1021. Utility of Cell-Free DNA Sequencing in Diagnosing Murine typhus in Children

Background

Murine typhus is a zoonotic infection caused by Rickettsia typhi and transmitted through infected fleas. Geographic distribution within the United States is limited primarily to South Texas and Southern California. Infection is typically associated with a triad of fever, headache, and rash, although is only present in one-third of cases. Immunofluorescence assay (IFA) is currently the gold standard for diagnosis, but it has its limitations as it is dependent on the time to seroconversion and has low specificity due to cross-reactivity among other rickettsial species. Cell-free DNA (cfDNA) sequencing for broad-range pathogen detection may offer higher sensitivity at the early stages of the disease.

Methods

We performed a retrospective electronic medical record search of children with cfDNA sequencing detection of Murine typhus hospitalized at Driscoll Children’s Hospital, Corpus Christi, Texas, between June 2020 and May 2021.

Results

We found 4 children (range 9-15 year-old) positive for R. typhi by cfDNA sequencing. All patients presented with fever of unknown origin and rash. Also, 2 patients were diagnosed with pneumonia. One patient exhibited severe illness with acute kidney injury, elevation of transaminases and encephalitis that warranted admission to the pediatric intensive care unit. All patients defervesced and improved within 48 hours of doxycycline initiation; average length of stay 6 days (range 3-12 days). In one patient, M. typhus was detected by Karius® test only, in the other three was concordant with serology.

Conclusion

We highlight next-generation cfDNA sequencing as a useful tool in identifying the etiologic agent of patients with fever of known origin, where murine typhus is one of the possible etiologies. Preventing extensive laboratory workup and subsequent delay of assessment and management. The rapid turnaround time of cfDNA test allows for de-escalation of therapy and initiation of appropriate treatment.

Disclosures

Jaime Fergie, MD, AstraZeneca (Scientific Research Study Investigator)Explify (Speaker’s Bureau)Karius (Speaker’s Bureau)Pfizer, Merck, AstraZeneca, and Sanofi (Speaker’s Bureau)Pfizer, Merck, Sanofi, and Moderna (Consultant, Advisor or Review Panel member)

Just a bad flu? Tackling the "infodemic" in Ireland through a comparative analysis of hospitalised cases of COVID-19 and influenza

OBJECTIVES

COVID-19 infection has been compared to seasonal influenza as an argument against non-pharmacological population-based infection control measures known as "lockdowns". Our study sought to compare disease severity measures for patients in Ireland hospitalised with COVID-19 against those hospitalised with seasonal influenza.

STUDY DESIGN

This is a retrospective population-based cohort study.

METHODS

COVID-19 hospital episodes and seasonal influenza hospital episodes were identified using relevant International Classification of Disease (ICD-10) codes from the Irish national hospitalisation dataset. The occurrences of key metrics of disease severity, length of stay, intensive care admission, ventilatory support, haemodialysis and in-hospital mortality were measured and compared between the two groups using odds ratios with 95% confidence intervals (CIs), stratified by age.

RESULTS

Hospitalised COVID-19 episodes had a mean length of stay more than twice as long as hospitalised influenza episodes (17.7 days vs 8.3 days). The likelihood of all measures of disease severity was greater in COVID-19 episodes, and the odds of in-hospital mortality were five-fold higher in this group compared with seasonal influenza episodes (OR 5.07, 95% CI 4.29-5.99, P < 0.001). Greater likelihood of increased disease severity was observed for COVID-19 episodes in most age groups.

CONCLUSIONS

COVID-19 is a more severe illness than seasonal influenza in hospitalised cohorts. It is imperative that public health professionals ensure that evidence-based advocacy is part of the response to COVID-19 to tackle a dangerous "infodemic" that can undermine public health control measures.

A phase I study of bevacizumab in combination with sunitinib in advanced solid tumors

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Background: Bevacizumab is a humanized monoclonal antibody that binds to all biologically active isoforms of human vascular endothelial growth factor (VEGF). Sunitinib is a potent tyrosine kinase inhibitor of VEGFR-2, PDGFR, KIT, and FLT3. This phase I trial of bevacizumab and sunitinib was undertaken to determine the maximal tolerated dose (MTD), dose-limiting toxicity (DLT), and to evaluate for any tumor response for this novel combination. Methods: Patients (pts) with advanced solid tumors, ECOG performance status 0 or 1, and having adequate organ function were eligible. Patients received bevacizumab IV on days 1, 15, and 29 of a 42 day cycle. Sunitinib was given for 28 days with a 14 day rest. DLT was defined as any grade 4 toxicity, grade 3 cardiac event, hypertension not controlled to < 160/90 mmHg with medication, or proteinuria > 3.5 gm/24 hours. Results: Nine patients, 6 male and 3 female, with tumor types including renal carcinoma (2), bladder (2), pancreatic, testicular, melanoma, gastric, and neuroendocrine were enrolled. The median patient age was 55 years (range 37 to 83). Median number of prior systemic therapies was 2 (range 0 to 3). A total of 15 cycles have been administered (cycles range 1 to 4). Grade 1 or 2 toxicities that occurred with a > 20% incidence included anorexia, bleeding, diarrhea, dyspnea, fatigue, fever, hypomagnesemia, nausea, pain, vomiting, and weight loss. Grade 3 toxicities included hypertension (3 pts), fatigue and hypokalemia (2 pts) and one episode each of hand-foot syndrome, and hypophosphatemia. At the dose level bevacizumab 3 mg/kg and sunitnib 25 mg/day no DLTs were observed. One patient experienced DLTs of grade 4 hypertension and headache at the dose level of bevacizumab 5 mg/kg and sunitinib 37.5 mg/day. This dose level has expanded to six patients and toxicity assessment is continuing. One patient with papillary renal carcinoma has an unconfirmed partial response and three patients have experienced stable disease. Conclusions: Enrollment and toxicity evaluations are ongoing. DLTs of headache and hypertension have occurred. This trial will determine the maximal tolerated dose of this novel anti-angiogenic combination for future renal cell carcinoma studies. Supported by the NCI/Clinical Therapeutic Evaluation Program Grant U01 CA62502.

No significant financial relationships to disclose.

Use of an optical comparator for radiographic measurement of bone loss around endosseous implants: a pilot study

A technique for the measurement of bone loss around endosseous implants using an optical comparator was investigated. Five operators were asked to measure the mesial and distal alveolar bone levels around a screw type dental implant on a periapical radiograph mounted on an optical comparator. The known size of a threaded implant was used as a reference. The bone loss around the implant was calculated by taking the average of the mesial and distal measurements. Statistical analysis at the 95 percent confidence level demonstrated that there was no significant difference among the measurements. Although the initial results are encouraging, additional research is necessary with a larger sample size to validate the accuracy of optical comparator readings and compare the efficacy of this technique with other currently used methods for determining bone loss around root form implants.

The effects of impaired liver function on the elimination of antineoplastic agents

OBJECTIVE

To critically review available data on the disposition of cancer chemotherapy in patients with hepatic dysfunction, and to derive at dose recommendation.

DATA SOURCES

All published studies in English.

STUDY SELECTION

Both human and animal studies.

DATA SYNTHESIS

The available studies were sequentially qualitatively described and critically discussed.

CONCLUSIONS

The liver is responsible for the metabolism and elimination of many anticancer agents. Their accumulation during hepatic insufficiency may expose the patient to increased risk of drug toxicity. A variety of clinical methods have been described to estimate the need to decrease doxorubicin dose according to degree of hepatic failure to avoid serious toxicity. In some studies prospective ascertainment of clinical indices such as hepatic enzymes and bilirubin was successful in preventing doxorubicin-induced hepatotoxicity. Liver dysfunction has a major impact on cyclophosphamide pharmacokinetics. However, because such impairment leads to less production of the active aldophosphamide, fewer adverse effects were observed in hepatically impaired patients. Vinca alkaloids are extensively metabolized by the liver and excreted in the bile. Systemic exposure to these drugs is inversely correlated to the degree of hepatic failure measured by serum alkaline phosphatase. Although hepatic metabolism is a major route of elimination of fluorouracil, the kidney also plays an important role in its elimination. It has been suggested to reduce its dose in cirrhotic patients. Available pharmacokinetic data and their clinical implications are also discussed for azathioprine, mercaptopurine, etoposide, epirubicin, amsacrine, cytarabine, and other less-studied drugs. Recommendations for dose adjustments are presented and discussed.

Kinetic and chemical evidence for the inability of oxidized alpha 1-proteinase inhibitor to protect lung elastin from elastolytic degradation

The oxidation of human alpha 1-proteinase inhibitor results in the conversion of this protein into a form which cannot protect lung elastin from degradation by elastolytic proteinases. Data indicate that this is primarily because of the lowering of the association rate between the modified inhibitor and neutrophil elastase, as well as in a change in Ki from near 10(-14) to near 10(-10)M. This is consistent with the hypothesis that oxidation of alpha 1-proteinase inhibitor in the lung by cigarette smoke results in a lowering of the protection of this organ from elastolytic degradation.

Determination of oxidized alpha-1-proteinase inhibitor in serum

When alpha-1-PI is oxidized, it loses its ability to inhibit porcine elastase, although it retains its TIC. Therefore the ratio of TIC to EIC increases in proportion to the degree of oxidation of the inhibitor. We have developed a rapid procedure for determining the percentage of oxidized alpha-1-PI in plasma or serum based on the ratio of TIC to EIC of alpha-1-PI in these tissues. The TIC/EIC ratio is not influenced by the other proteins in serum nor by the concentration of alpha-1-PI. When this technique was adapted to measure to proportion of oxidized alpha-1-PI in the serum of young adult, healthy smokers and nonsmokers, 23% oxidized inhibitor was found in the smokers' sera, whereas no oxidized alpha-1-PI was detectable in sera of nonsmokers. Thus smoking leads to oxidation damage to circulating alpha-1-PI. Reduction of the EIC of the alpha-1-PI in the serum of smokers was compensated by a 1.43-fold increase in their serum alpha-1-PI titers; however, these data do not exclude the possibility of local depletion of the absolute EIC in the extravascular space of the lungs. This assay for oxidized alpha-1-PI may be useful in studies of the relationship between oxidation of alpha-1-PI and the development of pulmonary emphysema.

The effect of alpha 2-macroglobulin on the interaction of alpha 1-proteinase inhibitor with porcine trypsin

The rate of dissociation of the alpha 1-proteinase inhibitor:porcine trypsin complex was compared with that in the presence of alpha 2-macroglobulin. In the presence of the latter inhibitor the dissociation was more rapid and active alpha 1-proteinase inhibitor could be recovered in the mixture. However, no active inhibitor could be detected after dissociation in the absence of alpha 2-macroglobulin. This recovery of active alpha 1-proteinase inhibitor from complexes with porcine trypsin is the first demonstration of a thermodynamic equilibrium between this inhibitor and proteinase. Consequently, the transfer of trypsin from complexes with alpha 1-proteinase inhibitor to alpha 2-macroglobulin may be explained as a passive phenomenon which does not require a physical collision between alpha 2-macroglobulin and the alpha 1-proteinase inhibitor:porcine trypsin complex. The dissociation of the complex occurs more rapidly in the presence of alpha 2-macroglobulin because this inhibitor complexes trypsin leaving the alpha 1-proteinase inhibitor:porcine trypsin complex by both the irreversible breakdown step and by reversible dissociation of the complex.

Kinetics of association of serine proteinases with native and oxidized alpha-1-proteinase inhibitor and alpha-1-antichymotrypsin

The association rate constants for the interaction of alpha-1-proteinase inhibitor, oxidized alpha-1-proteinase inhibitor, and alpha-1-antichymotrypsin with several mammalian serine proteinases have been determined. The results indicate that leukocyte elastase reacts more rapidly with alpha-1-proteinase inhibitor than any other proteinase tested, while leukocyte cathepsin G shows the strongest association with alpha-1-antichymotrypsin. Oxidation of the critical methionine residue of alpha-1-proteinase inhibitor reduces the association with leukocyte elastase by a factor of more than 2000 and also lowers the association with all of the other enzymes tested with the exception of chymotrypsin. Significantly, oxidation completely abolishes any interaction of alpha-1-proteinase inhibitor with porcine elastase, human plasmin or human thrombin. These data support previous results (Johnson, D., and Travis, J. (1979) J. Biol. Chem. 254, 4022-4026) which indicated that oxidation of human alpha-1-proteinase inhibitor in vivo could reduce the effectiveness of this inhibitor in controlling proteolysis. In the lung, in particular, oxidizing agents of both chemical and biological sources could, indirectly, augment elastolysis in this tissue, resulting in the development of pulmonary emphysema.