The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was meas... more The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was measured in each of four seasons. Ten freshly collected feces were placed on pasture, and concentrations of Escherichia coli , enterococci, and Campylobacter spp. were monitored until exhaustion of the fecal samples. In all four seasons, there was an increase in enterococcal concentrations by up to 3 orders of magnitude, with peak concentrations recorded between 11 and 28 days after deposition. E. coli concentrations increased in three out of four seasons by up to 1.5 orders of magnitude, with peak concentrations recorded between 8 and 14 days after deposition. The apparent growth of E. coli and enterococci was strongly influenced by the initial water content of the feces and the moisture gained during periods of rehydration following rainfalls. Conversely, the results suggested that dehydration promoted inactivation. Campylobacter spp. did not grow and were rapidly inactivated at a rate tha...
Adequate sewage treatment is essential for maintaining both New Zealand and global economic and s... more Adequate sewage treatment is essential for maintaining both New Zealand and global economic and sustainable existences. Treatment, such as pathogen removal, is required to protect the public health and the environment from anthropogenic activities. Investigating enzymatic virus removal mechanisms can aid development of pathogen removal models and increase the knowledge of these processes to enable the efficient, low-cost, running of waste stabilisation ponds.
Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established f... more Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established for quantifying its filtration removal in porous media. Carboxyl polystyrene microspheres with size, density, and shape similar to C. parvum were coated with biotin (free and containing amine, NH(2)) and glycoprotein. These biomolecules have isoelectric points similar to C. parvum (pH ≈ 2), and glycoprotein is a major type of surface protein that oocysts possess. Zeta potential (ζ) and filtration removal of particles in sand of two different grain sizes were examined. Compared to unmodified microspheres, modified microspheres achieved a superior match to the oocysts in ζ, concentration, mass recovery, and collision coefficient. They showed the same log reduction in concentration as oocysts, whereas results from unmodified microspheres deviated by 1 order of magnitude. Of the three types of modified microspheres, glycoprotein-coated microspheres best resembled oocyst concentration, despite having ζ similar to NH(2)-biotin-coated microspheres, suggesting that surface protein also played an important role in particle attachment on solid surfaces. With further validation in environmental conditions, the surrogates developed here could be a cost-effective new tool for assessing oocyst filtration in porous media, for example, to evaluate the performance of sand filters in water and wastewater treatment, water recycling through riverbank filtration, and aquifer recharge.
Background and Objectives. Anecdotal reports on the efficacy of secretin in autism raised great h... more Background and Objectives. Anecdotal reports on the efficacy of secretin in autism raised great hopes for the treatment of children with this disorder. Initial single-dose, randomized, controlled trials failed to demonstrate any therapeutic effects of secretin. The present study is the first ...
Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiv... more Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium. Methods and Results: Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium spp., Penicillium chrysogenum and Candida albicans) for various time periods. Culture on potato dextrose agar and an in situ viability assay using the fluorochrome FUN-1 were used to determine whether spores had survived. The results showed increased die off of fungal isolates tested compared to aluminium. In addition, copper also prevented the germination of spores present, thereby reducing the risk of the release of spores. Conclusions: Copper offered an antifungal surface and prevented subsequent germination of spores present. FUN-1 demonstrated that fungal spores entered into a viable but not culturable (VBNC) state on copper indicating the importance of using such methods when assessing the effect of an antifungal as culture alone may give false results. Significance and impact of study: Copper offers a valuable alternative to aluminium which could be used in air-conditioning systems in buildings, particularly in hospital environments where patients are more susceptible to fungal infections.
Clostridium difficile is rapidly becoming a major cause of hospital-acquired infections worldwide... more Clostridium difficile is rapidly becoming a major cause of hospital-acquired infections worldwide, due in part to transmission of the faecal pathogen between contaminated hands and contact surfaces. Accordingly, this study evaluated survival of C. difficile vegetative cells and spores on the contact surface commonly found in healthcare settings, stainless steel, compared to five copper alloys (65e100% copper content). C. difficile requires prolonged incubation to grow and therefore the total number and number of viable cells was estimated using a fluorescence dual-staining technique. For viability assessment the redox dye 5-cyano-2,3-ditolyl tetrazolium (CTC) was used to measure metabolic activity. Results demonstrated that copper alloys with a copper content >70% provide a significant reduction in survival of C. difficile vegetative cells and spores on copper alloys compared with stainless steel. Complete death of spores was observed after 24e48 h on copper alloys whereas no significant death rate was observed on stainless steel even after 168 h. The use of CTC gave comparable results to culture and offers a more rapid viability analysis (8 h) than culture. The results suggest that using copper alloys in hospitals and other healthcare facilities could offer the potential to reduce spread of C. difficile from contaminated surfaces.
The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was meas... more The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was measured in each of four seasons. Ten freshly collected feces were placed on pasture, and concentrations of Escherichia coli, enterococci, and Campylobacter spp. were monitored until exhaustion of the fecal samples. In all four seasons, there was an increase in enterococcal concentrations by up to 3 orders of magnitude, with peak concentrations recorded between 11 and 28 days after deposition. E. coli concentrations increased in three out of four seasons by up to 1.5 orders of magnitude, with peak concentrations recorded between 8 and 14 days after deposition. The apparent growth of E. coli and enterococci was strongly influenced by the initial water content of the feces and the moisture gained during periods of rehydration following rainfalls. Conversely, the results suggested that dehydration promoted inactivation. Campylobacter spp. did not grow and were rapidly inactivated at a rate that tended to be faster at higher temperatures. Pulsed-field gel electrophoresis (PFGE) of a selection of Campylobacter spp. suggested that these survival data are applicable to a range of Campylobacter spp., including the most frequently isolated PFGE genotype from sheep in New Zealand, and to genotypes previously observed to cause disease in humans. The results of this study are currently being incorporated into a fecal microbe reservoir model that is designed to assist water managers' abilities to estimate microbial loads on pastures grazed by sheep, including the influence of factors such as rainfall and temperature.
The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was meas... more The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was measured in each of four seasons. Ten freshly collected feces were placed on pasture, and concentrations of Escherichia coli , enterococci, and Campylobacter spp. were monitored until exhaustion of the fecal samples. In all four seasons, there was an increase in enterococcal concentrations by up to 3 orders of magnitude, with peak concentrations recorded between 11 and 28 days after deposition. E. coli concentrations increased in three out of four seasons by up to 1.5 orders of magnitude, with peak concentrations recorded between 8 and 14 days after deposition. The apparent growth of E. coli and enterococci was strongly influenced by the initial water content of the feces and the moisture gained during periods of rehydration following rainfalls. Conversely, the results suggested that dehydration promoted inactivation. Campylobacter spp. did not grow and were rapidly inactivated at a rate tha...
Adequate sewage treatment is essential for maintaining both New Zealand and global economic and s... more Adequate sewage treatment is essential for maintaining both New Zealand and global economic and sustainable existences. Treatment, such as pathogen removal, is required to protect the public health and the environment from anthropogenic activities. Investigating enzymatic virus removal mechanisms can aid development of pathogen removal models and increase the knowledge of these processes to enable the efficient, low-cost, running of waste stabilisation ponds.
Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established f... more Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established for quantifying its filtration removal in porous media. Carboxyl polystyrene microspheres with size, density, and shape similar to C. parvum were coated with biotin (free and containing amine, NH(2)) and glycoprotein. These biomolecules have isoelectric points similar to C. parvum (pH ≈ 2), and glycoprotein is a major type of surface protein that oocysts possess. Zeta potential (ζ) and filtration removal of particles in sand of two different grain sizes were examined. Compared to unmodified microspheres, modified microspheres achieved a superior match to the oocysts in ζ, concentration, mass recovery, and collision coefficient. They showed the same log reduction in concentration as oocysts, whereas results from unmodified microspheres deviated by 1 order of magnitude. Of the three types of modified microspheres, glycoprotein-coated microspheres best resembled oocyst concentration, despite having ζ similar to NH(2)-biotin-coated microspheres, suggesting that surface protein also played an important role in particle attachment on solid surfaces. With further validation in environmental conditions, the surrogates developed here could be a cost-effective new tool for assessing oocyst filtration in porous media, for example, to evaluate the performance of sand filters in water and wastewater treatment, water recycling through riverbank filtration, and aquifer recharge.
Background and Objectives. Anecdotal reports on the efficacy of secretin in autism raised great h... more Background and Objectives. Anecdotal reports on the efficacy of secretin in autism raised great hopes for the treatment of children with this disorder. Initial single-dose, randomized, controlled trials failed to demonstrate any therapeutic effects of secretin. The present study is the first ...
Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiv... more Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium. Methods and Results: Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium spp., Penicillium chrysogenum and Candida albicans) for various time periods. Culture on potato dextrose agar and an in situ viability assay using the fluorochrome FUN-1 were used to determine whether spores had survived. The results showed increased die off of fungal isolates tested compared to aluminium. In addition, copper also prevented the germination of spores present, thereby reducing the risk of the release of spores. Conclusions: Copper offered an antifungal surface and prevented subsequent germination of spores present. FUN-1 demonstrated that fungal spores entered into a viable but not culturable (VBNC) state on copper indicating the importance of using such methods when assessing the effect of an antifungal as culture alone may give false results. Significance and impact of study: Copper offers a valuable alternative to aluminium which could be used in air-conditioning systems in buildings, particularly in hospital environments where patients are more susceptible to fungal infections.
Clostridium difficile is rapidly becoming a major cause of hospital-acquired infections worldwide... more Clostridium difficile is rapidly becoming a major cause of hospital-acquired infections worldwide, due in part to transmission of the faecal pathogen between contaminated hands and contact surfaces. Accordingly, this study evaluated survival of C. difficile vegetative cells and spores on the contact surface commonly found in healthcare settings, stainless steel, compared to five copper alloys (65e100% copper content). C. difficile requires prolonged incubation to grow and therefore the total number and number of viable cells was estimated using a fluorescence dual-staining technique. For viability assessment the redox dye 5-cyano-2,3-ditolyl tetrazolium (CTC) was used to measure metabolic activity. Results demonstrated that copper alloys with a copper content >70% provide a significant reduction in survival of C. difficile vegetative cells and spores on copper alloys compared with stainless steel. Complete death of spores was observed after 24e48 h on copper alloys whereas no significant death rate was observed on stainless steel even after 168 h. The use of CTC gave comparable results to culture and offers a more rapid viability analysis (8 h) than culture. The results suggest that using copper alloys in hospitals and other healthcare facilities could offer the potential to reduce spread of C. difficile from contaminated surfaces.
The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was meas... more The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was measured in each of four seasons. Ten freshly collected feces were placed on pasture, and concentrations of Escherichia coli, enterococci, and Campylobacter spp. were monitored until exhaustion of the fecal samples. In all four seasons, there was an increase in enterococcal concentrations by up to 3 orders of magnitude, with peak concentrations recorded between 11 and 28 days after deposition. E. coli concentrations increased in three out of four seasons by up to 1.5 orders of magnitude, with peak concentrations recorded between 8 and 14 days after deposition. The apparent growth of E. coli and enterococci was strongly influenced by the initial water content of the feces and the moisture gained during periods of rehydration following rainfalls. Conversely, the results suggested that dehydration promoted inactivation. Campylobacter spp. did not grow and were rapidly inactivated at a rate that tended to be faster at higher temperatures. Pulsed-field gel electrophoresis (PFGE) of a selection of Campylobacter spp. suggested that these survival data are applicable to a range of Campylobacter spp., including the most frequently isolated PFGE genotype from sheep in New Zealand, and to genotypes previously observed to cause disease in humans. The results of this study are currently being incorporated into a fecal microbe reservoir model that is designed to assist water managers' abilities to estimate microbial loads on pastures grazed by sheep, including the influence of factors such as rainfall and temperature.
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Papers by L. Weaver