Jorunn Cavanagh - Academia.edu (original) (raw)

Papers by Jorunn Cavanagh

Research paper thumbnail of Outer membrane vesicles as realistic models of bacterial membranes in interaction studies by Surface Plasmon Resonance

bioRxiv (Cold Spring Harbor Laboratory), Jul 7, 2023

One way to mitigate the ongoing antimicrobial resistance crisis is to discover and develop new cl... more One way to mitigate the ongoing antimicrobial resistance crisis is to discover and develop new classes of antibiotics. As all antibiotics at some point needs to either cross or interact with the bacterial membrane, there is a need for representative models of bacterial membranes and efficient methods to characterize the interactions to novel antimicrobials-both to generate new knowledge and to screen compound libraries. Since the bacterial cell envelope is a complex assembly of lipids, lipopolysaccharides, membrane proteins and other components, constructing realistic synthetic liposome-based models of the membrane is both difficult and expensive. We here propose to let the bacteria do the hard work for us. Outer membrane vesicles (OMVs) are naturally secreted by Gram-negative bacteria, playing a role in communication between bacteria, as virulence factors, molecular transport or being a part of the antimicrobial resistance mechanism. OMVs consist of the bacterial outer membrane and thus inherit many components and properties of the native outer cell envelope. In this work we have isolated and characterized OMVs from E. coli mutant strains and clinical isolates of the ESKAPE members Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa. The OMVs were shown to be representative models for the bacterial membrane in terms of lipid composition with strain specific variations. The OMVs were further used to probe the interactions between OMV and antimicrobial peptides (AMPs) as model compounds by Surface Plasmon Resonance (SPR) and provide proof-of-principle that OMVs can be used as an easily accessible and highly realistic model for the bacterial surface in interaction studies. This further enables direct monitoring of the effect of induction by antibiotics, or the response to host-pathogen interactions.

Research paper thumbnail of Exhaled nitric oxide is associated with inflammatory biomarkers and risk of acute respiratory exacerbations in children with HIV‐associated chronic lung disease

HIV Medicine

ObjectivesChronic lung disease is a recognized complication in children with HIV. Acute respirato... more ObjectivesChronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels.MethodsIndividuals aged 6–19 years with HIV‐associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo‐controlled randomized trial investigating the effect of 48‐week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels.ResultsIn total, 172 participants were included in this sub‐study, 86 from the placebo...

Research paper thumbnail of Staphylococcus aureus Membrane-Derived Vesicles Promote Bacterial Virulence and Confer Protective Immunity in Murine Infection Models

Frontiers in Microbiology, Feb 20, 2018

Staphylococcus aureus produces membrane-derived vesicles (MVs), which share functional properties... more Staphylococcus aureus produces membrane-derived vesicles (MVs), which share functional properties to outer membrane vesicles. Atomic force microscopy revealed that S. aureus-derived MVs are associated with the bacterial surface or released into the surrounding environment depending on bacterial growth conditions. By using a comparative proteomic approach, a total of 131 and 617 proteins were identified in MVs isolated from S. aureus grown in Luria-Bertani and brain-heart infusion broth, respectively. Purified S. aureus MVs derived from the bacteria grown in either media induced comparable levels of cytotoxicity and neutrophil-activation. Administration of exogenous MVs increased the resistance of S. aureus to killing by whole blood or purified human neutrophils ex vivo and increased S. aureus survival in vivo. Finally, immunization of mice with S. aureus-derived MVs induced production of IgM, total IgG, IgG1, IgG2a, and IgG2b resulting in protection against subcutaneous and systemic S. aureus infection. Collectively, our results suggest S. aureus MVs can influence bacterial-host interactions during systemic infections and provide protective immunity in murine models of infection.

Research paper thumbnail of Teicoplanin resistance in Staphylococcus haemolyticus is associated with mutations in histidine kinases VraS and WalK

Diagnostic Microbiology and Infectious Disease, Mar 1, 2018

We investigated the genetic basis of glycopeptide resistance in laboratory-derived strains of S. ... more We investigated the genetic basis of glycopeptide resistance in laboratory-derived strains of S. haemolyticus with emphasis on differences between vancomycin and teicoplanin. The genomes of two stable teicoplanin-resistant laboratory mutants selected on vancomycin or teicoplanin were sequenced and compared to parental S. haemolyticus strain W2/124. Only the two nonsynonymous mutations, VraS Q289K and WalK V550L were identified. No other mutations or genome rearrangements were detected. Increased cell wall thickness, resistance to lysostaphininduced lysis and adaptation of cell growth rates specifically to teicoplanin were phenotypes observed in a sequenced strain with the VraS Q289K mutation. Neither of the VraS Q289K and WalK V550L mutations was present in the genomes of 121 S. haemolyticus clinical isolates. However, all but two of the teicoplanin resistant strains carried non-synonymous SNPs in vraSRTU and walKR-YycHIJ operons pointing to their importance for the glycopeptide resistance.

Research paper thumbnail of Chronic lung disease in children and adolescents with HIV: a case–control study

Tropical Medicine & International Health, 2020

ObjectiveTo describe the features of HIV‐associated chronic lung disease (CLD) in older children ... more ObjectiveTo describe the features of HIV‐associated chronic lung disease (CLD) in older children and adolescents living with HIV and to examine the clinical factors associated with CLD. This is a post hoc analysis of baseline data from the BREATHE clinical trial (ClinicalTrials.gov, NCT02426112).MethodsChildren and adolescents aged 6–19 years were screened for CLD (defined as a FEV1 z‐score <−1 with no reversibility post‐bronchodilation with salbutamol) at two HIV clinics in Harare, Zimbabwe, and Blantyre, Malawi. Eligible participants with CLD (cases) were enrolled, together with a control group without CLD [frequency‐matched by age group and duration on antiretroviral therapy (ART)] in a 4:1 allocation ratio. A clinical history and examination were undertaken. The association between CLD and a priori‐defined demographic and clinical covariates was investigated using multivariable logistic regression.ResultsOf the 1585 participants screened, 419 (32%) had a FEV1 z‐score <−1, ...

Research paper thumbnail of Bifidobacterium longumSubspeciesinfantisBacteremia in 3 Extremely Preterm Infants Receiving Probiotics

Emerging Infectious Diseases, 2016

Intentional introduction of disease has been rare (3). Consequently, the incident identified by T... more Intentional introduction of disease has been rare (3). Consequently, the incident identified by Thalassinou and her colleagues arouses readers' interest and inspires speculation.

Research paper thumbnail of Dual inhibition of complement C5 and CD14 attenuates inflammation in a cord blood model

Research paper thumbnail of Development of Early Life Gut Resistome and Mobilome Across Gestational Ages and Microbiota-Modifying Treatments

Research paper thumbnail of Additional file 3 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 3: Table S3. Workflow for bacterial protein surface shaving samples. X = performe... more Additional file 3: Table S3. Workflow for bacterial protein surface shaving samples. X = performed, − = not performed

Research paper thumbnail of Additional file 2 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 2: Table S2. FASTA sequences of the proteins from the cell surface shaving and LC... more Additional file 2: Table S2. FASTA sequences of the proteins from the cell surface shaving and LC-MS/MS analysis.

Research paper thumbnail of Additional file 1 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 1: Table S1. The cell surface shaving and LC-MS/MS analysis results identified 32... more Additional file 1: Table S1. The cell surface shaving and LC-MS/MS analysis results identified 325 proteins with ≥ #2 peptide-spectrum matches (PSMs).

Research paper thumbnail of Lactoferricin-inspired peptide AMC-109 augments the effect of ciprofloxacin against Pseudomonas aeruginosa biofilm in chronic murine wounds

Journal of Global Antimicrobial Resistance, 2021

The pathophysiology of chronic wounds is characterized by prolonged inflammation, low mitogenic-a... more The pathophysiology of chronic wounds is characterized by prolonged inflammation, low mitogenic-activity, high protease-/low inhibitor-activity, microbiota changes and biofilm formation, in combination with the etiology of the original insult. One strategy to promote healing is to terminate the parasitism-like-relationship between the biofilm-growing-pathogen and the host response. The antimicrobial peptide AMC-109 is a potential treatment with low resistance-potential and broad-spectrum coverage with rapid bactericidal effect. Our purpose was to investigate if adjunctive AMC-109 could augment the ciprofloxacin effect in a chronic Pseudomonas aeruginosa wound model. Third-degree-burns were inflicted on 33BALB/c mice. P.Aeruginosa embedded in seaweed alginate was injected under the eschar to mimic a biofilm. Mice were randomized to receive AMC-109, combined AMC-109 and ciprofloxacin, ciprofloxacin or placebo for 5 days followed by sample collection. Lower bacterial load was seen in the double treated group when compared to both monotherapy groups (AMC-109, p=0.008 and ciprofloxacin, p=0.03). To evaluate the innate host response, quantification of cytokines and growth factors were performed. The pro-inflammatory response was dampened in the double-treated mice, compared to the mono-ciprofloxacin-treated group (p=0.0009). A lower mobilization of neutrophils from the bone marrow was indicated by reduced granulocyte-colony-stimulating factor in all treatment groups compared to the placebo group. Improved tissue-remodeling was indicated by the highest level of tissue inhibitor of metalloproteases and low metalloprotease level in the double-treated group. AMC-109 revealed adjunctive anti-pseudomonas abilities augmenting the antimicrobial effect of ciprofloxacin in this wound model. The study indicates a potential role for AMC-109 in treating chronic wounds with complicating biofilm infections.

Research paper thumbnail of Erratum for Vimberg et al., “Ribosome-Mediated Attenuation of vga(A) Expression Is Shaped by the Antibiotic Resistance Specificity of Vga(A) Protein Variants”

Antimicrobial Agents and Chemotherapy, 2020

Citation Vimberg V, Cavanagh JP, Novotna M, Lenart J, Nguyen Thi Ngoc B, Vesela J, Pain M, Kobers... more Citation Vimberg V, Cavanagh JP, Novotna M, Lenart J, Nguyen Thi Ngoc B, Vesela J, Pain M, Koberska M, Balikova Novotna G. 2021. Erratum for Vimberg et al., “Ribosome-mediated attenuation of vga(A) expression is shaped by the antibiotic resistance specificity of vga(A) protein variants.” Antimicrob Agents Chemother 65:e02242-20. https://doi.org/10 .1128/AAC.02242-20. Copyright © 2020 American Society for Microbiology. All Rights Reserved. Address correspondence to Gabriela Balikova Novotna, gnovotna@biomed.cas.cz. Published ERRATUM

Research paper thumbnail of Effects of fecal microbiota transplantation in subjects with irritable bowel syndrome are mirrored by changes in gut microbiome

Gut Microbes, 2020

Irritable bowel syndrome (IBS) is a common disorder of the lower gastrointestinal tract. The path... more Irritable bowel syndrome (IBS) is a common disorder of the lower gastrointestinal tract. The pathophysiology is far from settled, but a gut microbial dysbiosis is hypothesized to be a contributing factor. We earlier published a randomized double-blind placebo-controlled clinical trial on fecal microbiota transplantation (FMT) for IBS-the REFIT trial. The present data set describes the engraftment and includes participants from the study who received active FMT; 14 participants with effect of FMT (Effect) and 8 without (No effect). Samples were collected at baseline, after 6 and 12 months. Samples from the transplants (Donor) served as a comparator. In total 66 recipient samples and 17 donor samples were subjected to deep metagenomic sequencing, and taxonomic and functional analyses were performed. Alpha diversity measures showed a significantly increased diversity and evenness in the IBS groups compared to the donors. Taxonomic profiles showed higher relative abundance of phylum Firmicutes, and lower relative abundance of phylum Bacteroidetes, compared to donors at baseline. This profile was shifted toward the donor profile following FMT. Imputed growth rates showed that the resulting growth pattern was a conglomerate of donor and recipient activity. Thirty-four functional subclasses showed distinct differences between baseline samples and donors, most of which were shifted toward a donor-like profile after FMT. All of these changes were less pronounced in the No effect group. We conclude that FMT induces long-term changes in gut microbiota, and these changes mirror the clinical effect of the treatment. The study was registered in ClinicalTrials.gov (NCT02154867).

Research paper thumbnail of The synthetic antimicrobial peptide LTX 21 induces inflammatory responses in a human whole blood model and a murine peritoneum model

APMIS, 2019

The global spread of antimicrobial resistance and the increasing number of immune-compromised pat... more The global spread of antimicrobial resistance and the increasing number of immune-compromised patients are major challenges in modern medicine. Targeting bacterial virulence or the human host immune system to increase host defence are important strategies in the search for novel antimicrobial drugs. We investigated the inflammatory response of the synthetic short antimicrobial peptide LTX21 in two model systems: a human whole blood ex vivo model and in a murine in vivo peritoneum model-both reflecting early innate immune response. In the whole blood model, LTX21 increased secretion of a range of different cytokines, decreased the level of tumour necrosis factor (TNF), and activated the complement system. In a haemolysis assay, we found 2.5% haemolysis at a LTX21 concentration of 500 mg/L. In the murine model, increased influx of white blood cells (WBC) and polymorphonuclear neutrophils (PMN) in the murine peritoneal cavity was observed after treatment with LTX21. In addition, LTX21 increased monocyte chemoattractant protein-1 (MCP-1). In conclusion, LTX21 affected the inflammatory response; the increase in cytokine secretion, complement activation and WBC influx indicates an activated inflammatory response. The present results indicate impact of LTX21 on host-pathogen interplay. Whether this will also affect the course of infection has to be investigated.

Research paper thumbnail of Bifidobacterium Bacteremia: Clinical Characteristics and a Genomic Approach To Assess Pathogenicity

Journal of Clinical Microbiology, 2017

Bifidobacteria are commensals that colonize the orogastrointestinal tract and rarely cause invasi... more Bifidobacteria are commensals that colonize the orogastrointestinal tract and rarely cause invasive human infections. However, an increasing number of bifidobacterial blood culture isolates has lately been observed in Norway. In order to investigate the pathogenicity of the Bifidobacterium species responsible for bacteremia, we studied Bifidobacterium isolates from 15 patients for whom cultures of blood obtained from 2013 to 2015 were positive. We collected clinical data and analyzed phenotypic and genotypic antibiotic susceptibility. All isolates (11 Bifidobacterium longum , 2 B. breve , and 2 B. animalis isolates) were subjected to whole-genome sequencing. The 15 patients were predominantly in the extreme lower or upper age spectrum, many were severely immunocompromised, and 11 of 15 had gastrointestinal tract-related conditions. In two elderly patients, the Bifidobacterium bacteremia caused a sepsis-like picture, interpreted as the cause of death. Most bifidobacterial isolates ha...

Research paper thumbnail of Composition of gut microbiota of children and adolescents with perinatal HIV infection taking antiretroviral therapy in Zimbabwe

The Journal of Infectious Diseases, 2019

Background HIV infection causes impairment of the gastrointestinal barrier, with substantial depl... more Background HIV infection causes impairment of the gastrointestinal barrier, with substantial depletion of CD4+ T-cells in the gut. Antiretroviral therapy (ART) restores CD4+ counts and may have beneficial effects on gut microbiota in adults. Little is known about effect of long-term ART on gut microbiome in HIV infected children. We investigated composition of gut microbiota in HIV infected and uninfected children and assessed associations between gut microbiota and patient characteristics. Methods In a cross-sectional study, rectal swabs were collected from 177 HIV infected and 103 HIV uninfected controls. Gut microbial composition was explored using 16S rRNA sequencing (Illumina Miseq). Results HIV infected children had significantly lower alpha-diversity and higher beta-diversity compared to HIV uninfected. No association was observed between microbiome diversity and CD4+ T-cell count, HIV viral load or HIV-associated chronic lung disease. We found enriched levels of Corynebacter...

Research paper thumbnail of A bacteriocin-based treatment option for Staphylococcus haemolyticus biofilms

Scientific Reports, 2021

Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel... more Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel treatment options for multidrug-resistant pathogens. In this study, we designed a novel hybrid bacteriocin, Hybrid 1 (H1), by combing the N-terminal part and the C-terminal part of the related bacteriocins enterocin K1 (K1) and enterocin EJ97 (EJ97), respectively. Like the parental bacteriocins, H1 used the membrane-bound protease RseP as receptor, however, it differed from the others in the inhibition spectrum. Most notably, H1 showed a superior antimicrobial effect towards Staphylococcus haemolyticus—an important nosocomial pathogen. To avoid strain-dependency, we further evaluated H1 against 27 clinical and commensal S. haemolyticus strains, with H1 indeed showing high activity towards all strains. To curtail the rise of resistant mutants and further explore the potential of H1 as a therapeutic agent, we designed a bacteriocin-based formulation where H1 was used in combination with t...

Research paper thumbnail of Ribosome-Mediated Attenuation of vga (A) Expression Is Shaped by the Antibiotic Resistance Specificity of Vga(A) Protein Variants

Antimicrobial Agents and Chemotherapy, 2020

Vga(A) protein variants confer different levels of resistance to lincosamides, streptogramin A, a... more Vga(A) protein variants confer different levels of resistance to lincosamides, streptogramin A, and pleuromutilins (LS A P) by displacing antibiotics from the ribosome. Here, we show that expression of vga (A) variants from Staphylococcus haemolyticus is regulated by cis -regulatory RNA in response to the LS A P antibiotics by the mechanism of ribosome-mediated attenuation. The specificity of induction depends on Vga(A)-mediated resistance rather than on the sequence of the riboregulator.

Research paper thumbnail of Proteome profiling of secreted and membrane vesicle associated proteins of an invasive and a commensal Staphylococcus haemolyticus isolate

Data in Brief, 2019

Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial... more Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial isolates of S. haemolyticus are the most antibiotic resistant members of the coagulase negative staphylococci (CoNS), but information about other S. haemolyticus virulence factors is scarce. Bacterial membrane vesicles (MVs) are one mediator of virulence by enabling secretion and long distance delivery of bacterial effector molecules while protecting the cargo from proteolytic degradation from the environment. We wanted to determine if the MV protein cargo of S. haemolyticus is strain specific and enriched in certain MV associated proteins compared to the totalsecretome. The present study shows that both clinical and commensal S. haemolyticus isolates produce membrane vesicles. The MV cargo of both strains was enriched in proteins involved in adhesion and acquisition of iron. The MV cargo of the clinical strain was further enriched in antimicrobial resistance proteins. Data are available via ProteomeXchange with identifier PXD010389. Biological significance: Clinical isolates of Staphylococcus haemolyticus are usually multidrug resistant, their main virulence factor is formation of biofilms, both factors leading to infections that are difficult to treat. We show that both clinical and commensal S. haemolyticus isolates produce membrane vesicles. Identification of staphylococcal membrane vesicles can potentially be used in novel approaches to combat staphylococcal infections, such as development of vaccines.

Research paper thumbnail of Outer membrane vesicles as realistic models of bacterial membranes in interaction studies by Surface Plasmon Resonance

bioRxiv (Cold Spring Harbor Laboratory), Jul 7, 2023

One way to mitigate the ongoing antimicrobial resistance crisis is to discover and develop new cl... more One way to mitigate the ongoing antimicrobial resistance crisis is to discover and develop new classes of antibiotics. As all antibiotics at some point needs to either cross or interact with the bacterial membrane, there is a need for representative models of bacterial membranes and efficient methods to characterize the interactions to novel antimicrobials-both to generate new knowledge and to screen compound libraries. Since the bacterial cell envelope is a complex assembly of lipids, lipopolysaccharides, membrane proteins and other components, constructing realistic synthetic liposome-based models of the membrane is both difficult and expensive. We here propose to let the bacteria do the hard work for us. Outer membrane vesicles (OMVs) are naturally secreted by Gram-negative bacteria, playing a role in communication between bacteria, as virulence factors, molecular transport or being a part of the antimicrobial resistance mechanism. OMVs consist of the bacterial outer membrane and thus inherit many components and properties of the native outer cell envelope. In this work we have isolated and characterized OMVs from E. coli mutant strains and clinical isolates of the ESKAPE members Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa. The OMVs were shown to be representative models for the bacterial membrane in terms of lipid composition with strain specific variations. The OMVs were further used to probe the interactions between OMV and antimicrobial peptides (AMPs) as model compounds by Surface Plasmon Resonance (SPR) and provide proof-of-principle that OMVs can be used as an easily accessible and highly realistic model for the bacterial surface in interaction studies. This further enables direct monitoring of the effect of induction by antibiotics, or the response to host-pathogen interactions.

Research paper thumbnail of Exhaled nitric oxide is associated with inflammatory biomarkers and risk of acute respiratory exacerbations in children with HIV‐associated chronic lung disease

HIV Medicine

ObjectivesChronic lung disease is a recognized complication in children with HIV. Acute respirato... more ObjectivesChronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels.MethodsIndividuals aged 6–19 years with HIV‐associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo‐controlled randomized trial investigating the effect of 48‐week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels.ResultsIn total, 172 participants were included in this sub‐study, 86 from the placebo...

Research paper thumbnail of Staphylococcus aureus Membrane-Derived Vesicles Promote Bacterial Virulence and Confer Protective Immunity in Murine Infection Models

Frontiers in Microbiology, Feb 20, 2018

Staphylococcus aureus produces membrane-derived vesicles (MVs), which share functional properties... more Staphylococcus aureus produces membrane-derived vesicles (MVs), which share functional properties to outer membrane vesicles. Atomic force microscopy revealed that S. aureus-derived MVs are associated with the bacterial surface or released into the surrounding environment depending on bacterial growth conditions. By using a comparative proteomic approach, a total of 131 and 617 proteins were identified in MVs isolated from S. aureus grown in Luria-Bertani and brain-heart infusion broth, respectively. Purified S. aureus MVs derived from the bacteria grown in either media induced comparable levels of cytotoxicity and neutrophil-activation. Administration of exogenous MVs increased the resistance of S. aureus to killing by whole blood or purified human neutrophils ex vivo and increased S. aureus survival in vivo. Finally, immunization of mice with S. aureus-derived MVs induced production of IgM, total IgG, IgG1, IgG2a, and IgG2b resulting in protection against subcutaneous and systemic S. aureus infection. Collectively, our results suggest S. aureus MVs can influence bacterial-host interactions during systemic infections and provide protective immunity in murine models of infection.

Research paper thumbnail of Teicoplanin resistance in Staphylococcus haemolyticus is associated with mutations in histidine kinases VraS and WalK

Diagnostic Microbiology and Infectious Disease, Mar 1, 2018

We investigated the genetic basis of glycopeptide resistance in laboratory-derived strains of S. ... more We investigated the genetic basis of glycopeptide resistance in laboratory-derived strains of S. haemolyticus with emphasis on differences between vancomycin and teicoplanin. The genomes of two stable teicoplanin-resistant laboratory mutants selected on vancomycin or teicoplanin were sequenced and compared to parental S. haemolyticus strain W2/124. Only the two nonsynonymous mutations, VraS Q289K and WalK V550L were identified. No other mutations or genome rearrangements were detected. Increased cell wall thickness, resistance to lysostaphininduced lysis and adaptation of cell growth rates specifically to teicoplanin were phenotypes observed in a sequenced strain with the VraS Q289K mutation. Neither of the VraS Q289K and WalK V550L mutations was present in the genomes of 121 S. haemolyticus clinical isolates. However, all but two of the teicoplanin resistant strains carried non-synonymous SNPs in vraSRTU and walKR-YycHIJ operons pointing to their importance for the glycopeptide resistance.

Research paper thumbnail of Chronic lung disease in children and adolescents with HIV: a case–control study

Tropical Medicine & International Health, 2020

ObjectiveTo describe the features of HIV‐associated chronic lung disease (CLD) in older children ... more ObjectiveTo describe the features of HIV‐associated chronic lung disease (CLD) in older children and adolescents living with HIV and to examine the clinical factors associated with CLD. This is a post hoc analysis of baseline data from the BREATHE clinical trial (ClinicalTrials.gov, NCT02426112).MethodsChildren and adolescents aged 6–19 years were screened for CLD (defined as a FEV1 z‐score <−1 with no reversibility post‐bronchodilation with salbutamol) at two HIV clinics in Harare, Zimbabwe, and Blantyre, Malawi. Eligible participants with CLD (cases) were enrolled, together with a control group without CLD [frequency‐matched by age group and duration on antiretroviral therapy (ART)] in a 4:1 allocation ratio. A clinical history and examination were undertaken. The association between CLD and a priori‐defined demographic and clinical covariates was investigated using multivariable logistic regression.ResultsOf the 1585 participants screened, 419 (32%) had a FEV1 z‐score <−1, ...

Research paper thumbnail of Bifidobacterium longumSubspeciesinfantisBacteremia in 3 Extremely Preterm Infants Receiving Probiotics

Emerging Infectious Diseases, 2016

Intentional introduction of disease has been rare (3). Consequently, the incident identified by T... more Intentional introduction of disease has been rare (3). Consequently, the incident identified by Thalassinou and her colleagues arouses readers' interest and inspires speculation.

Research paper thumbnail of Dual inhibition of complement C5 and CD14 attenuates inflammation in a cord blood model

Research paper thumbnail of Development of Early Life Gut Resistome and Mobilome Across Gestational Ages and Microbiota-Modifying Treatments

Research paper thumbnail of Additional file 3 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 3: Table S3. Workflow for bacterial protein surface shaving samples. X = performe... more Additional file 3: Table S3. Workflow for bacterial protein surface shaving samples. X = performed, − = not performed

Research paper thumbnail of Additional file 2 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 2: Table S2. FASTA sequences of the proteins from the cell surface shaving and LC... more Additional file 2: Table S2. FASTA sequences of the proteins from the cell surface shaving and LC-MS/MS analysis.

Research paper thumbnail of Additional file 1 of Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

Additional file 1: Table S1. The cell surface shaving and LC-MS/MS analysis results identified 32... more Additional file 1: Table S1. The cell surface shaving and LC-MS/MS analysis results identified 325 proteins with ≥ #2 peptide-spectrum matches (PSMs).

Research paper thumbnail of Lactoferricin-inspired peptide AMC-109 augments the effect of ciprofloxacin against Pseudomonas aeruginosa biofilm in chronic murine wounds

Journal of Global Antimicrobial Resistance, 2021

The pathophysiology of chronic wounds is characterized by prolonged inflammation, low mitogenic-a... more The pathophysiology of chronic wounds is characterized by prolonged inflammation, low mitogenic-activity, high protease-/low inhibitor-activity, microbiota changes and biofilm formation, in combination with the etiology of the original insult. One strategy to promote healing is to terminate the parasitism-like-relationship between the biofilm-growing-pathogen and the host response. The antimicrobial peptide AMC-109 is a potential treatment with low resistance-potential and broad-spectrum coverage with rapid bactericidal effect. Our purpose was to investigate if adjunctive AMC-109 could augment the ciprofloxacin effect in a chronic Pseudomonas aeruginosa wound model. Third-degree-burns were inflicted on 33BALB/c mice. P.Aeruginosa embedded in seaweed alginate was injected under the eschar to mimic a biofilm. Mice were randomized to receive AMC-109, combined AMC-109 and ciprofloxacin, ciprofloxacin or placebo for 5 days followed by sample collection. Lower bacterial load was seen in the double treated group when compared to both monotherapy groups (AMC-109, p=0.008 and ciprofloxacin, p=0.03). To evaluate the innate host response, quantification of cytokines and growth factors were performed. The pro-inflammatory response was dampened in the double-treated mice, compared to the mono-ciprofloxacin-treated group (p=0.0009). A lower mobilization of neutrophils from the bone marrow was indicated by reduced granulocyte-colony-stimulating factor in all treatment groups compared to the placebo group. Improved tissue-remodeling was indicated by the highest level of tissue inhibitor of metalloproteases and low metalloprotease level in the double-treated group. AMC-109 revealed adjunctive anti-pseudomonas abilities augmenting the antimicrobial effect of ciprofloxacin in this wound model. The study indicates a potential role for AMC-109 in treating chronic wounds with complicating biofilm infections.

Research paper thumbnail of Erratum for Vimberg et al., “Ribosome-Mediated Attenuation of vga(A) Expression Is Shaped by the Antibiotic Resistance Specificity of Vga(A) Protein Variants”

Antimicrobial Agents and Chemotherapy, 2020

Citation Vimberg V, Cavanagh JP, Novotna M, Lenart J, Nguyen Thi Ngoc B, Vesela J, Pain M, Kobers... more Citation Vimberg V, Cavanagh JP, Novotna M, Lenart J, Nguyen Thi Ngoc B, Vesela J, Pain M, Koberska M, Balikova Novotna G. 2021. Erratum for Vimberg et al., “Ribosome-mediated attenuation of vga(A) expression is shaped by the antibiotic resistance specificity of vga(A) protein variants.” Antimicrob Agents Chemother 65:e02242-20. https://doi.org/10 .1128/AAC.02242-20. Copyright © 2020 American Society for Microbiology. All Rights Reserved. Address correspondence to Gabriela Balikova Novotna, gnovotna@biomed.cas.cz. Published ERRATUM

Research paper thumbnail of Effects of fecal microbiota transplantation in subjects with irritable bowel syndrome are mirrored by changes in gut microbiome

Gut Microbes, 2020

Irritable bowel syndrome (IBS) is a common disorder of the lower gastrointestinal tract. The path... more Irritable bowel syndrome (IBS) is a common disorder of the lower gastrointestinal tract. The pathophysiology is far from settled, but a gut microbial dysbiosis is hypothesized to be a contributing factor. We earlier published a randomized double-blind placebo-controlled clinical trial on fecal microbiota transplantation (FMT) for IBS-the REFIT trial. The present data set describes the engraftment and includes participants from the study who received active FMT; 14 participants with effect of FMT (Effect) and 8 without (No effect). Samples were collected at baseline, after 6 and 12 months. Samples from the transplants (Donor) served as a comparator. In total 66 recipient samples and 17 donor samples were subjected to deep metagenomic sequencing, and taxonomic and functional analyses were performed. Alpha diversity measures showed a significantly increased diversity and evenness in the IBS groups compared to the donors. Taxonomic profiles showed higher relative abundance of phylum Firmicutes, and lower relative abundance of phylum Bacteroidetes, compared to donors at baseline. This profile was shifted toward the donor profile following FMT. Imputed growth rates showed that the resulting growth pattern was a conglomerate of donor and recipient activity. Thirty-four functional subclasses showed distinct differences between baseline samples and donors, most of which were shifted toward a donor-like profile after FMT. All of these changes were less pronounced in the No effect group. We conclude that FMT induces long-term changes in gut microbiota, and these changes mirror the clinical effect of the treatment. The study was registered in ClinicalTrials.gov (NCT02154867).

Research paper thumbnail of The synthetic antimicrobial peptide LTX 21 induces inflammatory responses in a human whole blood model and a murine peritoneum model

APMIS, 2019

The global spread of antimicrobial resistance and the increasing number of immune-compromised pat... more The global spread of antimicrobial resistance and the increasing number of immune-compromised patients are major challenges in modern medicine. Targeting bacterial virulence or the human host immune system to increase host defence are important strategies in the search for novel antimicrobial drugs. We investigated the inflammatory response of the synthetic short antimicrobial peptide LTX21 in two model systems: a human whole blood ex vivo model and in a murine in vivo peritoneum model-both reflecting early innate immune response. In the whole blood model, LTX21 increased secretion of a range of different cytokines, decreased the level of tumour necrosis factor (TNF), and activated the complement system. In a haemolysis assay, we found 2.5% haemolysis at a LTX21 concentration of 500 mg/L. In the murine model, increased influx of white blood cells (WBC) and polymorphonuclear neutrophils (PMN) in the murine peritoneal cavity was observed after treatment with LTX21. In addition, LTX21 increased monocyte chemoattractant protein-1 (MCP-1). In conclusion, LTX21 affected the inflammatory response; the increase in cytokine secretion, complement activation and WBC influx indicates an activated inflammatory response. The present results indicate impact of LTX21 on host-pathogen interplay. Whether this will also affect the course of infection has to be investigated.

Research paper thumbnail of Bifidobacterium Bacteremia: Clinical Characteristics and a Genomic Approach To Assess Pathogenicity

Journal of Clinical Microbiology, 2017

Bifidobacteria are commensals that colonize the orogastrointestinal tract and rarely cause invasi... more Bifidobacteria are commensals that colonize the orogastrointestinal tract and rarely cause invasive human infections. However, an increasing number of bifidobacterial blood culture isolates has lately been observed in Norway. In order to investigate the pathogenicity of the Bifidobacterium species responsible for bacteremia, we studied Bifidobacterium isolates from 15 patients for whom cultures of blood obtained from 2013 to 2015 were positive. We collected clinical data and analyzed phenotypic and genotypic antibiotic susceptibility. All isolates (11 Bifidobacterium longum , 2 B. breve , and 2 B. animalis isolates) were subjected to whole-genome sequencing. The 15 patients were predominantly in the extreme lower or upper age spectrum, many were severely immunocompromised, and 11 of 15 had gastrointestinal tract-related conditions. In two elderly patients, the Bifidobacterium bacteremia caused a sepsis-like picture, interpreted as the cause of death. Most bifidobacterial isolates ha...

Research paper thumbnail of Composition of gut microbiota of children and adolescents with perinatal HIV infection taking antiretroviral therapy in Zimbabwe

The Journal of Infectious Diseases, 2019

Background HIV infection causes impairment of the gastrointestinal barrier, with substantial depl... more Background HIV infection causes impairment of the gastrointestinal barrier, with substantial depletion of CD4+ T-cells in the gut. Antiretroviral therapy (ART) restores CD4+ counts and may have beneficial effects on gut microbiota in adults. Little is known about effect of long-term ART on gut microbiome in HIV infected children. We investigated composition of gut microbiota in HIV infected and uninfected children and assessed associations between gut microbiota and patient characteristics. Methods In a cross-sectional study, rectal swabs were collected from 177 HIV infected and 103 HIV uninfected controls. Gut microbial composition was explored using 16S rRNA sequencing (Illumina Miseq). Results HIV infected children had significantly lower alpha-diversity and higher beta-diversity compared to HIV uninfected. No association was observed between microbiome diversity and CD4+ T-cell count, HIV viral load or HIV-associated chronic lung disease. We found enriched levels of Corynebacter...

Research paper thumbnail of A bacteriocin-based treatment option for Staphylococcus haemolyticus biofilms

Scientific Reports, 2021

Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel... more Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel treatment options for multidrug-resistant pathogens. In this study, we designed a novel hybrid bacteriocin, Hybrid 1 (H1), by combing the N-terminal part and the C-terminal part of the related bacteriocins enterocin K1 (K1) and enterocin EJ97 (EJ97), respectively. Like the parental bacteriocins, H1 used the membrane-bound protease RseP as receptor, however, it differed from the others in the inhibition spectrum. Most notably, H1 showed a superior antimicrobial effect towards Staphylococcus haemolyticus—an important nosocomial pathogen. To avoid strain-dependency, we further evaluated H1 against 27 clinical and commensal S. haemolyticus strains, with H1 indeed showing high activity towards all strains. To curtail the rise of resistant mutants and further explore the potential of H1 as a therapeutic agent, we designed a bacteriocin-based formulation where H1 was used in combination with t...

Research paper thumbnail of Ribosome-Mediated Attenuation of vga (A) Expression Is Shaped by the Antibiotic Resistance Specificity of Vga(A) Protein Variants

Antimicrobial Agents and Chemotherapy, 2020

Vga(A) protein variants confer different levels of resistance to lincosamides, streptogramin A, a... more Vga(A) protein variants confer different levels of resistance to lincosamides, streptogramin A, and pleuromutilins (LS A P) by displacing antibiotics from the ribosome. Here, we show that expression of vga (A) variants from Staphylococcus haemolyticus is regulated by cis -regulatory RNA in response to the LS A P antibiotics by the mechanism of ribosome-mediated attenuation. The specificity of induction depends on Vga(A)-mediated resistance rather than on the sequence of the riboregulator.

Research paper thumbnail of Proteome profiling of secreted and membrane vesicle associated proteins of an invasive and a commensal Staphylococcus haemolyticus isolate

Data in Brief, 2019

Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial... more Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial isolates of S. haemolyticus are the most antibiotic resistant members of the coagulase negative staphylococci (CoNS), but information about other S. haemolyticus virulence factors is scarce. Bacterial membrane vesicles (MVs) are one mediator of virulence by enabling secretion and long distance delivery of bacterial effector molecules while protecting the cargo from proteolytic degradation from the environment. We wanted to determine if the MV protein cargo of S. haemolyticus is strain specific and enriched in certain MV associated proteins compared to the totalsecretome. The present study shows that both clinical and commensal S. haemolyticus isolates produce membrane vesicles. The MV cargo of both strains was enriched in proteins involved in adhesion and acquisition of iron. The MV cargo of the clinical strain was further enriched in antimicrobial resistance proteins. Data are available via ProteomeXchange with identifier PXD010389. Biological significance: Clinical isolates of Staphylococcus haemolyticus are usually multidrug resistant, their main virulence factor is formation of biofilms, both factors leading to infections that are difficult to treat. We show that both clinical and commensal S. haemolyticus isolates produce membrane vesicles. Identification of staphylococcal membrane vesicles can potentially be used in novel approaches to combat staphylococcal infections, such as development of vaccines.