MAST® D72C test: a novel option for ESBL, AmpC and carbapenemase detection.

PURPOSE: The MAST® D72C test is a phenotypical test which can detect ESBL and AmpC production in Enterobacterales. It can also identify the suspected presence of carbapenemase. The aim of the present study was to assess the sensitivity and specificity of this test and to discuss its usefulness in laboratories, especially those that use only an automated AST system. METHOD: The performance of the MAST® D72C test was assessed against a collection of 119 non-redundant Enterobacterales isolates characterized for their content in ß-lactamases, and compared with that of the reference double disk synergy test. ß-lactamase content was established from phenotypic and genotypic analyses to collect a broad diversity of resistance mechanisms and bacterial strains, including 30 ESBL-producing strains, 32 strains overproducing chromosomal AmpC, 10 strains producing plasmid-encoded AmpC, 12 carbapenemase-producing strains, 13 strains combining the production of several ß-lactamases, and 22 strains that produced other ß-lactamases. RESULTS: The sensitivity and specificity for ESBL-detection were comparable with those of the synergy test, 75 versus 72.5%, and 94.9 versus 93.7%, respectively. The sensitivity and specificity for AmpC-detection were 71.7% and 100%, respectively, and sensitivity reached 78.7% if we excluded carbapenem-resistant isolates. Carbapenemase-detection sensitivity was 90%. CONCLUSION: These results show that the MAST® D72C test can be a useful tool for the detection of ESBL- and AmpC-production in clinical laboratories.

Evaluation of two detergent-disinfectants and a detergent on a Klebsiella pneumoniae biofilm formed within Tygon tubes.

BACKGROUND: Transmission of infections via contaminated endoscopes is a common problem. Manual cleaning, using at least a detergent, is an important step in endoscope processing and should be performed as soon as possible to avoid drying of organic residues that might interfere with high-level disinfection and promote biofilm formation. AIM: To assess the efficacy of two detergent-disinfectants, enzymatic and non-enzymatic, and of an enzymatic detergent used during the manual cleaning against a Klebsiella pneumoniae biofilm. METHODS: A 24 h biofilm statically formed in a Tygon tube was exposed to detergent-disinfectants at 20 °C and 35 °C for 10 mn, and to enzymatic detergent at 45 °C for 60 mn. The logarithmic reduction in bacteria in the Tygon tube and the number of bacteria in the product supernatant were calculated. FINDINGS: Biofilm formation was reproducible between assays. After exposure to detergent-disinfectants, the logarithmic reduction was between 6.32 and 6.71 log10 cfu/cm2 in the Tygon tubes. No bacteria were found in their supernatants. Results in the detergent-disinfectant group were not affected by the exposure temperature or the addition of enzymes. No decrease in the bacterial load was observed in the Tygon tubes after exposure to the enzymatic detergent. Bacteria were found in its supernatant. CONCLUSION: These results show the importance of the choice of products used during the manual cleaning phase. They also show the potential benefit of combining detergent and disinfectant activity to decrease the bacterial load during the manual cleaning step of endoscope processing.