- Volume 1, Issue 10, 2019

The female mosquito Aedes aegypti needs a blood meal to reproduce and is therefore a vector of arthropod borne viruses (arboviruses) such as Zika (ZIKV) or chikungunya (CHIKV) viruses. Even though mosquitoes transmit viruses, they possess different immune pathways to fight against pathogens. Surprisingly, the analysis of immune gene expression in different tissues from non blood fed (NBF) or blood fed (BF) females revealed that these genes were repressed in the digestive tract from 2 to 30 h following blood meal. As the digestive tract is the first barrier to be overcome by an arbovirus during the first few hours/days after blood meal, our findings could explain the high susceptibility of Ae. aegypti mosquitoes to arboviruses. To investigate this hypothesis, it is required to identify the mechanism by which gut immunodeficiency is triggered. We would then be able to inhibit it and analyse the impact on mosquito infection/transmission. In addition to the acquisition of a blood meal, the female must mate before laying fertilized eggs. Mating has been shown to cause changes in the female physiology and behaviour such as refractoriness to further mating in many insects but also, mating has been shown to influence immunity in Drosophila. We found that mating transiently antagonizes the immune gene repression in the digestive tract of BF females compared to virgin BF females. The mechanisms by which blood-feeding and mating modulate gut immunity are under investigation and will be presented during the conference.

The female mosquito Aedes aegypti needs a blood meal to reproduce and is therefore a vector of arthropod borne viruses (arboviruses) such as Zika (ZIKV) or chikungunya (CHIKV) viruses. Even though mosquitoes transmit viruses, they possess different immune pathways to fight against pathogens. Surprisingly, the analysis of immune gene expression in different tissues from non blood fed (NBF) or blood fed (BF) females revealed that these genes were repressed in the digestive tract from 2 to 30 h following blood meal. As the digestive tract is the first barrier to be overcome by an arbovirus during the first few hours/days after blood meal, our findings could explain the high susceptibility of Ae. aegypti mosquitoes to arboviruses. To investigate this hypothesis, it is required to identify the mechanism by which gut immunodeficiency is triggered. We would then be able to inhibit it and analyse the impact on mosquito infection/transmission. In addition to the acquisition of a blood meal, the female must mate before laying fertilized eggs. Mating has been shown to cause changes in the female physiology and behaviour such as refractoriness to further mating in many insects but also, mating has been shown to influence immunity in Drosophila. We found that mating transiently antagonizes the immune gene repression in the digestive tract of BF females compared to virgin BF females. The mechanisms by which blood-feeding and mating modulate gut immunity are under investigation and will be presented during the conference.

The emergence of multidrug resistant bacteria has driven the need for novel antibiotics. Lichens naturally produce a wide range of unique defence chemicals and have already, historically shown medicinal efficacy. Antimicrobial properties of Lichens were investigated. Ten common churchyard species were sampled and extracted in acetone, namely Caloplaca flavescens, Diploicia canescens, Cladonia fimbriata, Psilolechia lucida, Lecanora campestris subsp. Campestris, Lecanora sulphurea, Pertusaria amara f.amara, Lepraria incana, Porpidia tuberculosa and Xanthoria calcicola. Extracts were impregnated into filter paper discs and tested against Gram positive and Gram negative bacteria and two fungi using the disc diffusion susceptibility test method. Extracts of Diploicia canescens, Psilolechia lucida, Lecanora sulphurea, Pertusaria amara f. amara and Lepraria incana showed inhibition against Gram positive bacteria. Diploicia canescens, Pertusaria amara and Lepraria incana also inhibited the dermatophyte fungi tested. Further studies should isolate their metabolites in order to find the agents responsible for the antimicrobial activity. These agents may or may not be novel to medicine but could be of current medicinal interest.

Area of expertise: Microbiology, biochemistry, antimicrobials, medieval Welsh texts exploration.

Future goals: Medieval and other historical Welsh texts are newly being translated into English, which include the Red Book of Hergest used by the Physicians of Myddfai, the famous Welsh medical practitioners of the 12th century. The previous translations have so far only been studied for Welsh Language (esp. poetry) and cultural aspects, while these books also contain a wealth of information on historical approaches to societal, environmental and medical problems. We aimed to explore the translated texts for the recovery of (bio)chemical, public health and environmental knowledge of the ancient Welsh environment and society.

The newly translated medieval Welsh antimicrobial recipes were reviewed for plant names/parts and other sources, medical indication of application, and materials or processes related to extraction and formulation of the remedy in order to better understand principal components and their activities, and to be able to redesign recipes using modern chemical extraction protocols. Statistical analysis showed that a wide range of materials could potentially function for selective extraction or for precipitation of (non-)active components. Clear descriptions of processes and protocols were usually missing. It therefore requires considerable human and material resources to truly assess the merits of medieval recipes.

It would therefore be worthwhile to discuss the merit of a systematic review of historical extraction and purification principles, to be able to suggest common principles aiding effective rediscovery and redesign of antimicrobials from historical texts. Did medieval societies employ “Standard Operating Procedures”? How can modern scientists accurately and efficiently assess the merits of historical treatment alternatives to infection in the age of increasing antimicrobial resistance?

Area of expertise: Microbiology, biochemistry, antimicrobials, medieval Welsh texts exploration.

Future goals: Medieval and other historical Welsh texts are newly being translated into English, which include the Red Book of Hergest used by the Physicians of Myddfai, the famous Welsh medical practitioners of the 12th century. The previous translations have so far only been studied for Welsh Language (esp. poetry) and cultural aspects, while these books also contain a wealth of information on historical approaches to societal, environmental and medical problems. We aimed to explore the translated texts for the recovery of (bio)chemical, public health and environmental knowledge of the ancient Welsh environment and society.

The newly translated medieval Welsh antimicrobial recipes were reviewed for plant names/parts and other sources, medical indication of application, and materials or processes related to extraction and formulation of the remedy in order to better understand principal components and their activities, and to be able to redesign recipes using modern chemical extraction protocols. Statistical analysis showed that a wide range of materials could potentially function for selective extraction or for precipitation of (non-)active components. Clear descriptions of processes and protocols were usually missing. It therefore requires considerable human and material resources to truly assess the merits of medieval recipes.

It would therefore be worthwhile to discuss the merit of a systematic review of historical extraction and purification principles, to be able to suggest common principles aiding effective rediscovery and redesign of antimicrobials from historical texts. Did medieval societies employ “Standard Operating Procedures”? How can modern scientists accurately and efficiently assess the merits of historical treatment alternatives to infection in the age of increasing antimicrobial resistance?

Area of expertise: My research interests focus on identifying novel compounds that can disrupt key phenotypes associated with antibiotic resistance such as biofilm formation and motility in the pathogens Acinetobacter baumannii and Pseudomonas aeruginosa. To this end we have developed a range of screens and assays to facilitate compound identification and mechanism of action profiling in these pathogens. These include: Antibiotic Resistance Inhibitor Screens, Biofilm Inhibition Screens, Biofilm Disruption Screens, Signalling Pathway Specific Biosensor Screens , Mechanism of Action Assays, Resistance Development Screens, Antibiotic Resistance Inhibitor Screens, In vivo biofilm and pathogenicity models to validate lead compounds and perform toxicity profiling.

Future goals: Future goals include being part of a collaborative multidisciplinary drug discovery network that has access to diverse and bespoke extract/compound collections and the expertise to identify the bioactive leads, characterise their mechanism of action and ultimately take them forward to clinical trials. Further to this the goal is to target national and international funding opportunities that will facilitate taking active compounds right through the drug discovery pipeline from the bench to the bedside. I am hoping to identify collaborators across all aspects of drugs discovery, particularly collaborators with: Access to compound or extract collections, Expertise in compound identification ,Clinical trial expertise.

Area of expertise: My research interests focus on identifying novel compounds that can disrupt key phenotypes associated with antibiotic resistance such as biofilm formation and motility in the pathogens Acinetobacter baumannii and Pseudomonas aeruginosa. To this end we have developed a range of screens and assays to facilitate compound identification and mechanism of action profiling in these pathogens. These include: Antibiotic Resistance Inhibitor Screens, Biofilm Inhibition Screens, Biofilm Disruption Screens, Signalling Pathway Specific Biosensor Screens , Mechanism of Action Assays, Resistance Development Screens, Antibiotic Resistance Inhibitor Screens, In vivo biofilm and pathogenicity models to validate lead compounds and perform toxicity profiling.

Future goals: Future goals include being part of a collaborative multidisciplinary drug discovery network that has access to diverse and bespoke extract/compound collections and the expertise to identify the bioactive leads, characterise their mechanism of action and ultimately take them forward to clinical trials. Further to this the goal is to target national and international funding opportunities that will facilitate taking active compounds right through the drug discovery pipeline from the bench to the bedside. I am hoping to identify collaborators across all aspects of drugs discovery, particularly collaborators with: Access to compound or extract collections, Expertise in compound identification ,Clinical trial expertise.

Area of expertise: I have a very strong background on the action of antimicrobials and their resistance, I originally trained on the study of disinfectant mechanisms of action and resistance with a number of publications on the topic. For some years I have investigated the antimicrobial properties of plant extracts such as tinctures and oils as well as specific phytochemicals. More recently, through a collaboration with a company in North Yorkshire I have become involved in the study of propolis, a product of the hive. Propolis is a resinous substance used by the bees for protection. It is highly complex, comprising in excess of 300 different chemicals; it is also very variable as its chemical composition depends on the time of year collected, the plants the bees are harvesting from and thus the geographical location.

In my group we are utilising our expertise to study the antimicrobial and antioxidant properties of propolis from different geographical locations in order to establish a link between the different aspects of biological activity with chemical composition. We are also investigating the effect of propolis on biofilm formation and quorum sensing, as well as its effects on antibiotic resistance.

Future goals: There is general awareness of the potential of propolis, from researchers and clinicians alike. However, understanding of this amazing product is relatively limited particularly regarding its biological activity as most of the research has been carried out by chemists analysing the different components. We would like to further understand the extent of the biological activity of propolis particularly regarding its antimicrobial and antioxidant activity. So that in the future we will be able to elucidate its mechanism (or most likely mechanisms) of action.

The main hurdles we currently face is regarding solubility which makes the use of established methodologies such as MICs very challenging. We are looking for researchers with experience in alternatives to these tests, particularly for test compounds with very limited solubility, as many phytochemicals are.

It has been suggested by colleagues that perhaps it would be necessary to investigate the effects of propolis on the whole organism at the molecular level, and thus carry out genomic and proteomic analysis following exposure to propolis. We would like to make links with researchers with experience of this kind of analysis to help us further understand the outcome of this kind of investigations. In the longer term in order to be able to work towards conducting clinical trials we would benefit from contacts with researchers that have taken work through this process.

Area of expertise: I have a very strong background on the action of antimicrobials and their resistance, I originally trained on the study of disinfectant mechanisms of action and resistance with a number of publications on the topic. For some years I have investigated the antimicrobial properties of plant extracts such as tinctures and oils as well as specific phytochemicals. More recently, through a collaboration with a company in North Yorkshire I have become involved in the study of propolis, a product of the hive. Propolis is a resinous substance used by the bees for protection. It is highly complex, comprising in excess of 300 different chemicals; it is also very variable as its chemical composition depends on the time of year collected, the plants the bees are harvesting from and thus the geographical location.

In my group we are utilising our expertise to study the antimicrobial and antioxidant properties of propolis from different geographical locations in order to establish a link between the different aspects of biological activity with chemical composition. We are also investigating the effect of propolis on biofilm formation and quorum sensing, as well as its effects on antibiotic resistance.

Future goals: There is general awareness of the potential of propolis, from researchers and clinicians alike. However, understanding of this amazing product is relatively limited particularly regarding its biological activity as most of the research has been carried out by chemists analysing the different components. We would like to further understand the extent of the biological activity of propolis particularly regarding its antimicrobial and antioxidant activity. So that in the future we will be able to elucidate its mechanism (or most likely mechanisms) of action.

The main hurdles we currently face is regarding solubility which makes the use of established methodologies such as MICs very challenging. We are looking for researchers with experience in alternatives to these tests, particularly for test compounds with very limited solubility, as many phytochemicals are.

It has been suggested by colleagues that perhaps it would be necessary to investigate the effects of propolis on the whole organism at the molecular level, and thus carry out genomic and proteomic analysis following exposure to propolis. We would like to make links with researchers with experience of this kind of analysis to help us further understand the outcome of this kind of investigations. In the longer term in order to be able to work towards conducting clinical trials we would benefit from contacts with researchers that have taken work through this process.

Introduction: P. aeruginosa and S. aureus are opportunistic pathogens that cause a wide range of infections. Their increasing resistance to antibiotics is a serious concern and making them susceptible to treatments is now more essential than ever. There is a need to discover new biofilm inhibitors to increase the susceptibility of these bacteria to antibiotics.

Hypothesis and aims: To evaluate the antibiofilm activity of heather honey, propolis and medicinal plant extracts against P. aeruginosa and S. aureus.

Methodology: Determination of optimum biofilm growth was carried out using a time-course assay over 24 h intervals, using P. aeruginosa PA14 and S. aureus NCTC 4135 strains. The inhibitory effects of all extracts were determined by biofilm inhibition assay in 24-well plates, with biofilms stained with crystal violet and de-stained with ethanol:acetone; OD were measured at 550 nm. Planktonic growth was measured at 600 nm and samples from the wells were streaked to determine bactericidal effects.

Results: Heather honey extracts inhibited both P. aeruginosa and S. aureus by 68%. At 60 μg/mL, one of the propolis extracts promoted biofilm growth of both pathogens. Two other propolis extracts also promoted growth in P. aeruginosa but inhibited biofilm formation in S. aureus by 76.5% and 13.8%, respectively. Three plant extracts inhibited S. aureus biofilm by 7.5%, 10.2% and 87.6% and inhibited P. aeruginosa by −34.9%, 34.7% and 19.4%, respectively.

Conclusion: All samples showed varying biofilm inhibition capabilities, but biofilm formation seemed to be more easily inhibited in S. aureus than in P. aeruginosa.

Introduction: P. aeruginosa and S. aureus are opportunistic pathogens that cause a wide range of infections. Their increasing resistance to antibiotics is a serious concern and making them susceptible to treatments is now more essential than ever. There is a need to discover new biofilm inhibitors to increase the susceptibility of these bacteria to antibiotics.

Hypothesis and aims: To evaluate the antibiofilm activity of heather honey, propolis and medicinal plant extracts against P. aeruginosa and S. aureus.

Methodology: Determination of optimum biofilm growth was carried out using a time-course assay over 24 h intervals, using P. aeruginosa PA14 and S. aureus NCTC 4135 strains. The inhibitory effects of all extracts were determined by biofilm inhibition assay in 24-well plates, with biofilms stained with crystal violet and de-stained with ethanol:acetone; OD were measured at 550 nm. Planktonic growth was measured at 600 nm and samples from the wells were streaked to determine bactericidal effects.

Results: Heather honey extracts inhibited both P. aeruginosa and S. aureus by 68%. At 60 μg/mL, one of the propolis extracts promoted biofilm growth of both pathogens. Two other propolis extracts also promoted growth in P. aeruginosa but inhibited biofilm formation in S. aureus by 76.5% and 13.8%, respectively. Three plant extracts inhibited S. aureus biofilm by 7.5%, 10.2% and 87.6% and inhibited P. aeruginosa by −34.9%, 34.7% and 19.4%, respectively.

Conclusion: All samples showed varying biofilm inhibition capabilities, but biofilm formation seemed to be more easily inhibited in S. aureus than in P. aeruginosa.

Wounds from various sources such as burns and ulcers which have been in a prolonged state of inflammation and rubor, both exudative and non-exudative, are decidedly prone to becoming infected by various opportunistic and commensal microorganisms, both bacterial and fungal due to the warm moist environment at the wound site (Que et al.,2019). The typical approach in treating these wounds is to reduce the level of infection and inflammation, thus encouraging an appropriate environment for successful re-epithelisation resulting in faster healing of the wound.

Bacterial cellulose (BC) is an ideal material to produce wound dressings due to the intrinsic properties such as; high chemical stability, high tensile strength and flexibility, large water holding capacity, permeable to gases and liquids, and excellent biocompatibility (Gupta et al., 2016; Gupta et al.,2017, Wahid et al., 2019).

In this study, BC produced by Komagataeibacter xylinus was used as a hydrogel matrix and loaded with a well-known antimicrobial agent- curcumin encapsulated in solubility enhancing carriers, hydroxypropyl- β-cyclodextrin (CUR:HPβCD) (Abbas et al., 2019, Gupta et al., 2019). BC was loaded with 2% (w/v) aqueous CUR:HPβCD inclusion complex under constant agitation at 170 rpm at 20°C (room temperature) for 24 hours.

Antimicrobial activity was tested against two representative organisms:

Candida albicans and Staphylococcus aureus by disc diffusion method. We have previously reported the antibacterial activity of CUR:HPβCD-loaded BC (Gupta et al., 2019). The current study is an extension of our ongoing research where we made an attempt of testing the anti-fungal activity of CUR:HPβCD-loaded BC and compared it with anti-bacterial activity. 8mm discs were aseptically cut and placed on TSA plates seeded with overnight cultures of one of the microorganisms under investigation and incubated at 37°C for 24 hours.

The results indicated that C. albicans and S. aureus were both susceptible to CUR:HPβCD inclusion complex with an average zone of inhibition of 12.25±2.2mm and 11±1.2mm respectively (n=4, ±=SD, p <0.05). The results against S. aureus are in accordance with our previously reported findings (Gupta et al., 2019). Current findings support the wound management applications of CUR:HPβCd-loaded BC hydrogels for chronic wounds.

References

Abbas, M., Hussain, T., Arshad, M., Ansari, A., Irshad, A., Nisar, J., Hussain, F., Masood, N., Nazir, A. and Iqbal, M. (2019). Wound healing potential of curcumin cross-linked chitosan/polyvinyl alcohol. International Journal of Biological Macromolecules, 140, pp.871-876.

Gupta, A., Keddie, D., Kannappan, V., Gibson, H., Khalil, I., Kowalczuk, M., Martin, C., Shuai, X. and Radecka, I. (2019). Production and characterisation of bacterial cellulose hydrogels loaded with curcumin encapsulated in cyclodextrins as wound dressings. European Polymer Journal, 118, pp.437-450.

Gupta, A., Low, W., Britland, S., Radecka, I. and Martin, C. (2017). Physicochemical characterisation of biosynthetic bacterial cellulose as a potential wound dressing material. British Journal of Pharmacy, 2(2), pp.S37-S38.

Gupta, A., Low, W., Radecka, I., Britland, S., Mohd Amin, M. and Martin, C. (2016). Characterisation and in vitro antimicrobial activity of biosynthetic silver-loaded bacterial cellulose hydrogels. Journal of Microencapsulation, 33(8), pp.725-734.

Que, A., Nguyen, N., Do, N., Nguyen, N., Tran, N. and Le, T. (2019). Infection of burn wound by Aspergillus fumigatus with gross appearance of fungal colonies. Medical Mycology Case Reports, 24, pp.30-32.

Wahid, F., Hu, X., Chu, L., Jia, S., Xie, Y. and Zhong, C. (2019). Development of bacterial cellulose/chitosan based semi-interpenetrating hydrogels with improved mechanical and antibacterial properties. International Journal of Biological Macromolecules, 122, pp.380-387.

Wounds from various sources such as burns and ulcers which have been in a prolonged state of inflammation and rubor, both exudative and non-exudative, are decidedly prone to becoming infected by various opportunistic and commensal microorganisms, both bacterial and fungal due to the warm moist environment at the wound site (Que et al.,2019). The typical approach in treating these wounds is to reduce the level of infection and inflammation, thus encouraging an appropriate environment for successful re-epithelisation resulting in faster healing of the wound.

Bacterial cellulose (BC) is an ideal material to produce wound dressings due to the intrinsic properties such as; high chemical stability, high tensile strength and flexibility, large water holding capacity, permeable to gases and liquids, and excellent biocompatibility (Gupta et al., 2016; Gupta et al.,2017, Wahid et al., 2019).

In this study, BC produced by Komagataeibacter xylinus was used as a hydrogel matrix and loaded with a well-known antimicrobial agent- curcumin encapsulated in solubility enhancing carriers, hydroxypropyl- β-cyclodextrin (CUR:HPβCD) (Abbas et al., 2019, Gupta et al., 2019). BC was loaded with 2% (w/v) aqueous CUR:HPβCD inclusion complex under constant agitation at 170 rpm at 20°C (room temperature) for 24 hours.

Antimicrobial activity was tested against two representative organisms:

Candida albicans and Staphylococcus aureus by disc diffusion method. We have previously reported the antibacterial activity of CUR:HPβCD-loaded BC (Gupta et al., 2019). The current study is an extension of our ongoing research where we made an attempt of testing the anti-fungal activity of CUR:HPβCD-loaded BC and compared it with anti-bacterial activity. 8mm discs were aseptically cut and placed on TSA plates seeded with overnight cultures of one of the microorganisms under investigation and incubated at 37°C for 24 hours.

The results indicated that C. albicans and S. aureus were both susceptible to CUR:HPβCD inclusion complex with an average zone of inhibition of 12.25±2.2mm and 11±1.2mm respectively (n=4, ±=SD, p <0.05). The results against S. aureus are in accordance with our previously reported findings (Gupta et al., 2019). Current findings support the wound management applications of CUR:HPβCd-loaded BC hydrogels for chronic wounds.

References

Abbas, M., Hussain, T., Arshad, M., Ansari, A., Irshad, A., Nisar, J., Hussain, F., Masood, N., Nazir, A. and Iqbal, M. (2019). Wound healing potential of curcumin cross-linked chitosan/polyvinyl alcohol. International Journal of Biological Macromolecules, 140, pp.871-876.

Gupta, A., Keddie, D., Kannappan, V., Gibson, H., Khalil, I., Kowalczuk, M., Martin, C., Shuai, X. and Radecka, I. (2019). Production and characterisation of bacterial cellulose hydrogels loaded with curcumin encapsulated in cyclodextrins as wound dressings. European Polymer Journal, 118, pp.437-450.

Gupta, A., Low, W., Britland, S., Radecka, I. and Martin, C. (2017). Physicochemical characterisation of biosynthetic bacterial cellulose as a potential wound dressing material. British Journal of Pharmacy, 2(2), pp.S37-S38.

Gupta, A., Low, W., Radecka, I., Britland, S., Mohd Amin, M. and Martin, C. (2016). Characterisation and in vitro antimicrobial activity of biosynthetic silver-loaded bacterial cellulose hydrogels. Journal of Microencapsulation, 33(8), pp.725-734.

Que, A., Nguyen, N., Do, N., Nguyen, N., Tran, N. and Le, T. (2019). Infection of burn wound by Aspergillus fumigatus with gross appearance of fungal colonies. Medical Mycology Case Reports, 24, pp.30-32.

Wahid, F., Hu, X., Chu, L., Jia, S., Xie, Y. and Zhong, C. (2019). Development of bacterial cellulose/chitosan based semi-interpenetrating hydrogels with improved mechanical and antibacterial properties. International Journal of Biological Macromolecules, 122, pp.380-387.

Wounds from various sources such as burns and ulcers which have been in a prolonged state of inflammation and rubor, both exudative and non-exudative, are decidedly prone to becoming infected by various opportunistic and commensal microorganisms, both bacterial and fungal due to the warm moist environment at the wound site (Que et al.,2019). The typical approach in treating these wounds is to reduce the level of infection and inflammation, thus encouraging an appropriate environment for successful re-epithelisation resulting in faster healing of the wound.

Bacterial cellulose (BC) is an ideal material to produce wound dressings due to the intrinsic properties such as; high chemical stability, high tensile strength and flexibility, large water holding capacity, permeable to gases and liquids, and excellent biocompatibility (Gupta et al., 2016; Gupta et al.,2017, Wahid et al., 2019).

In this study, BC produced by Komagataeibacter xylinus was used as a hydrogel matrix and loaded with a well-known antimicrobial agent- curcumin encapsulated in solubility enhancing carriers, hydroxypropyl- β-cyclodextrin (CUR:HPβCD) (Abbas et al., 2019, Gupta et al., 2019). BC was loaded with 2% (w/v) aqueous CUR:HPβCD inclusion complex under constant agitation at 170 rpm at 20°C (room temperature) for 24 hours.

Antimicrobial activity was tested against two representative organisms:

Candida albicans and Staphylococcus aureus by disc diffusion method. We have previously reported the antibacterial activity of CUR:HPβCD-loaded BC (Gupta et al., 2019). The current study is an extension of our ongoing research where we made an attempt of testing the anti-fungal activity of CUR:HPβCD-loaded BC and compared it with anti-bacterial activity. 8mm discs were aseptically cut and placed on TSA plates seeded with overnight cultures of one of the microorganisms under investigation and incubated at 37°C for 24 hours.

The results indicated that C. albicans and S. aureus were both susceptible to CUR:HPβCD inclusion complex with an average zone of inhibition of 12.25±2.2mm and 11±1.2mm respectively (n=4, ±=SD, p <0.05). The results against S. aureus are in accordance with our previously reported findings (Gupta et al., 2019). Current findings support the wound management applications of CUR:HPβCd-loaded BC hydrogels for chronic wounds.

References

Abbas, M., Hussain, T., Arshad, M., Ansari, A., Irshad, A., Nisar, J., Hussain, F., Masood, N., Nazir, A. and Iqbal, M. (2019). Wound healing potential of curcumin cross-linked chitosan/polyvinyl alcohol. International Journal of Biological Macromolecules, 140, pp.871-876.

Gupta, A., Keddie, D., Kannappan, V., Gibson, H., Khalil, I., Kowalczuk, M., Martin, C., Shuai, X. and Radecka, I. (2019). Production and characterisation of bacterial cellulose hydrogels loaded with curcumin encapsulated in cyclodextrins as wound dressings. European Polymer Journal, 118, pp.437-450.

Gupta, A., Low, W., Britland, S., Radecka, I. and Martin, C. (2017). Physicochemical characterisation of biosynthetic bacterial cellulose as a potential wound dressing material. British Journal of Pharmacy, 2(2), pp.S37-S38.

Gupta, A., Low, W., Radecka, I., Britland, S., Mohd Amin, M. and Martin, C. (2016). Characterisation and in vitro antimicrobial activity of biosynthetic silver-loaded bacterial cellulose hydrogels. Journal of Microencapsulation, 33(8), pp.725-734.

Que, A., Nguyen, N., Do, N., Nguyen, N., Tran, N. and Le, T. (2019). Infection of burn wound by Aspergillus fumigatus with gross appearance of fungal colonies. Medical Mycology Case Reports, 24, pp.30-32.

Wahid, F., Hu, X., Chu, L., Jia, S., Xie, Y. and Zhong, C. (2019). Development of bacterial cellulose/chitosan based semi-interpenetrating hydrogels with improved mechanical and antibacterial properties. International Journal of Biological Macromolecules, 122, pp.380-387.

Wounds from various sources such as burns and ulcers which have been in a prolonged state of inflammation and rubor, both exudative and non-exudative, are decidedly prone to becoming infected by various opportunistic and commensal microorganisms, both bacterial and fungal due to the warm moist environment at the wound site (Que et al.,2019). The typical approach in treating these wounds is to reduce the level of infection and inflammation, thus encouraging an appropriate environment for successful re-epithelisation resulting in faster healing of the wound.

Bacterial cellulose (BC) is an ideal material to produce wound dressings due to the intrinsic properties such as; high chemical stability, high tensile strength and flexibility, large water holding capacity, permeable to gases and liquids, and excellent biocompatibility (Gupta et al., 2016; Gupta et al.,2017, Wahid et al., 2019).

In this study, BC produced by Komagataeibacter xylinus was used as a hydrogel matrix and loaded with a well-known antimicrobial agent- curcumin encapsulated in solubility enhancing carriers, hydroxypropyl- β-cyclodextrin (CUR:HPβCD) (Abbas et al., 2019, Gupta et al., 2019). BC was loaded with 2% (w/v) aqueous CUR:HPβCD inclusion complex under constant agitation at 170 rpm at 20°C (room temperature) for 24 hours.

Antimicrobial activity was tested against two representative organisms:

Candida albicans and Staphylococcus aureus by disc diffusion method. We have previously reported the antibacterial activity of CUR:HPβCD-loaded BC (Gupta et al., 2019). The current study is an extension of our ongoing research where we made an attempt of testing the anti-fungal activity of CUR:HPβCD-loaded BC and compared it with anti-bacterial activity. 8mm discs were aseptically cut and placed on TSA plates seeded with overnight cultures of one of the microorganisms under investigation and incubated at 37°C for 24 hours.

The results indicated that C. albicans and S. aureus were both susceptible to CUR:HPβCD inclusion complex with an average zone of inhibition of 12.25±2.2mm and 11±1.2mm respectively (n=4, ±=SD, p <0.05). The results against S. aureus are in accordance with our previously reported findings (Gupta et al., 2019). Current findings support the wound management applications of CUR:HPβCd-loaded BC hydrogels for chronic wounds.

References

Abbas, M., Hussain, T., Arshad, M., Ansari, A., Irshad, A., Nisar, J., Hussain, F., Masood, N., Nazir, A. and Iqbal, M. (2019). Wound healing potential of curcumin cross-linked chitosan/polyvinyl alcohol. International Journal of Biological Macromolecules, 140, pp.871-876.

Gupta, A., Keddie, D., Kannappan, V., Gibson, H., Khalil, I., Kowalczuk, M., Martin, C., Shuai, X. and Radecka, I. (2019). Production and characterisation of bacterial cellulose hydrogels loaded with curcumin encapsulated in cyclodextrins as wound dressings. European Polymer Journal, 118, pp.437-450.

Gupta, A., Low, W., Britland, S., Radecka, I. and Martin, C. (2017). Physicochemical characterisation of biosynthetic bacterial cellulose as a potential wound dressing material. British Journal of Pharmacy, 2(2), pp.S37-S38.

Gupta, A., Low, W., Radecka, I., Britland, S., Mohd Amin, M. and Martin, C. (2016). Characterisation and in vitro antimicrobial activity of biosynthetic silver-loaded bacterial cellulose hydrogels. Journal of Microencapsulation, 33(8), pp.725-734.

Que, A., Nguyen, N., Do, N., Nguyen, N., Tran, N. and Le, T. (2019). Infection of burn wound by Aspergillus fumigatus with gross appearance of fungal colonies. Medical Mycology Case Reports, 24, pp.30-32.

Wahid, F., Hu, X., Chu, L., Jia, S., Xie, Y. and Zhong, C. (2019). Development of bacterial cellulose/chitosan based semi-interpenetrating hydrogels with improved mechanical and antibacterial properties. International Journal of Biological Macromolecules, 122, pp.380-387.

Purpose. To investigate the effect of daily toothbrushing with 0.2 % chlorhexidine digluconate (CHX) on the colonization of dental plaque by pathogens associated with pneumonia amongst non-ventilated adults with a neuro-disability.

Methodology. Forty-nine patients living in long-term care were recruited. Daily toothbrushing with 0.2 % CHX gel was conducted for 48 weeks. Plaque accumulation was assessed and microbiological sampling was undertaken every 6 weeks.

Results. At any one time point at least 65 % (n=32) of subjects were found to harbour respiratory pathogens. Although there were significant changes in the proportion of individuals colonized over time with Gram-negative bacilli and Pseudomonas aeruginosa, the changes were not sustained. By week 48 there was no significant difference from the levels that had been recorded at baseline.

Conclusions. Bacteria known to be causal in pneumonia are present and colonize the dental plaque of non-ventilated adults with a neuro-disability. Daily toothbrushing with 0.2 % CHX gel did not produce a sustained reduction in intra-oral respiratory pathogen counts after 48 weeks.

Pseudomonas is the bacterial genus of Gram-negative bacteria with the highest number of recognized species. It is divided phylogenetically into three lineages and at least 11 groups of species. The Pseudomonas putida group of species is one of the most versatile and best studied. It comprises 15 species with validly published names. As a part of the Genomic Encyclopedia of Bacteria and Archaea (GEBA) project, we present the genome sequences of the type strains of five species included in this group: Pseudomonas monteilii (DSM 14164T), Pseudomonas mosselii (DSM 17497T), Pseudomonas plecoglossicida (DSM 15088T), Pseudomonas taiwanensis (DSM 21245T) and Pseudomonas vranovensis (DSM 16006T). These strains represent species of environmental and also of clinical interest due to their pathogenic properties against humans and animals. Some strains of these species promote plant growth or act as plant pathogens. Their genome sizes are among the largest in the group, ranging from 5.3 to 6.3 Mbp. In addition, the genome sequences of the type strains in the Pseudomonas taxonomy were analysed via genome-wide taxonomic comparisons of ANIb, gANI and GGDC values among 130 Pseudomonas strains classified within the group. The results demonstrate that at least 36 genomic species can be delineated within the P. putida phylogenetic group of species.

Septic arthritis of native joints is a potentially life-threatening disease. The most frequently isolated pathogens are Gram-positive cocci. Bacteroides fragilis is a rare pathogen in joint infections and is usually associated with immunocompromised and debilitated patients. Most cases of B. fragilis joint infection are related to skin or local perineal infections or are secondary to B. fragilis bacteraemia from another source, for example from the gastrointestinal tract. We present a clinical case of B. fragilis septic arthritis involving a native hip joint in a previously healthy paraplegic patient.

Introduction. Invasive infections due to Cellulosimicrobium spp. (a Gram-positive coryneform) are extremely rare. Only a few cases of bloodstream infections and endocarditis have been described, as bacteraemia due to coryneforms is usually discarded as blood culture contamination.

Case presentation. A 66-year-old female, with a history of aortic valve replacement, presented with fever, left leg purpura and acute kidney injury. Multiple repeated blood cultures were positive for Cellulosimicrobium cellulans , and targeted therapy was started. At first, endocarditis was excluded by echocardiograms, and the acute nephritis was interpreted as an atypical presentation of Henoch–Shönlein purpura. High-dose prednisone was started, and after 10 weeks the patient presented again with fever, mental confusion and acute left arm ischaemia. A subsequent echocardiogram and radiolabelled leukocyte scintigraphic evaluation revealed aortic prosthetic valve endocarditis with periprosthetic abscess and arterial brachial thrombosis. The patient deceased, and the autoptic examination confirmed an aortic valve periprosthetic abscess and revealed multiple arterial thromboses and septic embolisms in the kidneys, brain, spleen and myocardium.

Conclusion. Isolation of coryneform bacteria on blood culture should not always be discarded as blood culture contamination. In the case of endocarditis due to Cellulosimicrobium spp., the removal of any prosthetic material, along with prolonged in vitro active antimicrobial therapy, should be pursued in order to reduce persistence or relapses of infection.

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms found in soil and water. Infections caused by NTM are increasing with conditions ranging from harmless colonization to invasive infections, the latter being more common in immunocompromised hosts. In this report, we present a case of bacteraemia caused by Mycobacterium chelonae , a rapidly growing NTM belonging to Class IV in the Runyon classification, in a 71-year-old male with ocular myasthenia gravis undergoing treatment with oral prednisolone. Gram staining of these organisms from blood culture can be easily overlooked or confused with diptheroids. Detection of Gram-positive bacilli should prompt Ziehl–Neelsen staining to distinguish diphtheroids from rapidly growing mycobacteria in immunosuppressed patients. In addition, speciation and antimicrobial susceptibility testing are of paramount importance in such cases as there is considerable variation in the resistance patterns between different species of NTM. Line probe assay provides a rapid and reliable method for identification of NTM to the species level, which can guide treatment with appropriate antibiotics. This case report highlights the importance of early detection of such cases so as to optimize management and improve patient outcomes.