Kohei Uechi

Emergence of a colistin-resistant Escherichia coli clinical isolate harboring mcr-1 in Japan

The mcr-1 is a gene encoding a phosphoethanolamine transferase, which confers resistance to colistin by transferring phosphoethanolamine to lipid A. We describe here the emergence of a colistin-resistant Escherichia coli clinical isolate harboring plasmid-mediated mcr-1 in Japan. The isolate belonged to ST5702 and is suspected to come from livestock and transmitted to human. This is the first report of a clinical isolate harboring mcr-1 in Japan.

A Modified Carbapenem Inactivation Method, CIMTris, for Carbapenemase Production in Acinetobacter and Pseudomonas Species

ABSTRACT The carbapenem inactivation method (CIM) and modified CIM (mCIM) are simple and economical phenotypic screening methods for detecting carbapenemase production in Gram-negative bacteria. Although the mCIM has been recommended by the Clinical and Laboratory Standards Institute, both the CIM and mCIM have limitations. This study describes another modified CIM, called CIMTris, in which carbapenemase was extracted from bacteria with 0.5 M Tris-HCl (pH 7.6) buffer. The ability of the CIMTris to detect carbapenemase production was examined in Acinetobacter and Pseudomonas species. The CIMTris had an overall sensitivity of 97.6% and an overall specificity of 92.6%, whereas the mCIM had a sensitivity of 45.1% and a specificity of 100% for the isolates tested. These findings indicate that the CIMTris is useful for detecting carbapenemase production in Acinetobacter and Pseudomonas species.

A hemin auxotrophic Enterobacter cloacae clinical isolate with increased resistance to carbapenems and aminoglycosides

Small-colony variants (SCVs) were obtained from an Enterobacter cloacae clinical isolate in Okinawa, Japan. One variant showed auxotrophy for hemin with a deletion of 20 365 nucleotides, dosC-ydiK-mmuP-mmuM-tauA-tauB-tauC-tauD-hemB-yaiT-yaiV-ampH-yddQ-sbmA-yaiW-yaiY-yaiZ, including hemB, and was more resistant to aminoglycosides and carbapenems, but more susceptible to aztreonam, than the parent strain.

Emergence of IncX4 plasmids encoding mcr-1 in a clinical isolate of Klebsiella pneumoniae in Japan

The mcr-1 gene encodes a phosphoethanolamine transferase that confers resistance to colistin by transferring phosphoethanolamine to lipid A. A 33-kb IncX4 plasmid harboring mcr-1 was detected in a Klebsiella pneumoniae isolate and two Escherichia coli isolates, and a 66-kb IncI2 plasmid was detected in three E. coli isolates in hospitals in Okinawa, Japan.