Ayona Silva-Fletcher

Prof. Ayona Silva-Fletcher

orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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6 October 2021 in Microorganisms
Verified
Journal Article
Open access
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PDPavithra Dhanapala
Pavithra Dhanapala
RKRuwani Kalupahana
Ruwani Kalupahana
WKWasantha Kalupahana
Wasantha Kalupahana
DWD.P.H. Wijesekera
D.P.H. Wijesekera
SKSanda A. Kottawatta
Sanda A. Kottawatta
SJS. S. S. de S. Jagoda
S. S. S. de S. Jagoda
The aims of this study were to characterize and investigate antimicrobial susceptibility and presence of integrons in 161 Aeromonas spp. isolated from ornamental freshwater fish farming environment, apparently healthy and diseased fish. Phylogenetic analyses of the gyrB gene sequences identified Aeromonas veronii as the most abundant species (75.8%) followed by Aeromonashydrophila (9.3%), Aeromonas caviae (5%), Aeromonas jandaei (4.3%), Aeromonas dhakensis (3.7%), Aeromonas sobria (0.6%), Aeromonas media (0.6%), and Aeromonas popoffii (0.6%). Susceptibility to thirteen antimicrobials was determined and antimicrobial resistance frequencies were: amoxicillin (92.5%), enrofloxacin (67.1%), nalidixic acid (63.4%), erythromycin (26.1%), tetracycline (23.6%), imipenem (18%), trimethoprim-sulfamethoxazole (16.8%), and gentamicin (16.8%). Multi-drug resistance (MDR) was widespread among the isolates (51.6%, 83/161) with 51.6% (63/122) A. veronii isolates being MDR. In addition, 68.3% of isolates had multiple antibiotic resistance (MAR) indexes higher than 0.2, suggesting that they originated from a high-risk source of contamination where antimicrobials are often used. In all, 21.7% isolates carried class 1 integrons, with 97.1% having gene cassettes, while there were 12 isolates carrying class 2 integron gene cassettes. Our findings highlight that the aquatic environment and ornamental fish act as reservoirs of multidrug resistant Aeromonas spp. and underline the need for a judicious use of antimicrobials and timely surveillance of antimicrobial resistance (AMR) in aquaculture.

1 December 2015 in Journal of Veterinary Medical Education
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Journal Article
Closed access
SMStephen May
Stephen May
ASAyona Silva-Fletcher
Ayona Silva-Fletcher
Veterinary discipline experts unfamiliar with the broader educational literature can find the adoption of an evidence-based approach to curriculum development challenging. However, greater societal and professional demands for achieving and verifying Day One knowledge and skills, together with continued progress in information generation and technology, make it all the more important that the defined period for initial professional training be well used. This article presents and discusses nine pedagogical principles that have been used in modern curricular development in Australia, the United Kingdom, and the United States: (1) outcomes-based curriculum design; (2) valid and reliable assessments; (3) active learning; (4) integrated knowledge for action; (5) tightly controlled core curriculum; (6) “just-in-time” rather than “just-in-case” knowledge; (7) vertical integration, the spiral curriculum, and sequential skills development; (8) learning skills support; and (9) bridges from classroom to workplace. Crucial to effective educational progress is active learning that embraces the skills required by the modern professional, made possible by tight control of curricular content. In this information age, professionals' ability to source information on a “just-in-time” basis to support high quality reasoning and decision making is far more important than the memorization of large bodies of increasingly redundant information on a “just-in-case” basis. It is important that those with responsibility for veterinary curriculum design ensure that their programs fully equip the modern veterinary professional for confident entry into the variety of roles in which society needs their skills.

21 October 2020 in Animals
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Worapong KosarukWorapong Kosaruk
Worapong Kosaruk
JBJanine L. Brown
Janine L. Brown
Tithipong PlangsangmasTithipong Plangsangmas
Tithipong Plangsangmas
PTPatcharapa Towiboon
Patcharapa Towiboon
Veerasak PunyapornwithayaVeerasak Punyapornwithaya
Veerasak Punyapornwithaya
CSChaleamchat Somgird
Chaleamchat Somgird
Asian elephants have been an important part of wildlife ecotourism in Thailand for over two decades. Elephants in tourist camps are exposed to a variety of management styles and daily activities that can potentially affect health and welfare. This study investigated relationships between a novel welfare biomarker, immunoglobulin A (IgA), and daily camp activities, and compared results to glucocorticoid (GC) measures. Often no-riding camps are portrayed as providing better welfare than camps that offer riding. Therefore, we predicted that elephants at no-riding camps would have lower GC and higher IgA concentrations, and a low GC/IgA ratio. Forty-four female elephants from six elephant camps were divided into three groups based on riding activities: saddle-riding, bareback-riding, and no-riding. Fecal and salivary samples were collected monthly for 1 year along with evaluations of body condition, foot health, and wounding. Camp environment and management varied among camps, although the major difference was in riding activities. Concentrations of GCs and IgA varied among the working groups, but not always consistently between sample matrices. Overall fecal glucocorticoid metabolite concentrations were lowest in the saddle-riding group. Only in one bareback-riding camp did the elephants exhibit a potentially positive welfare response with a low GC/IgA ratio over time. Other results varied between the two biomarkers, with considerable variability across camps, suggesting there is more to good welfare than whether elephants participate in riding or not. Several other human-induced stressors, like chaining, ankus use, and limited social opportunities are likely to be impacting well-being and should be considered to ensure management practices meet physical and psychological welfare needs.

27 March 2022 in Antibiotics
Verified
Journal Article
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YGYasodhara Deepachandi Gunasekara
Yasodhara Deepachandi Gunasekara
TKTierney Kinnison
Tierney Kinnison
SKSanda Arunika Kottawatta
Sanda Arunika Kottawatta
ASAyona Silva-Fletcher
Ayona Silva-Fletcher
RKRuwani Kalupahana
Ruwani Kalupahana
Reducing the growth of antimicrobial resistance (AMR) through public understanding is a goal of the World Health Organization. It is especially important in countries where antibiotics are widely available for common ailments without prescription. This study assessed understanding of antibiotics and AMR alongside perception of antibiotic usage among the general public in two diverse Sri Lankan communities: ordinary urban and indigenous rural. A cross-sectional questionnaire survey was conducted, gaining 182 urban and 147 rural responses. The majority of urban respondents (69.2%) believed that they had very good or good knowledge about antibiotics compared to 40.1% of rural respondents. Belief about knowledge and actual knowledge (measured via a test question) were correlated (r = 0.49, p = 0.001) for rural respondents, but not for urban respondents. Several misconceptions about antibiotics were highlighted, including that Paracetamol, a painkiller, was thought to be an antibiotic by more than 50% of both urban and rural respondents. In addition, 18.5% of urban and 35.4% of rural participants would keep and re-use what they perceived as leftover antibiotics. It is urgent that we pay attention to educating the general public regarding the identified misconceptions of these powerful drugs and their appropriate use.

2 August 2012 in BMC Chemistry
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Journal Article
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KKKris Korsak
Kris Korsak
NDNazanin F Dolatshad
Nazanin F Dolatshad
ASAyona Silva-Fletcher
Ayona Silva-Fletcher
MSM Jill Saffrey
M Jill Saffrey
Ageing is associated with gastrointestinal dysfunction, which can have a major impact on quality of life of the elderly. A number of changes in the innervation of the gut during ageing have been reported, including neuronal loss and degenerative changes. Evidence indicates that reactive oxygen species (ROS) are elevated in ageing enteric neurons, but that neurotrophic factors may reduce generation of neuronal ROS. Two such factors, glial cell line derived neurotrophic factor (GDNF) and neurotrophin-3 (NT-3) have also been found to protect enteric neurons against oxidative stress induced cell death of enteric ganglion cells in vitro. We have investigated the possible roles of neurotrophic factors further, by examining their expression in the gut during ageing, and by analysing their effects on antioxidant enzyme production in cultures of enteric ganglion cells. Analysis of the expression of GDNF and its receptors c-Ret and GFR α − 1 in rat gut by RT-PCR showed that expression continues throughout life and into ageing, in both ad libitum(AL) and calorically-restricted (CR) animals. Levels of expression of GDNF and GFR α − 1 were elevated in 24 month AL animals compared to 24 month CR animals, and to 24 CR and 6 month control animals respectively. The related factor Neurturin and its receptor GFR α − 2 were also expressed throughout life, the levels of the GFR – α-2(b) isoform were reduced in 24 m AL animals. Immunolabelling showed that c-Ret and GFR α − 1 proteins were expressed by myenteric neurons in ageing animals. GDNF, but not NT-3, was found to increase expression of Cu/Zn superoxide dismutase and catalase by cultured enteric ganglion cells. The neurotrophic factors GDNF and neurturin and their receptors continue to be expressed in the ageing gut. Changes in the levels of expression of GDNF , GFR α-1 and GFR α-2(b) isoform occurred in 24 m AL animals. GDNF, but not NT-3, increased the levels of antioxidant enzymes in cultured enteric ganglion cells, indicating a possible mechanism for the reported protective effect of GDNF against menadione-induced neuronal apoptosis in the ageing gut. Together these data suggest that GDNF family members may play a protective role in the gut throughout life, and support the suggestion that dysregulation of neurotrophic factor support could contribute to neuronal ageing in the gut.

17 January 2020 in Animals
Verified
Journal Article
Open access
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Tithipong PlangsangmasTithipong Plangsangmas
Tithipong Plangsangmas
JBJanine L. Brown
Janine L. Brown
Chatchote ThitaramChatchote Thitaram
Chatchote Thitaram
ASAyona Silva-Fletcher
Ayona Silva-Fletcher
KEKatie Edwards
Katie Edwards
CSChaleamchat Somgird
Chaleamchat Somgird
Salivary immunoglobulin A (sIgA) has been proposed as a potential indicator of welfare for various species, including Asian elephants, and may be related to adrenal cortisol responses. This study aimed to distinguish circadian rhythm effects on sIgA in male and female Asian elephants and compare patterns to those of salivary cortisol, information that could potentially have welfare implications. Subjects were captive elephants at an elephant camp in Chiang Mai province, Thailand (n = 5 males, 5 females). Salivette® kits were used to collect saliva from each elephant every 4 h from 06:00 to 22:00 h for 3 consecutive days (n = 15 samples/elephant). Enzyme immunoassays were used to quantify concentrations of IgA and cortisol in unextracted saliva. Circadian rhythm patterns were determined using a generalized least-squares method. Both sIgA and cortisol followed a circadian rhythm, although the patterns differed. sIgA displayed a daily quartic trend, whereas cortisol concentrations demonstrated a decreasing linear trend in concentrations throughout the day. There was no clear relationship between patterns of sIgA and salivary cortisol, implying that mechanisms of control and secretion differ. Results demonstrate for the first time that circadian rhythms affect sIgA, and concentrations follow a daily quartic pattern in Asian elephants, so standardizing time of collection is necessary.