Predictors of mortality of streptococcal bacteremia and the role of infectious diseases consultation; a retrospective cohort study.

BACKGROUND: Streptococcal bacteremia is associated with high mortality. The study aims to identify predictors of mortality among patients with streptococcal bacteremia. METHODS: This retrospective study was conducted at the Lausanne University Hospital, Switzerland and included episodes of streptococcal bacteremia among adult patients from 2015 to 2023. RESULTS: During the study period, 861 episodes of streptococcal bacteremia were included. The majority of episodes were categorized in the Mitis group (348 episodes; 40%), followed by the Pyogenic group (215; 25%). Endocarditis was the most common source of bacteremia (164; 19%). The overall 14-day mortality rate was 8% (65 episodes). The results from the Cox multivariable regression model showed that a Charlson comorbidity index >4 (P 0.001; HR 2.87, CI 1.58-5.22), S. pyogenes (P 0.011; HR 2.54, CI 1.24-5.21), sepsis (P < 0.001; HR 7.48, CI 3.86-14.47), lower respiratory tract infection (P 0.002; HR 2.62, CI 1.42-4.81), and absence of source control interventions within 48 hours despite being warranted (P 0.002; HR 2.62, CI 1.43-4.80) were associated with 14-day mortality. Conversely, interventions performed within 48 hours of bacteremia onset, such as infectious diseases consultation (P < 0.001; HR 0.29, CI 0.17-0.48), and appropriate antimicrobial treatment (P < 0.001; HR 0.28, CI 0.14-0.57) were associated with improved outcome. CONCLUSIONS: Our findings underscore the pivotal role of infectious diseases consultation in guiding antimicrobial treatment and recommending source control interventions for patients with streptococcal bacteremia.

Predictors of mortality of bloodstream infections among internal medicine patients in a Swiss Hospital: Role of quick Sequential Organ Failure Assessment.

BACKGROUND: Sepsis has been associated with high morbidity and mortality. The aims were to determine predictors of mortality among patients with bloodstream infections (BSIs) and to ascertain the role of quick Sequential Organ Failure Assessment (qSOFA) in predicting poor outcomes. METHODS: All internal medicine patients with BSIs at the Hospital of Jura, Switzerland during a three year period (July 2014 to June 2017) were included. RESULTS: Among 404 BSIs, Escherichia coli represented the most common species isolated (156 episodes; 38.6%), followed by Staphylococcus aureus (68; 16.8%). The most common site of infection was urinary tract accounting for 39.6% of BSIs (160 episodes). Thirty-day mortality was 18.1%. Multivariate analysis revealed BSI due to staphylococci, malignancy (haematologic or solid organ), qSOFA≥2 points, Pitt bacteraemia score as independent predictors of mortality, while appropriate empiric antibiotic therapy and administration of antibiotic therapy within three hours from infection's recognition were identified as a predictor of good prognosis. qSOFA showed the highest sensitivity (87.7%), negative predictive value (96.6%) and accuracy (0.83) as compared to other scores. Mortality among 141 septic patients was 45.4%. Malignancy (haematologic or solid organ), primary BSI, Pitt bacteraemia score, were independently associated with mortality, while appropriate empiric antibiotic therapy and administration of antibiotic therapy within the first hour from infection's recognition were associated with better prognosis. CONCLUSION: qSOFA as compared to other severity scores showed an excellent negative predictive value. Better prognosis was associated with administration of appropriate empiric antibiotic therapy and its timely initiation.

PRC1 components exhibit different binding kinetics in Polycomb bodies.

BACKGROUND INFORMATION: Polycomb group (PcG) proteins keep the memory of cell identity by maintaining the repression of numerous target genes. They accumulate into nuclear foci called Polycomb bodies, which function in Drosophila cells as silencing compartments where PcG target genes convene. PcG proteins also exert their activities elsewhere in the nucleoplasm. In mammalian cells, the dynamic organisation and function of Polycomb bodies remain to be determined. RESULTS: Fluorescently tagged PcG proteins CBXs and their partners BMI1 and RING1 form foci of different sizes and intensities in human U2OS cells. Fluorescence recovery after photobleaching (FRAP) analysis reveals that PcG dynamics outside foci is governed by diffusion as complexes and transient binding. In sharp contrast, recovery curves inside foci are substantially slower and exhibit large variability. The slow binding component amplitudes correlate with the intensities and sizes of these foci, suggesting that foci contained varying numbers of binding sites. CBX4-green fluorescent protein (GFP) foci were more stable than CBX8-GFP foci; yet the presence of CBX4 or CBX8-GFP in the same focus had a minor impact on BMI1 and RING1 recovery kinetics. CONCLUSION: We propose that FRAP recovery curves provide information about PcG binding to their target genes outside foci and about PcG spreading onto chromatin inside foci.

Short exposure to the DNA intercalator DRAQ5 dislocates the transcription machinery and induces cell death.

The fluorescent probe DRAQ5 which rapidly permeates cells and binds to DNA is potentially useful for functional studies of molecular dynamics and interactions in living nuclei. Within minutes after the incubation of human osteosarcoma U2OS cells with 5µm DRAQ5, the distributions of RNA polymerase II and some of its associated regulatory proteins HEXIM and cyclin T1 in the nucleus are severely impaired, and transcription is inhibited. Furthermore, 30min exposure to DRAQ5 induces death of U2OS cells 24h later. Incubation with Hoechst 33342 under similar conditions does not induce these effects. These results emphasize the importance of carefully examining the functional consequences of labeling DNA with intercalating fluorescent dyes before use.

3D collagen type I matrix inhibits the antimigratory effect of doxorubicin.

BACKGROUND: The cell microenvironment, especially extracellular matrix proteins, plays an important role in tumor cell response to chemotherapeutic drugs. The present study was designed to investigate whether this microenvironment can influence the antimigratory effect of an anthracycline drug, doxorubicin, when tumor cells are grown in a matrix of type I collagen, a three-dimensional (3D) context which simulates a natural microenvironment. METHODS: To this purpose, we studied the migratory parameters, the integrin expression, and the activation state of focal adhesion kinase (FAK) and GTPase RhoA involved in the formation of focal adhesions and cell movement. These parameters were evaluated at non toxic concentrations which did not affect HT1080 cell proliferation. RESULTS: We show that while doxorubicin decreased cell migration properties by 70% in conventional two-dimensional (2D) culture, this effect was completely abolished in a 3D one. Regarding the impact of doxorubicin on the focal adhesion complexes, unlike in 2D systems, the data indicated that the drug neither affected beta1 integrin expression nor the state of phosphorylation of FAK and RhoA. CONCLUSION: This study suggests the lack of antiinvasive effect of doxorubicin in a 3D environment which is generally considered to better mimic the phenotypic behaviour of cells in vivo. Consistent with the previously shown resistance to the cytotoxic effect in a 3D context, our results highlight the importance of the matrix configuration on the tumor cell response to antiinvasive drugs.

Raman spectral imaging of single living cancer cells: a preliminary study.

Raman microspectroscopy allows probing subcellular compartments and provides a unique spectral fingerprint indicative of endogenous molecular composition. Although several spectroscopic cell studies have been reported on fixed samples, only few attempts concern single growing cells. Here, we have tested different optical substrates that would best preserve cell integrity and allow direct measurement of Raman spectra at the single living cell level. Calu-1 lung cancer cells were used as a model and their morphology and growth were assessed on Raman substrates like quartz, calcium fluoride, and zinc selenide. Data show that quartz was the most appropriate taking into consideration both cell morphology and proliferation rate (47% on quartz vs. 55% of BrdU-positive cells on conventional plastic). Using quartz, 40 cells were analysed and Raman spectra were collected from nuclei and cytoplasms using a 785 nm laser excitation of 30 mW at the sample, in the spectral range of 580-1750 cm(-1), and an acquisition time of 2 x 10 sec/spectrum. Discriminant spectral information related to nucleus and cytoplasm were extracted by multivariate statistical methods and attributed to nucleic acids, lipids, and proteins. Finally, Raman spectral imaging was performed to show the distribution of these components within the cell.

Extracellular matrix proteins protect human HT1080 cells against the antimigratory effect of doxorubicin.

In solid tumors, the cell microenvironment appears to be a key determinant in the emergence of drug resistance, a major obstacle to the successful use of antitumor drugs. Our aim was to determine whether type I collagen and fibronectin, proteins of the extracellular matrix, were able to influence the antimigratory properties induced by the antitumor drug doxorubicin. These properties were investigated at doxorubicin concentrations of 10 and 20 nM, which do not affect cell proliferation on a 24 h drug exposure. Using videomicroscopy, we found that these subtoxic doses of doxorubicin were sufficient to inhibit individual tumor cell motion on two-dimensional plastic surfaces. Such a drug treatment induced a dramatic disturbance of actin stress fiber formation and of vinculin distribution in 80% of cells. In contrast, on extracellular matrix proteins, cell speed was unaffected by drug and perturbation of both actin network and vinculin distribution was detected in only 50% of cells, suggesting a protective effect of the microenvironment. In addition, the phosphorylation of focal adhesion kinase and GTPase RhoA was less affected by doxorubicin with cells cultured on extracellular matrix proteins. In conclusion, our findings indicate that the cell microenvironment prevents drug-dependent inhibition of cell migration in vitro. They reveal cell locomotion as a key factor of microenvironment-mediated drug resistance. This new concept needs to be exploited in in vitro models to optimize the screening of new antimigratory drugs.

In situ analysis of doxorubicin uptake and cytotoxicity in a 3D culture model of human HT-1080 fibrosarcoma cells.

In solid tumors, chemotherapeutics must adequately diffuse through the extracellular compartment to achieve their cytotoxic effect. Using quantitative microspectrofluorometry, both Doxorubicin penetration through three-dimensional (3D) collagen I matrices and its subsequent intranuclear accumulation into HT-1080 cells cultured in this microenvironment were directly assessed. Evidence that collagen delayed the Doxorubicin penetration for 1 h is presented. During that period, drug concentrations were lower in the nuclei in 3D compared to 2D matrices. Anthracyclines were also found to exhibit similar cytotoxicity in 2D and 3D after long term incubation. In conclusion, in this 3D culture model, collagen type I matrices delayed the early distribution of low molecular weight therapeutics and failed to affect their long-term cytotoxic effects, as previously reported. This model may provide a rationale for avoiding the emergence of intrinsic chemoresistance in tissue.

Assessment of the antiinvasive potential of the anthracycline aclacinomycin (Aclarubicin) in a human fibrosarcoma cell line.

Aclacinomycin (Aclarubicin) is a trisaccharide anthracycline anticancer drug active against a wide variety of solid tumors and haematological malignancies. We have evaluated its antimigrative and antiinvasive properties in a Boyden chamber with or without Matrigel and in wound repair assays. Aclacinomycin was demonstrated to inhibit HT-1080 cell migration and invasion while being more potent than the classical anthracycline doxorubicin. This decrease occurred in a dose-dependent manner and without affecting cell proliferation. Importantly, the antiinvasive effect was not associated to a modification in the production of the matrix-degrading enzymes MMP-2 and MMP-9 but rather to changes in cytoskeletal and focal contact formation. Indeed, the drug reduces cell polarity, impairs the actin-mediated membrane ruffling at the leading edge and decreases beta1 integrin expression and activation. Dramatic alterations in the distribution of vinculin and in the expression and phosphorylation state of both FAK and Src kinases were also detected. As a conclusion, these data suggest a novel application for this chemotherapeutic agent due to its ability to reduce tumor cell invasion. Combination of aclacinomycin with MMP inhibitors could have therapeutic potential in preventing tumor metastasis.