In Vitro Assessment of the Synergy between Polymyxin B (PMB) and Polymyxin B Nonapeptide (PMBN) and Antibiotics on Biofilms from Diabetic Foot Infections

Background: The increasing resistance of Gram-negative bacteria isolated from nosocomial infections and chronic wounds, such as diabetic foot ulcers has renewed research interests in the use of polymyxins in the treatment of multidrug resistant infections. The added resistance conferred by biofilm development in such infections and the absence of novel antibiotics presuppose that polymyxins are the likely drugs of choice in spite of their nephrotoxicity. The effects of PMB and PMBN have been previously assessed on planktonic bacteria isolated from various infections. Methods: This current study assessed the synergy between a PMB/PMBN and two antibiotics (ceftazidime and levofloxacin) in an attempt to develop a strategy for biofilm disruption using the Minimum Biofilm Eradication Concentration Physiology and Genetic assay (MBEC™ P & G, Innovotech Inc, Edmonton, Alberta, Canada) according to manufacturer’s instructions. Klebsiella pneumoniae (K. pneumoniae) and Proteus mirabilis (P. mirabilis) biofilms of initial broth suspensions of 108 colony forming units per mL, cultivated on the pegs of the MBEC device were challenged with 5120 µg/mL of both ceftazidime and levofloxacin in a ten-fold dilution assay and in the presence of 100 and 500 µg/mL PMB and PMBN. Results: From table of results (Table 1), it can be deduced that both ceftazidime and levofloxacin are very effective in inhibiting biofilm development (as shown by percentage inhibition (PI)) when augmented with PMB and PMBN. This is about 100-fold increase in efficacy when compared to the antibiotics used on their own. The percentage reduction (PR) in biofilm was also increased considerably when PMB and PMBN concentrations were increased to 500 µg/mL. PMB was more effective than its less antibacterial derivative PMBN. Levofloxacin was also found to be more effective than ceftazidime when combined with both PMB and PMBN due to its enhanced cell-membrane permeability and as an anti-DNA replication uncoupling agent. Conclusion: The above results indicate that the synergy between antibiotics and cell membrane permeabilising agents may provide alternate strategies towards biofilm eradicatio

Cinnamaldehyde increases the susceptibility of quorum-sensing-mediated biofilms to conventional antibiotics

The role of bacterial communication, also known as quorum sensing is an important mechanism in biofilm formation which is fundamental to the development of anti-biofilm strategies. In this current study, the synergy between a quorum sensing inhibitor (cinnamaldehyde) and two antibiotics (ceftazidime and levofloxacin) was evaluated in an attempt to develop a strategy for biofilm disruption using the high-throughput minimum biofilm eliminating concentration (MBEC) assay. Klebsiella pneumoniae and Proteus mirabilis biofilms of initial broth suspensions of 108 colony forming units (CFU) per mL, cultivated on the pegs of the MBEC device were challenged with 5120 µg/ml of ceftazidime and levofloxacin in a double dilution assay in the presence of 500 µM cinnamaldehyde. The minimum inhibitory concentrations (MIC) in the presence of cinnamaldehyde for ceftazidime and levofloxacin were 0.125% (640 µg/mL) and 0.0625% (320 µg/mL) respectively with no significant bacterial growth on LB agar. The MBECs for ceftazidime and levofloxacin were above 5120 and 2560 µg/mL respectively which yielded over 70% reduction in both Klebsiella pneumoniae and Proteus mirabilis biofilms. The above results indicate the possibility that the synergy between antimicrobial agents may lead to biofilm eradication

The in vitro assessment of the synergistic effects of antibiotics and wound dressings on biofilms from diabetic foot pathogens

The impact of biofilm in the effective control of wound microbiome is an ongoing dilemma which has seen the use of different treatment strategies. The effects of wound dressings and antibiotics on both planktonic bacteria and biofilms have been separately evaluated in previous studies. In this current study, the combined antimicrobial effects of some selected wound dressings (silver-impregnated: Acticoat and Silvercel; and honey-impregnated: Medihoney™ Apinate) and antibiotics (ceftazdime and levofloxacin) on Klebsiella pneumoniae and Proteus mirabilis in their quasi-biofilm state were assessed using zone of inhibition (ZOI) test. Before the addition of the wound dressings, bacterial suspension of 108 colony forming units per mL and different concentrations of ceftazidime and levofloxacin (256, 512, 1024 and 5120µg/mL) of a final volume of 1mL were inoculated on Mueller Hinton agar and allowed to dry. Wound dressings cut into circular shapes (2cm diameter) were aseptically placed on the agar plates and incubated at 35 – 37°C for 24 hours. ZOIs associated with Acticoat, Silvercel and Medihoney™ Apinate dressings were compared with that of Atrauman (non-medicated control) dressing. All three dressings showed significant (p < 0.05) biofilm-inhibiting activity against both bacteria at antibiotic concentrations of 1024 and 5120µg/mL with ZOI between 17.5 and 35mm

In vitro study of the effect of wound dressings on planktonic and biofilms from diabetic foot isolates

The management of wound bioburden has previously been evaluated using various antimicrobial wound dressings on bacterial pathogens isolated from various wounds. In this present study, the antimicrobial effect of silver-impregnated dressings (Acticoat and Silvercel) and honey-impregnated dressing (Medihoney™ Apinate) on both planktonic bacteria and quasi-biofilms by Staphylococcus aureus and Proteus mirabilis were assessed using a 6-well plate and standard agar technique. In the 6-well plate assay, a bacterial suspension of 108 colony forming unit (CFU)/mL was inoculated on each dressing in excess Luria-Bertani broth and incubated at 35 – 37°C for 30 and 60 minutes and 24 hours. After each incubation time, bacteria were recovered in sodium thioglycolate solution (STS) and the CFU/mL determined on LB agar. Dressings were cut into circular shapes (2cm diameter and placed on Mueller Hinton agar plates pre-inoculated with bacterial suspensions to determine their zones of inhibition (ZOI) after 24 hours incubation. None of the dressings was effective to significantly inhibit bacterial growth or biofilm formation at all the times tested. Acticoat and Medihoney™ Apinate produced ZOIs between 1.5 – 15 mm against both Staphylococcus aureus and Proteus mirabilis. It is possible that, dressings augmented with antibiotics can significantly reduce quasi-biofilms on standard agar

Ultrafast polychromatic ionization of dielectric solids

The modeling of the laser-induced damage processes can be divided into thermal and electronic processes. Especially, electronic damage seems to be well understood. In corresponding models, the damage threshold is linked to the excitation of valence electrons into the conduction band, and often the damage is obtained if a critical density of free electrons is exceeded. For the modeling of the electronic excitation, rate equation models are applied which can vary in the different terms representing different excitation channels. According to the current state of the art, photoionization and avalanche ionization contribute the major part to the ionization process, and consequently the determination of laser-induced damage thresholds is based on the calculation of the respective terms. For the theoretical description of both, well established models are available. For the quantitative calculation of the photoionization, the Keldysh theory is used most frequently, and for the avalanche processes the Drude theory is often applied. Both, Drude and Keldysh theory calculations depend on the laser frequency and use a monochromatic approach. For most applications the monochromatic description matches very well with the experimental findings, but in the range of few-cycle pulses the necessary broadening of the laser emission spectrum leads to high uncertainty for the calculation. In this paper, a novel polychromatic approach is presented including photo-and avalanche ionization as well as the critical electron density. The simulation combines different ionization channels in a Monte-Carlo procedure according to the frequency distribution of the spectrum. The resulting influence on the wavelength and material dependency is discussed in detail for various pulse shapes and pulse durations. The main focus of the investigation is concentrated on the specific characteristics in the dispersion and material dependency of the laser-induced damage threshold respecting the polychromatic characteristics of the ultra-short pulse (USP) laser damage. © 2016 SPIE. Downloading of the abstract is permitted for personal use only.Ministry for Science and Culture of Lower SaxonyVolkswagen Stiftun

The Craft Industry, Oral Literature and Language in the Development of Tourism in Ghana: Prospects and Challenges

This paper examines the role the craft industry, Oral Literature and language play in the development of tourism in Ghana.  From the study, it was found that all the three are important for several reasons, namely economic value, exchange of information, sharing of experiences or world-views and finally changing biases.  However, lack of outlets and finishing of products constitute major problems. Key Words: Artifact, Cosmo-vision, pragmatic interpretation, equiparable, lyrical interpretation

A Loop Region in the N-Terminal Domain of Ebola Virus VP40 Is Important in Viral Assembly, Budding, and Egress

Ebola virus (EBOV) causes viral hemorrhagic fever in humans and can have clinical fatality rates of ~60%. The EBOV genome consists of negative sense RNA that encodes seven proteins including viral protein 40 (VP40). VP40 is the major Ebola virus matrix protein and regulates assembly and egress of infectious Ebola virus particles. It is well established that VP40 assembles on the inner leaflet of the plasma membrane of human cells to regulate viral budding where VP40 can produce virus like particles (VLPs) without other Ebola virus proteins present. The mechanistic details, however, of VP40 lipid-interactions and protein-protein interactions that are important for viral release remain to be elucidated. Here, we mutated a loop region in the N-terminal domain of VP40 (Lys127, Thr129, and Asn130) and find that mutations (K127A, T129A, and N130A) in this loop region reduce plasma membrane localization of VP40. Additionally, using total internal reflection fluorescence microscopy and number and brightness analysis we demonstrate these mutations greatly reduce VP40 oligomerization. Lastly, VLP assays demonstrate these mutations significantly reduce VLP release from cells. Taken together, these studies identify an important loop region in VP40 that may be essential to viral egress

Using GIS for spatial exploratory analysis of borehole data: a firsthand approach towards groundwater development

Groundwater is an inimitable resource that provides water to communities especially in arid and semi-arid regions. However, the spatial variability of the resource as well as the heterogeneity and complex nature of aquifer systems that store groundwater presents difficulties for groundwater development. Thus, understanding the spatial structure of aquifer characteristics could be used as a resourceful tool and as a first point of call towards groundwater development. The study investigated aquifer characteristics particularly on transmissivity and specific capacity to determine how aquifer characteristics could be used in making predictions for new sites that need to be identified for potential groundwater development. Prediction maps were developed for transmissivity and specific capacity using ordinary kriging J-Bessel and exponential semi variograms techniques. The study revealed that 28% of the study area had high potential for groundwater development with transmissivity ranges of 34.40 – 46.52 m2/d. Equally, viable areas of 16% and 20% were identified with transmissivities of 27.99 – 34.39 m2/d and 13.07 – 19.47 m2/d respectively. Based on specific capacity, 21% of the study area was identified to have groundwater development potential with corresponding specific capacity of 13.54 – 20.7 m2/d. Similarly, 24% and 34% of the study area were also identified to be good for the exploitation of groundwater with corresponding specific capacities of 8.74 – 13.55 m2/d and 5.52 – 8.74 m2/d respectively. In terms of spatial structure, transmissivity was found to be variable compared to specific capacity. The application of Geographic Information Systems (GIS) is thus considered to be an immeasurable tool that could be used in mapping aquifer characteristics that can serve as firsthand information for groundwater development.Keywords: Spatial, Groundwater, Transmissivity, Specific capacity, Kriging, Semivariogram        

Physico-chemical Assessment of Drinking Water with Special Emphasis on Fluoride Concentration in the Akatsi-North district in the Volta Region of Ghana

The present article has emerged from investigation into the water situation in three villages in the Akatsi-North district, to test the extent to which expectations of the United Nations (UN) Resolution 64/292 stipulations have been met in this part of the Volta region of Ghana. Thirty-six water samples were collected from twelve different boreholes (three villages) in the Akatsi-North district and analysed for their physico-chemical parameters using appropriate certified and acceptable international standards. Most of the physico-chemical parameters measured were within WHO guidelines for quality drinking water. The results showed that groundwater from two of the three villages were soft with pH ranging from 6.3 to 7.9. Cadmium concentrations for the groundwater samples analysed were above the critical value of 0.003 mg/L. Lead and nickel were not detected while the concentrationsof phosphate (0.50 – 0.53 mg/L) and copper (0.32-0.37 mg/L ) provided basis for the incidence of gastrointestinal and/or purgative effects experienced by most inhabitants prior to questionnaire analysis. Iron concentrations recorded for the three villages were within the ranges of 0.005-0.130mg/L, 0.13-0.23 mg/L, and 0.85-1.41 mg/L for Ave Xevi, Ave Afiadenyigba and Ave Etekorfe respectively. Mean concentrations of Ca2+, Mg2+, CO32-, and total alkalinity obtained for the three villages were (112, 168, 517) mg/L, (68, 112, 208) mg/L, (49, 80, 256) mg/L, and (220, 260, 380) mg/L respectively. Fluoride concentrations were low (0.07 mg/L and 0.16mg/L) for two of the three villages which may be responsible for the incidence of tooth decay among the inhabitants

Analysis of Relationship between Root Length Density and Water Uptake by Roots of Five Crops Using Minirhizotron in the Semi-Arid Tropics

Experiments were carried out to analyse the root and water dynamics simultaneously using a minirhizotron on an Alfisol soil in the semi-arid tropics in 1993. Sorghum (CSH 5), pearl millet (ICMV 221), pigeonpea (ICP 1-6), groundnut (ICGS 11) and cowpea (EC 82-7) were used to describe the relationship between the root length density (RLD) and water uptake by roots per day (WU). During the periods from 37 to 46, from 51 to 59 and from 72 to 77 days after sowing, the average values of RLD of sorghum and pearl millet at the soil depth of 15-60 cm were consistently higher than those of pigeonpea, groundnut and cowpea, whereas the average values of WU of the cereals were not always higher than those of the grain legumes. Thus, there was no significant relationship between RLD and WU for the 5 crops due to the higher values of the specific root water uptake (SRWU) of grain legumes than those of cereals in each period. In this study, it was demonstrated that WU and SRWU as well as RLD for the 5 crops could be estimated by using the minirhizotron since dynamic values of the root length of the 5 crops and soil moisture content (SMC) in each soil layer could be quantified from datasets by frequent observations and with limited sampling errors. Therefore the minirhizotron was found to be a suitable tool for simultaneous monitoring of the root and water dynamics in soil layers except for the soil surface