Aphanomyces euteiches is a soil-borne pathogen that causes root rot of pea and can significantly affect pea production in western Canada. This study aimed to isolate and identify soil bacteria with antagonistic activity towards A. euteiches mycelial and zoospore developmental stages under in vitro conditions and assess their potential as biocontrol agents against aphanomyces root rot in field pea under growth chamber conditions. In vitro screening of soil bacteria identified 184 antagonistic isolates, including 22 from an existing culture collection. Mean mycelial growth inhibition zones ranged from 1 to 12 mm, and mean zoospore germination inhibition ranged from 0% to 100%. Use of 16S rDNA sequence analysis placed isolates into 18 different bacterial genera. Screening of 47 bacteria that inhibited both infective stages identified 29 potential biocontrol strains, including Rhizobium spp. that significantly (α = 0.05) suppressed aphanomyces root rot in field pea grown in vermiculite, suggesting the intriguing possibility of using N-fixing Rhizobium inoculants as biocontrol agents for aphanomyces control. Further screening of 20 isolates as soil inoculants identified K-Hf-L9 (Pseudomonas fluorescens), PSV1-7 (Pantoea agglomerans), and K-Hf-H2 (Lysobacter capsici) isolates as having the highest biocontrol activity, significantly (α = 0.05) suppressing aphanomyces root rot in field pea in growth chamber trials. This study demonstrates the possibility of aphanomyces root rot management using biocontrol agents.Résumé : Aphanomyces euteiches est un agent pathogène du sol responsable du piétin du pois. Ce champignon nuit parfois de façon importante à la production de cette légumineuse dans l'Ouest canadien. Les auteurs voulaient isoler puis identifier les bactéries du sol susceptibles d'agir in vitro contre le mycélium et les zoospores d'A. euteiches, et établir si on pourrait s'en servir comme moyen de lutte biologique contre le piétin du pois de grande culture en chambre de croissance. La sélection in vitro de bactéries telluriques a débouché sur l'identification de 184 isolats antagonistes, dont 22 d'une collection de cultures existante. Les plages moyennes d'inhibition de la croissance du mycélium varient de 1 à 12 mm et le degré moyen d'inhibition de la germination des zoospores, de 0 à 100 pour cent. Le séquençage de l'ADNr 16S situe les isolats dans 18 genres bactériens. L'examen de 47 bactéries inhibant les deux stades infectieux ont permis d'identifier 29 souches susceptible de servir à la lutte biologique, y compris des espèces du genre Rhizobium supprimant de manière significative (α = 0,05) le piétin causé par Aphanomyces chez le pois cultivé dans de la vermiculite, signe d'un intrigante possibilité où l'inoculation de Rhizobium fixateur d'azote permettrait aussi de lutter contre la maladie. Une étude plus poussée de 20 isolats comme inoculants a permis d'établir que les souches K-Hf-L9 (Pseudomonas fluorescens), PSV1-7 (Pantoea agglomerans) et K-Hf-H2 (Lysobacter capsici) ont la plus forte activité antagonis...

Background The effectiveness of Helicobacter pylori (H. pylori) eradication depends on the treatment protocol. This study investigates the H. pylori eradication rate in Africa using the best available evidence from databases. Methods Databases were searched and results were pooled together. Heterogeneity between studies was assessed using I2 test statistics. Stata version 13 software was employed to compute the pooled eradication rate. In the subgroup analysis comparison, the finding is considered significant when the confidence intervals did not overlap. Results Twenty-two studies from 9 African countries with a total population of 2,163 were included in this study. The pooled eradication rate of H. pylori was 79% (95% CI: 75%-82%), heterogeneity (I2 = 93.02%). In the subgroup analysis by study design, a higher eradication rate was reported from observational studies (85%, 95% CI: 79%-90%), compared to randomized control trials (77%, 95% CI: 73%-82%); by the duration of therapy, higher eradication rate was reported in 10-days regimen (88%, 95% CI: 84%-92%), compared to 7-days regimen (66%, 95% CI: 55%-77%); by country, the highest eradication rate was found in Ethiopia (90%; 95% CI: 87%-93%) and the lowest eradication rate was reported in Ivory Coast (22.3%; 95% CI:15%-29%); by type of H. pylori test, the highest eradication rate was reported when rapid urease test coupled with histology (88%, 95% CI: 77%-96%), and the lowest eradication rate was reported with histology alone (22.3%; 95% CI:15%-29%). Significant heterogeneity was observed with pooled prevalence (I2 = 93.02%, P < 0.000). Conclusions In Africa, the first-line therapy showed a variable eradication rate for H. pylori. This study demonstrates the necessity to optimize current H. pylori treatment regimens in each country, taking into account the antibiotic susceptibility. Future RCT studies with standardized regimens are warranted.

The increasing incidence and prevalence of the pathogen Aphanomyces euteiches in various pulse-growing regions worldwide necessitates the development of effective management strategies, including biological control agents. Numerous labs have undertaken research examining biological control methods to evaluate aphanomyces root rot suppression in multistep processes that include isolation of inhibitory organisms, lab assays, growth chamber assays, and field trials. Given the emergence of various biocontrol agents and the need to mitigate aphanomyces yield losses, we have undertaken a meta-analysis approach to analyze the effectiveness of biocontrol agents in relation to application method, biocontrol agent richness, biocontrol agent type, the type of study, and reporting system-oriented moderator variables. An effect size, calculated as a natural log response ratio, resulted in a summary weighted mean of −0.411, suggesting the overall effectiveness of biocontrol agents (p &lt; .001). Aphanomyces root rot suppression using biological treatments showed significant heterogeneity for all moderator variables, confirming that the studies do not share a common effect size and the use of a random effect model was appropriate. Across studies, meta-analyses revealed that soil amendments, biocontrol agent application as a seed coating and suspension, bacterial and fungal biocontrol agents, mixed applications, growth chamber and field studies, and qualitative and quantitative reporting systems were all associated with significantly positive outcomes for aphanomyces root rot suppression. Our findings suggest that there is potential promise for biological control of aphanomyces root rot, and more field trials need to be conducted to demonstrate the efficacy level observed under growth chamber conditions. Moreover, we identified a lack of detailed understanding of the mechanism(s) of biological control of aphanomyces root rot as a research priority.

Background The effectiveness of Helicobacter pylori (H. pylori) eradication depends on the treatment protocol. This study aimed to investigate the H. pylori eradication effectiveness in Africa using the best available evidence from databases. Methods PubMed, Google Scholar, Hinari, Scopus, and the directory of Open Access Journals (DOAJ) were searched. The quality of each included study was assessed using Cochrane risk-of-bias tool for randomized trials (RoB2) and Risk of Bias in Non-Randomized Studies of Intervention (ROBINS-I) for observational studies. Heterogeneity between studies was assessed using I2 test statistics based on the random effect model. Stata version 13 (College Station, Texas 77845 USA) software was employed to compute the pooled eradication rate. Forest plots and tables were used to present the data. Results Twenty-two studies from 9 African countries with a total population of 2,163 met the inclusion criteria and were included in the analysis. The pooled eradication rate of H. pylori by standard therapy was 79% (95% CI: 75%, 82%), with heterogeneity (I2 = 93.02%). In the subgroup analysis by study design, a higher eradication rate was reported from observational studies (85%, 95% CI: 79%-90%), compared to randomized control trials (77%, 95% CI: 73%-82%); by the duration of therapy, higher eradication rate was reported in 10-days regimen (88%, 95% CI: 84–92), compared to 7-days regimen (66%, 95% CI: 55–77); by country, the highest eradication rate was found in Ethiopia (90%; 95% CI: 87%-93%) and the lowest eradication rate was reported in Ivory Coast (22.3%; 95% CI:15%-29%); by type of H. pylori test, the highest eradication rate was reported when rapid urease test coupled with histology (88%, 95% CI: 77–96), and the lowest eradication rate was reported using histology alone (22.3%; 95% CI:15%-29%). Conclusions Eradication therapy for H. pylori in Africa had eradication rates that could be considered effective even in the lowest reported cases. This study demonstrates the necessity to optimize current H. pylori treatment regimens in each country, taking into account the antibiotic susceptibility of the bacteria.

Aphanomyces euteiches is a soilborne plant pathogen. It causes severe root rot in leguminous crop species. We report the complete genome sequence of a biocontrol strain, Pseudomonas simiae K-Hf-L9. The strain inhibited Aphanomyces euteiches mycelia and zoospores and suppressed root rot in field peas grown under controlled growth chamber conditions.