Biology subjects

Scheier, T. C.

Publications and source records attributed to Scheier, T. C..

3 recordsLinked to original sources

bioRxiv2022

Group A Streptococcus antibiotic tolerance in necrotizing fasciitis

ObjectivesGroup A Streptococcus (GAS) necrotizing fasciitis (NF) is a difficult-to-treat bacterial infection associated with high morbidity and mortality despite extensive surgery and targeted antibiotic treatment. Bacteria surviving prolonged antibiotic exposure without displaying genetic resistance, so-called persisters, are associated with difficult-to-treat infections, such as GAS-NF. In the present study, we investigated the presence of persistent GAS in tissue freshly debrided from three NF patients and examined more in depth the persisters phenomenon in GAS-NF clinical isolates. MethodsTime-lapse imaging of freshly isolated GAS-NF clinical isolates, the image analysis software ColTapp and antibiotic challenge-based persisters assays were used to assess the presence of persisters. ResultsWe show for the first time that GAS recovered directly from freshly debrided NF patients tissue are characterized by increased colony appearance time heterogeneity, indicating the presence of persisters. Acidic pH or nutrient stress exposure, mimicking the NF-like environment in vitro, similarly leads to phenotypic heterogeneity resulting in enhanced antibiotic survival and confirming the presence of GAS persisters. ConclusionsGAS persisters are present in the tissue freshly debrided from GAS-NF patients and might be one explanation for antibiotic treatment failure and surgery requirement in GAS-NF. Tailored treatment options, including the use of persisters-targeting drugs, need to be developed to increase GAS-NF therapy success.

microbiology↗

bioRxiv2022

Rapid detection of Staphylococcus aureus and Streptococcus pneumoniae by real-time analysis of volatile metabolites

Rapid detection of pathogenic bacteria is needed for rapid diagnostics allowing adequate and timely treatment. In this study, we aimed to evaluate the technical feasibility of Secondary Electro-Spray Ionization-High Resolution Mass Spectrometry (SESI-HRMS) as a diagnostic tool for rapid detection of bacterial infections and compare its performance with the current standard of diagnostics. We compared the time required to confirm growth of the pathogenic bacteria Staphylococcus aureus and Streptococcus pneumoniae by conventional detection by culture and MAL-DI-TOF vs. detection of specific volatile organic compounds (VOCs) produced by these human pathobionts. SESI-HRMS could consistently detect VOCs produced by S. aureus or S. pneumoniae on blood agar plates within minutes, allowing to positively identify bacteria within hours. Unique S. aureus and S. pneumoniae features were detected already at bacterial densities as low as [~]103 colony forming units. Rich mass spectral fingerprints allowed for the distinction of these two bacteria on a species and even strain level. To give an incentive towards clinical application of this technology, further analyzed 17 clinical samples previously diagnosed by conventional methods. We predominantly obtained a separation of samples which showed growth (i.e. presence of living bacteria) compared to samples with no bacterial growth (i.e. presence of dead bacteria). We conclude that SESI-HRMS allows rapid identification of unique bacterial features. Further development of real-time analysis of clinical samples by SESI-HRMS will shorten the time required for microbiological diagnosis with a high level of confidence and sensitivity and should help to improve patients tailored treatment. IMPORTANCEA timely identification of a pathogenic bacteria causing the infection is of pivotal importance for the initiation of an adequate antimicrobial therapy. In this regard, different technologies have been developed with the aim to achieve a highly reliable, specific, and overall fast identification of pathogenic bacteria. However, conventional diagnostic techniques still require long preprocessing times (hours to days) to acquire enough biological material for an accurate identification of the pathogen. Therefore, in this work, we aimed to further shorten the detection time of current gold standards for microbiological diagnostics by providing a system capable of a fast, sensitive and specific discrimination of different pathogenic bacteria. This system relies on the real-time mass spectrometric detection of volatile organic compounds (VOCs) produced by a given organism during its growth, potentially leading to a significant shortening of the time required to obtain a positive reliable diagnostic.

microbiology↗

bioRxiv2022

Intervertebral disc cell chondroptosis elicits neutrophil response in Staphylococcus aureus spondylodiscitis

ObjectiveTo understand the pathophysiology of spondylodiscitis due to Staphylococcus aureus, an emerging infectious disease of the intervertebral disc (IVD) and vertebral body with a high complication rate, by combining clinical insights and experimental approaches. DesignClinical data and histological material of nine patients suffering from S. aureus spondylodiscitis were retrospectively collected at a single center. To mirror the clinical findings experimentally, we developed a novel porcine ex vivo model mimicking acute S. aureus spondylodiscitis and assessed the interaction between S. aureus and IVD cells within their native environment. In addition, the inflammatory features underlying this interaction were assessed in primary human IVD cells. Finally, mirroring the clinical findings, we assessed primary human neutrophils for their ability to respond to secreted inflammatory modulators of IVD cells upon S. aureus challenge. ResultsAcute S. aureus spondylodiscitis in patients was characterized by tissue necrosis and neutrophil infiltration. Additionally, the presence of empty IVD cells lacunae was observed. This was mirrored in the ex vivo porcine model, where S. aureus induced extensive IVD cell death, leading to empty lacunae. Concomitant engagement of the apoptotic and pyroptotic cell death pathways was observed in primary human IVD cells, resulting in cytokine release. Among the released cytokines, functionally intact neutrophil-priming as well as broad pro- and anti-inflammatory cytokines known for their involvement in IVD degeneration were found. ConclusionsIn patients as well as ex vivo in a novel porcine model, S. aureus spondylodiscitis infection caused IVD cell death, resulting in empty lacunae, which was accompanied by release of inflammation markers and recruitment of neutrophils. These findings offer valuable insights into the important role of inflammatory IVD cell death during the onset of spondylodiscitis and potential future therapeutic approaches.

immunology↗