Klebsiella Species and Enterobacter cloacae Isolates Harboring blaOXA-181 and blaOXA-48: Resistome, Fitness Cost, and Plasmid Stability.

IncX3 and IncL plasmids have been named as catalysts advancing dissemination of blaOXA-181 and blaOXA-48 genes. However, their impact on the performance of host cells is vastly understudied. Genetic characteristics of blaOXA-48- and blaOXA-181-containing Klebsiella pneumoniae (EFN299), Klebsiella quasipneumoniae (EFN262), and Enterobacter cloacae (EFN743) isolated from clinical samples in a Ghanaian hospital were investigated by whole-genome sequencing. Transfer of plasmids by conjugation and electroporation, plasmid stability, fitness cost, and genetic context of blaOXA-48, blaOXA-181, and blaDHA-1 were assessed. blaOXA-181 was carried on two IncX3 plasmids, an intact 51.5-kb IncX3 plasmid (p262-OXA-181) and a 45.3-kb IncX3 plasmid (p743-OXA-181) without replication protein sequence. The fluoroquinolone-resistant gene qnrS1 region was also excised, and unlike in p262-OXA-181, the blaOXA-181 drug-resistant region was not found on a composite transposon. blaOXA-48 was carried on a 74.6-kb conjugative IncL plasmid with unknown ~10.9-kb sequence insertion. This IncL plasmid proved to be highly transferable, with a conjugation efficiency of 1.8 × 10-2. blaDHA-1 was present on an untypeable 22.2 kb genetic structure. Plasmid stability test revealed plasmid loss rate between 4.3% and 12.4%. The results also demonstrated that carriage of IncX3-blaOXA-181 or IncL-blaOXA-48 plasmids was not associated with any fitness defect, but rather an enhanced competitive ability of host cells. This study underscores the significant contribution of IncX3 and IncL plasmids in the dissemination of resistance genes and their efficient transfer calls for regular monitoring to control the expansion of resistant strains. IMPORTANCE The growing rate of antibiotic resistance is an important global health threat. This threat is exacerbated by the lack of safe and potent alternatives to carbapenems in addition to the slow developmental process of newer and effective antibiotics. Infections by carbapenem-resistant Gram-negative bacteria are becoming almost untreatable, leading to poor clinical outcomes and high mortality rates. OXA-48-like carbapenemases are one of the most widespread carbapenemases accounting for resistance among Enterobacteriaecae. We characterized OXA-48- and OXA-181-producing Enterobacteriaecae to gain insights into the genetic basis and mechanism of resistance to carbapenems. Findings from the study showed that the genes encoding these enzymes were carried on highly transmissible plasmids, one of which had sequences absent in other similar plasmids. This implies that mobile genetic elements are important players in the dissemination of resistance genes. Further characterization of this plasmid is warranted to determine the role of this sequence in the spread of resistance genes.

Plasmid analysis of NDM metallo-ß-lactamase-producing Enterobacterales isolated in Vietnam.

Carbapenem-resistant Enterobacterales (CRE) represent a serious threat to public health due to the lack of treatment and high mortality. The rate of antimicrobial resistance of Enterobacterales isolates to major antimicrobials, including carbapenems, is much higher in Vietnam than in Western countries, but the reasons remain unknown due to the lack of genomic epidemiology research. A previous study suggested that carbapenem resistance genes, such as the carbapenemase gene blaNDM, spread via plasmids among Enterobacterales in Vietnam. In this study, we characterized blaNDM-carrying plasmids in Enterobacterales isolated in Vietnam, and identified several possible cases of horizontal transfer of plasmids both within and among species of bacteria. Twenty-five carbapenem-nonsusceptible isolates from a medical institution in Hanoi were sequenced on Illumina short-read sequencers, and 13 blaNDM-positive isolates, including isolates of Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Morganella morganii, and Proteus mirabilis, were further sequenced on an Oxford Nanopore Technologies long-read sequencer to obtain complete plasmid sequences. Almost identical 73 kb IncFII(pSE11)::IncN hybrid plasmids carrying blaNDM-1 were found in a P. mirabilis isolate and an M. morganii isolate. A 112 kb IncFII(pRSB107)::IncN hybrid plasmid carrying blaNDM-1 in an E. coli isolate had partially identical sequences with a 39 kb IncR plasmid carrying blaNDM-1 and an 88 kb IncFII(pHN7A8)::IncN hybrid plasmid in a C. freundii isolate. 148-149 kb IncFIA(Hl1)::IncA/C2 plasmids and 75-76 kb IncFII(Yp) plasmids, both carrying blaNDM-1 were shared among three sequence type 11 (ST11) isolates and three ST395 isolates of K. pneumoniae, respectively. Most of the plasmids co-carried genes conferring resistance to clinically relevant antimicrobials, including third-generation cephalosporins, aminoglycosides, and fluoroquinolones, in addition to blaNDM-1. These results provide insight into the genetic basis of CRE in Vietnam, and could help control nosocomial infections.

[Necessity of Serum Calcium Concentration Measurement for Investigating Hypocalcemia Induced by Denosumab].

Denosumab is widely used for treating bone metastases in patients with advanced cancer. However, hypocalcemia has been reported as a serious adverse effect during this treatment. Therefore, monitoring serum calcium concentration is essential. During long-term continuous administration ofdenosumab, the burden ofeach blood sampling occasion and medical economics should be clarified; however, the appropriate blood sampling frequency has not yet been confirmed. In the present study, we performed a retrospective investigation of serum calcium concentration after denosumab administration. The results indicated that serum calcium concentration tended to increase with repeated administration. A significant increase was observed at the time ofthe third and sixth administration. This suggested that it was possible to reduce the frequency ofblood sampling during long-term administration ofdenosumab with appropriate calcium supplementation.

[Safety Assessment of a Short Hydration Regimen for Outpatient Cisplatin-Based Chemotherapy].

BACKGROUND: During administration of thecisplatin (CDDP)containing regimen, hospitalization is necessary to ensure adequate hydration. However, short hydration is widely used when administering CDDP in outpatient chemotherapy centers. METHOD: To assess the safety of the administration of CDDP during short hydration, we retrospectively evaluated adverse events and complications in the outpatients who received CDDP during short hydration between April 2012 and December 2014 in our hospital. RESULT: Sixty patients received CDDP during short hydration. Eighteen patients with non-small cell lung cancer, 17 with gastric cancer, 10 with small cell lung cancer, 9 with cervical cancer, 4 with biliary tract cancer, 1 with endometrial cancer, and 1 with duodenal papilla cancer were retrospectively evaluated. Fifty-five patients completed CDDP treatment(including treatment until PD). The reasons for discontinuation of CDDP treatment were deterioration of general condition, ileus, pneumothorax, cholangitis, and rejection of oral rehydration. Hydronephrosis after CDDP treatment during short hydration(weekly CDDP regimen)was observed in 1 patient. No patient discontinued CDDP due to grade 3 or 4 adverse events. CONCLUSION: No discontinuation of CDDP associated with a short hydration regimen suggests that it has enabled thesafeadministration of CDDP to outpatients.

Noninvasive assessment of insulin resistance in the liver using the fasting (13)C-glucose breath test.

Evaluating hepatic insulin resistance (IR) is the key to making a sensitive an accurate diagnosis of glucose intolerance. However, there is currently no suitable method to perform this procedure. This study was conducted to investigate whether the fasting (13)C-glucose breath test (FGBT) is useful as a convenient and highly sensitive clinical test for evaluating hepatic IR. Healthy nonobese subjects and a disease group consisting of patients with mild glucose intolerance were administered 100 mg (13)C-glucose after an overnight fast. A series of breath samples was collected until 360 minutes after ingestion, and the (13)CO2-to-(12)CO2 ratio was measured using an infrared spectrometer and was plotted as a kinetic curve of (13)C excretion. The area under the curve until 360 minutes (AUC360) of the (13)C excretion kinetic curve of the FGBT reflects the efficiency of energy production in the liver. First, we assessed the correlations between the AUC360 (or the (13)C excretion rate at 120 minutes) and the HOMA-IR and HbA1c levels as standard measurements of IR and diabetes mellitus (DM). There were relatively strong correlation coefficients (r = -0.49 to -0.81, r(2) = 0.24-0.66, P < 0.01; n = 35 males, n = 33 females). Second, we compared the AUC360 of healthy subjects and that of the patients with mild glucose intolerance. The AUC360 of the healthy subjects was consistently higher than that of the patients with mild glucose intolerance. The presence of IR or DM in males and females was diagnosed using cutoff values. The FGBT is a novel glucose metabolism test that can be used conveniently and safely to evaluate the balance of glucose metabolism in the liver. This test has excellent sensitivity for diagnosing alterations in hepatic glucose metabolism, particularly hepatic IR.