| 1. |
- Andrésen, Cecilia, et al.
(författare)
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Critical biophysical properties in the Pseudomonas aeruginosa efflux gene regulator MexR are targeted by mutations conferring multidrug resistance
- 2010
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Ingår i: Protein Science. - : Cold Spring Harbor Laboratory Press. - 0961-8368 .- 1469-896X. ; 19:4, s. 680-692
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Tidskriftsartikel (refereegranskat)abstract
- The self-assembling MexA-MexB-OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR-wt as well as a selected set of MDR single mutants distant from the proposed DNA-binding helix. Although DNA affinity and MexA-MexB-OprM repression were both drastically impaired in the selected MexR-MDR mutants, MexR-wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR-MDR mutants, secondary structure content and oligomerization properties were very similar to MexR-wt despite their lack of DNA binding. Despite this, the MexR-MDR mutants showed highly varying stabilities compared with MexR-wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA-binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR-wt in both free and DNA-bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations stability, domain interactions, and internal hydrophobic surfaces are also critical for the regulation of MexR DNA binding.
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| 2. |
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| 3. |
- Björling, Gunilla, Docent, et al.
(författare)
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Tolerability and performance of BIP endotracheal tubes with noble metal alloy coating : a randomized clinical evaluation study
- 2015
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Ingår i: BMC Anesthesiology. - : BioMed Central. - 1471-2253 .- 1471-2253. ; 15, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundHospital acquired infections worsen the outcome of patients treated in intensive care units and are costly. Coatings with silver or metal alloys may reduce or alter the formation of biofilm on invasive medical devices. An endotracheal tube (ETT) is used to connect the patient to a ventilator and coated tubes have been tested in relation to bacterial colonization and respiratory infection. In the present study, we aimed to evaluate and compare a coated and uncoated ETT for patient symptoms and local tracheal tolerability during short term clinical use. Degree of bacterial colonization was also described.MethodsA silver-palladium-gold alloy coating (‘Bactiguard®’Infection Protection, BIP) has been extensively used on urinary tract catheters and lately also on central venous catheters. We performed a randomised, single-blinded, controlled, first in man, post Conformité Européenne (EC) certification and CE marking study, focused on Bactiguard® coated ETTs (BIP ETT). Thirty patients at a tertiary university hospital scheduled for upper abdominal elective surgery with an expected duration of anaesthesia of at least 3 h were randomised; BIP ETT (n = 20) or standard ETT (n = 10). The tolerability was assessed with a modified version of Quality of Life Head and Neck Module, QLQ-H&N35 and by inspection of the tracheal mucosa with a fibre-optic bronchoscope before intubation and at extubation. Adverse Events (AE) and bacterial adherence were also studied. Statistical evaluations were carried out with the Fisher’s Exact Test, the Clopper-Pearson method, as well as a Proportional Odds Model.ResultsDifferences between groups were identified in 2 of 8 patient related symptoms with regard to tolerability by QLQ-H&N35 (cough, p = 0.022 and dry mouth, p = 0.014 in the treatment group.). No mucosal damage was identified with bronchoscopy. A low level of bacterial colonization with normal flora, equal between groups, was seen after short-term of intubation (median 5 h). No serious Adverse Events related to the use of an ETT were observed. The results should be treated with caution due to statistical confounders, a small study size and large inter-individual variability in bacterial adhesion.ConclusionsThe new device BIP ETT is well tolerated and has good clinical performance during short-term intubation. Studies with larger sample sizes and longer intubation periods (>24 h) in the ICU-setting are needed and can now be planned in order to identify possible differences in clinical outcomes.
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| 4. |
- Jalal, Shah
(författare)
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Molecular mechanisms of fluoroquinolone resistance in Pseudomonas aeruginosa
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pseudomonas aeruginosa is an opportunistic nosocomial pathogen. In compromised human, it can cause infections in urinary tract, wound and respiratory tract such as pneumonia and progressive lung diseases. Particularly the risk groups are cystic fibrosis individuals, bum victims, cancer patients and patients requiring long stays in intensive care units. P. aeruginosa can cause a number of infections in animals, and plants, vegetables and fruits. Diseases of economical importance include hemorrhagic pneumonia in mink and mastitis in cattle. Although many vaccine candidates against P. aeruginosa are under active investigations, there is no safe and effective vaccine available yet for public health purposes. The management of P. aeruginosa infection is entirely dependent on antibiotic treatment. The only available antibiotics for effective oral treatment of P. aeruginosa infection are the fluoroquinolones (FQs) such as norfloxacin and ciprofloxacin. However, for P. aeruginosa and some other bacteria, resistance develops rapidly during FQ therapy, which severely limits the use of these drugs. In addition, if P. aeruginosa is resistant to one antibiotic it is often resistant to one or more chemically unrelated antibiotics. We have found that 15-24% of P. aeruginosa strains are resistant or intermediately resistant to quinolones in Stockholm. Similar findings are also shown in a recent study of 25 European university hospitals. This picture could be worse in developing countries where anyone can buy antibiotics without prescription. Winning the challenge of Pseudomonas will require detailed knowledge of mechanisms of FQ resistance. Therefore, the aim of this study was to examine the quinolone-target genes: gyrA, gyrB, parC, and parE, and to characterize multidrug resistant efflux: mexAB-oprM, mexCD-oprJ, and mexEF-oprN, which are regulated by mexR, nfxB and mexT respectively. The overall goal was to increase understanding the mechanisms of FQ resistance. In this thesis, we reviewed the genetic mechanisms by which P. aeruginosa develop and disseminate FQ resistance. We also reviewed how the knowledge of bacterial genetics has significantly accelerated the ability to understand the spread of resistance. We found that the point mutations in quinolone-target genes are the major component of resistance mechanisms in clinical isolates. Efflux-mediated resistance to FQ seems to dominating resistance-mechanism in cystic fibrosis isolates and laboratory mutants. However, high-level resistance is the result of accumulation of mutations in the quinolone targets and efflux systems. In addition, RESA (restriction enzyme site-protection assay) showed that a reduced DNA binding activity of the regulatory protein of multidrug efflux might render the bacterium to become resistant to drugs. The efflux-mediated resistance mechanisms are widely distributed among the human pathogens and are often multidrug resistant. In addition, the efflux systems are highly homologous within Gram-negatives and also for Gram-positives. Therefore, inhibition of efflux systems with broad-spectrum inhibitors would seem to be a prudent approach to combat and/or prevent FQ resistance or even multidrug resistance. We introduced NIRCA (Non-isotopic RNase cleavage assay) as a rapid, simple and highly sensitive method for detection of mutations in P. aeruginosa. We also established RESA to assess DNA binding activities of the regulatory protein for the efflux pump in this organism.
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| 5. |
- Khadim, Adeeba, et al.
(författare)
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Investigation of fragmentation behaviors of steroidal drugs with Li+, Na+, K+ adducts by tandem mass spectrometry aided with computational analysis
- 2022
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Ingår i: Arabian Journal of Chemistry. - : Elsevier BV. - 1878-5352 .- 1878-5379. ; 15:7
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we have investigated the fragmentation of the widely used steroidal pharmaceutical drugs (n = 14), complexed by a singly charged proton or alkali metal ion (Li+, Na+, K+) using Ion trap and quadrupole time-of-flight mass spectrometers. Spectra were collected by LC-MS/MS analysis using system automated collision energy i.e., of 25–60 eV. Theoretical calculations were also calculated using DFT software. The metal complexes showed different fragmentation pathways not commonly observed for protonated compounds. There was a distinct difference observed in the relative intensities of some common fragments for free vs. metallated drugs. Some major fragments from protonated and lithium adducts showed close resemblance, while sodium and potassium adducts showed different fragments. Theoretical calculations showed a distinct difference in the position of attachment of proton and metals. This adducts ion fragmentation information will be helpful for the identification of these compounds in complex samples.
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| 6. |
- Micah, Angela E., et al.
(författare)
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Tracking development assistance for health and for COVID-19 : a review of development assistance, government, out-of-pocket, and other private spending on health for 204 countries and territories, 1990-2050
- 2021
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 398:10308, s. 1317-1343
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Forskningsöversikt (refereegranskat)abstract
- Background The rapid spread of COVID-19 renewed the focus on how health systems across the globe are financed, especially during public health emergencies. Development assistance is an important source of health financing in many low-income countries, yet little is known about how much of this funding was disbursed for COVID-19. We aimed to put development assistance for health for COVID-19 in the context of broader trends in global health financing, and to estimate total health spending from 1995 to 2050 and development assistance for COVID-19 in 2020. Methods We estimated domestic health spending and development assistance for health to generate total health-sector spending estimates for 204 countries and territories. We leveraged data from the WHO Global Health Expenditure Database to produce estimates of domestic health spending. To generate estimates for development assistance for health, we relied on project-level disbursement data from the major international development agencies' online databases and annual financial statements and reports for information on income sources. To adjust our estimates for 2020 to include disbursements related to COVID-19, we extracted project data on commitments and disbursements from a broader set of databases (because not all of the data sources used to estimate the historical series extend to 2020), including the UN Office of Humanitarian Assistance Financial Tracking Service and the International Aid Transparency Initiative. We reported all the historic and future spending estimates in inflation-adjusted 2020 US$, 2020 US$ per capita, purchasing-power parity-adjusted US$ per capita, and as a proportion of gross domestic product. We used various models to generate future health spending to 2050. Findings In 2019, health spending globally reached $8. 8 trillion (95% uncertainty interval [UI] 8.7-8.8) or $1132 (1119-1143) per person. Spending on health varied within and across income groups and geographical regions. Of this total, $40.4 billion (0.5%, 95% UI 0.5-0.5) was development assistance for health provided to low-income and middle-income countries, which made up 24.6% (UI 24.0-25.1) of total spending in low-income countries. We estimate that $54.8 billion in development assistance for health was disbursed in 2020. Of this, $13.7 billion was targeted toward the COVID-19 health response. $12.3 billion was newly committed and $1.4 billion was repurposed from existing health projects. $3.1 billion (22.4%) of the funds focused on country-level coordination and $2.4 billion (17.9%) was for supply chain and logistics. Only $714.4 million (7.7%) of COVID-19 development assistance for health went to Latin America, despite this region reporting 34.3% of total recorded COVID-19 deaths in low-income or middle-income countries in 2020. Spending on health is expected to rise to $1519 (1448-1591) per person in 2050, although spending across countries is expected to remain varied. Interpretation Global health spending is expected to continue to grow, but remain unequally distributed between countries. We estimate that development organisations substantially increased the amount of development assistance for health provided in 2020. Continued efforts are needed to raise sufficient resources to mitigate the pandemic for the most vulnerable, and to help curtail the pandemic for all. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.
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| 7. |
- Sartorius, Karin, et al.
(författare)
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Bacteraemia in patients with hidradenitis suppurativa undergoing carbon dioxide laser surgery: detection and quantification of bacteria by lysis-filtration.
- 2006
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Ingår i: Dermatology. - : S. Karger AG. ; 213:4, s. 305-312
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- BACKGROUND: Hidradenitis suppurativa (HS) is a cicatrising and persistent disease of apocrine gland-bearing areas in adults. The severity of this condition varies from a few suppurating lesions to widespread, disabling disease. The aetiology is obscure, but suggested contributory factors include a genetic predisposition, comedones occluding the pilosebaceous apparatus, bacterial infections, and hormonal factors. Treatment consists mainly of surgery, while medical therapies serve principally as adjunct therapy. OBJECTIVES: The aim of the study was to determine the number and type of bacteria circulating in the bloodstream in patients with HS undergoing surgical treatment with a carbon dioxide laser stripping-secondary intention technique. METHODS: Twenty-one patients (20 females and 1 male, mean age 36, range 20-55 years) were included in the study. One blood sample (8.3 ml) was taken before surgery, one during the operation and the last one 10 min after surgery. Five healthy persons (all females, mean age 36, range 23-48 years) not undergoing any operation were used as the controls. The blood was cultured by a lysis-filtration technique which had been shown to be very sensitive. Since the filter catches the microorganisms and colonies are formed during culturing, the number of bacteria in the samples is easily determined. RESULTS: In 6 patients, all samples were negative, which indicates that the method of surgery itself caused no spread of bacteria from the lesions. Bacterial growth in the first blood sample was found in 9 patients, from the second sample in 10 and from the third one in 6. In 1 patient, bacteria were detected in three samples. At least 12 bacterial species were identified. The dominating bacteria were coagulase-negative staphylococci of which most were subtyped as Staphylococcus warneri. Among the anaerobic microorganisms, Propionibacterium acnes and P.granulosum were the most frequently isolated bacteria. The bacterial findings in the blood samples accord well with the results from a previous study in which cultures were taken from the deep parts of the HS lesions. In the 5 controls, no microbial growth was detected. CONCLUSION: The carbon dioxide laser stripping technique caused no additional spread of bacteria into the bloodstream. The evaluation of cultures containing microorganisms from normal skin flora is controversial. Since the bacteria encountered in this study are in close agreement with the findings in cultures from the deeper parts of HS lesions they seem to be relevant. The growth of bacteria in the first blood sample taken before surgery may indicate that some of these patients have bacteria continuously circulating in their blood.
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