Bactericidal and Bacteriostatic Effects of Four Different Parts of 2 Plants Moringa Extracts against the Bacteria Vibrio cholerae and Salmonella typhi, and some Phytochemical Properties

International audienceBackground and Objectives: Typhoid fever and cholera are two major health challenges in many developing countries. The use of extracts of the plants Moringa for their treatment is often done without perfect knowledge of the antimicrobial properties of each part of plant. This study aims to evaluate the bactericidal and bacteriostatic effects of extracts of M. oleifera and M. stenopetala against the bacteria S. typhi and V. cholerae which cause typhoid fever and cholera respectively. Materials and Methods: Four different parts (leaves, seeds, stem, and roots) of each plant species were dried and then ground. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the extracts of each part of the plants against the considered bacteria were determined by dilution method. Their phytochemical profiles were determined by chromatographic and mass spectral analyses. Results: It has been noted that MICs and MBCs varied from one part to another of the same Moringa species, and from one bacterium to another for the same extract. With M. oleifera, the lowest MBC (0.078 mg/mL) against S. typhi and V. cholerae came from seeds and roots extracts, respectively. With M. stenopetala, the lowest MBCs against S. typhi (0.156 mg/mL) and V. cholerae (0.312 mg/mL) were from seeds extracts. Extracts of different parts of M. oleifera have bactericidal effects against S. typhi, and bacteriostatic effects against V. cholerae. Extracts from all considered parts of M. stenopetala have bacteriostatic effects against both bacteria. Although some phytochemicals were found in both Moringa, others were specific to one species or to a given part. Conclusion: In case of co-infection by both bacteria, M. oleifera roots extracts could be the most recommended in the treatment because of their lowest MIC and MBC. With M. stenopetala, roots and seeds extracts could be the most recommended because of their relatively lower MIC and MBC, respectively. The next studies will determine for each microorganism, the activity of each identified and purified chemical compound. GRAPHICAL ABSTRAC

Effects of aqueous and hydro-ethanolic Moringa oleifera Lam leaf extracts on the cultivability of 2 Bacillus strains isolated from rainwater

International audienceIn most developing countries, rainwater is used by many people to meet their water needs. Many Bacillus species known to be harmful to humans have also been identified in rainwater samples. Improving the microbiological quality of the rainwater using modern techniques seems expensivein rural areas for poor people. Extracts from several medicinal plants are often used in rural areas to treat certain bacterial infections. Water and alcohol are often used in traditional therapy to extract the principles of medicinal plants. But little is known about their functional differences orsimilarities. This study aims to assess the effects of aqueous and hydro-ethanolic leaf extracts of Moringa oleifera Lam on the cultivability of Bacillus cereus and Bacillus thuringiensis isolated from rainwater. Leaf extracts of concentrations 2, 1.5, 1 and 0.5 g/L in contact with cells were incubated at 23°C and 37°C for 3 h, 6 h, 9 h and 24 h. The results showed a decrease in cultivable cells abundance. In most cases, cell abundances between the aqueous extract and hydro-ethanolic extract were not significantly different (P>0.05). A significant difference (P<0.05) was noted amongst cell abundances from each incubation period to another. The effectiveness of each extract for cell inhibition was evaluated and then expressed as a decrease percentage in the number of cultivable cells. A decrease in cultivable B. thuringiensis abundance varied from 75.09 to 99.68% in hydro-ethanolic extract and from 70.75 to 97.94% in aqueous extract. That of B. cereus varied from 0 to 98.86% in hydro-ethanolic extract and from 41.09 to 92.20% in the other. This difference could be linked to the differences in the cell species intrinsic properties. It could also be linked to the presence of some compounds identified. Some of these compounds would act as nutrients for cell growth, counterbalancing cell inhibition caused by others that have antimicrobial effects

Antibiotics susceptibility of some Bacillus strains isolated in the ground and rainwater in urbanized area in Cameroon (Central Africa), and potential impact of the season change

International audienceThis study assessed the antibiotics susceptibility of Bacillus cereus, B. thuringiensis and B. subtilis strains isolated in wells and rainwater samples in Yaounde (Cameroon). Water samples in wells were collected monthly during a long dry season (LDS), a short dry season (SDS), a long rainy season (LRS) and a short rainy season (SRS), and during the LRS and the SRS for rainwater. The antibiotics considered included Imipenem, Amikacin, Gentamycin, Ciprofloxacin, Ofloxacin, Sulfamethazol, and Tetracycline. With strains from the groundwater, the antibiotic inhibition diameters varied from 9.13 mm (Sulfametazole during SDS) to 32.78 mm (Imipenem during LDS) with B. thuringiensis, from 8.2 mm (Sulfametazole during SDS) to 35.25 mm (Imipenem during LDS) with B. cereus, and from 5.05 mm (Ofloxacin during LRS) to 29.25 mm (Imipenem during LDS) with B. subtilis. With those from the rainwater, they varied from 4.55 mm (Sulfametazole during LRS) to 25.65mm (Imipenem during LRS) with B. thuringiensis, from 2.13 mm (Imipenem during LRS) to 20.05mm (Imipenem during SRS) with B. cereus, and from 5.03 mm (Gentamicin during SRS) to 25.15mm (Tetracycline during SRS) with B. subtilis. Bacillus strains isolated during LRS were multiresistant to the majority of antibiotics. The inhibition diameters of the most antibiotics varied significantly from one season to another (p<0.05)

Relative importance of the bacteria Brucella, Salmonella, Staphylococcus and other indicator bacteria in some mountain farm waters in West-Cameroon (Central Africa) and the potential role of some environmental factors

International audienceA bacteriological and physicochemical study was conducted in the waters of farms in mountainous regions of Cameroon. The different water samples were collected during two campaigns in December 2018 and February 2019. Ten stations representing the drinking water supply points in our study area were identified. The results showed that these waters contained both pathogenic and commensal fecal bacteria. The highest abundances reached 10x10 3 CFU/100mL for Salmonella sp., 72x10 3 CFU/100mL for Staphylococcus aureus, 102x10 3 CFU/100mL for Brucella suis and 40x10 3 CFU/100mL for Brucella abortus. These abundances were subject to space-time fluctuations. Water contamination by tweezers was not general and was present only in surface waters (rivers and ponds). The water in the ponds, rivers and wells analyzed were all basic, with low mineralization on average. The dissolved oxygen ranged from 37.5 to 70.6%, nitrate from 3.7 to 19.8 mg/L and iron from 0.01 to 3.5 mg/L. Most of the physicochemical parameters were relatively stable during the two campaigns. The degree of correlation between the physicochemical parameters and the abundance dynamics of the isolated bacteria was heterogeneous. This was clearly more pronounced with Salmonella sp. and Brucella suis. This would be due to the fraction of metabolically active cells present when the bacteria are exposed to unfavorable conditions. Correlations with the abiotic factors were less marked with Staphylococcus aureus and Brucella abortus; this would be due to their tolerance to environmental stresses

Antibiotic susceptibility of four Enterobacteriaceae strains (Enterobacter cloacae, Citrobacter freundii, Salmonella typhi and Shigella sonnei) isolated from wastewater, surface water and groundwater in the equatorial zone of Cameroon (Central Africa)

International audienceThe health problems caused waterborne pathogens bacteria belonging to the Enterobacteriaceae family are aggravated by the rise of antimicrobial resistant bacteria phenomenon. This has been identified as one of the biggest global health challenges. The present study aims to make a comparative approach of the sensitivity/resistance to antibiotics of 4 Enterobacteriaceae Enterobacter cloacae, Citrobacter freundii, Salmonella typhi and Shigella sonnei isolated from wastewater, streams and groundwater in Yaounde town (Cameroon, Central Africa). Bacteria were isolated using standard methods their identification using the API 20E systems. The antibiogram tests were carried out using the Müller-Hinton antibiotic disc diffusion method. Results showed that inhibition diameters of antibiotic varied (P<0.05) with respect to the bacterial species on one hand, and with respect to the type of water harbored cells on the other hand. The proportion of bacterial strains of each isolated species, and which were sensitive or resistant varied from one antibiotic to another within the same antibiotics family. For β-lactams tested, no E. cloacae strain has been sensitive. The proportion of sensitive strains of other species varied between 5.88% and 23.53%. For the 2 aminoglycosides tested, 5.88% of the strains of each isolated species were resistant to gentamycin. Of the 3 quinolones tested, all strains of E. cloacae and C. freundii isolated were fully resistant to Norfloxacin and of Ofloxacin. For the 3 Sulfonamides+trimethoprim, all strains of C. freundii and S. typhi isolated were resistant to Nurofurantoin and Fosfomycin. Most of bacteria strains isolated in wastewater and surface water were resistant to all the antibiotics tested. Many bacterial strains tested were multi-resistant. This multidrug resistance was more marked in E. cloacae and C. freundii species isolated from wastewater and surface water. This represents a health risk for humans and the aquatic environment