Point-of-care molecular diagnostics for the detection of group A Streptococcus in non-invasive skin and soft tissue infections: a validation study

Close, Ryan M; Sutcliffe, Catherine G.; Galdun, Patrick; Reid, Angelina; Askew, Morgan R.; Davidson, Anne; Kellywood, Kamellia; Parker, Dennie; Patel, Jayshree; Romancito, Eugene; Brown, Laura B.; McAuley, James B.; Hammitt, Laura L.

doi:10.1016/j.diagmicrobio.2022.115729

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…To mimic the sample collection conditions, we pipetted 5 µL of diluted culture on a clean petri dish and collected the bacterial sample by swabbing from this culture and transferring the swap to a tube containing Tris buffer and our ACP-paper. Sample collection using swabs is typically used for nasal, [37] throat, [38] skin, [39] and environmental [40] samples. We pursued with RPA and DNA detection following the protocol described above.…”

Section: Resultsmentioning

confidence: 99%

Paper‐Based Bacterial Lysis Enables Sample‐to‐Answer Home‐based DNA Testing

Chondrogiannis

Réu

Hamedi

2022

Adv Materials Technologies

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Nucleic acid amplification testing (NAAT) is the gold standard for infectious disease diagnostics. Currently NAATs are mainly limited to centralized laboratories, while paper‐based antigen tests are used for rapid home‐based diagnostics. DNA extraction, the initial sample preparation step in NAATs, remains a bottleneck that hinders its development toward home‐based kits. This step requires the use of compounds detrimental to the enzymes in downstream DNA amplification. Here, this work overcomes this bottleneck by immobilizing the enzyme achromopeptidase (ACP) on nitrocellulose, to both store and enable the separation of the enzymes from the other steps. This work provides proof‐of‐concept that immobilized ACP is effective at lysis and release of amplifiable DNA from gram‐positive Staphylococcus epidermidis and enables the use of the lysate directly for DNA amplification, without the need for heat deactivation of the enzyme. This sample preparation method requires only incubation at 37 °C and mild agitation, which allows to implement it with fully disposable and affordable equipment. Consequently, this work enables to combine the paper‐based DNA extraction method with the isothermal recombinase polymerase amplification (RPA) followed by lateral flow detection to demonstrate a sample‐to‐answer NAAT packaged as an instrument free self‐test kit expanding the capabilities of home‐testing beyond antigen tests.

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Section: Resultsmentioning

confidence: 99%

Paper‐Based Bacterial Lysis Enables Sample‐to‐Answer Home‐based DNA Testing

Chondrogiannis

Réu

Hamedi

2022

Adv Materials Technologies

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“…In wound care, the search for a reliable biomarker that allows for early intervention without depending on an overt expression of inflammation or infection is underway. Several biomarkers for early detection of high bacterial presence have been proposed, including protease-based detection ( Heinzle et al., 2013 ; Serena TE and Brosnan, 2022 ), a Strep A rapid swab test ( Close et al., 2022 ), rapid enzyme analysis/activity detection ( Hajnsek et al., 2013 ; Blokhuis-Arkes MH et al., 2015 ), a capsulized vesicle activated by bacterial toxins ( Young AE et al., 2020 ), pH and uric acid monitoring bandages ( Pal et al., 2018 ), and volatile organic compound detection ( Ashrafi M et al., 2017 ). Though promising, some are still experimental, are technically challenging, lack portability or accessibility, or require invasive measures – and few provide bedside results.…”

Section: Discussionmentioning

confidence: 99%

Use of fluorescence imaging to optimize location of tissue sampling in hard-to-heal wounds

Serena

Snyder

Bowler³

2023

Front. Cell. Infect. Microbiol.

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IntroductionWound microflora in hard-to-heal wounds is invariably complex and diverse. Determining the interfering organisms(s) is therefore challenging. Tissue sampling, particularly in large wounds, is subjective and, when performed, might involve swabbing or biopsy of several locations. Fluorescence (FL) imaging of bacterial loads is a rapid, non-invasive method to objectively locate microbial hotspots (loads >104 CFU/gr). When sampling is deemed clinically necessary, imaging may indicate an optimal site for tissue biopsy. This study aimed to investigate the microbiology of wound tissue incisional biopsies taken from sites identified by FL imaging compared with sites selected by clinical judgment.MethodsA post hoc analysis of the 350-patient FLAAG wound trial was conducted; 78 wounds were included in the present study. All 78 wounds were biopsied at two sites: one at the center of the wound per standard of care (SoC) and one site guided by FL-imaging findings, allowing for comparison of total bacterial load (TBL) and species present.ResultsThe comparison between the two biopsy sites revealed that clinical uncertainty was higher as wound surface area increased. The sensitivity of a FL-informed biopsy was 98.7% for accurately finding any bacterial loads >104 CFU/g, compared to 87.2% for SoC (p=0.0059; McNemar test). Regarding species detected, FL-informed biopsies detected an average of 3 bacterial species per biopsy versus 2.2 species with SoC (p < 0.001; t-test). Microbial hotspots with a higher number of pathogens also included the CDC’s pathogens of interest.Conclusions & perspectiveFL imaging provides a more accurate and relevant microbiological profile that guides optimal wound sampling compared to clinical judgment. This is particularly interesting in large, complex wounds, as evidenced in the wounds studied in this post hoc analysis. In addition, fluorescence imaging enables earlier bacterial detection and intervention, guiding early and appropriate wound hygiene and potentially reducing the need for antibiotic use. When indicated, this diagnostic partnership with antibiotic stewardship initiatives is key to ameliorating the continuing threat of antibiotic resistance.

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“…RMDT for GAS detection also exist, although less spread, probably owing to the absence of resistance issue. Notably, the molecular Cobas Liat point-of-care tool has evidenced excellent performances compared with culture from SSTI swabs (concordance >99%) [39 ▪ ]. Yet, therapeutic approaches based on early GAS antigen detection have been scarcely investigated and yielded disappointing results [40,41].…”

Section: The Key Contribution Of the Microbiology Laboratory In The M...mentioning

confidence: 99%

“…First, GAS stands as the leading pathogen in severe CA-SSTI: the detection of these bacteria through RMDT on clinical samples might allow both early de-escalation to narrow-spectrum β-lactams and rapid identification of patients who may benefit from antitoxin medications such as clindamycin – or polyvalent intra-venous immunoglobulins for those with associated toxic shock syndrome [64–67]. As mentioned above, the Cobas Liat point-of-care assay has a >99% concordance with culture for the detection of GAS from SSTI swabs, with a median time-to-result of 17 min; however, this approach is of course not predictive of the monomicrobial nature of the explored infection and its therapeutic input remains to be fully investigated [39 ▪ ].…”

Section: Opportunities and Barriers For Antimicrobial Stewardship In ...mentioning

confidence: 99%

Rapid diagnostics for skin and soft tissue infections: the current landscape and future potential

Barbier

Woerther

Timsit

2023

Current Opinion in Infectious Diseases

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Purpose of reviewManaging antimicrobial therapy in patients with complicated skin and soft tissue infections (SSTI) constitutes a growing challenge due to the wide spectrum of potential pathogens and resistance phenotypes. Today, microbiological documentation relies on cultural methods. This review summarizes the available evidence regarding the clinical input of rapid microbiological diagnostic tools (RMDT) and their impact on the management of antimicrobial therapy in SSTI.Recent findingsAccurate tools are already available for the early detection of methicillin-resistant Staphylococcus aureus (MRSA) in SSTI samples and may help avoiding or shortening empirical anti-MRSA coverage. Further research is necessary to develop and evaluate RMDT detecting group A streptococci (e.g., antigenic test) and Gram-negative pathogens (e.g., multiplex PCR assays), including through point-of-care utilization. Next-generation sequencing (NGS) methods could provide pivotal information for the stewardship of antimicrobial therapy, especially in case of polymicrobial or fungal SSTI and in the immunocompromised host; however, a shortening in the turnaround time and prospective data regarding their therapeutic input are needed to better appraise the clinical positioning of these promising approaches.SummaryThe clinical input of RMDT in SSTI is currently limited due to the scarcity of available dedicated assays and the polymicrobial feature of certain cases. NGS appears as a relevant tool but requires further developments before its implementation in routine clinical practice.

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Point-of-care molecular diagnostics for the detection of group A Streptococcus in non-invasive skin and soft tissue infections: a validation study

Cited by 7 publications

References 25 publications

Paper‐Based Bacterial Lysis Enables Sample‐to‐Answer Home‐based DNA Testing

Paper‐Based Bacterial Lysis Enables Sample‐to‐Answer Home‐based DNA Testing

Use of fluorescence imaging to optimize location of tissue sampling in hard-to-heal wounds

Rapid diagnostics for skin and soft tissue infections: the current landscape and future potential

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