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Despite available diagnostic tests and recent advances, diagnosis of pulmonary invasive aspergillosis (IPA) remains challenging. We performed a longitudinal case-control pilot study to identify host-specific, novel, and immune-relevant molecular candidates indicating IPA in patients post allogeneic stem cell transplantation (alloSCT). Supported by differential gene expression analysis of six relevant in vitro studies, we conducted RNA sequencing of three alloSCT patients categorized as probable IPA cases and their matched controls without Aspergillus infection (66 samples in total). We additionally performed immunoassay analysis for all patient samples to gain a multi-omics perspective. Profiling analysis suggested LGALS2, MMP1, IL-8, and caspase-3 as potential host molecular candidates indicating IPA in investigated alloSCT patients. MMP1, IL-8, and caspase-3 were evaluated further in alloSCT patients for their potential to differentiate possible IPA cases and patients suffering from COVID-19-associated pulmonary aspergillosis (CAPA) and appropriate control patients. Possible IPA cases showed differences in IL-8 and caspase-3 serum levels compared with matched controls. Furthermore, we observed significant differences in IL-8 and caspase-3 levels among CAPA patients compared with control patients. With our conceptual work, we demonstrate the potential value of considering the human immune response during Aspergillus infection to identify immune-relevant molecular candidates indicating IPA in alloSCT patients. These human host candidates together with already established fungal biomarkers might improve the accuracy of IPA diagnostic tools.
Background
Joint aspiration with analysis of synovial fluid white blood cell count (WBC) and microbiological culture is a widely established aspect in the diagnosis of shoulder joint infections (SJI). In case of a two stage revision for SJI, joint aspiration before re−/implantation of a total shoulder arthroplasty (TSA) was used to rule out persistent infection for years but its value is under debate. Shoulder specific data on all aspects is rare. The current study aims to answer the following research questions: Does joint aspiration have an insufficient predictive value in the diagnosis of SJI in (1) initial workup and (2) before definite arthroplasty with polymethylmethacrylate (PMMA)-Spacer in place?
Methods
This retrospective evaluation investigates 35 patients that were treated for SJI with a two staged implantation of a TSA after debridement and implantation of an PMMA-Spacer. Joint aspirations were performed preoperatively (PA) and before re−/implantation of the prosthesis while spacer was in place (interstage aspiration, IA). Samples were taken for microbiological culture and analysis of WBC. Sensitivity and specificity were calculated with reference to intraoperative microbiological samples. Receiver Operating Characteristic (ROC), Area-Under-Curve analysis (AUC) and calculation of the Youden index were performed to find optimum cut-off for WBC.
Results
The sensitivity of microbiological cultures from PA was 58.3% and the specificity was 88.9%. The mean WBC was 27,800 leucocytes/mm3 (range 400-96,300). The maximum Youden index (0.857) was a cut-off of 2600 leucocytes/mm3 with a sensitivity of 85.7% and a specificity of 100.0%. The sensitivity and specificity of IA were 0.0% and 88.5%, respectively.
Conclusions
Preoperative aspiration is likely to miss Cutibacteria spp. and CoNS and cannot rule out infection for sure. However, we recommend it for its advantages of targeted antibiotic therapy in case of germ identification. Empiric antibiotic therapy should cover Cutibacteria and CoNS even if aspiration showed negative microbiological cultures. In contrast, the diagnostic value of interstage aspiration does not qualify for its routine use.
Non-aureus staphylococci (NAS) are ubiquitous bacteria in livestock-associated environments where they may act as reservoirs of antimicrobial resistance (AMR) genes for pathogens such as Staphylococcus aureus. Here, we tested whether housing conditions in pig farms could influence the overall AMR-NAS burden. Two hundred and forty porcine commensal and environmental NAS isolates from three different farm types (conventional, alternative, and organic) were tested for phenotypic antimicrobial susceptibility and subjected to whole genome sequencing. Genomic data were analysed regarding species identity and AMR gene carriage. Seventeen different NAS species were identified across all farm types. In contrast to conventional farms, no AMR genes were detectable towards methicillin, aminoglycosides, and phenicols in organic farms. Additionally, AMR genes to macrolides and tetracycline were rare among NAS in organic farms, while such genes were common in conventional husbandries. No differences in AMR detection existed between farm types regarding fosfomycin, lincosamides, fusidic acid, and heavy metal resistance gene presence. The combined data show that husbandry conditions influence the occurrence of resistant and multidrug-resistant bacteria in livestock, suggesting that changing husbandry practices may be an appropriate means of limiting the spread of AMR bacteria on farms.
Bone concentration of ampicillin/sulbactam: a pilot study in patients with osteonecrosis of the jaw
(2022)
Osteonecrosis of the jaw (ONJ) occurs typically after irradiation of the head and neck area or after the intake of antiresorptive agents. Both interventions can lead to compromised bone perfusion and can ultimately result in infection and necrosis. Treatment usually consists of surgical necrosectomy and prolonged antibiotic therapy, usually through beta-lactams such as ampicillin/sulbactam. The poor blood supply in particular raises the question as to whether this form of antibiosis can achieve sufficient concentrations in the bone. Therefore, we investigated the antibiotic concentration in plasma and bone samples in a prospective study. Bone samples were collected from the necrosis core and in the vital surrounding bone. The measured concentrations in plasma for ampicillin and sulbactam were 126.3 ± 77.6 and 60.2 ± 35.0 µg/mL, respectively. In vital bone and necrotic bone samples, the ampicillin/sulbactam concentrations were 6.3 ± 7.8/1.8 ± 2.0 µg/g and 4.9 ± 7.0/1.7 ± 1.7 µg/g, respectively. These concentrations are substantially lower than described in the literature. However, the concentration seems sufficient to kill most bacteria, such as Streptococci and Staphylococci, which are mostly present in the biofilm of ONJ. We, therefore, conclude that intravenous administration of ampicillin/sulbactam remains a valuable treatment in the therapy of ONJ. Nevertheless, increasing resistance of Escherichia coli towards beta-lactam antibiotics have been reported and should be considered.
Patients suffering from coronavirus disease-2019 (COVID-19) are susceptible to deadly secondary fungal infections such as COVID-19-associated pulmonary aspergillosis and COVID-19-associated mucormycosis. Despite this clinical observation, direct experimental evidence for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)-driven alterations of antifungal immunity is scarce. Using an ex-vivo whole blood stimulation assay, we challenged blood from twelve COVID-19 patients with Aspergillus fumigatus and Rhizopus arrhizus antigens and studied the expression of activation, maturation, and exhaustion markers, as well as cytokine secretion. Compared to healthy controls, T-helper cells from COVID-19 patients displayed increased expression levels of the exhaustion marker PD-1 and weakened A. fumigatus- and R. arrhizus-induced activation. While baseline secretion of proinflammatory cytokines was massively elevated, whole blood from COVID-19 patients elicited diminished release of T-cellular (e.g., IFN-γ, IL-2) and innate immune cell-derived (e.g., CXCL9, CXCL10) cytokines in response to A. fumigatus and R. arrhizus antigens. Additionally, samples from COVID-19 patients showed deficient granulocyte activation by mold antigens and reduced fungal killing capacity of neutrophils. These features of weakened anti-mold immune responses were largely decoupled from COVID-19 severity, the time elapsed since diagnosis of COVID-19, and recent corticosteroid uptake, suggesting that impaired anti-mold defense is a common denominator of the underlying SARS-CoV-2 infection. Taken together, these results expand our understanding of the immune predisposition to post-viral mold infections and could inform future studies of immunotherapeutic strategies to prevent and treat fungal superinfections in COVID-19 patients.
Background
PCR testing is considered the gold standard for SARS-CoV-2 diagnosis but its results are earliest available hours to days after testing. Rapid antigen tests represent a diagnostic tool enabling testing at the point of care. Rapid antigen tests have mostly been validated by the manufacturer or in controlled laboratory settings only. External validation at the point of care, particularly in general practice where the test is frequently used, is needed. Furthermore, it is unclear how well point of care tests are accepted by the practice staff.
Methods
In this prospective multicenter validation study in primary care, general practitioners included adult individuals presenting with symptoms suggesting COVID-19. Each patient was tested by the general practitioner, first with a nasopharyngeal swab for the point of care test (Roche SARS-CoV-2 Rapid Antigen Test) and then with a second swab for PCR testing. Using the RT-PCR result as a reference, we calculated specificity, sensitivity, positive predictive value and negative predictive value, with their 95% confidence intervals. General practitioners and medical assistants completed a survey to assess feasibility and usefulness of the point of care tests.
Results
In 40 practices in Würzburg, Germany, 1518 patients were recruited between 12/2020 and 06/2021. The point of care test achieved a sensitivity of 78.3% and a specificity of 99.5% compared to RT-PCR. With a prevalence of 9.5%, the positive predictive value was 93.9% and the negative predictive value was 97.8%. General practitioners rated the point of care test as a helpful tool to support diagnostics in patients with signs and symptoms suggestive for infection, particularly in situations where decision on further care is needed at short notice.
Conclusion
The point of care test used in this study showed a sensitivity below the manufacturer’s specification (Sensitivity 96.25%) in the practice but high values for specificity and high positive predictive value and negative predictive value. Although widely accepted in the practice, measures for further patient management require a sensitive interpretation of the point of care test results.
Background and objective
Prompt pathogen identification of blood stream infections is essential to provide appropriate antibiotic treatment. Therefore, the objective of this prospective single centre study was to establish an inexpensive, fast and accurate protocol for bacterial species identification with SDS protein-extraction directly from BacT/Alert® blood culture (BC) bottles by VitekMS®.
Results
Correct species identification was obtained for 198/266 (74.4%, 95%-CI = [68.8%, 79.6%]) of pathogens. The protocol was more successful in identifying 87/96 (91.4%, 95%-CI = [83.8%, 93.2%]) gram-negative bacteria than 110/167 (65.9%, 95%-CI = [58.1%, 73.0%]) gram-positive bacteria. The hands-on time for sample preparation and measurement was about 15 min for up to five samples. This is shorter than for most other protocols using a similar lysis-centrifugation approach for the combination of BacT/Alert® BC bottles and the Vitek® MS mass spectrometer. The estimated costs per sample were approx. 1.80€ which is much cheaper than for commercial kits.
Conclusion
This optimized protocol allows for accurate identification of bacteria directly from blood culture bottles for laboratories equipped with BacT/Alert® blood culture bottles and VitekMS® mass spectrometer.
Background
Bacterial meningitis is a life-threatening disease that occurs when pathogens such as Neisseria meningitidis cross the meningeal blood cerebrospinal fluid barrier (mBCSFB) and infect the meninges. Due to the human-specific nature of N. meningitidis, previous research investigating this complex host–pathogen interaction has mostly been done in vitro using immortalized brain endothelial cells (BECs) alone, which often do not retain relevant barrier properties in culture. Here, we developed physiologically relevant mBCSFB models using BECs in co-culture with leptomeningeal cells (LMCs) to examine N. meningitidis interaction.
Methods
We used BEC-like cells derived from induced pluripotent stem cells (iBECs) or hCMEC/D3 cells in co-culture with LMCs derived from tumor biopsies. We employed TEM and structured illumination microscopy to characterize the models as well as bacterial interaction. We measured TEER and sodium fluorescein (NaF) permeability to determine barrier tightness and integrity. We then analyzed bacterial adherence and penetration of the cell barrier and examined changes in host gene expression of tight junctions as well as chemokines and cytokines in response to infection.
Results
Both cell types remained distinct in co-culture and iBECs showed characteristic expression of BEC markers including tight junction proteins and endothelial markers. iBEC barrier function as determined by TEER and NaF permeability was improved by LMC co-culture and remained stable for seven days. BEC response to N. meningitidis infection was not affected by LMC co-culture. We detected considerable amounts of BEC-adherent meningococci and a relatively small number of intracellular bacteria. Interestingly, we discovered bacteria traversing the BEC-LMC barrier within the first 24 h post-infection, when barrier integrity was still high, suggesting a transcellular route for N. meningitidis into the CNS. Finally, we observed deterioration of barrier properties including loss of TEER and reduced expression of cell-junction components at late time points of infection.
Conclusions
Here, we report, for the first time, on co-culture of human iPSC derived BECs or hCMEC/D3 with meningioma derived LMCs and find that LMC co-culture improves barrier properties of iBECs. These novel models allow for a better understanding of N. meningitidis interaction at the mBCSFB in a physiologically relevant setting.
The host's defense against invasive mold infections relies on diverse antimicrobial activities of innate immune cells. However, studying these mechanisms in vitro is complicated by the filamentous nature of such pathogens that typically form long, branched, multinucleated and compartmentalized hyphae. Here we describe a novel method that allows for the visualization and quantification of the antifungal killing activity exerted by human granulocytes against hyphae of the opportunistic pathogen Aspergillus fumigatus. The approach relies on the distinct impact of fungal cell death on the morphology of mitochondria that were visualized with green fluorescent protein (GFP). We show that oxidative stress induces complete fragmentation of the tubular mitochondrial network which correlates with cell death of affected hyphae. Live cell microscopy revealed a similar and non-reversible disruption of the mitochondrial morphology followed by fading of fluorescence in Aspergillus hyphae that were killed by human granulocytes. Quantitative microscopic analysis of fixed samples was subsequently used to estimate the antifungal activity. By utilizing this assay, we demonstrate that lipopolysaccharides as well as human serum significantly increase the killing efficacy of the granulocytes. Our results demonstrate that evaluation of the mitochondrial morphology can be utilized to assess the fungicidal activity of granulocytes against A. fumigatus hyphae.
Background: The diagnosis of periprosthetic shoulder infection (PSI) requires a thorough diagnostic workup. Synovial fluid aspiration has been proven to be a reliable tool in the diagnosis of joint infections of the lower extremity, but shoulder specific data is limited. This study defines a threshold for synovial fluid white blood cell count (WBC) and assesses the reliability of microbiological cultures. Methods: Retrospective study of preoperative and intraoperative fluid aspiration of 31 patients who underwent a revision of a shoulder arthroplasty (15 with PSI defined by IDSA criteria, 16 without infection). The threshold for WBC was calculated by ROC/AUC analysis. Results: WBC was significantly higher in patients with PSI than in other patients. A threshold of 2800 leucocytes/mm\(^3\) showed a sensitivity of 87% and a specificity of 88% (AUROC 0.92). Microbiological cultures showed a sensitivity of 76% and a specificity of 100%. Conclusions: A threshold of 2800 leucocytes/mm\(^3\) in synovial fluid can be recommended to predict PSI. Microbiological culture has an excellent specificity and allows for targeted antibiotic therapy. Joint aspiration presents an important pillar to diagnose PSI.