| 1. |
- Angulo, Julio, 1980-, et al.
(författare)
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Understanding the user experience of secure mobile online transactions in realistic contexts of use
- 2012
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Ingår i: Symposium on Usable Privacy and Security (SOUPS) 2012. - Washington D.C.,USA : Association for Computing Machinery (ACM). ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- Possible attacks on mobile smart devices demand higher security for applications handling payments or sensitive information. The introduction of a tamper-proof area on future generations of mobile devices, called Trusted Execution Environment (TEE), is being implemented. Before devices with embedded TEEs can be deployed to the public, investigations on usability aspects of Trusted User Interfaces (TUI) are needed. This article describes the process we have followed at gathering requirements, prototyping and testing suitable designs for TUIs in combination with a touch-screen biometric system. At the end, we present relevant findings of a pilot study that we have conducted using an Experience Sampling Method (ESM) as part of our ongoing work.
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| 2. |
- Gullberg, Erik, 1980-
(författare)
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Selection of Resistance at very low Antibiotic Concentrations
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The extensive medical and agricultural use and misuse of antibiotics during the last 70 years has caused an enrichment of resistant pathogenic bacteria that now severely threatens our capacity to efficiently treat bacterial infections. While is has been known for a long time that high concentrations of antibiotics can select for resistant mutants, less is known about the lower limit at which antibiotics can be selective and enrich for resistant bacteria.In this thesis we investigated the role of low concentrations of antibiotics and heavy metals in the enrichment and evolution of antibiotic resistance. Selection was studied using Escherichia coli and Salmonella enterica serovar Typhimurium LT2 with different resistance mutations, different chromosomal resistance genes as well as large conjugative multidrug resistance plasmids. Using very sensitive competition experiments, we showed that antibiotic and heavy metal levels more than several hundred-fold below the minimal inhibitory concentration of susceptible bacteria can enrich for resistant bacteria. Additionally, we demonstrated that subinhibitory levels of antibiotics can select for de novo resistant mutants, and that these conditions can select for a new spectrum of low-cost resistance mutations. The combinatorial effects of antibiotics and heavy metals can cause an enrichment of a multidrug resistance plasmid, even if the concentration of each compound individually is not high enough to cause selection.These results indicate that environments contaminated with low levels of antibiotics and heavy metals such as, for example, sewage water or soil fertilized with sludge or manure, could provide a setting for selection, enrichment and transfer of antibiotic resistance genes. This selection could be a critical step in the transfer of resistance genes from environmental bacteria to human pathogens.
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| 3. |
- Khan, David, et al.
(författare)
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Predicting mutant selection in competition experiments with ciprofloxacin-exposed Escherichia coli
- 2018
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Ingår i: International Journal of Antimicrobial Agents. - : Elsevier BV. - 0924-8579 .- 1872-7913. ; 51:3, s. 399-406
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Tidskriftsartikel (refereegranskat)abstract
- Predicting competition between antibiotic-susceptible wild-type (WT) and less susceptible mutant (MT) bacteria is valuable for understanding how drug concentrations influence the emergence of resistance. Pharmacokinetic/pharmacodynamic (PK/PD) models predicting the rate and extent of takeover of resistant bacteria during different antibiotic pressures can thus be a valuable tool in improving treatment regimens. The aim of this study was to evaluate a previously developed mechanism-based PK/PD model for its ability to predict in vitro mixed-population experiments with competition between Escherichia coli (E. coli) WT and three well-defined E. coli resistant MTs when exposed to ciprofloxacin. Model predictions for each bacterial strain and ciprofloxacin concentration were made for in vitro static and dynamic time–kill experiments measuring CFU (colony forming units)/mL up to 24 h with concentrations close to or below the minimum inhibitory concentration (MIC), as well as for serial passage experiments with concentrations well below the MIC measuring ratios between the two strains with flow cytometry. The model was found to reasonably well predict the initial bacterial growth and killing of most static and dynamic time–kill competition experiments without need for parameter re-estimation. With parameter re-estimation of growth rates, an adequate fit was also obtained for the 6-day serial passage competition experiments. No bacterial interaction in growth was observed. This study demonstrates the predictive capacity of a PK/PD model and further supports the application of PK/PD modelling for prediction of bacterial kill in different settings, including resistance selection.
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