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Erland Baath - One of the best experts on this subject based on the ideXlab platform.
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partial drying accelerates Bacterial Growth recovery to rewetting
Soil Biology & Biochemistry, 2017Co-Authors: Ainara Leizeaga, Johannes Rousk, Annelein Meisner, Erland BaathAbstract:Fluctuations in soil moisture create drying-rewetting events affecting the activity of microorganisms. Microbial responses to drying-rewetting are mostly studied in soils that are air-dried before rewetting. Upon rewetting, two patterns of Bacterial Growth have been observed. In the Type 1 pattern, Bacterial Growth rates increase immediately in a linear fashion. In the Type 2 pattern, Bacterial Growth rates increase exponentially after a lag period. However, soils are often only partially dried. Partial drying (higher remaining moisture content before rewetting) may be considered a less harsh treatment compared with air-drying. We hypothesized that a soil with a Type 2 response upon rewetting air-dried soil would transform into a Type 1 response if dried partially before rewetting. Two soils were dried to a gradient of different moisture content. Respiration and Bacterial Growth rates were then measured before and during 48 h after rewetting to 50% of water holding capacity (WHC). Initial moisture content determined Growth and respiration in a sigmoidal fashion, with lowest activity in air-dried soil and maximum above ca. 30% WHC. Partial drying resulted in shorter lag periods, shorter recovery times and lower maximum Bacterial Growth rates after rewetting. The respiration after rewetting was lower when soil was partially dried and higher when soils were air-dried. The threshold moisture content where transition from a Type 2 to a Type 1 response occurred was about 14% WHC, while >30% WHC resulted in no rewetting effect. We combine our result with other recent reports to propose a framework of response patterns after drying-rewetting, where the harshness of drying determines the response pattern of bacteria upon rewetting dried soils.
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prolonged drought changes the Bacterial Growth response to rewetting
Soil Biology & Biochemistry, 2015Co-Authors: Annelein Meisner, Johannes Rousk, Erland BaathAbstract:Rewetting a dry soil can result in two response patterns of Bacterial Growth and respiration. In type 1, Bacterial Growth starts to increase linearly immediately upon rewetting and respiration rates are highest immediately upon rewetting. In type 2, Bacterial Growth starts to increase exponentially after a lag period with a secondary increase in respiration occurring at the start of the exponential increase in Growth. We previously observed that the type 1 response occurred after rewetting 4-day dried soil and type 2 for 1-year dried soil. Here we studied in detail how the duration of drought related to the two types of responses of Bacterial Growth and respiration to rewetting. Soil was air dried for different time periods from 4 days up to 48 weeks. Upon rewetting, Bacterial Growth and respiration was measured repeatedly at 17 °C during one week. Drought periods of ≤2 weeks resulted in a type 1 response whereas drought periods of ≥4 weeks resulted in a type 2 response. The lag period increased with drought duration and reached a maximum of ca. 18 h. The Bacterial Growth response was also affected by incubation of moist soil before drying–rewetting. The lag period increased with duration of moist soil incubation before the 4-day drying–rewetting event and reached also a maximum of ca. 18 h. The exponential Growth increase in the type 2 response coincided with a secondary increase in respiration, which increased in magnitude with increasing drought duration. Cumulative respiration increased with drought duration and was ca. 4 times higher after 48 weeks of drought compared to 4 days. Thus, prolonged drought affected the response type of Bacterial Growth and respiration to rewetting, and also increased lag period, the magnitude of the secondary increase in respiration and total C release. The effect of drought was, however, modified by the lenght of the incubation period of moist soil before drought, suggesting that soil conditions before a drying–rewetting event need consideration when evaluating microbial responses.
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threshold concentration of glucose for Bacterial Growth in soil
Soil Biology & Biochemistry, 2015Co-Authors: Stephanie Reischke, Manoj G K Kumar, Erland BaathAbstract:The activity of heterotrophic soil microorganisms is usually limited by the availability and quality of carbon (C). Adding organic substances will thus trigger a microbial response. We studied the response in Bacterial Growth and respiration after the addition of low amounts of glucose. First we determined if additions of glucose, at concentrations which did not result in an exponential increase in respiration after the lag phase, still stimulated Bacterial Growth. The second aim was to determine the threshold concentration of glucose needed to induce Bacterial Growth. Adding glucose-C at 1000 mu g g(-1) soil resulted in an increased respiration rate, which was stable during 12 h, and then decreased without showing any exponential increase in respiration. Bacterial Growth, determined as leucine incorporation, did not change compared to an unamended control during the first 12 h, but then increased to levels 5 times higher than in the control. Thus, after the lag phase, a period with increasing Bacterial Growth, but at the same time decreasing respiration rates, was found. Similar results, but with a more modest increase in Bacterial Growth, were found using 500 mu g glucose-C g(-1) soil. Adding 50-700 mu g glucose-C g(-1) resulted in increased respiration during 24 h correlating with the addition rate. In contrast, Bacterial Growth after 24 h was only stimulated by glucose additions >200 mu g C g(-1) soil. Thus, there was a threshold concentration of added substrate for inducing Bacterial Growth. Below the threshold concentration Growth and respiration appear to be uncoupled. (C) 2014 Elsevier Ltd. All rights reserved.
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soil Bacterial Growth and nutrient limitation along a chronosequence from a glacier forefield
Soil Biology & Biochemistry, 2011Co-Authors: Harry Olde Venterink, Hans Goransson, Erland BaathAbstract:Resource availability and limiting factors for Bacterial Growth during early stages of soil development (8-138 years) were studied along a chronosequence from the glacial forefield of the Damma glacier in the Swiss Alps. We determined Bacterial Growth (leucine incorporation) and we investigated which resource (C, N or P) limited Bacterial Growth in soils formed by the retreating glacier. The latter was determined by adding labile sources of C (glucose), N and P to soil samples and then measuring the Bacterial Growth response after a 40 h incubation period. Bacterial Growth increased with increasing soil age in parallel with the build up of organic matter. However, lower Bacterial Growth, when standardized to the amount of organic C, was found with time since the glacier retreat, indicating decreasing availability of soil organic matter with soil age. Bacterial Growth in older soils was limited by the lack of C. The bacteria were never found to be limited by only N, only P. or N + P. In the youngest soils, however, neither the addition of C, N nor P singly increased Bacterial Growth, while a combination of C and N did. Bacterial Growth was relatively more limited by lack of N than P when the C limitation was alleviated, suggesting that N was the secondary limiting resource. The availability of N for Bacterial Growth increased with time, as seen by an increased Bacterial Growth response after adding only C in older soils. This study demonstrated that Bacterial Growth measurements can be used not only to indicate direct Growth effects, but also as a rapid method to indicate changes in Bacterial availability of nutrients during soil development. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved. (Less)
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fungal and Bacterial Growth responses to n fertilization and ph in the 150 year park grass uk grassland experiment
FEMS Microbiology Ecology, 2011Co-Authors: P C Brookes, Johannes Rousk, Erland BaathAbstract:The effects of nitrogen (N) fertilization (0-150 kg N ha(-1) year(-1) since 1865) and pH (3.3-7.4) on fungal and Bacterial Growth, biomass and phospholipid fatty acid (PLFA) composition were investigated in grassland soils from the 'Park Grass Experiment', Rothamsted Research, UK. Bacterial Growth decreased and fungal Growth increased with lower pH, resulting in a 50-fold increase in the relative importance of fungi between pH 7.4 and 3.3. The PLFA-based fungal : Bacterial biomass ratio was unchanged between pH 4.5 and 7.4, and decreased only below pH 4.5. Respiration and substrate-induced respiration biomass both decreased three- to fourfold with lower pH, but biomass concentrations estimated using PLFAs were unaffected by pH. N fertilization did not affect Bacterial Growth and marginally affected fungal Growth while PLFA biomass marker concentrations were all reduced by higher N additions. Respiration decreased with higher N application, suggesting a reduced quality of the soil organic carbon. The PLFA composition was strongly affected by both pH and N. A comparison with a pH gradient in arable soil allowed us to generalize the pH effect between systems. There are 30-50-fold increases in the relative importance of fungi between high (7.4-8.3) and low (3.3-4.5) pH with concomitant reductions of respiration by 30-70%. (Less)
Niels Frimodtmoller - One of the best experts on this subject based on the ideXlab platform.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
Antimicrobial Agents and Chemotherapy, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effects predominantly on rapidly growing Bacterial cells; yet, the Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, a means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as a readout of in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (quantitative PCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average level and on a single-cell level, from one single biological specimen. Here, we asked whether the in situ Growth rate predicts antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as a proof of concept. Our data demonstrate that the activities of the commonly used antibiotics ceftriaxone and gentamicin correlated with pretreatment Bacterial Growth rate; both drugs performed better during rapid Growth than during slow Growth. Conversely, ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic’s dependency on active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
bioRxiv, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effect predominantly on rapidly growing Bacterial cells, yet Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as readout for in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (qPCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average and on a single-cell level; from one single biological specimen. Here, we asked whether the in situ Growth rate could predict antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as proof-of-concept. Our data demonstrate that the activity of commonly used antibiotics Ceftriaxone and Gentamicin correlated with pre-treatment Bacterial Growth rate; both drugs performing better during rapid Growth than during slow Growth. Conversely, Ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic's dependency upon active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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chromosome replication as a measure of Bacterial Growth rate during escherichia coli infection in the mouse peritonitis model
Scientific Reports, 2018Co-Authors: Maria Schei Haugan, Godefroid Charbon, Niels Frimodtmoller, Anders LobnerolesenAbstract:The efficacy of most antibiotics is dependent on active Bacterial Growth, yet little is known about the Growth dynamics during infection. Therefore, means to measure in-host Bacterial Growth rate is of importance. Here, we use chromosome replication as readout for in situ Bacterial Growth rate during infection; obtained from a single biological specimen. We have applied two independent methods: quantitative PCR (qPCR) and fluorescence microscopy, to quantify the level of chromosome replication present during Escherichia coli propagation in the mouse peritonitis model. We find that the methods complement each other and allow for quantification of Growth rate, both on a population average and on a single-cell level. We demonstrate the presence of heterogeneous Growth rates within Bacterial populations propagating during infection. Also, no Growth cessation was observed during the apparent stationary phase in vivo, and, by comparison of Growth dynamics at different anatomical sites, we demonstrate that E. coli is unlikely to grow independently intravascularly. These findings provide novel insight into Bacterial Growth during host infection, and underscore the importance of pinpointing the primary site of infection in septicaemia of unknown origin and ensuring antibiotic availability at this site.
Johannes Rousk - One of the best experts on this subject based on the ideXlab platform.
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partial drying accelerates Bacterial Growth recovery to rewetting
Soil Biology & Biochemistry, 2017Co-Authors: Ainara Leizeaga, Johannes Rousk, Annelein Meisner, Erland BaathAbstract:Fluctuations in soil moisture create drying-rewetting events affecting the activity of microorganisms. Microbial responses to drying-rewetting are mostly studied in soils that are air-dried before rewetting. Upon rewetting, two patterns of Bacterial Growth have been observed. In the Type 1 pattern, Bacterial Growth rates increase immediately in a linear fashion. In the Type 2 pattern, Bacterial Growth rates increase exponentially after a lag period. However, soils are often only partially dried. Partial drying (higher remaining moisture content before rewetting) may be considered a less harsh treatment compared with air-drying. We hypothesized that a soil with a Type 2 response upon rewetting air-dried soil would transform into a Type 1 response if dried partially before rewetting. Two soils were dried to a gradient of different moisture content. Respiration and Bacterial Growth rates were then measured before and during 48 h after rewetting to 50% of water holding capacity (WHC). Initial moisture content determined Growth and respiration in a sigmoidal fashion, with lowest activity in air-dried soil and maximum above ca. 30% WHC. Partial drying resulted in shorter lag periods, shorter recovery times and lower maximum Bacterial Growth rates after rewetting. The respiration after rewetting was lower when soil was partially dried and higher when soils were air-dried. The threshold moisture content where transition from a Type 2 to a Type 1 response occurred was about 14% WHC, while >30% WHC resulted in no rewetting effect. We combine our result with other recent reports to propose a framework of response patterns after drying-rewetting, where the harshness of drying determines the response pattern of bacteria upon rewetting dried soils.
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prolonged drought changes the Bacterial Growth response to rewetting
Soil Biology & Biochemistry, 2015Co-Authors: Annelein Meisner, Johannes Rousk, Erland BaathAbstract:Rewetting a dry soil can result in two response patterns of Bacterial Growth and respiration. In type 1, Bacterial Growth starts to increase linearly immediately upon rewetting and respiration rates are highest immediately upon rewetting. In type 2, Bacterial Growth starts to increase exponentially after a lag period with a secondary increase in respiration occurring at the start of the exponential increase in Growth. We previously observed that the type 1 response occurred after rewetting 4-day dried soil and type 2 for 1-year dried soil. Here we studied in detail how the duration of drought related to the two types of responses of Bacterial Growth and respiration to rewetting. Soil was air dried for different time periods from 4 days up to 48 weeks. Upon rewetting, Bacterial Growth and respiration was measured repeatedly at 17 °C during one week. Drought periods of ≤2 weeks resulted in a type 1 response whereas drought periods of ≥4 weeks resulted in a type 2 response. The lag period increased with drought duration and reached a maximum of ca. 18 h. The Bacterial Growth response was also affected by incubation of moist soil before drying–rewetting. The lag period increased with duration of moist soil incubation before the 4-day drying–rewetting event and reached also a maximum of ca. 18 h. The exponential Growth increase in the type 2 response coincided with a secondary increase in respiration, which increased in magnitude with increasing drought duration. Cumulative respiration increased with drought duration and was ca. 4 times higher after 48 weeks of drought compared to 4 days. Thus, prolonged drought affected the response type of Bacterial Growth and respiration to rewetting, and also increased lag period, the magnitude of the secondary increase in respiration and total C release. The effect of drought was, however, modified by the lenght of the incubation period of moist soil before drought, suggesting that soil conditions before a drying–rewetting event need consideration when evaluating microbial responses.
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temperature adaptation of Bacterial Growth and c 14 glucose mineralisation in a laboratory study
Soil Biology & Biochemistry, 2013Co-Authors: Johanna Birgander, Stephanie Reischke, Davey L. Jones, Johannes RouskAbstract:Microbial decomposition of soil organic matter (SOM) is the source of most of the terrestrial carbon dioxide emission. Consequently, our ability to predict how climate warming will affect the global carbon (C) budget relies on our understanding of the temperature relationship and adaptability of microbial processes. We exposed soil microcosms to temperatures between 0 and 54 degrees C for 2 months. After this, Bacterial Growth (leucine incorporation) and functioning (C-14-glucose mineralisation) were estimated at 8 temperatures in the interval 0-54 degrees C to determine temperature relationships and apparent minimum (T-min) and optimum (T-opt) temperatures for Growth and mineralisation. We predicted that incubation at temperatures above the initial T-opt for bacteria would select for a warm-adapted community, i.e. a positive shift in T-min and T-opt for Bacterial Growth, and that this adaptation of the Bacterial community would coincide with a similar shift also for their functioning. As anticipated, we found that exposure to temperatures below T-opt did not change the temperature relationship of Bacterial Growth or mineralisation. Interestingly, T-opt for glucose mineralisation was >20 degrees C higher than that for Growth. For Bacterial Growth, the temperature relationship for the Bacterial community was modulated when soils were incubated at temperature above their initial T-opt (approximate to 30 degrees C). This was shown by an increase in T-min of 0.8 degrees C for every 1 degrees C increase in soil temperature, evidencing a shift towards warm-adapted bacteria. Similarly, the Q-10 (15-25 degrees C) for Bacterial Growth increased at temperature higher than T-opt. We could not detect a corresponding temperature adaptation of the decomposer functioning. We discuss possible underlying reasons for the temperature-responses of Bacterial processes. We note that a temperature adaptation will be rapid when exceeding the T-opt, which initially were >20 degrees C higher for glucose mineralisation than Growth. This difference could suggest that different responses to warming exposure should be expected for these microbial processes. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
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Bacterial Growth and respiration responses upon rewetting dry forest soils impact of drought legacy
Soil Biology & Biochemistry, 2013Co-Authors: Hans Goransson, Douglas L Godbold, David L Jones, Johannes RouskAbstract:Longer periods of drought and droughts of higher intensity are expected to become increasingly frequent with future climate change. This has implications for the microbially mediated turnover of soil organic matter (SOM), which will feedback to the global C cycle. In this study, we addressed the microbial dynamics underlying the pulse of respiration following rewetting of dry soil, and how the drought-legacy of the soil modulated this response. We studied the microbial dynamics upon rewetting of dry soils from a field-experiment in a temperate forest soil exposed to two seasons of experimental summer-drought, or ambient conditions, by rewetting air-dried soil samples, and monitoring the respiration and Bacterial Growth responses. The respiratory responses in drought-exposed soils were slower and reached lower rates than control soils, translating to less C mineralised one week after rewetting. While the Bacterial Growth in drought-exposed soil also was slower, this was only a delayed response, and no differences in cumulative Bacterial Growth one week after rewetting could be established between drought-exposed and control soils. The pulse in respiration and microbial Growth following the rewetting appeared to be due to facilitated microbial C availability caused by physical perturbation of the soil induced by the rewetting event. Reduced C input by trees during drought probably contributed to differences between drought-treated and control soils. Our results indicate that a history of drought increases the microbial C-use efficiency during a rewetting, suggesting a negative feedback to climate warming.
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Fungal and Bacterial Growth following the application of slurry and anaerobic digestate of livestock manure to temperate pasture soils
Biology and Fertility of Soils, 2012Co-Authors: John J. Walsh, Johannes Rousk, Gareth Edwards-jones, Davey L. Jones, A. Prysor WilliamsAbstract:How land-application of digestate sourced from anaerobic digestion (AD) of animal waste influences the functioning of a mixed pasture agroecosystem is not well characterised, particularly with regard to the response of the actively growing microbial community. We studied the impact of the liquid AD digestate on the decomposer community in two different soils, seeded with two different common grassland crops; a mixture of either grass or grass/clover in a greenhouse experiment. We studied Bacterial (leucine incorporation into bacteria) and fungal (acetate incorporation into ergosterol) Growth responses to AD cattle slurry digestate, undigested cattle slurry, mineral fertiliser (NPK and N) added at a rate equivalent to 150 kg N ha−1, and a no-fertiliser control treatment. Differences in fungal and Bacterial Growth were evident between the soil and sward types. However, the fertilisers consistently stimulated a higher Bacterial Growth than the no-fertiliser control, and liquid digestate resulted in a level of Bacterial Growth higher or equal to that of mineral fertiliser, whilst undigested slurry resulted in lower Bacterial Growth. These fertiliser effects on Bacterial Growth mirrored the effects on plant Growth. In contrast, the fungal community responded only marginally to fertiliser treatments. We conclude that the application of digestate stimulates the Bacterial decomposer community in a similar way to that of mineral fertilisers. Our results suggest that mineral fertiliser can be exchanged for liquid digestate with limited impact on the actively growing soil microbial community that, in turn, regulate important soil processes including nutrient cycling in agricultural soils.
Anders Lobnerolesen - One of the best experts on this subject based on the ideXlab platform.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
Antimicrobial Agents and Chemotherapy, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effects predominantly on rapidly growing Bacterial cells; yet, the Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, a means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as a readout of in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (quantitative PCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average level and on a single-cell level, from one single biological specimen. Here, we asked whether the in situ Growth rate predicts antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as a proof of concept. Our data demonstrate that the activities of the commonly used antibiotics ceftriaxone and gentamicin correlated with pretreatment Bacterial Growth rate; both drugs performed better during rapid Growth than during slow Growth. Conversely, ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic’s dependency on active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
bioRxiv, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effect predominantly on rapidly growing Bacterial cells, yet Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as readout for in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (qPCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average and on a single-cell level; from one single biological specimen. Here, we asked whether the in situ Growth rate could predict antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as proof-of-concept. Our data demonstrate that the activity of commonly used antibiotics Ceftriaxone and Gentamicin correlated with pre-treatment Bacterial Growth rate; both drugs performing better during rapid Growth than during slow Growth. Conversely, Ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic's dependency upon active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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chromosome replication as a measure of Bacterial Growth rate during escherichia coli infection in the mouse peritonitis model
Scientific Reports, 2018Co-Authors: Maria Schei Haugan, Godefroid Charbon, Niels Frimodtmoller, Anders LobnerolesenAbstract:The efficacy of most antibiotics is dependent on active Bacterial Growth, yet little is known about the Growth dynamics during infection. Therefore, means to measure in-host Bacterial Growth rate is of importance. Here, we use chromosome replication as readout for in situ Bacterial Growth rate during infection; obtained from a single biological specimen. We have applied two independent methods: quantitative PCR (qPCR) and fluorescence microscopy, to quantify the level of chromosome replication present during Escherichia coli propagation in the mouse peritonitis model. We find that the methods complement each other and allow for quantification of Growth rate, both on a population average and on a single-cell level. We demonstrate the presence of heterogeneous Growth rates within Bacterial populations propagating during infection. Also, no Growth cessation was observed during the apparent stationary phase in vivo, and, by comparison of Growth dynamics at different anatomical sites, we demonstrate that E. coli is unlikely to grow independently intravascularly. These findings provide novel insight into Bacterial Growth during host infection, and underscore the importance of pinpointing the primary site of infection in septicaemia of unknown origin and ensuring antibiotic availability at this site.
Maria Schei Haugan - One of the best experts on this subject based on the ideXlab platform.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
Antimicrobial Agents and Chemotherapy, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effects predominantly on rapidly growing Bacterial cells; yet, the Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, a means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as a readout of in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (quantitative PCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average level and on a single-cell level, from one single biological specimen. Here, we asked whether the in situ Growth rate predicts antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as a proof of concept. Our data demonstrate that the activities of the commonly used antibiotics ceftriaxone and gentamicin correlated with pretreatment Bacterial Growth rate; both drugs performed better during rapid Growth than during slow Growth. Conversely, ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic’s dependency on active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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comparative activity of ceftriaxone ciprofloxacin and gentamicin as a function of Bacterial Growth rate probed by escherichia coli chromosome replication in the mouse peritonitis model
bioRxiv, 2018Co-Authors: Maria Schei Haugan, Anders Lobnerolesen, Niels FrimodtmollerAbstract:Commonly used antibiotics exert their effect predominantly on rapidly growing Bacterial cells, yet Growth dynamics taking place during infection in a complex host environment remain largely unknown. Hence, means to measure in situ Bacterial Growth rate is essential to predict the outcome of antiBacterial treatment. We have recently validated chromosome replication as readout for in situ Bacterial Growth rate during Escherichia coli infection in the mouse peritonitis model. By the use of two complementary methods (qPCR and fluorescence microscopy) for differential genome origin and terminus copy number quantification, we demonstrated the ability to track Bacterial Growth rate, both on a population average and on a single-cell level; from one single biological specimen. Here, we asked whether the in situ Growth rate could predict antibiotic treatment effect during infection in the same model. Parallel in vitro Growth experiments were conducted as proof-of-concept. Our data demonstrate that the activity of commonly used antibiotics Ceftriaxone and Gentamicin correlated with pre-treatment Bacterial Growth rate; both drugs performing better during rapid Growth than during slow Growth. Conversely, Ciprofloxacin was less sensitive to Bacterial Growth rate, both in a homogenous in vitro Bacterial population and in a more heterogeneous in vivo Bacterial population. The method serves as a platform to test any antibiotic's dependency upon active in situ Bacterial Growth. Improved insight into this relationship in vivo could ultimately prove helpful in evaluating future antiBacterial strategies.
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chromosome replication as a measure of Bacterial Growth rate during escherichia coli infection in the mouse peritonitis model
Scientific Reports, 2018Co-Authors: Maria Schei Haugan, Godefroid Charbon, Niels Frimodtmoller, Anders LobnerolesenAbstract:The efficacy of most antibiotics is dependent on active Bacterial Growth, yet little is known about the Growth dynamics during infection. Therefore, means to measure in-host Bacterial Growth rate is of importance. Here, we use chromosome replication as readout for in situ Bacterial Growth rate during infection; obtained from a single biological specimen. We have applied two independent methods: quantitative PCR (qPCR) and fluorescence microscopy, to quantify the level of chromosome replication present during Escherichia coli propagation in the mouse peritonitis model. We find that the methods complement each other and allow for quantification of Growth rate, both on a population average and on a single-cell level. We demonstrate the presence of heterogeneous Growth rates within Bacterial populations propagating during infection. Also, no Growth cessation was observed during the apparent stationary phase in vivo, and, by comparison of Growth dynamics at different anatomical sites, we demonstrate that E. coli is unlikely to grow independently intravascularly. These findings provide novel insight into Bacterial Growth during host infection, and underscore the importance of pinpointing the primary site of infection in septicaemia of unknown origin and ensuring antibiotic availability at this site.