Bactericidal and Anti-biofilm Effects of Polyhexamethylene Biguanide in Models of Intracellular and Biofilm of Staphylococcus aureus Isolated from Bovine Mastitis

Staphylococcus aureus infection is a common cause of mastitis, reducing milk yield, affecting animal welfare and causing huge economic losses within the dairy industry. In addition to the problem of acquired drug resistance, bacterial invasion into udder cells and the formation of surface biofilms are believed to reduce antibiotic efficacy, leading to treatment failure. Here, we investigated the antimicrobial activities of enrofloxacin, an antibiotic that is commonly used in mastitis therapy and polyhexamethylene biguanide (PHMB), an antimicrobial polymer. The antimicrobial activities were tested against intracellular S. aureus in infected Mac-T cells (host cells). Also, fluorescein-tagged PHMB was used to study PHMB uptake and localization with S. aureus within the infected Mac-T cells. Anti-biofilm activities were tested by treating S. aureus biofilms and measuring effects on biofilm mass in vitro. Enrofloxacin and PHMB at 15 mg/L killed between 42 to 92 and 99.9% of intracellular S. aureus, respectively. PHMB-FITC entered and colocalized with the intracellular S. aureus, suggesting direct interaction of the drug with the bacteria inside the host cells. Enrofloxacin and PHMB at 15 mg/L reduced between 10 to 27% and 28 to 37% of biofilms’ mass, respectively. The half-maximal inhibitory concentrations (IC50) obtained from a cytotoxicity assay were 345 ± 91 and 21 ± 2 mg/L for enrofloxacin and PHMB, respectively; therefore, both compounds were tolerated by the host cells at high concentrations. These findings suggest that both antimicrobials are effective against intracellular S. aureus and can disrupt biofilm structures, with PHMB being more potent against intracellular S. aureus, highlighting the potential application of PHMB in mastitis therapy

Exponential distribution of long heart beat intervals during atrial fibrillation and their relevance for white noise behaviour in power spectrum

The statistical properties of heart beat intervals of 130 long-term surface electrocardiogram recordings during atrial fibrillation (AF) are investigated. We find that the distribution of interbeat intervals exhibits a characteristic exponential tail, which is absent during sinus rhythm, as tested in a corresponding control study with 72 healthy persons. The rate of the exponential decay lies in the range 3-12 Hz and shows diurnal variations. It equals, up to statistical uncertainties, the level of the previously uncovered white noise part in the power spectrum, which is also characteristic for AF. The overall statistical features can be described by decomposing the intervals into two statistically independent times, where the first one is associated with a correlated process with 1/f noise characteristics, while the second one belongs to an uncorrelated process and is responsible for the exponential tail. It is suggested to use the rate of the exponential decay as a further parameter for a better classification of AF and for the medical diagnosis. The relevance of the findings with respect to a general understanding of AF is pointed out

Stakeholder collaboration in climate-smart agricultural production innovations: insights from the Cocoa industry in Ghana

Although collaboration is vital in addressing global environmental sustainability challenges, research understanding on stakeholder engagement in climate-smart production innovation adoption and implementation, remains limited. In this paper, we advance knowledge about stakeholder collaboration by examining the roles played by stakeholders in scaling up ecological sustainability innovations. Using the illustrative context and case of green cocoa industry in Ghana, the analysis identified three distinctive phases of stakeholder engagement in ecological sustainability innovations implemented from 1960-2017. We highlight defining periods of ecological challenges encompassing the production recovery sustainability initiative phase solely driven by the Ghana Cocoa Board (COCOBOD)–a governmental body responsible for production, processing and marketing of cocoa, coffee and sheanut. During the period, major initiatives were driven by non-governmental organisations in collaboration with COCOBOD to implement the Climate-Smart agriculture scheme in the cocoa sector. The findings have implications for cocoa production research and stakeholder collaboration in environmental innovations adoption

An integrated Socioeconomic Analysis of Innovation Adoption : The Case of Hybrid Cocoa in Ghana

This study employs a multidisciplinary model to explain the adoption of agricultural innovations in developing economies with reference to hybrid cocoa in Ghana. The empirical evidence shows that, in the adoption of hybrid cocoa, the support that small-scale farmers obtain via their social networks is more relevant than the advantage of farm size enjoyed by large-scale farmers. However, for large-scale farmers, access to a bank loan strongly increases their chance of adoption compared with small-scale farmers. Contacts with extension agents, education, and availability of hired labor also have positive effects on adoption. The social status of the farmers has only an indirect effect on adoption: farmers with higher social status are more likely to obtain a bank loan, and a bank loan has a positive impact on adoption. (C) 1999 Society for Policy Modeling. Published by Elsevier Science Inc