Smruthi Karthikeyan

Dr. Smruthi Karthikeyan

orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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7 July 2022 in Nature
Verified
Journal Article
Open access
PDF file
SKSmruthi Karthikeyan
Smruthi Karthikeyan
JLJoshua I. Levy
Joshua I. Levy
PHPeter De Hoff
Peter De Hoff
GHGreg Humphrey
Greg Humphrey
ABAmanda Birmingham
Amanda Birmingham
RKRob Knight
Rob Knight
As SARS-CoV-2 continues to spread and evolve, detecting emerging variants early is critical for public health interventions. Inferring lineage prevalence by clinical testing is infeasible at scale, especially in areas with limited resources, participation, or testing and/or sequencing capacity, which can also introduce biases1–3. SARS-CoV-2 RNA concentration in wastewater successfully tracks regional infection dynamics and provides less biased abundance estimates than clinical testing4,5. Tracking virus genomic sequences in wastewater would improve community prevalence estimates and detect emerging variants. However, two factors limit wastewater-based genomic surveillance: low-quality sequence data and inability to estimate relative lineage abundance in mixed samples. Here we resolve these critical issues to perform a high-resolution, 295-day wastewater and clinical sequencing effort, in the controlled environment of a large university campus and the broader context of the surrounding county. We developed and deployed improved virus concentration protocols and deconvolution software that fully resolve multiple virus strains from wastewater. We detected emerging variants of concern up to 14 days earlier in wastewater samples, and identified multiple instances of virus spread not captured by clinical genomic surveillance. Our study provides a scalable solution for wastewater genomic surveillance that allows early detection of SARS-CoV-2 variants and identification of cryptic transmission.

27 April 2021 in mSystems
Verified
Journal Article
Open access
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SKSmruthi Karthikeyan
Smruthi Karthikeyan
NRNancy Ronquillo
Nancy Ronquillo
PBPedro Belda-Ferre
Pedro Belda-Ferre
DADestiny Alvarado
Destiny Alvarado
TJTara Javidi
Tara Javidi
RKRob Knight
Rob Knight
Wastewater monitoring has a lot of potential for revealing coronavirus disease 2019 (COVID-19) outbreaks before they happen because the virus is found in the wastewater before people have clinical symptoms. However, application of wastewater-based surveillance has been limited by long processing times specifically at the concentration step.

SHSasha Harris-Lovett
Sasha Harris-Lovett
KNKara L Nelson
Kara L Nelson
PBPaloma Beamer
Paloma Beamer
HBHeather Bischel
Heather Bischel
Aaron BivinsAaron Bivins
Aaron Bivins
KKKatrina Korfmacher
Katrina Korfmacher
Wastewater surveillance for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging approach to help identify the risk of a coronavirus disease (COVID-19) outbreak. This tool can contribute to public health surveillance at both community (wastewater treatment system) and institutional (e.g., colleges, prisons, and nursing homes) scales. This paper explores the successes, challenges, and lessons learned from initial wastewater surveillance efforts at colleges and university systems to inform future research, development and implementation. We present the experiences of 25 college and university systems in the United States that monitored campus wastewater for SARS-CoV-2 during the fall 2020 academic period. We describe the broad range of approaches, findings, resources, and impacts from these initial efforts. These institutions range in size, social and political geographies, and include both public and private institutions. Our analysis suggests that wastewater monitoring at colleges requires consideration of local information needs, sewage infrastructure, resources for sampling and analysis, college and community dynamics, approaches to interpretation and communication of results, and follow-up actions. Most colleges reported that a learning process of experimentation, evaluation, and adaptation was key to progress. This process requires ongoing collaboration among diverse stakeholders including decision-makers, researchers, faculty, facilities staff, students, and community members.

31 August 2021 in mSystems
Verified
Journal Article
Open access
SKSmruthi Karthikeyan
Smruthi Karthikeyan
ANAndrew Nguyen
Andrew Nguyen
DMDaniel McDonald
Daniel McDonald
YZYijian Zong
Yijian Zong
NRNancy Ronquillo
Nancy Ronquillo
RKRob Knight
Rob Knight
Wastewater-based epidemiology can be particularly valuable at university campuses where high-resolution spatial sampling in a well-controlled context could not only provide insight into what affects campus community as well as how those inferences can be extended to a broader city/county context. In the present study, a large-scale wastewater surveillance was successfully implemented on a large university campus enabling early detection of 85% of COVID-19 cases thereby averting potential outbreaks.

20 February 2023 in The Lancet Regional Health - Americas
Verified
Journal Article
Open access
RFRebecca Fielding-Miller
Rebecca Fielding-Miller
SKSmruthi Karthikeyan
Smruthi Karthikeyan
TGTommi Gaines
Tommi Gaines
RGRichard S. Garfein
Richard S. Garfein
RSRodolfo A. Salido
Rodolfo A. Salido
EKEzra Kurzban
Ezra Kurzban
Schools are high-risk settings for SARS-CoV-2 transmission, but necessary for children's educational and social-emotional wellbeing. Previous research suggests that wastewater monitoring can detect SARS-CoV-2 infections in controlled residential settings with high levels of accuracy. However, its effective accuracy, cost, and feasibility in non-residential community settings is unknown. The objective of this study was to determine the effectiveness and accuracy of community-based passive wastewater and surface (environmental) surveillance to detect SARS-CoV-2 infection in neighborhood schools compared to weekly diagnostic (PCR) testing. We implemented an environmental surveillance system in nine elementary schools with 1700 regularly present staff and students in southern California. The system was validated from November 2020 to March 2021. In 447 data collection days across the nine sites 89 individuals tested positive for COVID-19, and SARS-CoV-2 was detected in 374 surface samples and 133 wastewater samples. Ninety-three percent of identified cases were associated with an environmental sample (95% CI: 88%-98%); 67% were associated with a positive wastewater sample (95% CI: 57%-77%), and 40% were associated with a positive surface sample (95% CI: 29%-52%). The techniques we utilized allowed for near-complete genomic sequencing of wastewater and surface samples. Passive environmental surveillance can detect the presence of COVID-19 cases in non-residential community school settings with a high degree of accuracy. County of San Diego, Health and Human Services Agency, National Institutes of Health, National Science Foundation, Centers for Disease Control.

1 March 2020 in Environmental Microbiology
Verified
Journal Article
Open access
PDF file
SKSmruthi Karthikeyan
Smruthi Karthikeyan
LRLuis M. Rodriguez‐R
Luis M. Rodriguez‐R
PHPatrick Heritier‐Robbins
Patrick Heritier‐Robbins
JHJanet K. Hatt
Janet K. Hatt
MHMarkus Huettel
Markus Huettel
KKKonstantinos T. Konstantinidis
Konstantinos T. Konstantinidis
Summary: Microbial communities ultimately control the fate of petroleum hydrocarbons (PHCs) that enter the natural environment, but the interactions of microbes with PHCs and the environment are highly complex and poorly understood. Genome‐resolved metagenomics can help unravel these complex interactions. However, the lack of a comprehensive database that integrates existing genomic/metagenomic data from oil environments with physicochemical parameters known to regulate the fate of PHCs currently limits data analysis and interpretations. Here, we curated a comprehensive, searchable database that documents microbial populations in natural oil ecosystems and oil spills, along with available underlying physicochemical data, geocoded via geographic information system to reveal their geographic distribution patterns. Analysis of the ~2000 metagenome‐assembled genomes (MAGs) available in the database revealed strong ecological niche specialization within habitats. Over 95% of the recovered MAGs represented novel taxa underscoring the limited representation of cultured organisms from oil‐contaminated and oil reservoir ecosystems. The majority of MAGs linked to oil‐contaminated ecosystems were detectable in non‐oiled samples from the Gulf of Mexico but not in comparable samples from elsewhere, indicating that the Gulf is primed for oil biodegradation. The repository should facilitate future work toward a predictive understanding of the microbial taxa and their activities that control the fate of oil spills.