Hyperammonemia syndrome due to Ureaplasma urealyticum in a kidney transplant recipient: A case of disseminated disease from a fluoroquinolone-resistant isolate.

Ureaplasma species (spp.) are common colonizers of the urogenital tract but may cause systemic infection in immunocompromised patients. They release significant amounts of ammonia via urea hydrolysis and have been recently implicated in the pathogenesis of hyperammonemia syndrome after organ transplantation. We describe a unique case of hyperammonemia syndrome after kidney transplant caused by U urealyticum infection, and the first, to our knowledge, case of a fluoroquinolone-resistant Ureaplasma strain causing hyperammonemia syndrome. A 17-year-old female developed intermittent fevers, rising creatinine, sterile pyuria and debilitating polyarthritis approximately 1 year after kidney transplant. Serum ammonia level was elevated, and urine PCR was positive for U urealyticum. Near the end of treatment with levofloxacin, she had rebound hyperammonemia, which preceded clinical relapse of polyarthritis and encephalopathy. Blood and urine PCR and synovial fluid culture were positive for U urealyticum. Susceptibility testing showed fluoroquinolone resistance, but she responded well to azithromycin and doxycycline. The frequency of Ureaplasma spp. infection in immunocompromised patients is probably underestimated due to diagnostic challenges. Ammonia levels were helpful biomarkers of response to antimicrobial therapy in our case. Susceptibility testing of clinical isolates should be pursued. In serious Ureaplasma spp. infections, particularly in immunocompromised patients, two empiric antibiotics may be indicated given the potential for antimicrobial resistance.

Using UV-absorbance of intrinsic dithiothreitol (DTT) during RP-HPLC as a measure of experimental redox potential in vitro.

Many in-vitro experiments performed to study the response of thiol-containing proteins to changes in environmental redox potentials use dithiothreitol (DTT) to maintain a preset redox environment throughout the experiments. However, the gradual oxidation of DTT during the course of the experiments, and the interaction between DTT and other components in the system, can significantly alter the initial redox potential and complicate data interpretation. Having an internal reporter of the actual redox potential of the assayed sample facilitates direct correlation of biochemical findings with experimental redox status. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a widely used, well-established tool for analysis and purification of biomolecules, including proteins and peptides. Here, we describe a simple, robust, and quantitative RP-HPLC method we developed and tested for determination of the experimental redox potential of an in-vitro sample at the time of the experiment. It exploits the specific UV-absorbance of the oxidized intrinsic DTT in the samples and retains the high resolving power and high sensitivity of RP-HPLC with UV detection.

Outcomes of coronavirus disease-2019 among veterans with pre-existing diagnosis of heart failure.

AIMS: Pre-existing cardiovascular disease in general and related risk factors have been associated with poor coronavirus disease-2019 (COVID-19) outcomes. However, data on outcomes of COVID-19 among people with pre-existing diagnosis of heart failure (HF) have not been studied in sufficient detail. We aimed to perform detailed characterization of the association of pre-existing HF with COVID-19 outcomes. METHODS AND RESULTS: A retrospective cohort study based on Veterans Health Administration (VHA) data comparing 30 day mortality and hospital admission rates after COVID-19 diagnosis among Veterans with and without pre-existing diagnosis of HF. Cox-regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) with adjustment for covariates. Among 31 051 veterans (97% male) with COVID-19, 6148 had pre-existing diagnosis of HF. The mean (SD) age of patients with HF was 70 (13) whereas the mean (SD) age of patients without HF was 57 (17). Within the HF group with available data on left ventricular ejection fraction (EF), 1844 patients (63.4%) had an EF of >45%, and 1063 patients (36.6%) had an EF of ≤45%. Patients in the HF cohort had higher 30 day mortality (5.4% vs. 1.5%) and admission (18.5% vs. 8.4%) rates after diagnosis of COVID-19. After adjustment for age, sex, and race, HRs (95% CIs) for 30 day mortality and for 30 day hospital admissions were 1.87 (1.61-2.17) and 1.79 (1.66-1.93), respectively. After additional adjustment for medical comorbidities, HRs for 30 day mortality and for 30 day hospital admissions were 1.37 (1.15-1.64) and 1.27 (1.16-1.38), respectively. The findings were similar among HF patients with preserved vs. reduced EF, among those taking vs. not taking angiotensin-converting enzyme inhibitors, angiotensin receptor blockers or angiotensin receptor neprilysin inhibitors, and among those taking vs. not taking anticoagulants. CONCLUSIONS: Patients with COVID-19 and pre-existing diagnosis of HF had a higher risk of 30 day mortality and hospital admissions compared to those without history of HF. The findings were similar by EF categories and by angiotensin-converting enzyme inhibitors/angiotensin receptor blocker/angiotensin receptor neprilysin inhibitors or anticoagulant use.