Simon A Schwensen1, Ziyap Acar1, Thomas V Sydenham1, Åsa C Johansson2, Ulrik S Justesen3. 1. Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark. 2. Department of Clinical Microbiology, Central Hospital, Växjo, Sweden. 3. Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark ujustesen@health.sdu.dk.
Abstract
OBJECTIVES: To investigate the performance of the meropenem and imipenem double-ended Etest ± EDTA and the tablet-based (meropenem and meropenem + dipicolinic acid) KPC/MBL Confirm Kit to detect cfiA metallo-β-lactamase (MBL) in Bacteroides fragilis. METHODS: Well-characterized B. fragilis isolates, most from previously published studies, harbouring the cfiA gene and covering a wide range of meropenem MICs were included (n = 21). RESULTS: The imipenem double-ended Etest showed an indeterminate result in 95% of the included isolates with the cfiA gene (20 of 21), whereas the meropenem double-ended Etest gave an MIC ratio ≥8 (positive test) with all the isolates. All isolates that were meropenem intermediate or resistant had a zone diameter difference ≥6 mm with the KPC/MBL Confirm Kit. CONCLUSIONS: The meropenem double-ended Etest and not imipenem should be preferred for phenotypic detection of MBLs in B. fragilis. The KPC/MBL Confirm Kit could be an alternative with isolates that are meropenem intermediate or resistant (MIC >2 mg/L).
OBJECTIVES: To investigate the performance of the meropenem and imipenem double-ended Etest ± EDTA and the tablet-based (meropenem and meropenem + dipicolinic acid) KPC/MBL Confirm Kit to detect cfiA metallo-β-lactamase (MBL) in Bacteroides fragilis. METHODS: Well-characterized B. fragilis isolates, most from previously published studies, harbouring the cfiA gene and covering a wide range of meropenem MICs were included (n = 21). RESULTS: The imipenem double-ended Etest showed an indeterminate result in 95% of the included isolates with the cfiA gene (20 of 21), whereas the meropenem double-ended Etest gave an MIC ratio ≥8 (positive test) with all the isolates. All isolates that were meropenem intermediate or resistant had a zone diameter difference ≥6 mm with the KPC/MBL Confirm Kit. CONCLUSIONS: The meropenem double-ended Etest and not imipenem should be preferred for phenotypic detection of MBLs in B. fragilis. The KPC/MBL Confirm Kit could be an alternative with isolates that are meropenem intermediate or resistant (MIC >2 mg/L).
Authors: Allison R Eberly; Meghan A Wallace; Samantha Shannon; Angela K Heitman; Audrey N Schuetz; Carey-Ann D Burnham; Sophonie Jean Journal: J Clin Microbiol Date: 2022-03-22 Impact factor: 11.677