| 1. |
- Augustinsson (Nilsdotter-Augustinsson), Åsa, 1962-, et al.
(författare)
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Interaction of staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes
- 2001
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 33:6, s. 408-412
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the interaction of Staphylococcus epidermis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p ≤ 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.
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| 2. |
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| 3. |
- Nilsdotter-Augustinsson, Åsa, 1962-, et al.
(författare)
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Adherence of Staphylococcus epidermidis to extracellular matrix proteins and effects of fibrinogen-bound bacteria on oxidase activity and apoptosis in neutrophils
- 2005
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 113:5, s. 361-373
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus epidermidis often causes foreign-body infections such as those associated with hip prostheses, but the underlying pathogenic mechanisms are not fully understood. We performed spectrophotometry to study the ability of S. epidermidis to bind to immobilised fibrinogen, fibronectin, vitronectin, and collagen. The strains were isolated from infected hip prostheses or from normal flora and the well-known protein-binding strain Staphylococcus aureus Cowan was used as positive control. We also analysed the interaction between neutrophils and a fibrinogen-bound prosthesis-derived strain of S. epidermidisby measuring chemiluminescence to determine the neutrophil oxidative response and binding of annexin V to indicate neutrophil apoptosis. We found that binding of S. epidermidis to extracellular matrix proteins varied under different growth conditions, and that prosthesis isolates adhered better to vitronectin than did strains from normal flora. The oxidative response caused by fibrinogen-bound S. epidermidis was not above the background level, which was in marked contrast to the distinct response induced by fibrinogen-associated S. aureus Cowan. Furthermore, fibrinogen-adhering S. epidermidis retarded neutrophil apoptosis. We conclude that surface-bound S. epidermidis induces only a weak inflammatory response, which in combination with the ability of the adherent bacteria to retard neutrophil apoptosis may contribute to low-grade inflammation and loosening of prostheses.
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| 4. |
- Nilsdotter-Augustinsson, Åsa, 1962-, et al.
(författare)
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Staphylococcus aureus, but not Staphylococcus epidermidis, modulates the oxidative response and induces apoptosis in human neutrophils
- 2004
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 112:2, s. 109-118
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Tidskriftsartikel (refereegranskat)abstract
- S. epidermidis is the most common isolate in foreign body infections. The aim of this study was to understand why S. epidermidis causes silent biomaterial infections. In view of the divergent inflammatory responses S. epidermidis and S. aureus cause in patients, we analyzed how they differ when interacting with human neutrophils. Neutrophils interacting with S. epidermidis strains isolated either from granulation tissue covering infected hip prostheses or from normal skin flora were tested by measuring the oxidative response as chemiluminescence and apoptosis as annexin V binding. Different S. aureus strains were tested in parallel. All S. epidermidis tested were unable to modulate the oxidative reaction in response to formyl-methionyl-leucyl-phenylalanine (fMLP) and did not provoke, but rather inhibited, apoptosis. In contrast, some S. aureus strains enhanced the oxidative reaction, and this priming capacity was linked to p38-mitogen-activated-protein-kinase (p38-MAPK) activation and induction of apoptosis. Our results may explain why S. epidermidis is a weak inducer of inflammation compared to S. aureus, and therefore responsible for the indolent and chronic course of S. epidermidis biomaterial infections.
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| 5. |
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| 6. |
- Nimeri, G, et al.
(författare)
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The influence of plasma proteins and platelets on oxygen radical production and F-actin distribution in neutrophils adhering to polymer surfaces
- 2002
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Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:8, s. 1785-1795
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that blood cell interactions with artificial surfaces might have deleterious effects on host tissue, however, the mechanisms involved are far from understood. In this study, neutrophil-platelet interaction on uncoated or protein-coated polymer surfaces was investigated. Cell spreading, reorganization of actin filaments and release of oxygen metabolites (measured as luminol-amplified chemiluminescence) were used as criteria for cell activation on positively charged, hydrophilic 1,2-diaminocyclohexane, and negatively charged, hydrophobic hexamethylene-disiloxane. The model surfaces were made by radio frequency plasma discharge polymerization. Neutrophil contact with the uncoated polymers induced a prolonged generation of oxygen radicals. Precoating of the polymer surfaces with human serum albumin (HSA) or fibrinogen, markedly reduced neutrophil activation, whereas coating with human immunoglobulin G (IgG), a well-known opsonin, resulted in significantly higher levels of cell activation. Consequently, protein coating overruled the activating effects of the polymer surfaces. The presence of unstimulated or thrombin-stimulated platelets markedly increased the reactivity of neutrophils against fibrinogen- and IgG-coated surfaces. However, neutrophils remained relatively unreactive in the presence of platelets on HSA-treated surfaces. Comparison of the different types of surfaces used, reveals a correlation between the degree of cell spreading, reorganization of the actin cytoskeleton and the amount of oxygen radicals produced. Our results suggest that the acute inflammatory reaction on a biomaterial surface is highly dependent on the nature and composition of the first adsorbed protein layer and the extent of platelet activation.
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| 7. |
- Tegnell, Anders, 1956-, et al.
(författare)
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A clone of coagulase-negative staphylococci among patients with post-cardiac surgery infections
- 2002
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Ingår i: Journal of Hospital Infection. - : Elsevier BV. - 0195-6701 .- 1532-2939. ; 52:1, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- Coagulase-negative staphylococci (CoNS) are important causes of hospital-acquired infections such as infections after cardiac surgery. Efforts to reduce these infections are hampered by the lack of knowledge concerning the epidemiology of CoNS in this setting. Forty strains of CoNS collected during the surgical revision of 27 patients operated on between 1997 and 2000 were analysed. Strains were also collected from the ambient air in the operating suite. Their pulsed-field gel electrophoresis (PFGE) characteristics and antibiotic resistance were analysed. Using PFGE 19 of 40 strains from 15 of 27 patients were shown to belong to one clone, and strains from this clone were also isolated from the ambient air. This clone had caused infections throughout the period. Antibiotic resistance did not correlate with PFGE patterns. Using PFGE one clone could be identified that caused 56% of the CoNS infections during this period. A strain from this clone was also found in the air of the operating suite suggesting the origin of the CoNS causing infections was the hospital environment.
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| 8. |
- Tegnell, Anders, 1956-, et al.
(författare)
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Changes in the appearance and treatment of deep sternal infections
- 2002
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Ingår i: Journal of Hospital Infection. - : Elsevier BV. - 0195-6701 .- 1532-2939. ; 50:4, s. 298-303
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Tidskriftsartikel (refereegranskat)abstract
- The Department of Thoracic Surgery at the University Hospital, Linköping, Sweden, has actively followed up infectious complications of cardiac surgery since 1989. The aim of this study was to investigate whether changes occurred during the 1990s in the appearance and the management of deep infections. This was done by studying patients undergoing surgical revision of infected wounds. We studied 42 patients during 1990–94 and 49 during 1997–98 (total number of operations in these periods, 3075 and 1646, respectively). Pre-operative and intra-operative variables were recorded for the two patient populations. The proportion of cardiac surgery procedures followed by a surgical revision for an infection in the sternal wound increased between the two periods (1.4% vs. 3.0%). Variables associated with the surgical procedures preceding the infection remained unchanged. In the later period, treatment was started earlier (64 vs. 24 days), and the length of antibiotic treatment was decreased (115 vs. 72 days). The incidence of osteomyelitis of the sternal bone was lower (61% vs. 27%). It appears that as the proportion of patients undergoing surgical revision increased, management of the infections became more effective, with aggressive surgical and antibiotic treatment policies and shorter treatment periods. This indicates that in order to evaluate the overall impact of measures designed to reduce infections after cardiac surgery, not only the incidence of infection needs to be followed up but other factors also need to be taken into account.
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| 9. |
- Tegnell, Anders, 1956-, et al.
(författare)
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Coagulase-negative staphylococci and sternal infections after cardiac operation
- 2000
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Ingår i: Annals of Thoracic Surgery. - 0003-4975 .- 1552-6259. ; 69:4, s. 1104-1119
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Tidskriftsartikel (refereegranskat)abstract
- Background. Coagulase negative staphylococci (CoNS) have been recognized as important pathogens in nosocomial infections, especially in connection with implanted foreign materials. In cardiac operation they are among the most common pathogens isolated from infected sternal wounds. The definition of the infection is very important. In this study we focus on deep postoperative chest infections.Methods. By studying 33 infected patients retrospectively and comparing them to 33 matched uninfected controls, we studied the characteristics and costs of the infections.Results. Typical for these infections is the late and insidious onset, and that the infections initially give only minor symptoms such as pain, redness, and serous secretion. We found the following risk factors for infection: number of preoperative days in a hospital, the total length of the operation, and if the patient had undergone an early reoperation due to causes other than infection. This kind of infection more than doubled the hospital costs for the patients affected.Conclusions. Coagulase negative staphylococci are the most important pathogens in deep postoperative infections in this material. They cause infections that are difficult to recognize since they give only discrete symptoms and start well after the patients leave the hospital. The risk factors for patients with CoNS infections are mostly associated with a long exposure to the hospital environment. The treatment is often difficult and costly because of multiresistant bacteria and frequent need for repeated surgical revisions.
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| 10. |
- Tegnell, Anders, 1956-, et al.
(författare)
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Wound infections after cardiac surgery : a Wound Scoring System may Improve Early Detection
- 2002
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 36:1, s. 60-64
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Tidskriftsartikel (refereegranskat)abstract
- Objective - This study was aimed at describing the early development of wound infections after cardiac surgery to identify markers for upcoming infections.Design - We followed a cohort of 200 patients for 3 months after cardiac surgery to establish the incidence of all types of postoperative infections. Wound healing and C-reactive protein (CRP) were followed for the first 2 weeks.Results - A total of 175 patients out of 200 could be followed up. Using a broad definition of wound infection a total of 30% of the patients had some kind of wound infection. The diagnosis of most infections occurred after the patients had left the cardiac surgery unit (median 12 d after surgery). Our wound scoring method shows significant differences at an early stage between infected and non-infected wounds. At the time of diagnoses CRP was elevated in patients with deep sternal infection.Conclusion - A long follow-up period is needed to establish the true incidence of infection. Wound scoring can give an early indication of wound infections and CRP can help in the diagnoses of deep infections.
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