| 1. |
- Ljunghill Hedberg, Anna, 1972-
(författare)
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Impact of the inflammatory response on specific immunity in neurosurgical patients
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vaccination with a T-cell-dependent pneumococcal conjugate vaccine (PCV) followed by a T-cell-independent pneumococcal polysaccharide vaccine (PPSV) is recommended after basilar skull fracture to reduce the risk of meningitis. The optimal time frame for vaccination has not yet been established and varies widely in practice. Because the risk of meningitis is at its peak shortly after the trauma incident, early vaccination might be more desirable. After trauma and central nervous system (CNS) injury, T-cell defects leading to trauma and CNS injury-induced immune deficiency syndromes may affect the vaccine response. In light of the above information, the overall aim of this thesis was to investigate the impact of neurotrauma and neurosurgery on the response to T-cell-dependent and T-cell-independent vaccines.In Paper I, we compared the antibody response to a T-cell-dependent conjugate vaccine in patients vaccinated within 10 days after neurotrauma or neurosurgery with those vaccinated after >3 weeks. To avoid interference with pneumococcal vaccination, a conjugate vaccine against Haemophilus influenzae type b (Hib) was chosen for the study. The majority of the patients responded to the vaccination, although the number of responders was significantly lower in patients vaccinated early.In Paper II, we investigated the antibody response to the T-cell-independent vaccine PPSV in patients vaccinated within 10 days after neurotrauma or neurosurgery and in patients vaccinated after >3 weeks. Patients vaccinated early responded similarly to those vaccinated after the acute period, indicating that PPSV can be administered early after neurotrauma or neurosurgery.In Paper III, we compared the response to Hib vaccine with the response to PPSV. We also examined whether individual clinical or immunological parameters might predict the response to T-cell-dependent vaccine and thereby help identify non-responders before vaccination. No correlation between Hib vaccine and PPSV responses was found, indicating that B-cell function is not similarly depressed as T-cell function. It was not possible to predict the T-cell-dependent vaccine response by standardized grading of the trauma or by parameters reflecting the innate immune response.In Paper IV, we found a significant reduction in the ex vivo CD4+ T-lymphocyte response to PCV in patients after neurotrauma or neurosurgery as compared with healthy controls.Our results suggest that PPSV might be a viable alternative to T-cell-dependent PCV in early vaccination after neurotrauma.
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| 2. |
- Skorup, Paul
(författare)
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Antibacterial Effect and Inflammatory Response in Relation to Antibiotic Treatment of Sepsis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sepsis defines as life-threatening organ dysfunction caused by a dysregulated host response to infection. The importance of early administration of antibiotics in septic shock is undisputed, but the optimal antibiotic choice remains uncertain. Some national guidelines advocate single β-lactam antibiotic treatment while others recommend a combination of β-lactam and aminoglycoside. This thesis aimed to investigate the anti-bacterial properties and antibiotic-induced inflammatory responses of ß-lactam antibiotic compared with effects of the addition of an aminoglycoside in clinically relevant E. coli porcine intensive care sepsis/septic shock models. We also studied the host's antibacterial capacities in primary and secondary sepsis.In Paper I the addition of an aminoglycoside, in comparison with single β-lactam antibiotic treatment, caused decreased bacterial growth in the liver and greater antibiotic-induced blood killing activity ex vivo. The results thereby constitute possible mechanisms to the previously reported improved survival in the most critically ill sepsis patients receiving the β-lactam/aminoglycoside combination. Also observed in this paper was that individual blood bactericidal capacity may have significant effects on antimicrobial outcome. In Paper II we investigated endotoxin release in vivo after antibiotic treatment in comparison with no treatment. There were no differences, however, antibiotics did increase an inflammatory IL-6 response that was associated with leukocyte activation and pulmonary organ dysfunction. A secondary finding was that the addition of an aminoglycoside to a β-lactam induced trends towards less inflammation compared with β-lactam alone.Paper III compared how challenge with different pre-killed E. coli activates the inflammatory response, resulting in higher cytokine responses, more leucocyte activation and inflammatory capillary leakage after single β-lactam compared with live or heat-killed bacteria. The addition of an aminoglycoside lowered the β-lactam-induced responses.Paper IV demonstrated that animals with secondary sepsis exhibited an attenuated inflammatory response as expected; however, contrary to our hypothesis, the animals’ antibacterial capacities were intact and partly enhanced.We conclude that there are likely several beneficial effects of the addition of an aminoglycoside to a β-lactam therapy regimen in septic shock. Because host antibacterial capacities in secondary sepsis are enhanced, the need for bactericidal antibiotic combinations is not greater in secondary than in primary sepsis.
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| 3. |
- Söderberg, Ewa
(författare)
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Experimental septic shock – Effects of endotoxemia with special reference to pathophysiological responses in the pig
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sepsis and septic shock are conditions, with severe outcome or in many cases death. Sepsis is a systemic inflammatory response trigger by bacteraemia but systemic inflammatory response can also be triggered by major trauma, major surgery, pancreatitis, severe burns etc.The systemic inflammatory reaction initiating the evolvement of septic organ dysfunction can be modelled using endotoxin, a Gram-negative bacterial lipopolysaccharide. This thesis used a porcine experimental sepsis model to examine timing of the inflammatory response due to endotoxin infusion (Paper I) and the influence of steroid treatment on the inflammatory response in endotoxemic pigs (Paper II). Timing of steroid treatment and the role of neutrophil granulocyte activation was evaluated with pig specific NGAL assessing neutrophil activation (Paper III). A clinical observational study was performed with the aim to differentiate between sepsis and other inflammatory conditions (e.g. trauma due to major surgery) evaluated by calprotectin as a marker of neutrophil activation (Paper IV).There was a dose-dependency in endotoxin tolerance which was measured with TNF-a. Pre-exposure to endotoxin did not reduce the pulmonary response to endotoxemic challenge. In fact, both PaO2 / FiO2 and static pulmonary compliance were reduced in this group when pre-treated with endotoxin at low dose.Endotoxemic animals treated with hydrocortisone were more stable in circulatory variables than those without such treatment. This was not explained by an ability of steroids to modulate the production of NO (Nitric oxide), which has been suggested to be a mechanism of steroids in this aspect.Pre-treatment with hydrocortisone attenuated the neutrophil granulocyte response and consequently diminished the release of NGAL in plasma. Circulatory derangement was associated with high plasma NGAL levels. Urine NGAL levels did not differ among the four groups.Plasma calprotectin levels on ICU admission is a sensitive marker of systemic inflammation and are markedly increased in patients with sepsis and patients with systemic inflammatory response. Plasma Calprotectin performed better than any of the other inflammatory variables in predicting mortality at 30 days, except from the composite mortality prediction score, SAPS 3.
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| 4. |
- Castegren, Markus, 1976-
(författare)
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Modulating Organ Dysfunction in Experimental Septic Shock : Effects of Aminoglycosides, Antiendotoxin Measures and Endotoxin Tolerance
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sepsis is a common diagnose in the intensive care population, burdened with a high mortality. The systemic inflammatory reaction underlying the development of septic organ dysfunction can be modeled using Gram-negative bacterial lipopolysaccharide, endotoxin. This thesis used a porcine endotoxemic experimental sepsis model to address clinical questions difficult to answer in clinical trials; furthermore a model of secondary sepsis was developed. No additional effect on the development of renal dysfunction by tobramycin was found, indicating that a single dose of tobramycin does not further compromise renal function in inflammatory-induced acute kidney injury. Antiendotoxin treatment had no measurable effect on TNF-α-mediated toxicity once the inflammatory cascade was activated. There was an effect on the leukocyte response that was associated with improvements in respiratory function and microcirculation, making it impossible to rule out fully the beneficial effect of this strategy. However, the effects were limited in relation to the magnitude of the endotoxin concentration reduction and the very early application of the antiendotoxin measure. The lungs stood out compared to the other organ systems as having a threshold endotoxin dose for the protective effect of endotoxin tolerance. As to the development of circulatory and renal dysfunction, tolerance to endotoxin was evident regardless of the endotoxin pre-exposure and challenge dose. There was a temporal variation of endotoxin tolerance that did not follow changes in plasma TNF-α concentrations and maximal tolerance was seen very early in the course. More pronounced endotoxin tolerance at the time of maximum tolerance was associated with a more marked hyperdynamic circulation, reduced oxygen consumption and thrombocytopenia eighteen hours later. It might be of interest to use the experimental model of long-term endotoxemia followed by a second hit, which has been designed to resemble an intensive care setting, for the study of treatment effects of immunomodulating therapies in secondary sepsis.
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| 5. |
- Lignell, Anders, 1975-
(författare)
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In vitro Pharmacodynamics of Antifungal Agents in the Treatment of Candida Infections
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pharmacodynamic studies are important for the optimal use of antimicrobial agents. Combination antifungal therapy may be one method to improve outcome in invasive Candida infections. An in vitro kinetic model to study the pharmacodynamic effects of a combination of two antifungal agents with different elimination rates was developed and the pharmacodynamics of amphotericin B (AMB), voriconazole (VRC) or the combination was evaluated. Exposure to VRC inhibited the fungicidal activity of sequential doses of AMB against VRC-susceptible strains of C. albicans. The interaction was VRC dose-dependent. AMB activity was regained once VRC was removed or it increased gradually when the concentration of VRC had fallen below the minimum inhibitory concentration (MIC). The VRC-AMB interaction, however, was also present against strains of C. albicans, C. glabrata and C. krusei despite reduced VRC susceptibility. Against these strains the interaction was not predicted by the MIC value, suggesting that mechanisms of resistance may be of importance. Until more data are available, a reasonable recommendation is probably to avoid the sequential use of VRC followed by AMB and to use the combination of VRC and AMB for the treatment of Candida infections with caution. Only the unbound fraction of a drug is generally accepted as pharmacologically active. The activity of posaconazole (POS) with a protein binding of 98-99% was tested in serum against Candida species and compared with the calculated unbound serum concentration in protein-free media. Significant differences emerged at clinically relevant POS serum concentrations of 1.0 and 0.10 mg/l compared with the serum control regimen against one strain of C. lusitaniae. In RPMI 1640 the corresponding calculated unbound concentrations resulted in no effect for the low dose regimen compared with the RPMI 1640 control regimen. Further, against seven additional Candida strains tested, the effect of POS was greater in serum than in RPMI 1640. A flux from serum protein bound to fungal lanosterol 14α-demethylase bound POS may be the explanatory mechanism.
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| 6. |
- Svensson, Tobias, 1977-
(författare)
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Infectious and bleeding complications in patients with hematological malignancies : Studies on diagnosis and prevention
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis is to improve knowledge about the prevention of infectious and bleeding complications in patients with hematological malignancies, primarily in those with chronic lymphocytic leukemia (CLL) and myelodysplatic syndrome (MDS).Hypogammaglobulinemia, impaired production of immunoglobulins (Ig), is an established risk factor for infection, but the impact of IgG pure subclass deficiency (IgG subclass deficiency with adequate production of IgG, IgA, and IgM) has been debated. In a retrospective single institution study, we concluded that pure IgG subclass deficiency in CLL patients is rare and is not associated with an increased risk of infection. Hence, routine analysis of IgG subclasses in patients with CLL is not warranted.There is no consensus on recommending vaccination against Streptococcus pneumoniae to CLL patients mainly because comparative studies are lacking. In our randomized trial, the efficacy of a conjugated pneumococcal vaccine on immune response was superior or equal to a polysaccharide vaccine for all pneumococcal serotypes common for the two vaccines. A conjugate pneumococcal vaccine should therefore be included in vaccination programs for patients with CLL.Bronchoalveolar lavage (BAL) is a well-established invasive method to identify the cause of pulmonary infiltrates in immunocompromised patients. In a retrospective trial, we have studied the diagnostic yield of BAL in patients with hematological malignancies. We concluded that BAL is highly useful in either verifying or excluding some of the important respiratory tract infections affecting these patients, particularly invasive pulmonary aspergillosis (IPA) and Pneumocystis jirovecii pneumonia (PJP). However, standardized procedures for BAL sampling should be continually revised to avoid unnecessary microbiological tests.Thrombocytopenia, an adverse prognostic factor in patients with MDS, can be aggravated by azacitidine, first-line treatment for high-risk MDS. Eltrombopag, a thrombopoietin-receptor agonist (TPO-R), alleviates thrombocytopenia in patients with immune thrombocytopenic purpura (ITP). In a phase I clinical trial, we concluded that the combination of eltrombopag and azacitidine in high-risk MDS patients with thrombocytopenia is feasible and well tolerated in doses up to 200 mg eltrombopag daily.
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| 7. |
- Tano, Eva, 1957-
(författare)
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Survival of infectious agents and detection of their resistance and virulence factors
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the first study, three different transport systems for bacteria were evaluated. The CLSI M40-A guideline was used to monitor the maintenance of both mono- and polymicrobial samples during a simulated transportation at room temperature that lasted 0-48 h. All systems were able to maintain the viability of all organisms for 24 h, but none of them could support all tested species after 48 h. The most difficult species to recover was Neisseria gonorrhoeae, and in polymicrobial samples overgrowth was an observed problem. The aim of the second study was to study the presence of TSST-1 and three other important toxin genes in invasive isolates of Staphylococcus aureus collected during the years 2000-2012 at two tertiary hospitals. The genes encoding the staphylococcal toxins were detected by PCR, and whole-genome sequencing was used for analyzing the genetic relatedness between isolates. The results showed that the most common toxin was TSST-1, and isolates positive for this toxin exhibited a clear clonality independent of year and hospital. The typical patient was a male aged 55-74 years and with a bone or a joint infection. The third study was a clinical study of the effect of silver-based wound dressings on the bacterial flora in chronic leg ulcers. Phenotypic and genetic silver-resistance were investigated before and after topical silver treatment, by determining the silver nitrate MICs and by detecting sil genes with PCR. The silver-based dressings had a limited effect on primary wound pathogens, and the activity of silver nitrate on S. aureus was mainly bacteriostatic. A silver-resistant Enterobacter cloacae strain was identified after only three weeks of treatment, and cephalosporin-resistant members of the Enterobacteriaceae family were relatively prone to developed silver-resistance after silver exposure in vitro. The last study was undertaken in order to develop an easy-to-use method for simulating the laundering process of hospital textiles, and apply the method when evaluating the decontaminating efficacy of two different washing temperatures. The laundering process took place at professional laundries, and Enterococcus faecium was used as a bioindicator. The results showed that a lowering of the washing temperature from 70°C to 60°C did not affect the decontamination efficacy; the washing cycle alone reduced the number of bacteria with 3-5 log10 CFU, whereas the following tumble drying reduced the bacterial numbers with another 3-4 log10 CFU, yielding the same final result independent of the washing temperature. To ensure that sufficient textile hygiene is maintained, the whole laundering process needs to be monitored. The general conclusion is that all developmental work in the bacterial field requires time and a large strain collection.
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| 8. |
- von Seth, Magnus, 1978-
(författare)
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Oxygen delivery and mitochondrial dysfunction as assessed by microdialysis during interventions in experimental sepsis
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Early administration of broad-spectrum antibiotics is the first goal in sepsis treatment. Besides from bacteriostatic/bactericidal effects, some antibiotics may also modify the host´s response to infection. The novel antibiotic tigecycline may exert such properties; however, this property has not been evaluated in large-animal trials. We compared tigecycline with doxycycline and placebo in relation to anti-inflammatory, circulatory and organ dysfunction effects in a sterile pig model of sepsis. Doxycycline, but not tigecycline, reduced the inflammatory response as manifested by tumor necrosis factor alpha levels in plasma. Tigecycline, however, had a stabilizing effect on the circulation not exerted by doxycycline or placebo.To achieve rapid restoration of the circulating blood volume - another major goal in sepsis treatment - fluid bolus administration of is some-times practiced. In addition to crystalloids, albumin-containing solutions are suggested. Yet, some animal-experimental data suggests that rapid bolus administration of albumin reduces albumin’s plasma-expanding effect. We compared a rapid intravenous bolus of radiolabeled albumin with a slow infusion in a sterile pig model of sepsis. Rapid bolus of administration did not reduce plasma levels of albumin following administration and did not increase the amount of albumin that left the circulation.Inadequate oxygen delivery (DO2) by the circulation to the tissues may cause increased plasma lactate, which is the most striking effect of sepsis on the metabolism. However, experimental data and clinical trials refute this link, instead, suggesting other mechanisms, including impaired oxygen extraction, mitochondrial dysfunction and accelerated aerobic glycolysis. We investigated the impact of DO2, oxygen consumption (VO2), hemodynamic parameters and inflammatory response on plasma lactate and organ dysfunction in two experimental sepsis models. In the most severe cases of shock, with DO2, there was an increase in plasma lactate, but without a decrease in VO2, invalidating the assumption that the increase in lactate is due to anaerobic metabolism.To identify critical steps in the sepsis-induced increase in lactate, we inhibited the major energy-producing step in the electron transport chain (ETC). The combination of sepsis and ETC inhibition led to a cellular energy crisis. This finding suggests that early sepsis induces a partial mitochondrial dysfunction.
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| 9. |
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| 10. |
- Sperber, Jesper
(författare)
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Protective Mechanical Ventilation in Inflammatory and Ventilator-Associated Pneumonia Models
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Severe infections, trauma or major surgery can each cause a state of systemic inflammation. These causes for systemic inflammation often coexist and complicate each other. Mechanical ventilation is commonly used during major surgical procedures and when respiratory functions are failing in the intensive care setting. Although necessary, the use of mechanical ventilation can cause injury to the lungs and other organs especially under states of systemic inflammation. Moreover, a course of mechanical ventilator therapy can be complicated by ventilator-associated pneumonia, a factor greatly influencing mortality. The efforts to avoid additional ventilator-induced injury to patients are embodied in the expression ‘protective ventilation’.With the use of pig models we have examined the impact of protective ventilation on systemic inflammation, on organ-specific inflammation and on bacterial growth during pneumonia. Additionally, with a 30-hour ventilator-associated pneumonia model we examined the influence of mechanical ventilation and systemic inflammation on bacterial growth. Systemic inflammation was initiated with surgery and enhanced with endotoxin. The bacterium used was Pseudomonas aeruginosa.We found that protective ventilation during systemic inflammation attenuated the systemic inflammatory cytokine responses and reduced secondary organ damage. Moreover, the attenuated inflammatory responses were seen on the organ specific level, most clearly as reduced counts of inflammatory cytokines from the liver. Protective ventilation entailed lower bacterial counts in lung tissue after 6 hours of pneumonia. Mechanical ventilation for 24 h, before a bacterial challenge into the lungs, increased bacterial counts in lung tissue after 6 h. The addition of systemic inflammation by endotoxin during 24 h increased the bacterial counts even more. For comparison, these experiments used control groups with clinically common ventilator settings.Summarily, these results support the use of protective ventilation as a means to reduce systemic inflammation and organ injury, and to optimize bacterial clearance in states of systemic inflammation and pneumonia.
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