The Impacts of Deep Surgical Site Infections on Readmissions, Length of Stay, and Costs: A Matched Case-Control Study Conducted in an Academic Hospital in the Netherlands.

OBJECTIVE: This study aimed to evaluate the impacts of deep surgical site infections (dSSIs) regarding hospital readmissions, prolonged length of stay (LoS), and estimated costs. PATIENTS AND METHODS: We designed and applied a matched case-control observational study using the electronic health records at the University Medical Center Groningen in the Netherlands. We compared patients with dSSI and non-SSI, matched on the basis of having similar procedures. A prevailing topology of surgeries categorized as clean, clean-contaminated, contaminated, and dirty was applied. RESULTS: Out of a total of 12,285 patients, 393 dSSI were identified as cases, and 2864 patients without SSIs were selected as controls. A total of 343 dSSI patients (87%) and 2307 (81%) controls required hospital readmissions. The median LoS was 7 days (P25-P75: 2.5-14.5) for dSSI patients and 5 days (P25-P75: 1-9) for controls (p-value: <0.001). The estimated mean cost per hospital admission was €9,016 (SE±343) for dSSI patients and €5,409 (SE±120) for controls (p<0.001). Independent variables associated with dSSI were patient's age ≥65 years (OR: 1.334; 95% CI: 1.036-1.720), the use of prophylactic antibiotics (OR: 0.424; 95% CI: 0.344-0.537), and neoplasms (OR: 2.050; 95% CI: 1.473-2.854). CONCLUSION: dSSI is associated with increased costs, prolonged LoS, and increased readmission rates. Elevated risks were seen for elderly patients and those with neoplasms. Additionally, a protective effect of prophylactic antibiotics was found.

Porcine fetal ventral mesencephalic cells are targets for primed xenoreactive human T cells.

Xenotransplantation of porcine fetal ventral mesencephalic (pfVM) cells to overcome the dopamine shortage in the striatum of patients with Parkinson's disease seems a viable alternative to allotransplantion of human fetal donor tissue, especially because the latter is complicated by both practical and ethical issues. There is, however, little known about the xenospecific immune responses involved in such an intracerebral xenotransplantation. The aim of our study was to investigate whether (1) naive human peripheral blood mononuclear cells (PMBC) display cytotoxicity against pfVM cells of E28 pig fetuses, and (2) priming of human PBMC by xenogeneic antigen presenting cells (APC) modulates pfVM-directed cellular cytotoxicity. For this purpose fresh PMBC from nine individual donors were primed by incubation with either irradiated pfVM cells or porcine spleen cells (PSC) as APC in the presence of IL-2 for 1 week before assessing cytotoxicity in a 51Cr release assay. Also, direct NK reactivity and antibody-dependent cellular cytotoxicity (ADCC) of fresh PMBC against pfVM cells was assessed. No direct cytotoxicity of naive cells (either NK reactivity or ADCC) against pfVM cells could be determined. Only PMBC primed with PSC were capable of lysing pfVM cells. PBMC primed with pfVM cells did not show cytolytic capacity towards pfVM. Interestingly, large differences in xenospecific T-cell responses exist between individual donor PBMC. Thus, human T cells are capable of killing pfVM cells in a xenoreactive response, but only after priming by donor APC. The large interindividual differences between human donors in their xenoreactive response may influence patient selection for xenotransplantation and chances of graft survival for individual patients.

Individual human serum differs in the amount of antibodies with affinity for pig fetal ventral mesencephalic cells and the ability to lyse these cells by complement activation.

Xenografting pig fetal ventral mesencephalic (pfVM) cells to repair the dopamine deficit in patients with Parkinson's disease is the focus of both experimental and clinical investigations. Although there have been marked advances in the experimental and even clinical application of these xenogeneic transplantations, questions regarding the host's xenospecific immune response remain unanswered. It has been shown that human serum is able to lyse pfVM tissue by both anti-gal-gal and non-anti-gal-gal antibodies by complement activation. The aim of this study was to investigate whether interindividual differences exist in the levels of pfVM cell-specific IgM and IgG subclass antibodies, their ability to lyse pfVM cells in vitro and the relationship between both. Pig fetal VM cells were incubated with heat-inactivated serum from 10 different individuals and binding of IgM antibodies and IgG subclass antibodies to pfVM cells was analyzed by flow cytometry. The ability to lyse pfVM cells was analyzed exposing 51Cr-labeled pfVM cells to fresh serum or isolated IgM and IgG from the same individuals and subsequent determination of released 51Cr from lysed cells. Strong differences were found between individuals in the levels of pfVM cell-specific IgM antibodies: antibody levels differed up to 40-fold. pfVM-specific IgG1 and IgG2 levels were only detectable in a few individuals. The ability to lyse pfVM cells ranged from negligible lysis up to 66.5% specific lysis. There was a strong correlation between the levels of individual pfVM-specific IgM antibodies and the ability to lyse pfVM cells in vitro. Isolated IgM, but not IgG, was able to lyse pfVM cells in the presence of complement. In conclusion, the interindividual differences in the levels of IgM with affinity for pfVM cells and their ability to lyse pfVM cells in vitro are considerable. Only few individuals possessed IgG1 and IgG2 subclass antibodies with affinity for pfVM. These findings may influence patient selection for porcine transplants and chances of graft survival in individual patients.

Detection of alloreactive T cells by flow cytometry: a new test compared with limiting dilution assay.

BACKGROUND: Frequencies of alloreactive T cells determined by limiting dilution assays (LDA) may not adequately reflect the donor-reactive immune status in transplant recipients. To reevaluate LDA frequencies, we developed a flow cytometry test for direct determination of alloreactive T-cell frequencies and compared these frequencies with classical LDA estimates of frequencies. METHODS: For determination of frequencies by flow cytometry, peripheral blood lymphocytes (or lymphocytes taken from primary mixed lymphocyte culture) were stimulated with either Epstein-Barr virus-transformed lymphoblastoid cell lines or T cell-depleted spleen cells and stained for intracellular interferon (IFN)-gamma production and CD69. In lung transplant recipients, frequencies of IFN+ alloreactive T cells were compared with LDA frequencies, that is, cytotoxic T lymphocyte precursors and helper T lymphocyte precursors. RESULTS: With flow cytometry, alloreactive T cells were detected after overnight allostimulation as IFN-gamma CD69bright cells (range, 0.1-0.58% and 0.1-0.66% of total CD4 and CD8 cells, respectively). Frequencies increased 25-fold or more when lymphocytes were prestimulated in primary mixed lymphocyte culture before testing. After lung transplantation, mean donor-specific IFN+ CD8 T-cell frequencies did not decrease as mean donor-specific LDA cytotoxic T lymphocyte precursor frequencies, whereas no difference was seen in pretransplantation samples or third-party-specific frequencies at both time points. Mean frequencies of IFN+ CD4 did not differ from helper T lymphocyte precursors at both time points, but frequencies did not correlate. CONCLUSIONS: The flow cytometry test allows a direct measurement of alloreactive T-cell frequencies and demonstrates a discrepancy between donor-specific IFN+ CD8 T-cell frequencies and LDA CLTp after transplantation. This may be a result of the existence of "functional diverse" alloreactive T cells or of activation-induced cell death of donor-reactive T cells during long (LDA) culturing, which is avoided in the flow cytometry test.