| 1. |
- Davidsson, Sabina, 1972-
(författare)
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Infection induced chronic inflammation and it's association with prostate cancer initiation and progression
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An association between cancer development and inflammation has long been suggested. Approximately 20% of all human cancers in adults are assumed to result from chronic inflammation. The aim of this thesis was to investigate if infection-induced chronic inflammation plays a role in prostate carcinogenesis.Our results revealed a greater infiltration of the bacterium Propionibacterium acnes in the prostate tissue obtained from men with prostate cancer compared to men without any histological evidence of the disease. These findings indicate that prostate cancer could potentially be included in the list of cancers with an infectious etiology.Further, we investigated whether chronic inflammation has a role in disease progression. Our results demonstrated that men with lethal prostate cancer had pronounced infiltration of immune cells with suppressive function of the anti-tumor immune response compared to men with a more indolent prostate cancer.Confirmation of our results may open up avenues for targeted prostate cancer treatment by offering men with chronic inflammation alternative therapies such as anti-inflammatory drugs. If the involvement of P. acnes in prostate cancer development is replicated in other studies, vaccination therapies may be feasible. To further individualize prostate cancer therapy, bolstering the anti-tumor immune response in order to reduce tumor progression may be determined to be advantageous for some patients.
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| 2. |
- Asfaw Idosa, Berhane, 1977-
(författare)
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Inflammasome polymorphisms and the Inflammatory Response to Bacterial Infections
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- NLRP3 inflammasome; a key component of the innate immune system, can be activated by a number of pathogens and other threats of the body. Activation of the NLRP3 inflammasome triggers caspase-1 mediated maturationof IL-1β and IL-18. Polymorphisms Q705K and C10X are two gene variants of the NLRP3 inflammasome that combined or per se have been associated with higher risk and severity of chronic inflammation and excessive production of IL-1β. Host genetic factors have been found an important determinants of susceptibility of infectious diseases and disease outcome. The aims of this thesis were to investigate the association between polymorphisms Q705K and C10X with bacterial infections and the inflammatory response, moreover to determine the inflammasome activation state in healthy carriers of these polymorphisms. The data of the thesis show higher levels of IL-1β and IL-33 in healthy carriers of combined polymorphisms of Q705K and C10X as compared to non-carrier controls. This may provide individuals with combined polymorphisms a more robust innate immune response against pathogens, but could also lead to the onset of chronic inflammation, and excessive inflammation during acute infection. In addition, individuals with C10X polymorphism per se showed association with the presence of bacteremia as compared withhealthy blood donors. No association was found in severely ill patients with negative blood culture bottle. In addition, the results show that LOS of N. meningitidis is responsible for the priming and activating steps of the inflammasome. The non-LOS components were found to contribute to the priming step. A higher inflammatory response to N. meningitidis was found in individuals who were non-carriers of the polymorphisms than individuals with the Q705K and C10X per se or combined regardless of the strain of bacteria. Taken together, the gene variations of the NLRP3 inflammasome are of importance in explaining inter-individual variation in susceptibility to infectious diseases.
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| 3. |
- Khan, Faisal Ahmad, 1986-
(författare)
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Carbapenemase-Producing Enterobacteriaceae in Wastewater-Associated Aquatic Environments
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The emergence of carbapenem resistance due to the carbapenem-hydrolyzing enzymes (carbapenemases) in Enterobacteriaceae has led to limited therapeutic options. The increased resistance to these “last-resort” antibiotics is fueled by overuse and misuse of antibiotics in human medicine and agriculture. According to the One-Health concept, the microbiomes of humans, animals and natural environments are interconnected reservoirs of antibiotic resistance genes (ARGs) and changes in one compartment will affect the other compartments. Thus, the environmental waters exposed to the pathogens, ARGs and other contaminants of human origin can play a significant role in the spread of resistance. The study aimed to characterize carbapenemase-producing Enterobacteriaceae (CPE) and ARGs in wastewaters and associated river and lake waters in Örebro, Sweden. The study also analyzed de novo development of resistance in Klebsiella oxytoca during long-term growth in river water and the effect of temperature on the emergence of resistance. OXA-48-producing Escherichia coli (ST131) and VIM-1-producing K.oxytoca (ST172) were repeatedly detected in the wastewaters and associated river, suggesting that these isolates were persistently present in these environments. Furthermore, K. oxytoca ST172 isolated from the river was genetically similar to two isolates previously recovered from patients in a local hospital, which shows the possibility of transmission of CPE from hospital to aquatic environments. A high diversity of ARGs was detected in these environments especially in hospital wastewater where ten different carbapenemase genes were detected. These results emphasized that the effective treatment of wastewaters must be ensured to reduce or eliminate the spread of antibiotic resistance. Increased resistance to meropenem (up to 8-fold) and ceftazidime (>10-fold) was observed in K. oxytoca after exposure to both river and tap water after 600 generations and resistance emerged earlier when the bacteria was grown at the higher temperature. The exposure to contaminants and increased environmental temperature may induce similar changes in the environmental microbiome, generating novel resistant variants at accelerated rates that may pose a significant threat to human health.
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| 4. |
- Månsson, Emeli, 1978-
(författare)
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Molecular epidemiology of Staphylococcus epidermidis in prosthetic joint infections
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Staphylococcus epidermidis is ubiquitous in the human microbiota, but also an important pathogen in healthcare-associated infections, such as prosthetic joint infections (PJIs). In this thesis, aspects of the molecular epidemiology of S. epidermidis in PJIs were investigated with the aim of improving our understanding of the pre- and perioperative measures required to reduce the incidence of S. epidermidis PJIs.In Paper I, S. epidermidis retrieved from air sampling in the operating field during arthroplasty was characterized by multilocus sequence typing and antibiotic susceptibility testing. No isolates belonging to sequence types (STs) 2 and 215, previously associated with PJIs, were found in the air of the operating field. During air sampling, several Staphylococcus pettenkoferi isolates were identified, and as a spin-off of Paper I, the genomic relatedness of these isolates to S. pettenkoferi isolates from blood cultures was described in Paper II.In Paper III, genetic traits distinguishing S. epidermidis isolated from PJIs were determined using genome-wide association study accounting for population effects after whole-genome sequencing (WGS) of a population- based 10-year collection of S. epidermidis isolates from PJIs and of nasal isolates retrieved from patients scheduled for arthroplasty. Genes associated with antimicrobial agents used for prophylaxis in arthroplasty, i.e., beta-lactam antibiotics, aminoglycosides, and chlorhexidine, were associated with PJI origin. S. epidermidis from PJIs were dominated by the ST2a, ST2b, ST5, and ST215 lineages.In Paper IV, selective agar plates were used to investigate colonization with methicillin resistant S. epidermidis (MRSE) in patients scheduled for arthroplasty. MRSE were further characterized by WGS. A subset of patients was found to harbour PJI-associated S. epidermidis lineages in their microbiota before hospitalization, but no isolates belonging to the ST2a lineage nor any rifampicin-resistant isolates were retrieved.
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| 5. |
- Sahdo, Berolla, 1984-
(författare)
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Inflammasomes : defense guardians in host-microbe defence
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The inflammasomes are emerging as key regulators of the innate immune response as they response to cellular infection, tissue damage and/or stress. Activated inflammasomes provide a signalling platform for caspase-1 activation which subsequently processes the maturation of interleukin (IL)-1β and IL-18, and in addition promotes cell death, named pyroptosis. These effector mechanisms of the inflammasome constitute an important part of the innate immune response in host-defence.The aims of this thesis were to elucidate if the inflammasome is activated by specific pathogens, and if genetic variations lead to susceptibility to severe inflammatory diseases, such as blood stream infections. We found that the commensal pathogens Staphylococcus aureus and Propionibacterium acnes induce caspase-1 activation, the latter being a stronger activator. The data also propose that it is rather the bacterial ligands than the secreted toxins of P. acnes that induce inflammasome activation. Even though the S. aureus PVL-toxin induces a caspase-1 activation, involvement of other virulence factors are of importance. Upon S. aureus and P. acnes stimulation, inter-individual variations were found, implying that the characteristics of the host innate immune system, rather than the properties of the bacteria, are decisive for the inflammatory response. Indeed, healthy individuals with the combined polymorphisms of the NLRP3 inflammasome (C10X/Q705K) have higher levels of spontaneous IL-1β, and most intriguingly C10X polymorphism showed a strong correlation with patients with bacteremia.In conclusion, these studies suggest that different pathogens activate the inflammasomes to various degrees. The genetics of the host innate immune system, rather than the properties of the bacteria, define the inflammatory response against these bacteria, and specific genetic variations such as C10X polymorphism can increase the susceptibility for disease development.
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| 6. |
- Sahlberg Bang, Charlotte, 1967-
(författare)
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Carbon monoxide and nitric oxide as antimicrobial agents : focus on ESBL-producing uropathogenic E.coli
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Urinary tract infections (UTI) are common in humans and most often caused by uropathogenic Escherichia coli (E. coli). Extended-spectrum beta-lactamase (ESBL)-producing E. coli are increasing worldwide and they are frequently multidrug-resistant with limited treatment options. The overall aim of this thesis was to study the role of the host-derived factors nitric oxide (NO) and carbon monoxide (CO) as antimicrobial agents against ESBL-producing uropathogenic strains of E. coli (UPEC).The NO-donor DETA/NO caused a temporary growth inhibition in ESBL-producing UPEC. The antibacterial effect of DETA/NO was improved when DETA/NO was combined with miconazole, a pharmacological inhibitor of NO-protective mechanisms. Combination treatment with DETA/NO, miconazole and polymyxin B nonapeptid prolonged the bacteriostatic effect in the majority of examined isolates. The CO-donor CORM-2 showed a pronounced antibacterial effect in ESBL-producing UPEC with a fast bactericidal effect. Moreover, CORM-2 was shown to reduce the bacterial viability of ESBL-producing UPEC grown under biofilm-like conditions and to decrease the bacterial colonization of human bladder epithelial cells. A microarray analysis was performed to define transcriptomic targets of CORM-2 after a single exposure and after repeated exposure to CORM-2. Many processes were affected by CORM-2, including a downregulation in energy metabolism and biosynthesis pathways and upregulation of the SOS response and DNA repair. Repeated exposure to CORM-2 did not change the gene expression patterns or fold changes and the growth inhibitory response to CORM-2 was not altered after repeated exposure.In conclusion, NO- and CO-donors have antibacterial effects against ESBL-producing UPEC and may be interesting candidates for development of new antibiotics to treat UTI caused by multidrug-resistant uropathogens.
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| 7. |
- Sid Ahmed, Mazen, 1970-
(författare)
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Molecular Epidemiology and Mechanisms of Antibiotic Resistance in Clinical Isolates of Pseudomonas aeruginosa from Qatar
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inappropriate and excessive use of antibiotics promotes antimicrobial resistance (AMR), particularly in Gram-negative bacteria (GNB). There is a noticeable increase in nosocomial infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa, which is associated with significant morbidity, mortality, and an increase in cost management. Although this is a global problem, there is a lack of sufficient data on regional differences that can contribute towards effective AMR management. This thesis presents a study of MDR-P. aeruginosa at five different hospitals in Qatar conducted prospectively between October 2014 - September 2017. The aim was to study the epidemiology, microbiological and clinical characteristics of MDR-P. aeruginosa infections as well as investigate the activity of new antibiotic combinations against these bacteria. The prevalence of MDR-P. aeruginosa isolates in the first year was 8.1% (205/2533), isolated from different clinical specimens, but the majority were from respiratory infections (44.9%, n=92). Most cases were exposed to antibiotics during the 90 days prior to isolation (85.4%, n=177), and the resistance to cefepime, ciprofloxacin, piperacillin/tazobactam, meropenem was >90%. To compare pre- and post-Antimicrobial Stewardship Program, there was a significant reduction in antibiotic consumption by 30.4% of total inpatient antibiotic prescriptions (p=0.008) and the prevalence of MDR-P. aeruginosa significantly declined from 9% to 5.4% (p=0.019). The in vitro investigation of ceftazidime/avibactam (CZA) and ceftolozane/tazobactam (C/T) against MDR-P. aeruginosa isolates, showed promising results with susceptibility of 68.8% (n=141/205) and 62.9% (n=129/205), respectively, which was higher than other antipseudomonal agents except colistin. Seventy-five isolates that were sequenced belonged to 29 different sequence types, with ST235 being predominant at 21.3% (16/75). Among the 42 isolates that were resistant to CZA and/or C/T, the most prevalent genes were blaOXA-488 and blaVEB-9 detected in 45.2% (19/42) of isolates. Spearman’s analysis showed that resistance to CZA and C/T were positively correlated with the presence of blaOXA-10, blaPDC-2a, blaVIM-2, and blaVEB-9 , respectively. The study highlights potential key mechanisms that could explain the resistance of MDR-P. aeruginosa to the new antibiotic combinations.
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| 8. |
- Wildeman, Peter, 1975-
(författare)
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Prosthetic Joint Infection of the Hip : Cause and Effect
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Every year, 18 000 patients in Sweden and more than 1 million worldwide undergo total hip arthroplasty (THA). The operation is of great benefit to patients, but is associated with several complications. Prosthetic joint infections (PJIs) are among the most common complications, and can be devastating in terms of suffering for the patient and cost for the healthcare provider. The aim of this thesis was to investigate different aspects of PJIs in order to gain a better understanding of the causes and effects of infection. Four studies were conducted covering genomic analysis of the causative organism, identification of risk factors for failure of treatment, evaluation of a national infection control program aimed at reducing the burden of infections (PRISS: Prosthesis-related infections shall be stopped), and examination of the long-term impact of a PJI on the patient’s health through patient-reported measurement questionnaires.The main findings were as follows. Commensal bacteria such as Cutibacterium avidum have the potential to cause PJIs, and should be specially accounted for when performing hip surgery with an anterior approach. S. aureus is both a commensal and a pathogen with invasive capacity, and the commensal strains do not differ from the PJI strains regarding prevalence of virulence genes and clonal complexes. The genomic traits of pathogens had no impact on treatment success or eradication of infection in S. aureus PJIs The long-term effects of a PJI in the hip include increased mortality, lower quality of life, and decreased hip function. The incidence of PJIs was higher following the PRISS project. Increasing risk factors contributing to PJI explain the increasing incidence of PJI after primary THA.In conclusion, PJIs of the hip have multifactorial causes which are difficult to reduce, and long-term effects are severe.
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| 9. |
- Ahlstrand, Erik, 1974-
(författare)
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Coagulase-negative staphylococci in hematological malignancy
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bacterial infections are common in hematological malignancy. Coagulase-negative staphylococci (CoNS) are among the most prevalent causes of bacteremia in patients with hematological malignancies.In this thesis, different aspects of CoNS in hematological malignancy have been studied in four papers:In paper 1, CoNS blood culture isolates from patients with hematological malignancies treated at the University Hospital of Örebro from 1980 to 2009 were revaluated for the presence of reduced sensitivity to glycopeptides. A high incidence of heterogeneous-intermediate glycopeptide resistance was observed and there was a trend towards increasing incidence of this phenotype over time.In paper 2, the colonization pattern of CoNS among patients undergoing intensive chemotherapy for hematological malignancy was investigated. A successive homogenization and an accumulation of CoNS phenotypes mutually present in a majority of included patients were demonstrated.In paper 3, a PCR method to determine the clinical significance of positive blood cultures of the CoNS species Staphylococcus epidermidis was evaluated. The test failed to discriminate bloodstream infection from blood culture contamination.Finally, in paper 4, the long-term molecular epidemiology of S. epidermidis blood culture isolates from patients with hematological malignancies was studied with multilocus sequence typing. A predominance of sequence type 2 was demonstrated during the entire 30 year study period.In conclusion, the results are consistent with that CoNS have established as important pathogens by its capacity to colonize the human skin, its ability to reside and spread in the hospital environment and its rapid adaptation to stressors such as antimicrobials.
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| 10. |
- Fagerström, Anna, 1980-
(författare)
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Long-term molecular epidemiology of extended-spectrum β-lactamase producing Escherichia coli in a low-endemic setting
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Escherichia coli is a commensal inhabitant in the gastro-intestinal tract of humans and animals but it is also the most common bacterial species causing urinary tract infection, which ranges in severity from distal cystitis to urosepsis and septic shock. During the past decades, the prevalence of antibiotic resistant E. coli has increased worldwide. Extended-spectrum β-lactamases (ESBL) causes resistance to β-lactam antibiotics, the most widely used class of antibiotics. The genes encoding ESBL, bla, are usually carried on conjugative plasmids, which can be transferred between different bacterial lineages and different species. These plasmids frequently also carry resistance genes to additional antibiotic classes, and ESBL-producing E. coli are therefore often multidrug-resistant. The aim of this thesis was to describe the long-term molecular epidemiology of ESBL-producing E. coli in Örebro County during the time when they first started to emerge. In addition, potential transmission to the environment was investigated by performing a comparative analysis on ESBL-producing E. coli isolated from patients and from the aquatic environment in Örebro city. In general, the E. coli population was genetically diverse, but the pandemic lineage ST131, first identified in 2004, appears to have been responsible for the dramatic increase of CTX-M-15-producing E.coli observed during the late 2000s. CTX-M-15 was the most prevalent ESBL-type followed by CTX-M-14 and these genes were mainly found on plasmids belonging to the IncF or IncI1 families. Continuous horizontal transmission of IncI1 ST31 and ST37 plasmids between diverse E. coli lineages have also contributed to the dissemination of blaCTX-M-15 in Örebro County. Extended spectrum β-lactamase-producing E. coli were found to be common in the aquatic environment in Örebro city and E. coli lineages genetically similar to those causing infections in humans were present in environmental waters indicating that transmission of ESBL-producing E. colifrom humans to the aquatic environment likely has occurred.
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