Molecular characterization of carbapenemase-producing clinical isolates of Enterobacteriaceae in a teaching hospital, Japan

Abstract

We examined the molecular characteristics of 13 phenotypically confirmed carbapenemasepositive Enterobacteriaceae clinical isolates, including the relationships between plasmidmediated quinolone-resistance genes (qnr), 69-N-aminoglycoside acetyltransferase-encoding genes [aac(69)] and AmpC-encoding genes (pAmpC). Twelve isolates were bla IMP-1 positive (92.3 %), while one was bla IMP-11 positive (7.7 %). We detected qnr, aac(69) and pAmpC genes designated bla ACT-1 -like in 76.9 %, 100 % and 53.8 %, respectively, of the 13 isolates. Plasmids were transferred successfully for three of the 13 metallo-b-lactamase (MBL)-producing isolates, and the sizes of plasmids extracted from these donors and transconjugants were deduced to be 65 kb or 70 kb. OmpC or OmpF protein expression was reduced in all Enterobacter cloacae, and one Klebsiella oxytoca lacked OmpK36. We demonstrate what appears to be the first evidence that, in Japan, Enterobacteriaceae producing MBLs carry various plasmid-mediated resistance genes, which may cause a further decrease in carbapenem susceptibility through reduction of the expression of outer-membrane proteins.

Altered Outer Membrane Transcriptome Balance with AmpC Overexpression in Carbapenem-Resistant Enterobacter cloacae

“…The authors described decreased expression of both ompF (5-fold) and ompC (500-fold) genes in resistant strains. The decrease in expression level of both major OM proteins was also recorded in the report published by Koyano et al (2013), Philippe et al (2015) and Jaskulski et al (2013). …”

Occurrence and characterization of carbapenem‐resistant Gram‐negative bacilli: A collaborative study of antibiotic‐resistant bacteria between Indonesia and Japan

“…[21][22][23][24][25][26][27][28][29][30][31][32][33][34] Koyano et al found that 13 (0.8%) of 1704 isolates from Tokyo were CPE, and mostly dominated by the IPM-1 gene (n = 12, 92.3%). 21 A study from another city in Japan showed that 20 CPE were included in two STs (ST2 and ST246), and 17 (85%) were bla OXA-23 type, 22 similar to results in Gunma University Hospital, Japan. 23 This is different from Vietnam, where NDM is dominant among CRE, similar to Indonesia.…”

Carbapenemase-Producing Gram-Negative Bacteria: Current Epidemics, Antimicrobial Susceptibility and Treatment Options

“…Various kinds of IMP enzyme were subsequently found in enteric and in glucose nonfermentative GNB species in other countries around the world [70][71][72]. To date, however, highly endemic GNB with IMP enzymes were only reported in Taiwan (bla IMP-8 ) [73] and in Japan (bla IMP-1 ) [74].…”