ranged from 78.8% (AST-N020) to 80.6% (AST-N062) and up to 84.2% (AST-N041). The specificities of the respective panels were 50.0% (AST-N041 and AST-N062) and 55.6% (AST-N020). In conclusion, the sensitivities and specificities of ESBL detection by the different methods differ depending on the microorganisms under study.

Evaluation of Brilliance ESBL Agar, a Novel Chromogenic Medium for Detection of Extended-Spectrum-Beta- Lactamase-Producing Enterobacteriaceae

“…In this study, we decided not to increase the incubation time beyond 24 h based on previous studies, which all indicated little gain in ESBL recovery rates but rather an increase in interfering growth of associated flora (7,8,17).…”

Current Trends in Culture-Based and Molecular Detection of Extended-Spectrum-β-Lactamase-Harboring and Carbapenem-Resistant Enterobacteriaceae

“…The majority of these utilized strains expressing commonly occurring TEM-, SHV-, and CTX-M-type ESBLs, although successful recovery of enterobacterial strains harboring ESBLs isolated less frequently (VEB, GES, BEL, PER, TLA-1, TLA-2, BES, and OXA-18) has also been demonstrated on chromID ESBL (22). However, the specificities observed for this medium have been very low (11% to 44%) due to growth of AmpC-overproducing organisms (8,10,16,21). A drastic decrease in specificity (44%) of chromID ESBL was observed when strains with chromosomal AmpC ␤-lactamases were tested compared to the high specificity (94%) of this medium while evaluating non-AmpC-producing Enterobacteriaceae (Table 1) (16).…”

“…Evaluation studies of ESBL chromogenic media using well-characterized strains are summarized in Table 1. Most studies comparing the performance of chromID ESBL to selective media, automated tests, or other chromogenic media have shown almost uniformly high sensitivities (Ͼ95%) of this medium (8,10,16,21,22). The majority of these utilized strains expressing commonly occurring TEM-, SHV-, and CTX-M-type ESBLs, although successful recovery of enterobacterial strains harboring ESBLs isolated less frequently (VEB, GES, BEL, PER, TLA-1, TLA-2, BES, and OXA-18) has also been demonstrated on chromID ESBL (22).…”

Evaluación de cuatro métodos para la detección de enterobacterias productoras de BLEE

“…En China, con tradición de consumo de alimentos crudos, existe una normativa de calidad que incluye recuento de mesófilos, identificación de organismos indicadores de higiene, e identificación específica de patógenos transmitidos por alimentos. 4 En Brasil existe una normativa de calidad para kibbeh crudo. 5 Estos hallazgos pueden sustentar la revisión de criterios de calidad para el consumo de preparaciones crudas y contribuir a prevenir y monitorear las ETA con el fin de avanzar en la planificación de la vigilancia epidemiológica en nuestros países.…”