Clinical and Microbiological Characteristics of Bacteremia Caused by Carbapenemase-producing Enterobacterales in Minami Ibaraki Area, Japan.

Although recent propagation of carbapenemase-producing Enterobacterales (CPE) has become a problem worldwide, the picture of CPE infection in Japan has not fully been elucidated. In this study, we examined clinical and microbiological characteristics of invasive CPE infection occurring at 8 hospitals in Minami Ibaraki Area between July 2001 to June 2017. Of 7294 Enterobacterales strains isolated from independent cases of bacteremia and/or meningitis, 10 (0.14%) were CPE (8 Enterobacter cloacae-complex, 1 Escherichia coli, and 1 Edwardsiella tarda）, all of which had the blaIMP-1 gene and susceptible to gentamicin and trimethoprim/sulfamethoxazole. These strains were isolated from 7 adult and 2 infant bacteremia (1 infant patient developed CPE bacteremia twice) after 2007. The most common portal of entry was intravenous catheters. All of the adult patients were recovered, while the infant patients eventually died. Genomic analyses showed that the 8 E. cloacae-complex strains were classified into 5 groups, each of which was exclusively detected in specific facilities at intervals of up to 3 years, suggesting persistent colonization in the facilities. This study showed that invasive CPE infection in the area was rare, caused by IMP-1-type CPE having susceptibility to various antibiotics, and nonfatal among adult patients.

High-level aminoglycoside resistance in Enterococcus faecalis and Enterococcus faecium causing invasive infection: Twelve-year surveillance in the Minami Ibaraki Area.

We examined prevalence of high-level aminoglycoside resistance (HLAR) in Enterococcus faecalis and Enterococcus faecium causing invasive infection in the Minami Ibaraki Area. Ten strains of both species each, recovered from the blood or the cerebrospinal fluid between 2003 and 2014, were randomly selected every year. High-level resistance to gentamicin (HLR-GM) and streptomycin (HLR-SM) was detected in 34% (41 of 120 strains) and 18% (21) of E. faecalis and 9% (11) and 39% (48) of E. faecium, respectively. In comparisons of the proportions among three four-year periods, HLR-SM among E. faecium was significantly lower in the 2011-2014 period. All strains with HLR-GM were positive for the aac(6')-Ie-aph(2″)-Ia gene. The ant(6')-Ia gene was detected in all with HLR-SM except for one E. faecalis strain. The present study showed that prevalence of HLR-GM among E. faecalis and E. faecium causing invasive infection in this area was nearly equivalent to that described in previous studies in Japan and that proportions of strains with HLAR did not vary during the study period except for that of HLR-SM among E. faecium.

Characteristics of bacteremia caused by extended-spectrum beta-lactamase-producing Proteus mirabilis.

Although Proteus mirabilis is a common human pathogen, bacteremia caused by the organism, especially strains producing extended-spectrum beta-lactamase (ESBL), has rarely been investigated. We examined 64 cases of P. mirabilis bacteremia identified in the Minami Ibaraki Area, Japan, between 2001 and 2010 and compared the characteristics of cases with ESBL-producing and ESBL-non-producing strains (13 and 51 cases, respectively). All ESBL-producing strains with the gene encoding the CTX-M-2-group were genetically nonidentical. Isolation of ESBL-producing strains was significantly associated with onset in a hospital (p = 0.030), receiving hemodialysis (p = 0.0050), and previous antibiotic use within 1 month (p = 0.036; especially penicillin and/or cephalosporin (p = 0.010) and fluoroquinolone (p = 0.0069)). Isolation was also associated with inappropriate antibiotic therapy on the 1st and 4th days (p = 0.011 and 0.032, respectively) but not with mortality on the 30th day. These findings indicate that, for P. mirabilis bacteremia, isolation of ESBL-producing strains causes delay of initiating appropriate antimicrobial therapy but may not be associated with mortality.