Kill Rate and Evaluation of Ex Vivo PK/PD Integration of Cefquinome Against Actinobacillus pleuropneumoniae

We wished to study the detailed and precise antibacterial activity of cefquinome against Actinobacillus pleuropneumoniae (APP) in vitro and ex vivo. We analyzed the relationships between kill rate and cefquinome concentration in broth and between pharmacokinetic/pharmacodynamic (PK/PD) parameters and antibacterial effect in serum and tissue cage fluid (TCF) of piglets. Cefquinome exhibited time-dependent antibacterial activity against APP according to the kill rate. The maximum kill rate was 0.48 log10 CFU/mL/h at the 0-9-h period in broth. In the ex vivo PK/PD study, the maximum concentration (Cmax), time to reach the maximum concentration (Tmax), terminal half-life (T1/2β), and area under the concentration time curve (AUCinfinity) were 5.65 μg/ml, 0.58 h, 2.24 h, and 18.48 μg·h/ml in serum and 1.13 μg/ml, 2.60 h, 12.22 h, and 20.83 μg·h/ml in TCF, respectively. The values of area under the curve during 24 h/minimum inhibitory concentration (AUC24h/MIC) for bacteriostatic, bactericidal, and bacterial eradication effects were 18.94, 246.8, and 1013.23 h in serum and 4.20, 65.81, and 391.35 h in TCF, respectively. Our findings will provide a valuable basis for optimization of dosage regimens when applying cefquinome to treat APP infection.

The pest kill rate of thirteen natural enemies as aggregate evaluation criterion of their biological control potential of Tuta absoluta

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). Finding an effective biological control agent among the tens to hundreds of natural enemies of a pest is a daunting task. Evaluation criteria help in a first selection to remove clearly ineffective or risky species from the list of candidates. Next, we propose to use an aggregate evaluation criterion, the pest kill rate, to compare the pest population reduction capacity of species not eliminated during the first selection. The pest kill rate is the average daily lifetime killing of the pest by the natural enemy under consideration. Pest kill rates of six species of predators and seven species of parasitoids of Tuta absoluta were calculated and compared. Several natural enemies had pest kill rates that were too low to be able to theoretically reduce the pest population below crop damaging densities. Other species showed a high pest reduction capacity and their potential for practical application can now be tested under commercial crop production conditions.

Increasing availability of palatable prey induces predator-dependence and increases predation on unpalatable prey

Understanding the factors governing predation remains a top priority in ecology. Using a dragonfly nymph-tadpole system, we experimentally varied predator density, prey density, and prey species ratio to investigate: (i) whether predator interference varies between prey types that differ in palatability, (ii) whether adding alternate prey influences the magnitude of predator interference, and (iii) whether patterns of prey selection vary according to the predictions of optimal diet theory. In single-prey foraging trials, predation of palatable leopard frog tadpoles was limited by prey availability and predator interference, whereas predation of unpalatable toad tadpoles was limited by handling time. Adding unpalatable prey did not affect the predator’s kill rate of palatable prey, but the presence of palatable prey increased the influence of predator density on the kill rate of unpalatable prey and reduced unpalatable prey handling time. Prey selection did not change with shifts in the relative abundance of prey types. Instead, predators selected easy-to-capture unpalatable prey at low total densities and harder-to-capture palatable prey at high densities. These results improve our understanding of generalist predation in communities with mobile prey, and illustrate that characteristics of the prey types involved govern the extent to which alternate prey influence the predator’s kill rate.

Can multidrug-resistant organisms become resistant to ultraviolet (UV) light following serial exposures? Characterization of post-UV genomic changes using whole-genome sequencing

Objectives: No-touch disinfection systems like xenon- or mercury-based ultraviolet (UV) are now commonly being used for hospital room disinfection. However, serial exposure to UV light can potentially lead to the development of bacterial resistance. We sought to determine whether UV resistance develops due to serial exposure to UV light using 3 epidemiologically important multidrug-resistant microbial strains. Methods: Methicillin-resistant Staphylococcus aureus (MRSA), carbapenemase–producing Klebsiella pneumoniae (KPC) and metallo-β-lactamase–producing Klebsiella pneumoniae (MBL) were serially exposed to 25 growth-irradiation cycles of UV produced by a xenon-based UV (Xe-UV) lamp for 5 minutes or a mercury-based UV (Hg-UV) lamp for 10 minutes. After each UV exposure cycle, the surviving colony-forming units (CFUs) were measured and compared with the initial inoculum of each cycle for each strain, respectively. Results: In each cycle, ˜1–10 million of MRSA, KPC, and MBL were used to test the effect of UV irradiation. Postexposure colony counts remained low (3–100 colonies) throughout the 25 serial exposures to both xenon- and mercury-based UV. The log-kill rate after each exposure showed no changes following UV disinfection by Xe-UV. The MRSA log-kill rate increased after repeated exposure to Hg-UV unlike KPC and MBL K. pneumoniae, which did not change. Whole-genome sequencing (WGS) analyses performed on these 3 strains demonstrated no significant genetic changes after multiple UV irradiation cycles. Conclusions: Exposure of multidrug-resistant bacteria to UV produced from 2 different UV sources did not engender UV resistance after 25 serial exposures, as demonstrated by WGS analysis; thus, UV disinfection is unlikely to generate UV-resistant hospital flora.

Uji Antibakteri Obat Kumur Ekstrak Etanol Tanaman Ciplukan (Physalis angulata l.) Terhadap Bakteri Gram Positif

Abstrak: Mulut memiliki mikrofloranormal bakteri sebagai pertahanan tubuh. Bakteri Streptococcus mutans merupakan bakteri yang berkelompok pada permukaan gigi yang memiliki peranan dalam pembentukan karies gigi. Daun dan batang Ciplukan (Physalis angulata L.) mengandung polifenol, flavonoid, dan etanol serta antioksidan yang kuat yang diduga memiliki aktivitas antimikroba yang sangat baik. Tujuan penelitian ini yatu untuk mengetahui daya antibakteri obat kumur ekstraksisi etanol campuran daun dan batang ciplukan (P. angulata L.) terhadap bakteri Streptococcus mutans. Metode penelitian bersifat eksperimental murni laboratorium yang menggunakan kulturisasi bakteri S. mutans.�Uji daya antibakteri menggunakan cara dengan dilusi cair dan dilanjutkan dengan dilusi padat. Uji analisis statistik menggunakan uji deskriptif. Dari hasil penelitian menunjukkan bahwa pada konsentrasi 15% obat kumur ekstraksi etanol campuran daun dan batang ciplukan mempunyai kadar hambat minimal (KHM) dan kadar bunuh minimal (KBM).� �Formulasi ini bisa direkomendasikan untuk dilakukan penelitian lebih lanjut agar bisa digunakan oleh masyarakat yang tinggal dikawasan suhu dingin.Kata Kunci: Ciplukan, obat kumur, Streptoccus mutans.�Abstrak: The mouth has microfloranormal bacteria as a defense of the body. Mutant Streptococcus bacteria are bacteria that cluster on the surface of the teeth that have a role in the formation of dental caries. Ciplukan leaves and stems (Physalis angulata L.) contain polyphenols, flavonoids, and ethanol as well as powerful antioxidants that are thought to have excellent antimicrobial activity. The purpose of this study was to find out the antibacterial power of ethanol extraction drugs mixed with leaves and stems ciplukan (P. angulata L.) against bacteria Streptococcus mutants. The research method is purely experimental laboratory that uses the culture of bacteria S. mutants.�Antibacterial power test using a means with liquid dilution and continued with solid dilution. Test statistical analysis using descriptive tests. From the results of the study showed that at a concentration of 15% mouthwash ethanol extraction mixed leaves and stems ciplukan have minimal levels of bland (KHM) and minimal kill rate (KBM).� �This formulation can be recommended for further research so that it can be used by people living in cold temperatures.Keywords: �Ciplukan, mouthwash, Streptoccus mutants�

Influence of Recurrent Rolling/Crimping on Cover Crop Termination, Soil Strength and Yield in No-Till Cotton

Rollers/crimpers have been used to terminate cover crops typically with supplemental herbicide application to speed-up termination. Due to environmental concerns, there is a need to reduce herbicide use. In the Southern USA, the cash crop is typically planted three weeks after a rolled cover crop reaches more than 90% kill rate which eliminates competition with the cash crop for water and nutrients. A three-year replicated field experiment was initiated in the fall of 2014 to determine the effects of recurring rolling by experimental rollers/crimpers in terminating a cereal rye cover crop in central Alabama and how multiple rolling affected soil strength. Experimental 2-stage (one smooth drum and one crimping drum), 4-stage (one smooth drum and three crimping drums), spiral, and smooth rollers were tested to roll rye 1, 2, and 3 times (conducted at the same day). A smooth roller with mounted spray boom applying glyphosate rolling once was also evaluated, and untreated rye was the control. Rye was terminated at the milk growth stage and was evaluated one, two and three weeks after rolling. At one week after rolling, the highest rye kill rate was obtained with rolling three times by the 4-stage (96%), 2-stage (92%), spiral roller (81%); rolling once by the smooth roller with glyphosate (94%) compared to the untreated rye at 37%. At two weeks after rolling no differences among rollers were found (91% to 98%); the untreated rye was 54%. Similarly, at three weeks after rolling no differences were detected among rollers (99% to 100%); the untreated rye was 86%. Rolling 2 or 3 times compared with rolling one time did not cause soil compaction. However, at the 15 cm depth cone index (CI) did exceed 2 MPa (a critical value of root penetration restriction); although this CI increase was solely related to decrease in gravimetric soil moisture content (GMC). In addition, over three growing seasons, the seed cotton yield was not affected by rolling treatments with the average yield of 3601 kg ha−1 (1512 kg ha−1 of cotton lint).

Biogeographical and ecological factors associated with kill rates of an apex predator

Kill rates and functional responses are fundamental to the study of predator ecology and the understanding of predatory-prey dynamics. As the most widely distributed apex predator in the western hemisphere pumas (Puma concolor) have been widely studied yet a biogeographical synthesis of their kill rates is currently lacking. We reviewed the literature and compiled data on sex- and age-specific kill rate estimates of pumas on ungulates, and conducted analyses aimed at understanding ecological factors explaining the observed variation across their range. Kill rate studies on pumas, while numerous, were primarily conducted in Temperate Conifer Forests (< 10% of puma range), revealing a dearth of knowledge across much of their range, especially from tropical and subtropical habitats. Across studies, kill rates in ungulates/week were highest for adult females with kitten(s) (1.24 ± 0.41 ungulates/week) but did not vary significantly between adult males (0.84 ± 0.18) and solitary adult females (0.99 ± 0.26). Kill rates in kg/day did not differ significantly among reproductive classes. Kill rates of adult pumas increased with ungulate density. Ungulate species richness had a weak negative association with adult male kill rates. Neither scavenger richness, the proportion of non-ungulate prey in the diet, nor regional human population density had a significant effect on ungulate kill rates. Our results had a strong temperate-ecosystem bias highlighting the need for further research across the diverse biomes pumas occupy in order to make species level inferences. Data from more populations would also allow for multivariate analyses providing deeper inference into the ecological and behavioural factors driving kill rates and functional responses of pumas, and apex predators in general.

Trap and kill of environmental microbes: Validation of a novel decontamination technology in Hospital ICU setting

Nosocomial infections, also known as hospital-acquired infections (HAI), appear 48 hours or more after hospital admission and are independent of the original infirmity of the patient. To prevent or to reduce HAI, the central paradigm is to construct protective barriers between the large number of people who are sick and whose immune systems are compromised in the precincts of the hospital. Microbes that result in HAI do so by two routes of infection: touch and aerosol. We describe here ZeBox technology, a voltage induced synergistic killing of the microbe on designed surfaces, as a game-changer in this domain. Its kill rate is hitherto unmatched by any known chemical or non-chemical (viz; UV, ionisation) technology. In an enclosed test chamber, under challenge conditions, ZeBox technology can kill about a billion microbes in 10 minutes. When tested under clinical settings, the device could effectively reduce microbes, both from air and surfaces with more than 90% efficiency. The optimum requirement to reduce HAI would be to construct an online microbicidal device that operates in a continuous trap and kill mode in the background of people and patient movement, and decontaminates air and surfaces. We present unequivocal data to fortify our claims of online, continuous, safe, trap and kill mechanism of ZeBox technology.

Treatment timing shifts the benefits of short and long antibiotic treatment over infection

Antibiotics are the major tool for treating bacterial infections. Rising antibiotic resistance, however, calls for a better use of antibiotics. While classical recommendations favor long and aggressive treatments, more recent clinical trials advocate for moderate regimens. In this debate, two axes of ‘aggression’ have typically been conflated: treatment intensity (dose) and treatment duration. The third dimension of treatment timing along each individual’s infection course has rarely been addressed. By using a generic mathematical model of bacterial infection controlled by immune response, we examine how the relative effectiveness of antibiotic treatment varies with its timing, duration and antibiotic kill rate. We show that short or long treatments may both be beneficial depending on treatment onset, the target criterion for success and on antibiotic efficacy. This results from the dynamic trade-off between immune response build-up and resistance risk in acute, self-limiting infections, and uncertainty relating symptoms to infection variables. We show that in our model early optimal treatments tend to be ‘short and strong’, while late optimal treatments tend to be ‘mild and long’. This suggests a shift in the aggression axis depending on the timing of treatment. We find that any specific optimal treatment schedule may perform more poorly if evaluated by other criteria, or under different host-specific conditions. Our results suggest that major advances in antibiotic stewardship must come from a deeper empirical understanding of bacterial infection processes in individual hosts. To guide rational therapy, mathematical models need to be constrained by data, including a better quantification of personal disease trajectory in humans. Lay summary: Bacterial infections are becoming more difficult to treat worldwide because bacteria are becoming resistant to the antibiotics used. Addressing this problem requires a better understanding of how treatment along with other host factors impact antibiotic resistance. Until recently, most theoretical research has focused on the importance of antibiotic dosing on antibiotic resistance, however, duration and timing of treatment remain less explored. Here, we use a mathematical model of a generic bacterial infection to study three aspects of treatment: treatment dose/efficacy (defined by the antibiotic kill rate), duration, and timing, and their impact on several infection endpoints. We show that short and long treatment success strongly depends on when treatment begins (defined by the symptom threshold), the target criterion to optimize, and on antibiotic efficacy. We find that if administered early in an infection, “strong and short” therapy performs better, while if treatment begins at higher bacterial densities, a “mild and long” course of antibiotics is favored. In the model host immune defenses are key in preventing relapses, controlling antibiotic resistant bacteria and increasing the effectiveness of moderate intervention. In order to improve rational treatments of human infections, we call for a better quantification of individual disease trajectories in bacteria-immunity space.