Use of Advanced Diagnostics for Timely Identification of Travel-associated Leptospira santarosai Infection in Four Adolescents Through Plasma Microbial Cell-free DNA Sequencing With the Karius Test

BACKGROUND

Leptospirosis is an important zoonotic infection worldwide. Diagnosis of leptospirosis is challenging given its nonspecific clinical symptoms that overlap with other acute febrile illnesses and limitations with conventional diagnostic testing. Alternative advanced diagnostics, such as microbial cell-free DNA (mcfDNA), are increasingly being used to aid in the diagnosis of infections and can be applied to pathogens with public health importance such as Leptospira , a nationally notifiable disease.

METHODS

The Karius Test uses plasma mcfDNA sequencing to detect and quantify DNA-based pathogens. This test offered through the Karius lab detected 4 cases of Leptospira santarosai during a 5-month period across the United States in 2021 and were clinically reviewed.

RESULTS

In our case series, 4 adolescents with recent travel to Central America (Costa Rica, n = 3 and Belize, n = 1) from April to August 2021 were diagnosed with leptospirosis. While a large workup was performed in all cases, mcfDNA testing was the first test to detect L. santarosai as the microbiological diagnosis in all cases.

CONCLUSIONS

Results of the Karius Test enabled rapid, noninvasive diagnosis of leptospirosis allowing for targeted therapy. Use of mcfDNA can be utilized for diagnosis of pathogens where conventional testing is challenging or limited. This in turn can enable quick diagnosis for targeted treatment and potentially aid in supporting case definitions of reportable diseases of public health concern.

Multimodal Surveillance Model for Enterovirus D68 Respiratory Disease and Acute Flaccid Myelitis among Children in Colorado, USA, 2022

Surveillance for emerging pathogens is critical for developing early warning systems to guide preparedness efforts for future outbreaks of associated disease. To better define the epidemiology and burden of associated respiratory disease and acute flaccid myelitis (AFM), as well as to provide actionable data for public health interventions, we developed a multimodal surveillance program in Colorado, USA, for enterovirus D68 (EV-D68). Timely local, state, and national public health outreach was possible because prospective syndromic surveillance for AFM and asthma-like respiratory illness, prospective clinical laboratory surveillance for EV-D68 among children hospitalized with respiratory illness, and retrospective wastewater surveillance led to early detection of the 2022 outbreak of EV-D68 among Colorado children. The lessons learned from developing the individual layers of this multimodal surveillance program and how they complemented and informed the other layers of surveillance for EV-D68 and AFM could be applied to other emerging pathogens and their associated diseases.

Duration of Enterovirus D68 RNA Shedding in the Upper Respiratory Tract and Transmission among Household Contacts, Colorado, USA

Enterovirus D68 (EV-D68) causes cyclical outbreaks of respiratory disease and acute flaccid myelitis. EV-D68 is primarily transmitted through the respiratory route, but the duration of shedding in the respiratory tract is unknown. We prospectively enrolled 9 hospitalized children with EV-D68 respiratory infection and 16 household contacts to determine EV-D68 RNA shedding dynamics in the upper respiratory tract through serial midturbinate specimen collections and daily symptom diaries. Five (31.3%) household contacts, including 3 adults, were EV-D68-positive. The median duration of EV-D68 RNA shedding in the upper respiratory tract was 12 (range 7-15) days from symptom onset. The most common symptoms were nasal congestion (100%), cough (92.9%), difficulty breathing (78.6%), and wheezing (57.1%). The median illness duration was 20 (range 11-24) days. Understanding the duration of RNA shedding can inform the expected rate and timing of EV-D68 detection in associated acute flaccid myelitis cases and help guide public health measures.

Qualitative detection of enterovirus D68 from PrimeStore® molecular transport medium: implications for home- and self-collection

To ensure proper specimen handling for detecting pathogens, like Enterovirus D68 (EV-D68), from home- and self-collection, alternative techniques are needed to ensure safe transport and reliable testing. PrimeStore® Molecular Transport Medium (MTM) may be an option since it does not require cold storage and inactivates virus while preserving RNA for detection. The purpose of this validation study was to demonstrate the ability to detect EV-D68 via rRT-PCR in MTM. Using a quantified EV-D68 positive control standard, MTM limit of detection for EV-D68 RNA is 10⁴ cp/mL and RNA remains stable up to 30 days unfrozen. Positive and negative residual respiratory specimens from the 2018 EV-D68 outbreak were used for clinical testing. There was an 80% positive and 100% negative agreement with samples in MTM compared to reference. This study demonstrates the feasibility of EV-D68 detection from respiratory specimens collected and stored in PrimeStore® MTM, with implications for home- and self-collection.

Reduction of paediatric head CT utilisation at a rural general hospital emergency department

BACKGROUND

Blunt head injury is a common pediatric injury and often evaluated in general emergency departments. It estimated that 50% of children will undergo a head computed tomography (CT), often unnecessarily exposing the child to ionizing radiation. Pediatric academic centers have shown quality improvement (QI) measures can reduce head CT rates within their emergency departments. We aimed to reduce head CT utilization at a rural community emergency department.

METHODS

Children presenting with a complaint of blunt head injury and were evaluated with or without a head CT. Head CT rate was the primary outcome. We developed a series of interventions and presented these to the general emergency department over the duration of the study. The pre and intervention data was analysed with control charts.

RESULTS

The preintervention and intervention groups consisted of 576 children: 237 patients with a median age of 8.0 years and 339 patients with a median age of 9.00 years (p=0.54), respectively. The preintervention HCT rate was 41.8% (95% CI 35.6% to 48.1%) and the postintervention rate was 27.7% (95% CI 23.3% to 32.7%), a decrease of 14.1% (95% CI 6.2% to 21.9%, p=0.0004). During the intervention period, there was a decrease in HCT rate of one per month (OR 0.96, 95% CI 0.92 to 1.00, p=0.07). The initial series of interventions demonstrated an incremental decrease in HCT rates corresponding with a special cause variation.

CONCLUSION

The series of interventions dispersed over the intervention period was an effective methodology and successfully reduced HCT utilisation among children with blunt head injury at a rural community emergency department.

Intracellular visualization of BrdU-labeled plasmid DNA/cationic liposome complexes

Difficulties in specific detection of transfected DNA in cells represent an important limitation in the study of the gene transfer process. We studied the cellular entry and fate of a plasmid DNA complexed with a cationic lipid, Vectamidine (3-tetradecylamino-N-tert-butyl-N'-tetradecylpropionamidine) in BHK21 cells. To facilitate its detection inside the cells, bromodeoxyuridine (BrdU) was incorporated into plasmid DNA under conditions that minimize plasmid alteration. BrdU was localized in cells incubated with Vectamidine/BrdU-labeled plasmid DNA complexes by immunogold labeling and electron microscopy (EM). Labeling was predominantly associated with aggregated liposome structures at the surface of and inside the cells. EM observations of cells transfected with Vectamidine/DNA complexes showed that the liposome/DNA aggregates accumulate in large vesicles in the cell cytosol. On the other hand, using rhodamine-labeled Vectamidine and revealing BrdU with FITC-conjugated antibodies permitted simultaneous detection in the cells of both components of the complexes with confocal laser scanning microscopy. The DNA and lipids co-localized at the surface of and inside the cells, indicating that the complex is internalized as a whole. Our results show that the BrdU-labeled plasmid DNA detection system can be a useful tool to visualize exogenous DNA entry into cells by a combination of electron and confocal microscopy.