Predictive Value of Vancomycin AUC24/MIC Ratio for 30-day Mortality in Patients with Severe or Complicated Methicillin-Resistant Staphylococcus aureus Infections: A Multicenter Retrospective Study.

BACKGROUND: Although vancomycin is typically employed against methicillin-resistant Staphylococcus aureus (MRSA) infections, the optimal ratio of 24-h area under the concentration-time curve to minimum inhibitory concentration (AUC24/MIC) for severe or complicated infections lacks clear guideline recommendations. This study aimed to determine the target AUC24/MIC ratio associated with treatment outcomes of infections treated with vancomycin. METHODS: This retrospective multicenter cohort study included adult patients receiving ≥ 5 days of vancomycin for severe/complicated MRSA infections (e.g., osteoarticular, pulmonary, endocarditis, etc.) between January 2018 and December 2023. The primary outcome was 30-day mortality, with secondary outcomes including clinical success, microbiological eradication, and nephrotoxicity. Receiver operating characteristic (ROC) curve analysis was used to identify the AUC24/MIC cutoff for 30-day mortality. Multivariate regression analysis was used to determine association between AUC24/MIC and outcomes. RESULTS: This study included 82 patients. ROC identified a target AUC24/MIC of ≥ 505 for 30-day mortality. The overall 30-day mortality rate (22.0%) was significantly higher for below average AUC24/MIC cutoff (34.1%) than for above AUC24/MIC cutoff group (9.8%). Multivariate analysis confirmed AUC24/MIC of < 505 as an independent predictor (adjusted odds ratio, 5.001; 95% confidence interval, 1.335-18.75). The clinical success rate differed significantly between below- and above-cutoff groups, whereas microbiological eradication tended to favor the above-cutoff group. The nephrotoxicity rates were comparable between groups. CONCLUSIONS: In treating severe/complicated MRSA infections, vancomycin AUC24/MIC ratio ≥ 505 was independently associated with favorable 30-day mortality. Given the retrospective nature of this study, further prospective studies are essential to confirm the reliability of the target AUC24/MIC ratios.

Vancomycin Hydrochloride as a Risk Factor for Acute Kidney Injury: A Retrospective Study.

INTRODUCTION: The incidence of acute kidney injury (AKI) caused by vancomycin hydrochloride (VCM) was reported to be 5-43%. VCM-induced AKI was reported to be more likely to occur 4-17 days after initiating VCM treatment; however, it may occur earlier. The aim of this study was therefore to investigate risk factors for the development of AKI within two (AKI2days) and seven (AKI7days) days of VCM administration. METHODS: This was a single-center, retrospective study including patients who underwent VCM therapy between April 1, 2013, and December 31, 2019. AKI was evaluated based on the Kidney Disease: Improving Global Outcomes criteria. RESULTS: In total, 287 patients were enrolled. The incidence of VCM-induced AKI within 7 days was 10.8% (31/286 cases), and the incidence of AKI within 2 days was 5.9% (15/252 cases). Serum VCM trough concentrations and tazobactam-piperacillin (TZP) were shown to be a risk factor for VCM-induced AKI. The serum VCM trough concentration was 12.67 µg/mL within the 48 h threshold (AKI2days) and 19.03 µg/mL within the 7-day threshold (AKI7days). CONCLUSION: Our study demonstrated that high serum VCM trough concentrations and the combination of VCM and TZP were independent risk factors for VCM-induced AKI. Avoiding the concomitant use of TZP, or thorough monitoring of renal function with the concomitant use of TZP, may be helpful in reducing the occurrence of AKI. Furthermore, monitoring serum VCM trough concentrations within 2 days may effectively reduce the incidence of AKI.

Space Exposure of Amino Acids and Their Precursors during the Tanpopo Mission.

Amino acids have been detected in extraterrestrial bodies such as carbonaceous chondrites (CCs), which suggests that extraterrestrial organics could be the source of the first life on Earth, and interplanetary dust particles (IDPs) or micrometeorites (MMs) are promising carriers of extraterrestrial organic carbon. Some amino acids found in CCs are amino acid precursors, but these have not been well characterized. The Tanpopo mission was conducted in Earth orbit from 2015 to 2019, and the stability of glycine (Gly), hydantoin (Hyd), isovaline (Ival), 5-ethyl-5-methylhydantoin (EMHyd), and complex organics formed by proton irradiation from CO, NH3, and H2O (CAW) in space were analyzed by high-performance liquid chromatography and/or gas chromatography/mass spectrometry. The target substances showed a logarithmic decomposition over 1-3 years upon space exposure. Recoveries of Gly and CAW were higher than those of Hyd, Ival, and EMHyd. Ground simulation experiments showed different results: Hyd was more stable than Gly. Solar ultraviolet light was fatal to all organics, and they required protection when carried by IDPs/MMs. Thus, complex amino acid precursors (such as CAW) were possibly more robust than simple precursors during transportation to primitive Earth. The Tanpopo 2 mission is currently being conducted to expose organics to more probable space conditions.

Progressive accumulation of intrinsic mouse uromodulin in the kidneys of transgenic mice harboring the mutant human uromodulin gene.

Familial juvenile hyperuricemic nephropathy (FJHN) and medullary cystic kidney disease type 2 (MCKD2) are autosomal dominant disorders characterized by juvenile hyperuricemia of the underexcretion type, juvenile gout and chronic renal failure in the adult. FJHN/MCKD2 constitute diseases caused by mutations of the human uromodulin (UMOD) gene that encodes uromodulin, the most abundant glycoprotein in normal human urine. The mutations affect the transport of uromodulin, resulting in the accumulation of uromodulin in the kidneys of FJHN/MCKD2 patients. The purpose of this study was to confirm the accumulation of uromodulin in the kidneys of transgenic mice harboring the mutant human UMOD gene with mouse UMOD gene promoter, and to determine the relationship between its accumulation and the effect on uromodulin transport. The mutant human UMOD mRNA and its protein were expressed in the kidneys of transgenic mice. Moreover, the staining of human uromodulin was colocalized with that of mouse uromodulin. Although the human UMOD mRNA levels increased, the protein levels did not change and the accumulation of human uromodulin was not observed. However, the mouse uromodulin consists of two forms, 103 and 117 kDa, and the 103 kDa protein was gradually increased in the kidneys of transgenic mice. Human and mouse uromodulins in the kidneys of transgenic mice were mainly detected in the Triton X-100 insoluble microsomal fraction. Therefore, the progressive accumulation of uromodulin was observed in the plasma membrane of the kidneys of transgenic mice but the accumulated uromodulin protein was not that encoded by the transgene.

Production and characterization of transgenic mice harboring mutant human UMOD gene.

Familial juvenile hyperuricemic nephropathy is caused by mutations in the UMOD gene encoding uromodulin. A transgenic mouse model was developed by introducing a human mutant UMOD (C148W) cDNA under control of the mouse umod promoter. Uromodulin accumulation was observed in the thick ascending limb cells in the kidney of transgenic mice. However, the urinary excretion of uromodulin in transgenic mice did not decrease and LC-MS/MS analysis indicated it was of mouse origin. Moreover, the creatinine clearance was not different between wildtype and transgenic animals. Consequently, the onset of the disease was not observed in transgenic mice until 24 weeks of age.