First report of KPC-2 Carbapenemase-producing Klebsiella pneumoniae in Japan.

We investigated a novel Japanese isolate of sequence type 11 (ST11), the Klebsiella pneumoniae carbapenemase-2 (KPC-2)-producing K. pneumoniae strain Kp3018, which was previously obtained from a patient treated at a Brazilian hospital. This strain was resistant to various antibiotic classes, including carbapenems, and harbored the gene blaKPC-2, which was present on the transferable plasmid of ca. 190 kb, in addition to the blaCTX-M-15 gene. Furthermore, the ca. 2.3-kb sequences (ISKpn8-blaKPC-2-ISKpn6-like), encompassing blaKPC-2, were found to be similar to those of K. pneumoniae strains from China.

Clinical Features, Genome Epidemiology, and Antimicrobial Resistance Profiles of Aeromonas spp. Causing Human Infections: A Multicenter Prospective Cohort Study.

Background: The genus Aeromonas is increasingly implicated in human infections, but knowledge of its clinical characteristics and antimicrobial resistance profiles has been limited owing to its complex taxonomy. Methods: We conducted a multicenter prospective cohort study of patients with Aeromonas infections at hospitals across Japan. Patients were eligible for inclusion if they had an Aeromonas spp. strain in a clinical culture and were considered infected at the culture site. Clinical data were collected, and isolates underwent susceptibility testing and whole-genome sequencing. Results: A total of 144 patients were included. Hepatobiliary infection accounted for a majority of infections (73% [105 of 144]), which mostly occurred in elderly patients with comorbid conditions, including hepatobiliary complications. The all-cause 30-day mortality rate was 10.0% (95% confidence interval, 4.9%-14.8%). By whole-genome sequencing, 141 strains (98%) belonged to 4 Aeromonas species-A caviae, A hydrophila, A veronii, and A dhakensis-with significant intraspecies diversity. A caviae was predominant in all infection sites except skin and soft tissue, for which A hydrophila was the prevailing species. The genes encoding chromosomally mediated class B, C, and D ß-lactamases were harbored by 92%-100% of the isolates in a species-specific manner, but they often lacked association with resistance phenotypes. The activity of cefepime was reliable. All isolates of A hydrophila and A dhakensis carried an mcr-3-like colistin resistance gene and showed reduced susceptibility to colistin. Conclusions: Hepatobiliary tract was the most common infection site of Aeromonas spp., with A caviae being the dominant causative species. The resistance genotype and phenotype were often incongruent for ß-lactam agents.

Plesiomonas shigelloides Septic Shock Following Ingestion of Dojo Nabe (Loach Hotpot).

Plesiomonas shigelloides is a gram-negative bacillus that commonly causes self-limited diarrhea in humans. We present the case of P shigelloides bacteremia in a 49-year-old man with alcoholic cirrhosis who developed septic shock a day after eating Dojo nabe (loach hotpot), a Japanese traditional dish.

Scedosporium prolificans Endocarditis: Case Report and Literature Review.

Scedosporium prolificans, a hyaline filamentous fungus, is widely distributed in the environment and is currently an emerging human pathogen, especially among immunocompromised patients. However, S. prolificans endocarditis is rare. We herein report a case of S. prolificans endocarditis in a 64-year-old patient with breast cancer in complete remission for 30 years after chemotherapy and radiation treatment who was not cured. Susceptibility testing showed resistance to all antifungal drugs, except echinocandin. A review of the literature revealed 10 cases of S. prolificans endocarditis; of these, only one involved an immunocompetent host with no risk factors and only two patients survived. In order to improve the mortality rate, it is necessary to establish rapid diagnostic methods and efficient therapeutic approaches.

Evaluation of a simple phenotypic method for the detection of carbapenemase-producing Enterobacteriaceae.

We investigated the performance of a phenotypic test, the Carbapenemase Detection Set (MAST-CDS), for the identification of carbapenemase-producing Enterobacteriaceae. Our results indicated that MAST-CDS is rapid, easily performed, simple to interpret, and highly sensitive for the identification of carbapenemase producers, particularly imipenemase producers.

A Case of Liver Abscess with Desulfovibrio desulfuricans Bacteremia.

Desulfovibrio spp. are gram-negative, sulfate-reducing, and anaerobic bacteria found in the digestive tract of humans. Because Desulfovibrio spp. are infrequent causative agents of infectious diseases and are difficult to isolate and to identify from clinical specimens, the appropriate antibiotic therapy to infection with Desulfovibrio spp. has not been determined. We report the first case of liver abscess with bacteremia due to Desulfovibrio desulfuricans to show the clinical presentation and treatment. The patient was successfully treated with intravenous piperacillin-tazobactam and oral amoxicillin-clavulanic acid.

Diversity of vancomycin-resistant enterococci in a low endemicity area.

Although vancomycin-resistant enterococci (VRE) are frequent nosocomial pathogens worldwide, in Japan their prevalence is low and their molecular epidemiology remains unclear. In The University of Tokyo Hospital (Tokyo, Japan), only five isolates of VRE (vanA-type Enterococcus faecium) were identified in the 20 years before 2010; however, nine isolates of vanB-type E. faecium were identified from 2011 to 2012. Multilocus sequence typing (MLST) revealed that they belonged to five sequence types (ST18, ST78, ST203, ST412 and ST612). Despite the limited isolation, including one from a medical tourist, there was significant diversity in genotypes. Increasing medical travel might enhance the diversity of VRE.

Antimicrobial susceptibility and mechanisms of high-level macrolide resistance in clinical isolates of Moraxella nonliquefaciens.

We investigated antimicrobial susceptibility and the molecular mechanism involved in conferring high-level macrolide resistance in 47 clinical isolates of Moraxella nonliquefaciens from Japan. Antimicrobial susceptibility was determined using Etest and agar dilution methods. Thirty-two erythromycin-non-susceptible strains were evaluated for the possibility of clonal spreading, using PFGE. To analyse the mechanism related to macrolide resistance, mutations in the 23S rRNA gene and the ribosomal proteins, and the presence of methylase genes were investigated by PCR and sequencing. The efflux system was examined using appropriate inhibitors. Penicillin, ampicillin, amoxicillin, cefixime, levofloxacin and antimicrobials containing ß-lactamase inhibitors showed strong activity against 47 M. nonliquefaciens isolates. Thirty-two (68.1 %) of the 47 isolates showed high-level MICs to macrolides (MIC ≥128 mg l(-1)) and shared the A2058T mutation in the 23S rRNA gene. The geometric mean MIC to macrolides of A2058T-mutated strains was significantly higher than that of WT strains (P<0.0001). Thirty-two isolates with high-level macrolide MICs clustered into 30 patterns on the basis of the PFGE dendrogram, indicating that the macrolide-resistant strains were not clonal. In contrast, no common mutations of the ribosomal proteins or methylase genes, or overproduction of the efflux system were observed in A2058T-mutated strains. Moreover, of the 47 M. nonliquefaciens strains, 43 (91.5 %) were bro-1 and 4 (8.5 %) were bro-2 positive. Our results suggest that most M. nonliquefaciens clinical isolates show high-level macrolide resistance conferred by the A2058T mutation in the 23S rRNA gene. This study represents the first characterization of M. nonliquefaciens.

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

We examined the molecular characteristics of 13 phenotypically confirmed carbapenemase-positive Enterobacteriaceae clinical isolates, including the relationships between plasmid-mediated quinolone-resistance genes (qnr), 6'-N-aminoglycoside acetyltransferase-encoding genes [aac(6')] 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(6') 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-ß-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.