Persistence and epidemic propagation of a Pseudomonas aeruginosa sequence type 235 clone harboring an IS26 composite transposon carrying the blaIMP-1 integron in Hiroshima, Japan, 2005 to 2012.

A 9-year surveillance for multidrug-resistant (MDR) Pseudomonas aeruginosa in the Hiroshima region showed that the number of isolates harboring the metallo-ß-lactamase gene bla(IMP-1) abruptly increased after 2004, recorded the highest peak in 2006, and showed a tendency to decline afterwards, indicating a history of an epidemic. PCR mapping of the variable regions of the integrons showed that this epidemic was caused by the clonal persistence and propagation of an MDR P. aeruginosa strain harboring the bla(IMP-1) gene and an aminoglycoside 6'-N-acetyltransferase gene, aac(6')-Iae in a class I integron (In113), whose integrase gene intl1 was disrupted by an IS26 insertion. Sequence analysis of the representative strain PA058447 resistance element containing the In113-derived gene cassette array showed that the element forms an IS26 transposon embedded in the chromosome. It has a Tn21 backbone and is composed of two segments sandwiched by three IS26s. In Japan, clonal nationwide expansion of an MDR P. aeruginosa NCGM2.S1 harboring chromosomally encoded In113 with intact intl1 is reported. Multilocus sequence typing and genomic comparison strongly suggest that PA058447 and NCGM2.S1 belong to the same clonal lineage. Moreover, the structures of the resistance element in the two strains are very similar, but the sites of insertion into the chromosome are different. Based on tagging information of the IS26 present in both resistance elements, we suggest that the MDR P. aeruginosa clone causing the epidemic in Hiroshima for the past 9 years originated from a common ancestor genome of PA058447 and NCGM2.S1 through an IS26 insertion into intl1 of In113 and through IS26-mediated genomic rearrangements.

[POSTOPERATIVE RECURRENCE OF RENAL CELL CARCINOMA AFTER THE LAPAROSCOPIC PARTIAL NEPHRECTOMY].

(Objectives)The usefulness of partial nephrectomy for renal tumors has been highlighted in various guidelines. Since 2006, we have been actively performing laparoscopic partial nephrectomy for renal tumors. We investigated the postoperative recurrence of renal tumors diagnosed as renal cell carcinoma after laparoscopic partial nephrectomy. (Patients and methods)From August 2006 to March 2020, 320 patients who underwent laparoscopic partial nephrectomy at our hospital and were pathologically diagnosed with renal cancer were included. A retrospective statistical study was conducted to analyze the postoperative recurrence. (Results)Postoperative recurrence was observed in 11 patients (3.4%). The median time to recurrence was 12 months (3-26 months), non-distant metastasis was observed in four cases (1.3%), and distant metastasis was observed in seven cases (2.2%). No statistically significant difference was found in the factors related to recurrence, in this study. (Conclusions)In this study, no statistically significant factors were found, but the higher the clinical stage, the higher the recurrence rate.

First isolation of blaIMP-7 in a Pseudomonas aeruginosa in Japan.

We report here the first isolation in Japan of a carbapenem-resistant Pseudomonas aeruginosa strain that carries the metallo-beta-lactamase gene bla(IMP-7). This isolate revealed high-level resistance to all of the tested antibiotics except for piperacillin, showing a multidrug-resistant phenotype.

Molecular characterization of imipenem-resistant Pseudomonas aeruginosa in Hiroshima, Japan.

Pseudomonas aeruginosa showing resistance to imipenem were found in 100 of 1,058 strains (9.5%) from six hospitals (a-f) in Hiroshima City, Japan. Of the 100 strains, 14 (14%) were double disk synergy test positive using sodium mercaptoacetic acid disks, and 18 (18%) were bla(IMP-1) or bla(VIM-2) allele positive by polymerase chain reaction (PCR). Among 100 imipenem-resistant strains, 32 were categorized into multi-drug resistant strains, in which 13 were positive for the metallo-beta-lactamase gene. Fifty-one strains (51%) among the 100 imipenem-resistant strains had elevated RND efflux pump activity against levofloxacin. But only 6 of 51 strains were classified as multi-drug resistant strains. The pulsed field gel electrophoresis analysis of the Spe I-digested DNA from the 100 isolates suggested not only clonal spread but spread of heterogeneous clones started to contribute to the prevalence of metallo-beta-lactamase producing P. aeruginosa strains in Japanese hospitals.