Jean-Fabrice Yala

Dr. Jean-Fabrice Yala


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

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

Representative Publications

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1 March 2015 in Journal of Ethnopharmacology
Verified
Journal Article
Closed access
GTGuy Raymond Feuya Tchouya
Guy Raymond Feuya Tchouya
ASAlain Souza
Alain Souza
JTJean Claude Tchouankeu
Jean Claude Tchouankeu
JYJean-Fabrice Yala
Jean-Fabrice Yala
MBMarlaine Boukandou
Marlaine Boukandou
JLJacques Lebibi
Jacques Lebibi

Ornella ZONG MINKOOrnella ZONG MINKO
Ornella ZONG MINKO
RMRolande Mabika Mabika
Rolande Mabika Mabika
RMRachel Moyen
Rachel Moyen
FMFranck Mounioko
Franck Mounioko
LOLéonce Fauster Ondjiangui
Léonce Fauster Ondjiangui
JYJean-Fabrice Yala
Jean-Fabrice Yala
Background: Gastric diseases caused, in particular, by Campylobacter, non-typhoidal Salmonella, and Shigella resulting from food and/or water problems, are a disproportionately distributed burden in developing countries in Central Africa. The aim of this work was to compile a list of studies establishing the prevalence of the involvement of these bacterial genera in diarrheal syndromes in Central Africa from 1998 to 2022. Methods: The Preferred Reporting Articles for Systemic Reviews and Meta-Analyses, six (6) database (Pubmed, Google Scholar, Semantic Scholar, Freefullpdf, and Scinapse) were perused for research on the role of Campylobacter, Salmonella and Shigella diarrheal infections in humans and animals, in 9 country of Central Africa over from 1998 to 2022. Results: Seventeen articles were selected, including 16 on humans and one on animals. These data were recorded in 6 of the 9 countries of Central Africa, including Gabon (5), Angola (3), Cameroon (3), the Democratic Republic of Congo (3), Chad (2), and the Central African Republic (1). Mono-infections with Salmonella spp. were the most predominant (55.56%, n = 5/9), followed by an equal proportion of Campylobacter spp. and Shigella spp. with 44.44% (4/9), respectively and, co-infections with Campylobacter/Salmonella spp. and Salmonella/Shigella spp. with a prevalence of 11.11% (1/9) respectively. The most used diagnostic tool was conventional culture (82.35%) against 17.65% for PCR or real-time PCR. Conclusion: Despite the paucity of recorded data on the prevalence of diarrheal infections due to Campylobacter in this sub-region, it is crucial that scientific studies focus on the diagnosis and monitoring of this zoonotic bacterium. Also, improved diagnosis will necessarily involve the integration of molecular tools in the diagnosis of these diarrheic syndromes in both humans and animals.

20 October 2023 in Plants
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Journal Article
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JYJean-Fabrice Yala
Jean-Fabrice Yala
RMRolande Mabika Mabika
Rolande Mabika Mabika
DIDavy Ulrich Ikabanga
Davy Ulrich Ikabanga
FMFranck Mounioko
Franck Mounioko
PMPrince Rodrigue Mokouapamba
Prince Rodrigue Mokouapamba
ASAlain Souza
Alain Souza
Diarrhea is a condition that particularly affects children under five the age of years old in developing countries. The aim of this study was to evaluate the efficacy of medicinal extracts plants used in treatment and to characterize their inhibitory capacity in the growth of bacteria isolates in childhood diarrhea in the southeast region of Gabon. An ethnobotanical survey on the plants used in the treatment of diarrhea in southeastern Gabon was carried out and a phytochemical screening of the collected plants was performed. The antimicrobial activity of aqueous extracts was evaluated; 33 plant species were identified, representing 28 genera and 19 families. Bark (39.5%) was the most commonly used plant part, followed by powder formulations (28.9%). The preferred method of preparation and chewing (44.7%), together with drinking (36.8%), were the most prevalent modes of administration. Phytochemical screening showed a plethora of secondary metabolites (terpenoids, alkaloids and phenolic compounds), and a marked level of anti-diarrheal activity was found with Sida acuta and Santiria. ebo against Shigella spp. (16.22 ± 0.7 mm and 14.05 ± 1.4 mm) and Yersinia pestis (16.35 ± 0.5 mm and 15.51 ± 0.5 mm). The high diversity of secondary plant metabolites and their inhibitory ability against enteric pathogens would justify their use at the local level to treat diarrheal infections.

21 December 2020 in Research Square
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RMRolande Mabika Mabika
Rolande Mabika Mabika
SOSandrine Lydie Oyegue-Liabagui
Sandrine Lydie Oyegue-Liabagui
FMFranck Mounioko
Franck Mounioko
SDSerge Ely Dibakou
Serge Ely Dibakou
ADArnaud Mongo Delis
Arnaud Mongo Delis
JYJean-Fabrice Yala
Jean-Fabrice Yala
Background Better knowledge of endogenous germs and their associated demographic and environmental risk factors in a locality are essential to treat childhood diarrheal diseases. The aim of the study was to identify and characterize bacterial and parasitic pathogens responsible for childhood diarrhea, and to identify environmental risk factors associated with diarrhea in children under 5 years old living in Koula-Moutou, East-Central Gabon. Methods A cross-sectional study was performed from May 2016 to February 2018. One-hundred and thirty-two (132) children under 5 years old were enrolled. The detection of pathogens in stool samples was performed using microscopic examination and MIF concentration for parasites, and conventional culture on selective media for enterobacteria. Results The prevalence of diarrheal pathogens was 46.1%, including bacterial enteropathogens (25.5%) and parasites (20.6%). A total of 228 pathogenic organisms were isolated, including 199 bacterial strains (87.3%) and 29 parasites (12.7%). The specific richness of the isolated enterobacteria was 24 species with a high prevalence of E. coli (39.8%), including 26.7% for the diarrheal cases and 13.1% for the controls. Twelve (12) parasite species were also isolated and the most common types of parasites were rhizopods (44.8%), which accounted for 37.9% of the diarrheal cases and 6.9% of the controls. Univariate analysis showed that the presence of watercourses (OR = 3.37) and domestic animals (OR = 1.65) were significant risk factors for diarrhea. Conclusion The findings show a high prevalence of bacterial enteropathogens but a low rate of parasites and bacteria-parasite co-infection in the study area. Risk factors associated with diarrhea among children under 5 years old were the presence of watercourses and domestic animals. These findings highlight the need to strengthen the routine examination of diarrheic stool samples for the diagnosis of pathogenic organisms. Further analyses are required to better understand the etiologies and risk factors associated with the transmission of bacteria and parasites in rural, semi-urban and urban regions of Gabon.

1 January 2021 in Egyptian Journal of Basic and Applied Sciences
Verified
Journal Article
Open access
RMRolande Mabika Mabika
Rolande Mabika Mabika
FMFranck Mounioko
Franck Mounioko
ASAlain Souza
Alain Souza
JYJean-Fabrice Yala
Jean-Fabrice Yala
In the face of the growing phenomenon of multidrug-resistant bacteria, studies on the sensitivity profiles of enteric pathogens are required to better manage the remaining antibiotic capital. The objective of this study was to investigate the sensitivity and to determine the genetic basis of quinolone-resistant enteric diarrheal pathogens isolated from children in the city of Koula-Moutou, Gabon. Thirty strains of the Salmonella genera, five strains of Shigella and two strains of Yersinia (2) were analyzed. The Kirby–Bauer method was used to determine the sensitivity of these isolates to five molecules in the quinolone family. The presence of chromosomal (gyrA) and plasmid (PMQR) quinolone resistance genes, including the QNR complex (qnrA, qnrB, and qnrS) were investigated by PCR. These enteric pathogens exhibited high levels of resistance to quinolones, particularly ofloxacin (100%) and ciprofloxacin (97.3%). Most isolates of Salmonella were found to be resistant to nalidixic acid (86.7%), however all isolates of the Shigella and Yersinia genera were susceptible to this antibiotic. Among the 37 strains, 21.6% had the gyrA gene, 13.5% had the qnrB and qnrS genes but the qnrA gene was not detected. Enteric pathogens isolated from the diarrheal feces of the children in Koula-Moutou exhibited high levels of phenotypic resistance to quinolones. This resistance is especially due to mutations occurring on the chromosomal determinant gyrA which also played a role in the reduced sensitivity of these strains to fluoroquinolones. The resistance is also linked to a lesser extent to the acquisition of the PMQR genes, notably qnrB and qnrS. In conclusion, this study highlights the high prevalence rate of enteric pathogens isolated from diarrheal feces of children in Gabon and shows the presence of the QNR complex genes (qnrB and qnrS) in the strains.

14 July 2020 in Journal of Food Science and Technology
Verified
Journal Article
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JMJean Ulrich Muandze-Nzambe
Jean Ulrich Muandze-Nzambe
ORONANGA RICHARD
ONANGA RICHARD
JYJean-Fabrice Yala
Jean-Fabrice Yala
NSNamwin Somda
Namwin Somda
CHCISSE HAMA
CISSE HAMA
ASAly Savadogo
Aly Savadogo
The purpose of this study was to provide contextual information on indigenous food’s technologies and safety from Gabon. The strategic focus being to promote local food with enhanced nutritional value and improved safety. An investigation and monitoring were carried out to elucidate their process flow diagrams and to identify safety failures. Samples were taken for microbiological analysis using conventional culture-based techniques. Detection and identification of Salmonella in samples were confirmed using PCR based method by targeting invasion plasmid antigen B (IpaB) gene. The investigation shows that women play a protagonist role in the technical know-how of Gabonese indigenous foods in a context that is evolving towards the disappearance of this knowledge. The food production process remains archaic, which makes the environment impact on food safety. Indeed, the proximity of food manufacturing environment to animals, waste, or latrines coupled with the lack of hygiene and manufacturing practices affect the quality of these foods. This is reflected in our study's microbiological results, namely, Aerobic Mesophilic Bacteria ranged from 3.53 to 11.96 log CFU/g and indicators of fecal contaminations of up to 8.21 log CFU/g. Salmonella is detected in 18.69% of samples. The presence of these bacteria is a risk for consumer health. Although some of these foods can be considered as a fermented food, the producers should be further educated and encouraged to take preventive measures to ensure the quality of these food products. A much more subtle approach based on microbial ecology of these foods should be explored for better exploitation.