The MAST registered D68C test: an interesting tool for detecting extended-spectrum beta -lactamase (ESBL)-producing Enterobacteriaceae

The Mast registered D68C test is a phenotypical test that allows the detection of extended-spectrum beta -lactamase (ESBL) production, even in AmpC-producing Enterobacteriaceae. We assessed its detection accuracy against a large collection of 106 Enterobacteriaceae isolates producing a wide diversit...

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Bibliographic Details
Published in:European journal of clinical microbiology & infectious diseases 2015-05, Vol.34 (5), p.975-983
Main Authors: Nourrisson, C, Tan, R N, Hennequin, C, Gibold, L, Bonnet, R, Robin, F
Format: Article
Language:English
Subjects:
Enterobacteriaceae
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Summary:The Mast registered D68C test is a phenotypical test that allows the detection of extended-spectrum beta -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 beta -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 beta -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 registered 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 %).
ISSN:0934-9723
1435-4373
DOI:10.1007/s10096-014-2305-6