Modification and evaluation of the Triton Hodge test for screening carbapenemase-producing Enterobacteriaceae

Detection of carbapenemase-producing Enterobacteriaceae (CPE) has become critical for appropriate antimicrobial therapy and for controlling the spread of infection. We evaluated Triton Hodge test (THT) for screening CPE. A spreader can be used to apply more constant volume of Triton on whole surface of Mueller-Hinton agar (MHA), or alternatively, a 10-μL inoculating loop can be used to apply a 20% Triton solution lineally. The THT procedure can be simplified by eliminating the 1/10 dilution step of indicator bacteria from the McFarland 0.5 turbidity suspension. The presence of Triton in the MHA plates significantly increased the enhanced growth size of not only Enterobacteriaceae producing NDM-1-like enzymes but also those producing the most prevalent KPC-2-like enzyme, resulting in 100% sensitivity of the test.