| 1. |
- Edberg, Andreas, et al.
(författare)
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A comparative study of three different PCR assays for detection of Mycoplasma genitalium in urogenital specimens from men and women
- 2008
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 57:Pt 3, s. 304-309
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare conventional 16S rRNA gene PCR, real-time 16S rRNA gene PCR and real-time Mycoplasma genitalium adhesin protein (MgPa) gene PCR as detection methods for M. genitalium infection. The study also determined the prevalence of M. genitalium in male and female patients attending a sexually transmitted infections clinic in a rural area in the west of Sweden. First void urine (FVU) and/or urethral swabs were collected from 381 men, and FVU and/or cervical swabs and/or urethral swabs were collected from 298 women. A total of 213 specimens were used in the PCR comparative study: 98 consecutively sampled specimens from patients enrolled in the prevalence study, 36 consecutively sampled specimens from patients with symptoms of urethritis and 79 specimens from patients positive for M. genitalium by real-time MgPa gene PCR in the prevalence study. A true-positive M. genitalium DNA specimen was defined as either a specimen positive in any two PCR assays or a specimen whose PCR product was verified by DNA sequencing. The prevalence of M. genitalium infection in men and women was 27/381 (7.1 %) and 23/298 (7.7 %), respectively. In the PCR comparative study, M. genitalium DNA was detected in 61/76 (80.3 %) of true-positive specimens by conventional 16S rRNA gene PCR, in 52/76 (68.4 %) by real-time 16S rRNA gene PCR and in 74/76 (97.4 %) by real-time MgPa gene PCR. Real-time MgPa gene PCR thus had higher sensitivity compared with conventional 16S rRNA gene PCR and had considerably increased sensitivity compared with real-time 16S rRNA gene PCR for detection of M. genitalium DNA. Real-time MgPa gene PCR is well suited for the clinical diagnosis of M. genitalium.
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| 2. |
- Kesarimangalam, Sriram, 1983, et al.
(författare)
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High diversity of bla NDM-1 -encoding plasmids in Klebsiella pneumoniae isolated from neonates in a Vietnamese hospital
- 2022
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Ingår i: International Journal of Antimicrobial Agents. - : Elsevier BV. - 1872-7913 .- 0924-8579. ; 59:2
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The carbapenemase-encoding gene blaNDM-1 has been reported in Vietnam during the last 10 years, and blaNDM-producing Enterobacteriaceae are now silently and rapidly spreading. A key factor behind dissemination of blaNDM-1 is plasmids, mobile genetic elements that commonly carry antibiotic resistance genes and spread via conjugation. The diversity of blaNDM-1-encoding plasmids from neonates at a large Vietnamese hospital was characterized in this study. Methods: 18 fecal Klebsiella pneumoniae and Klebsiella quasipneumoniae isolates collected from 16 neonates at a large pediatric hospital in Vietnam were studied using optical DNA mapping (ODM) and next-generation sequencing (NGS). Plasmids carrying the blaNDM-1 gene were identified by combining ODM with Cas9 restriction. The plasmids in the isolates were compared to investigate whether the same plasmid was present in different patients. Results: Although the same plasmid was found in some isolates, ODM confirmed that there were at least 10 different plasmids encoding blaNDM-1 among the 18 isolates, thus indicating wide plasmid diversity. The ODM results concur with the NGS data. Interestingly, some isolates had two distinct plasmids encoding blaNDM-1 that could be readily identified with ODM. The coexistence of different plasmids carrying the same blaNDM-1 gene in a single isolate has rarely been reported, probably because of limitations in plasmid characterization techniques. Conclusions: The plasmids encoding the blaNDM-1 gene in this study cohort were diverse and may represent a similar picture in Vietnamese society. The study highlights important aspects of the usefulness of ODM for plasmid analysis.
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| 3. |
- Abrahamsson, Thomas, et al.
(författare)
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Low gut microbiota diversity in early infancy precedes asthma at school age
- 2014
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 0954-7894 .- 1365-2222. ; 44:6, s. 842-850
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Tidskriftsartikel (refereegranskat)abstract
- Background Low total diversity of the gut microbiota during the first year of life is associated with allergic diseases in infancy, but little is known how early microbial diversity is related to allergic disease later in school age. Objective To assess microbial diversity and characterize the dominant bacteria in stool during the first year of life in relation to the prevalence of different allergic diseases in school age, such as asthma, allergic rhinoconjunctivitis (ARC) and eczema. Methods The microbial diversity and composition was analysed with barcoded 16S rDNA 454 pyrosequencing in stool samples at 1week, 1month and 12months of age in 47 infants which were subsequently assessed for allergic disease and skin prick test reactivity at 7years of age (ClinicalTrials.gov ID NCT01285830). Results Children developing asthma (n=8) had a lower diversity of the total microbiota than non-asthmatic children at 1week (P=0.04) and 1month (P=0.003) of age, whereas allergic rhinoconjunctivitis (n=13), eczema (n=12) and positive skin prick reactivity (n=14) at 7years of age did not associate with the gut microbiota diversity. Neither was asthma associated with the microbiota composition later in infancy (at 12months). Children having IgE-associated eczema in infancy and subsequently developing asthma had lower microbial diversity than those that did not. There were no significant differences, however, in relative abundance of bacterial phyla and genera between children with or without allergic disease. Conclusion and Clinical Relevance Low total diversity of the gut microbiota during the first month of life was associated with asthma but not ARC in children at 7years of age. Measures affecting microbial colonization of the infant during the first month of life may impact asthma development in childhood.
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| 4. |
- Forsberg, Anna, et al.
(författare)
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Pre- and post-natal Lactobacillus reuteri supplementation decreases allergen responsiveness in infancy
- 2013
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Ingår i: Clinical and Experimental Allergy. - : Wiley-Blackwell. - 0954-7894 .- 1365-2222. ; 43:4, s. 434-442
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWe have previously shown that Lactobacillus reuteri supplementation from pregnancy week 36 and to the infant through the first year of life decreased the prevalence of IgE-associated eczema at 2 years. The underlying immunological mechanisms are unknown, however.ObjectiveTo investigate the immunomodulatory effect of probiotic supplementation on allergen- and mitogen-induced immune responses in children until 2 years of age.MethodsBlood mononuclear cells were collected at birth, 6, 12 and 24 months from 61 children (29 probiotic and 32 placebo treated) and cultured with ovalbumin, birch and cat extract and Phytohaemagglutinin (PHA). Cytokine and chemokine secretion was determined using an in-house multiplexed Luminex assay and ELISA. Real-time PCR was performed to investigate the Ebi3, Foxp3, GATA-3 and T-bet mRNA expression.ResultsProbiotic treatment was associated with low cat-induced Th2-like responses at 6 months (IL-5, P = 0.01, and IL-13, P = 0.009), with a similar trend for IL-5 at 12 months (P = 0.09). Cat-induced IFN-γ responses were also lower after probiotic than after placebo treatment at 24 months (P = 0.007), with similar findings for the anti-inflammatory IL-10 at birth (P = 0.001) and at 12 months (P = 0.009). At 24 months, Th2-associated CCL22 levels were lower in the probiotic than in the placebo group after birch stimulation (P = 0.02), with a similar trend after ovalbumin stimulation (P = 0.07). Lower CCL22 levels were recorded at 12 and 24 months (P = 0.03 and P = 0.01) after PHA stimulation.Conclusion and Clinical RelevanceLactobacillus reuteri supplementation decreases allergen responsiveness and may enhance immunoregulatory capacity during infancy. L. reuteri supplementation from week 36 and during the first year of life significantly decreases IgE-associated eczema and lowers allergen and mitogen responsiveness.
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| 5. |
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| 6. |
- Bally, Marta, 1981, et al.
(författare)
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Norovirus GII.4 Virus-like Particles Recognize Galactosylceramides in Domains of Planar Supported Lipid Bilayers.
- 2012
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 51:48, s. 12020-4
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Tidskriftsartikel (refereegranskat)abstract
- A sticky situation: Domain-dependent recognition of the glycosphingolipid galactosylceramide by norovirus-like particles (see picture; red/yellow) is shown using supported lipid bilayers (purple) as model membranes. Optimal ligand presentation is found to promote strong binding to GalCer. This presentation can be found at the edges of the glycosphingolipid-enriched domains (green) and binding is repressed in the absence of these domains.
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| 7. |
- Raffetseder, Johanna
(författare)
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Interplay of human macrophages and Mycobacterium tuberculosis phenotypes
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mycobacterium tuberculosis (Mtb) is the pathogen causing tuberculosis (TB), a disease most often affecting the lung. 1.5 million people die annually due to TB, mainly in low-income countries. Usually considered a disease of the poor, also developed nations recently put TB back on their agenda, fueled by the HIV epidemic and the global emergence of drug-resistant Mtb strains. HIV-coinfection is a predisposing factor for TB, and infection with multi-drug resistant and extremely drug resistant strains significantly impedes and lengthens antibiotic treatment, and increases fatality. Mtb is transmitted from a sick individual via coughing, and resident macrophages are the first cells to encounter the bacterium upon inhalation. These cells phagocytose intruders and subject them to a range of destructive mechanisms, aiming at killing pathogens and protecting the host. Mtb, however, has evolved to cope with host pressures, and has developed mechanisms to submerge macrophage defenses. Among these, inhibition of phagosomal maturation and adaptation to the intracellular environment are important features. Mtb profoundly alters its phenotype inside host cells, characterized by altered metabolism and slower growth. These adaptations contribute to the ability of Mtb to remain dormant inside a host during latent TB infection, a state that can last for decades. According to recent estimates, one third of the world’s population is latently infected with Mtb, which represents a huge reservoir for active TB disease. Mtb is also intrinsically tolerant to many antibiotics, and adaptation to host pressures enhances tolerance to first-line TB drugs. Therefore, TB antibiotic therapy takes 6 to 9 months, and current treatment regimens involve a combination of several antibiotics. Patient noncompliance due to therapeutic side effects as well as insufficient penetration of drugs into TB lesions are reasons for treatment failure and can lead to the rise of drug-resistant populations. In view of the global spread of drug-resistant strains, new antibiotics and treatment strategies are urgently needed.In this thesis, we studied the interplay of the primary host cell of Mtb, human macrophages, and different Mtb phenotypes. A low-burden infection resulted in restriction of Mtb replication via phagolysosomal effectors and the maintenance of an inactive Mtb phenotype reminiscent of dormant bacteria. Macrophages remained viable for up to 14 days, and profiling of secreted cytokines mirrored a silent infection. On the contrary, higher bacterial numbers inside macrophages could not be controlled by phagolysosomal functions, and intracellular Mtb shifted their phenotype towards active replication. Although slowed mycobacterial replication is believed to render Mtb tolerant to antibiotics, we did not observe such an effect. Mtb-induced macrophage cell death is dependent on ESAT6, a small mycobacterial virulence factor involved in host cell necrosis and the spread of the pathogen. Although well-studied, the fate of ESAT6 inside infected macrophages has been enigmatic. Cultivation of Mtb is commonly carried out in broth containing detergent to avoid aggregation of bacilli due to their waxy cell wall. Altering cultivation conditions revealed the presence of a mycobacterial capsule, and ESAT6 situated on the mycobacterial surface. Infection of macrophages with this encapsulated Mtb phenotype resulted in rapid ESAT6-dependent host cell death, and ESAT6 staining was lost as bacilli were ingested by macrophages. These observations could reflect the earlier reported integration of ESAT6 into membranes followed by membrane rupture and host cell death.In conclusion, the work presented in this thesis shows that the phenotype of Mtb has a significant impact on the struggle between the pathogen and human macrophages. Taking the bacterial phenotype into account can lead to the development of drugs active against altered bacterial populations that are not targeted by conventional antibiotics. Furthermore, deeper knowledge on Mtb virulence factors can inform the development of virulence blockers, a new class of antibiotics with great therapeutic potential.
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| 8. |
- Yakymenko Alkaissi, Lina, 1988-
(författare)
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Bacterial epithelial interaction in intestinal inflammation
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The intestine is constantly exposed to bacteria, invading viruses and ingested food. The intestinal barrier serves as a gate preventing passage of harmful components, and at the same time maintaining absorption of nutrients and water. There are over 300 different bacteria species in the human gastrointestinal tract (GI) comprising over 10 times as many cells as the human body. These bacteria are both of commensal and pathogenic strains in which commensal bacteria and antimicrobial peptides have an important role of controlling the intestinal colonization. The intestinal flora is sampled by the membranous cells (M cells) that are present in the follicle associated epithelium (FAE). Antigens encounter immune cells found in Peyer’s patches located in the distal ileum with FAE overlaying them. Due to environmental factors, genetic predisposition, immune dysregulation or dysbiosis the balance can be shifted which, in turn, will lead to the defect in the barrier function, leading to the development of disorders such as Crohn’s disease (CD). CD is a chronic inflammation in the GI tract, often originating in the distal ileum in FAE and associated with an increased number of adherent invasive strains of bacteria. Specifically adherent invasive E.coli (AIEC) that have been isolated from the ileum and colon of CD patients.The aim of the present thesis was to study bacterial epithelial interaction during inflammation in in vivo, ex vivo and in vitro models.In the first project we found that that Faecalibacterium prausnitzii (FP), possess anti-inflammatory properties in the ileum of an in vivo DSS induced colitis mouse model.In the second project, we discovered that infliximab, known to have anti-inflammatory effects by binding soluble TNF and blocking TNF receptors, reduces bacterial transcytosis across colonic biopsies of CD patients and decreases transcytosis and internalization in cell monolayers in vitro. Moreover, we demonstrated that HM427 bacteria, isolated from colonic mucosa of CD patients, uses lipid raft formations to penetrate the barrier under the influence of TNF in an in vitro model.In project three, we demonstrated that LF82 bacteria, which is an adherent invasive strain of E.coli that has been isolated from the ileum of CD patients, exploits FAE of CD patients and non-IBD control patients to penetrate the barrier via the CEACAM6 receptor and long polar fimbriae. We further demonstrated that there is an increased expression of CEACM6 receptor in the FAE of CD patients, which leads to increased transcytosis of LF82 compared to non-IBD control group.In project four, our results suggested that human α-defensin 5 significantly decreases the passage of LF82 bacteria in an in vitro and ex vivo models. Moreover, we demonstrated that CD patients have a lower expression of human α-defensin 5 in the crypts compared to the non-IBD control patients.Taken together, our findings have given a novel insight into the etiology of CD and into the mechanisms involved in bacterial-epithelial interaction in CD.
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| 9. |
- Palkovicova, K., et al.
(författare)
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A monoclonal antibody specific for a unique biomarker, virenose, in a lipopolysaccharide of Coxiella burnetii
- 2009
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Ingår i: Clinical Microbiology and Infection. - : Elsevier. - 1198-743X .- 1469-0691. ; 15 Suppl 2, s. 183-4
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Tidskriftsartikel (refereegranskat)abstract
- Q fever is a zoonotic disease caused by Coxiella burnetii. Easy aerosol dissemination, strong environmental persistence and high infectivity make the bacterium a serious threat for humans and animals. A rapid, sensitive and specific test for the infectious agent is still a challenge in the field. C. burnetii expresses a spectrum of amphophilic macromolecules on its surface. Among them, a lipopolysaccharide (LPS) is of particular biological, immunological and medical significance [1]. Upon serial laboratory passages in yolk sacs of embryonated hen eggs, C.
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| 10. |
- Welin, Amanda, 1983, et al.
(författare)
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Inside or outside the phagosome? The controversy of the intracellular localization of Mycobacterium tuberculosis.
- 2012
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Ingår i: Tuberculosis (Edinburgh, Scotland). - : Elsevier BV. - 1873-281X .- 1472-9792. ; 92:2, s. 113-20
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Forskningsöversikt (refereegranskat)abstract
- The localization of Mycobacterium tuberculosis (Mtb) inside the macrophage has been a matter of debate in recent years. Upon inhalation, the bacterium is taken up into macrophage phagosomes, which are manipulated by the bacterium. Subsequent translocation of the bacilli into the cytosol has been observed by several groups, while others fail to observe this phenomenon. Here, we review the available literature in favour of and against this idea, and scrutinize the existing data on how human macrophages control Mtb infection, relating this to the robustness of the host cell. We conclude that both phagosomal maturation inhibition and escape from the phagosome are part of the greater infection strategy of Mtb. The balance between the host cell and the infecting bacterium is an important factor in determining the outcome of infection as well as whether phagosomal escape occurs and can be captured.
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