Ethnopharmacological Survey, Phytochemical Screening and Antimicrobial Activities of Medicinal Plants Used in the Treatment of Diarrhea in Southeastern Gabon.

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.

Evaluation of the bioresistance profile of enterobacteria isolated from faeces of children with diarrhoea in the town of Koula-Moutou, Gabon: prospective study.

Introduction: the emergence and expansion of multidrug resistance in Enterobacteriaceae responsible for various infections are increasing in the world. This study was designed to determine the phenotypic profiles of the resistance of enterobacteria strains isolated from the faeces of children with diarrhoeal diseases and to classify them according to the type of resistance. Methods: screening was carried out on 98 isolates divided into 2 groups: opportunistic pathogens and strict enteropathogens. Their sensitivity to 13 antibiotics was evaluated by the Mueller Hinton agar medium diffusion method. Results: a strong resistance to different classes of ß-lactams was found in the strains, 74.0% (n=45) and 83.3% (n=31) for opportunists and enteropathogens, respectively. These strains were completely resistant to doxycycline and erythromycin (100%; n=98) for both types of bacteria. Opportunists and enteropathogens were 95.1% (n=58) and 94.6% (n=35) resistant to gentamicin, and 31.1% (n=19) and 35.1% (n=13) resistant to chloramphenicol, respectively. Similarly, the total resistance of strains was observed with ofloxacin and amounted to 98.4% (n=60) and 96.7% with levofloxacin and norfloxacin, respectively. The analysis of ß-lactam resistance phenotypes revealed a dominance of the carbapenemase-producing strains (28.6%; n=28). However, 24.3% (n=9) of enteropathogens were pan-resistant versus 19.7% (n=12) for opportunists. Conclusion: the results of this study indicate a worryingly high level of antibiotic resistance in enterobacteria which might tend towards total resistance.

Technological and microbiological characteristics of indigenous food produced in Gabon.

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.

Ethnopharmacological surveys and pharmacological studies of plants used in traditional medicine in the treatment of HIV/AIDS opportunistic diseases in Gabon.

ETHNOPHARMACOLOGICAL RELEVANCE: Ethnopharmacological surveys were conducted in two regions of Gabon. This led to highlighting some of the medicinal plants used by local populations in the management of HIV/AIDS opportunistic diseases. Two regions with the highest occurrence of HIV/AIDS cases were visited and ethnopharmarcological data was gathered. These regions were the Estuaire Province (Libreville and its neighborhood) and the Haut-Ogooué Province (Franceville and its neighborhood). The opportunistic diseases and symptomatic conditions considered during this study were: diarrhea, respiratory tract infections, cough, tuberculosis, abscesses, stomach ache, skin rashes, venereal diseases, typhoid fever, anemia, general tiredness, hepatitis and vomiting. MATERIALS AND METHODS: The reported species were evaluated through three parameters: specificity, reliability and frequency. Plant parts of relevant species were harvested and extracted with an aqueous alcohol solution (ethanol/water: 1/1). The extracts obtained were submitted to phytochemical screening and in vitro microbiological assays on some clinical isolates and ATCC strains, involved in HIV/AIDS opportunistic diseases through the Agar well diffusion and Microbroth dilution methods. RESULTS: Among the 52 species identified during this survey, Coelocaryon klainei Pierre ex Heckel (Myristicaceae), Dacryodes klaineana (Pierre) H.J. Lam (Bursecaceae), Phyllanthus diandrus Pax (Euphorbiaceae), Saccoglotys gabonensis (Baill.) Urb. (Humiriaceae) and Tetrorchidium didymostemon (Baill.) Pax & K. Hoffm. (Euphorbiaceae) were submitted to in vitro microbiological assays. Phyllanthus diandrus bark and leaves show best antibacterial activities against Pseudomonas aeruginosa and Klebsiella pneumoniae with MIC value of 0.25 respectively. Phytochemical screening revealed the presence in all the plant parts extracts of potentially bioactive molecules, including polyphenols, especially flavonoids and tannins. CONCLUSION: It is concluded that some of these plants might be submitted to further scientific studies, including the identification and isolation of bioactive principles, that could be developed to drugs for the treatment of HIV/AIDS opportunistic diseases.

Elaboration of antibiofilm materials by chemical grafting of an antimicrobial peptide.

A peptide antibiotic, gramicidin A, was covalently bound to cystamine self-assembled monolayers on gold surfaces. Each step of the surface functionalization was characterized by polarization modulation infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy. The antimicrobial activity of the anchored gramicidin was tested against three Gram-positive bacteria (Listeria ivanovii, Enterococcus faecalis, and Staphylococcus aureus), the Gram-negative bacterium Escherichia coli and the yeast Candida albicans. The results revealed that the adsorbed gramicidin reduced, from 60% for E. coli to 90% for C. albicans, the number of culturable microorganisms attached to the surface. The activity was proven to be persistent overtime, up to 6 months after the first use. The bacteria attached to the functionalized surfaces were permeabilized as shown by confocal microscopy. Taken together, these results indicate a bacteriostatic mode of action of the immobilized peptide. Finally, using green fluorescent protein-expressing bacteria, it was shown that the development of a bacterial biofilm was delayed on peptide-grafted surfaces for at least 24 h.

The antibacterial activity of Magainin I immobilized onto mixed thiols Self-Assembled Monolayers.

An antibacterial peptide, Magainin I, was covalently bound to a mixed 11-mercaptoundecanoïc acid (MUA) and 6-mercaptohexanol (C6OH) (ratio 1:3) Self-Assembled Monolayer (SAM) on gold surfaces. Each step of the surface functionalization was characterized by Polarization Modulation Reflection Absorption InfraRed Spectroscopy (PM-RAIRS) and X-ray Photoelectron Spectroscopy (XPS). The antibacterial activity of the anchored Magainin was tested against three Gram-positive bacteria (Listeria ivanovii, Enterococcus faecalis and Staphylococcus aureus), and the results revealed that the adsorbed Magainin I reduced by more than 50% the adhesion of bacteria at the surface, together with the killing of the bacteria that nonetheless adhered to the surface. No release of the peptide was observed upon contact with the bacterial suspension; the activity has proven to be persistent overtime, up to six months after the first use.