The first case of septicemia caused by imipenem-susceptible, meropenem-resistant Klebsiella pneumoniae

Molecular characterization and antibiotic resistance of Acinetobacter baumannii in cerebrospinal fluid and blood

The increasing prevalence of carbapenem-resistant Acinetobacter baumannii (CRAB) caused nosocomial infections generate significant comorbidity and can cause death among patients. Current treatment options are limited. These infections pose great difficulties for infection control and clinical treatment. To identify the antimicrobial resistance, carbapenemases and genetic relatedness of Acinetobacter baumannii isolates from cerebrospinal fluid (CSF) and blood, a total of 50 nonrepetitive CSF isolates and 44 blood isolates were collected. The resistance phenotypes were determined, and polymerase chain reaction (PCR) was performed to examine the mechanisms of carbapenem resistance. Finally, multilocus sequence typing (MLST) was conducted to determine the genetic relatedness of these isolates. It was observed that 88 of the 94 collected isolates were resistant to imipenem or meropenem. Among them, the bla_OXA-23 gene was the most prevalent carbapenemase gene, with an observed detection rate of 91.5% (86/94), followed by the bla_OXA-24 gene with a 2.1% detection rate (2/94). Among all carbapenem-resistant Acinetobacter baumannii (CRAB) observations, isolates with the bla_OXA-23 gene were resistant to both imipenem and meropenem. Interestingly, isolates positive for the bla_OXA-24 gene but negative for the bla_OXA-23 gene showed an imipenem-sensitive but meropenem-resistant phenotype. The MLST analysis identified 21 different sequence types (STs), with ST195, ST540 and ST208 most frequently detected (25.5%, 12.8% and 11.7%, respectively). 80 of the 94 isolates (85.1%) were clustered into CC92 which showed a carbapenem resistance phenotype (except AB13). Five novel STs were detected, and most of them belong to CRAB. In conclusion, these findings provide additional observations and epidemiological data of CSF and blood A. baumannii strains, which may improve future infection-control measures and aid in potential clinical treatments in hospitals and other clinical settings.

Rapid identification of carbapenemase-type blaGES and ESBL-type blaGES using multiplex PCR

Guiana extended-spectrum (GES) β-lactamases are emerging in Japan. The GES family can be classified into 2 groups, one with extended-spectrum β-lactamase (ESBL)-like activity, which hydrolyzes penicillins and cephalosporins, and the other with carbapenemase-like activity with an extended spectrum toward carbapenems. This difference is mediated by variations in a specific amino acid in the GES protein: G170 N or G170S substitutions. We developed an amplification refractory mutation system (ARMS) PCR assay that enabled rapid identification of these variant genes without sequencing.

Klebsiella oxytoca-producing IMP-1 Detected as the First Strain of Carbapenem-resistant Enterobacteriaceae in Our Hospital

We herein report a case of Klebsiella oxytoca-producing IMP-1 that was detected as a first isolate of carbapenem-resistant Enterobacteriaceae (CRE) at our facility. Since K. oxytoca is an uncommon strain for CRE, we speculated that the resistant organism had already spread out inside the hospital. Metallo-β-lactamases promotes antibiotic resistance in Enterobacteriaceae, which potentially yields problematic issues in clinical settings. Active surveillance of antibiotic resistant strains is important and should be repeatedly highlighted. Furthermore, appropriate methods should be established to detect highly resistant strains.