Evaluation of commercial phenotypic assays for the detection of IMP- or New Delhi metallo-ß-lactamase-producing Enterobacteriaceae isolates in Japan.

OBJECTIVES: This study was designed to evaluate the sodium mercaptoacetic acid double disk synergy test (SMA-DDST), the Etest metallo-ß-lactamase (MBL) MP/MPI (Etest MP/MPI), and the Mastdiscs ID Carbapenemase Detection Disc Set (MAST-CDS) for the detection of MBL-producing Enterobacteriaceae isolates in Japan. METHODS: Fifty-one clinical isolates and four reference strains were tested. These isolates included 40, 4, and 11 IMP-, New Delhi MBL (NDM)-, and non-MBL-producers, respectively. SMA-DDST was performed with meropenem (MEPM)-containing disks. RESULTS: Sensitivities were 38/44 (86%), 40/44 (91%), and 15/44 (34%), and the cost ratio was 1:9.4:3.8 for MEPM-SMA-DDST:Etest MP/MPI:MAST-CDS, respectively. The specificity was 11/11 (100%) for all assays. MEPM-SMA-DDST detected IMP-producing isolates with high sensitivity (38/40; 95%), but the assay was inadequate for NDM-producing isolates (0/4; 0%). The Etest MP/MPI detected both IMP- (36/40; 90%) and NDM-producing isolates (4/4; 100%), but was the most expensive. MAST-CDS detected IMP-producing isolates with low sensitivity (11/40; 28%), but the assay worked well for NDM-producing isolates (4/4; 100%). CONCLUSIONS: Our results indicated that MEPM-SMA-DDST was the most cost-effective assay for the detection of IMP-producing isolates. Therefore, we conclude that MEPM-SMA-DDST is the optimal available assay for clinical first-line screening in IMP-endemic areas such as Japan. However, this assay could not detect NDM-producing isolates, whereas the Etest MP/MPI and MAST-CDS could. When MEPM-SMA-DDST is negative, the Etest MP/MPI and MAST-CDS could be used to obtain supportive data and prevent detection failure for NDM-producing isolates.

Cryptococcus gattii Genotype VGIIa Infection in an Immunocompetent Japanese Patient: A Case Report and Mini-review.

A 39-year-old man presented to our hospital with a four-week history of headache and a two-week history of low-grade fever. Chest X-rays showed a tumor of approximately 50 mm in size in the right lower field. A histopathological examination of a transbronchial lung biopsy specimen from the right S9/10 revealed numerous fungal elements that appeared as encapsulated yeast with clear halos. Gadolinium-enhanced brain magnetic resonance images showed multiple cerebral nodules. Cryptococcus gattii (Genotype VGIIa) was isolated from the bronchial lavage and cerebrospinal fluid specimens. The patient was an immunocompetent Japanese man who had not recently traveled to a C. gattii-endemic area.