title: The MAST® D68C test: an interesting tool for detecting extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae.
abstract: The Mast® D68C test is a phenotypical test that allows the detection of extended-spectrum β-lactamase (ESBL) production, even in AmpC-producing Enterobacteriaceae. We assessed its detection accuracy against a large collection of 106 Enterobacteriaceae isolates producing a wide diversity of well-characterized β-lactamases (53 ESBL producers, 25 Amp. producers, seven AmpC and ESBL producers, five carbapenemase producers, three carbapenemase and ESBL producers, one AmpC, carbapenemase, and ESBL producer, three TEM-1 producers, three SHV-1 producers, three OXA-1 producers, and one hyperOXY producer, ATCC 35218, ATCC 25922 [a β-lactamase-negative control strain]). The results were compared with those of the double disk test and the Clinical and Laboratory Standards Institute (CLSI) confirmatory test for the detection of ESBL. The sensitivity was 90.6 % for the synergy test, 87.5 % for the CLSI method, and only 73.1 % for D68C, which, however, reached 92.1 % if the strains for which supplementary investigations were recommended and the complex mutant TEM (CMT)-producing strains were excluded versus 94.1 % and 88.2 % for the other methods. The specificity was 90.2 % for the synergy test and 100 % for the CLSI method and D68C. D68C was also efficient in detecting AmpC-overproducing strains (sensitivity = 97 %, specificity = 95.9 %): among the 74 strains belonging to natural AmpC-producing species, the sensitivity and specificity were 100 and 94.8 %, respectively. The Mast® D68C-test is a promising method that is easy to perform for the detection of current ESBLs and could also be useful for the detection of plasmid-encoded AmpC enzymes (sensitivity = 100 %).
authors.affiliation: Laboratoire de Bactériologie, CHU Clermont-Ferrand, 58, rue Montalembert, 63003, Clermont-Ferrand, France.
authors.forename: C
authors.initials: C
authors.lastname: Nourrisson
authors.forename: R N
authors.initials: RN
authors.lastname: Tan
authors.forename: C
authors.initials: C
authors.lastname: Hennequin
authors.forename: L
authors.initials: L
authors.lastname: Gibold
authors.forename: R
authors.initials: R
authors.lastname: Bonnet
authors.forename: F
authors.initials: F
authors.lastname: Robin
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D004755:Enterobacteriaceae / Q000201:enzymology*; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D001618:beta-Lactamases