(−)-Brunneusine, a new phenolic compound with antibacterial properties in aqueous medium from the leaves of Agelanthus brunneus (Engl.) Tiegh (LORANTHACEAE)

Agelanthus brunneus (Loranthaceae) is a hemiparasitic plant growing on Senna siamea (Fabaceae). The chemical investigation of its leaves and flowers led to the isolation of one new phenolic compound namely (-)-brunneusine (1), together with 13 known compounds. The crude leaves and flowers extracts (CLE and CFLE) with their ethyl acetate fractions (EAFL and EAFFL) and some isolated compounds (1-3; 8-9 and 11-14) have been tested on four bacterial species of sanitary importance isolated in an aquatic environment. All the samples except compound 3 showed antibacterial activity with MICs ranging from 0.43 to 8.88.103 μg/mL and MBCs from 0.43 to 3.55.103 μg/mL. Compounds 9 and 14 showed better activity on all bacterial species tested with MICs ranging from 0.43 to 27.77 μg/mL. Only CLE, EAFL and compounds 14, 2, 8 and 9 showed bactericidal effects on all bacterial species tested

Distribution patterns of Vibrionaceae abundance on the landing stages in coastal area: Understanding the influence of physicochemical variables by using multiple linear regression models and corrgram for matrix correlation

International audienceThe present work used multiple linear regression (MLR) models and corrgram to assess the importance of environmental parameters on diversity and abundance dynamics of Vibrio sp. in waters of few landing stages in the city of Douala (Cameroon). It was recorded in all the five selected stations, the presence of four species of Vibrio namely, Vibrio parahaemolyticus, Vibrio cholerae, Vibrio fluvialis and Vibrio alginolyticus whose highest abundance reached 5.65, 6.26, 4.9 and 4.83 log CFU/100 ml respectively. Vibrio cholerae was the most isolated during the study with a frequency of 65%. The abundance dynamics of these germs is strongly influenced by nitrates, salinity, dissolved carbon dioxyde (CO 2) and ammonium ions (NH 4 +). The visualization of corrgram shows high degree of association between studied parameters. We note a coefficient of determination r 2 = 0.50 for the multiple linear regression model for Heterotrophic Aerobic Bacteria (HAB) and a coefficient of determination r 2 = 0.58 for the MLR model for V. cholerae. The physicochemical parameters explain at 43% (r 2 = 0.43) the distribution of the abundances of V. parahaemolyticus, at 45% (r 2 = 0.45) the distribution of abundances of V. alginolyticus and at 26% (r 2 = 0.26) for V. fluvialis

Distribution patterns of Vibrionaceae abundance on the landing stages in coastal area: Understanding the influence of physicochemical variables by using multiple linear regression models and corrgram for matrix correlation

International audienceThe present work used multiple linear regression (MLR) models and corrgram to assess the importance of environmental parameters on diversity and abundance dynamics of Vibrio sp. in waters of few landing stages in the city of Douala (Cameroon). It was recorded in all the five selected stations, the presence of four species of Vibrio namely, Vibrio parahaemolyticus, Vibrio cholerae, Vibrio fluvialis and Vibrio alginolyticus whose highest abundance reached 5.65, 6.26, 4.9 and 4.83 log CFU/100 ml respectively. Vibrio cholerae was the most isolated during the study with a frequency of 65%. The abundance dynamics of these germs is strongly influenced by nitrates, salinity, dissolved carbon dioxyde (CO 2) and ammonium ions (NH 4 +). The visualization of corrgram shows high degree of association between studied parameters. We note a coefficient of determination r 2 = 0.50 for the multiple linear regression model for Heterotrophic Aerobic Bacteria (HAB) and a coefficient of determination r 2 = 0.58 for the MLR model for V. cholerae. The physicochemical parameters explain at 43% (r 2 = 0.43) the distribution of the abundances of V. parahaemolyticus, at 45% (r 2 = 0.45) the distribution of abundances of V. alginolyticus and at 26% (r 2 = 0.26) for V. fluvialis

Less effect of wells physicochemical properties on the antimicrobial susceptibility Pseudomonas aeruginosa isolated in equatorial region of Central Africa

Abstract This study aimed at assessing the impact of some wells abiotic factors on the antimicrobial susceptibility of Pseudomonas aeruginosa isolated. A total of 14 well waters of Douala and Yaoundé towns (Cameroon, Central Africa) were chosen. Fifteen antibiotics were used to test antimicrobial susceptibility with the majority belonging to β-lactam, aminoglycoside and quinolone groups. Result showed that in Douala, electrical conductivity of water ranged from 145.38 to 559.69 μS/cm in well, while in Yaoundé, it ranged from 172.5 to 710.2 μS/cm. Dissolved oxygen ranged from 2.5 to 5.5 mg/l and from 3.9 to 5.1 mg/l, respectively, in Douala and Yaoundé. Organic matter varied from 2.3 to 7.2 mg/l and 1.4 to 5.2 mg/l in Douala and Yaoundé, respectively. As for pH, it fluctuated between 5.56 and 6.66 CU and between 5.1 and 7.0, respectively, in Douala and Yaoundé. The sampled waters harbour multi-drug-resistant P. aeruginosa strains. About 20.40% of strains from wells in Yaoundé metropolis expressed resistance to at least 5 antibiotics, whereas from wells in Douala town, up to 33.33% of strains were resistant to at least 8 antibiotics including ticarcillin, ceftazidime and gentamicin. The effect of abiotic factors on the sensitivity to antibiotics was assessed using the multiple regression tests. In both towns, less than 5% in the changes of physicochemical parameters of well waters explained the variance in inhibition diameter values of antibiotics (p ≤ 0.05). The pH significantly impacts on antimicrobial susceptibility. Environmental conditions are less stressful for P. aeruginosa and fairly affect its antimicrobial susceptibility

Using Principal Component Analysis to Assess Water Quality from the Landing Stages in Coastal Region

International audiencePrincipal component analysis (PCA) was used to comprehensively evaluate the relationship between physicochemical and bacteriological parameters of water on banks of Wouri. At each sampling station, the physicochemical analysis focused on Water temperature, pH, dissolved oxygen, dissolved CO 2 , electrical conductivity, suspended solids, nitrates, ammonium ions, orthophosphates, color, salinity, and turbidity. The bacteriological analysis consisted of the isolation of heterotrophic aerobe bacteria (HAB), faecal bacteria, and some pathogenic bacteria. PCA showed that two factorial axes F1 (49.48%) and F2 (25.18%) explained 74.67% of the total inertia. pH, Suspended Solids, electrical conductivity and color are significantly and positively correlated with each other and also significantly and positively correlated with the F1 axis. HAB, faecal bacteria, Shigellae, dissolved CO 2 and salinity are significantly and positively correlated with each other and, are also significantly and negatively correlated with the F1 axis and with the previous group of variables. The F1 axis discriminates in the negative coordinates of the Youpwe 1 and 2 stations, characterized by a high content of orthophosphates, ammonium ions, and low oxygenation. There is also a high concentration of bacteria such as HAB, faecal coliforms and Salmonella. The calculation of FC/FS ratio reflects exclusively contamination of animal origin in all the sampled stations

Assessment of the Effect of Light, HgCl2 and Organic Compound on Enterococcus faecalis and Escherichia coli Cells Survive in Aquatic Microcosm

International audienc

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

Minimum inhibition and bacterial concentrations of the plant Moringa Oleifera extracts against the bacteria Escherichia coli and Staphylococcus aureux

International audienceThis study aimed at assessing the MICs (Minimum Inhibitory Concentrations) and the MBCs (Minimum Bactericidal Concentrations) of the methanolic extracts from 4 different parts (leaves, seeds, stem, roots) of the plant Moringa oleifera against the bacteria E. coli and S. aureus. Phytochemical profile of each extract has been determined using LC/MS analyses. Microbial analyses were done using 96-wells plate method. Results showed that the four parts on the plants contain heterosides and glucosinolates. Iridoids were found in leaves, stem and roots. Flavonoids were found in leaves and stem. Phenolic acids were found only in leaves and carboxylic acids found only in stem. The abundance and the number of identified compounds of a given class varied from one part of plant to another. The MICs and MBCs varied with respect to the microorganism and the part of the plant. With E. coli, the MICs varied from 0.009 (leaves) to 1.25 mg/mL (seeds), and the MBCs varied from 0.156 (leaves) to 2.5 mg/mL (seeds and stem). With S. aureus, the MICs varied from 0.009 (stem and roots) to 0.039 mg/mL (leaves and roots), and the MBCs varied from 0.078 (leaves) to 4 mg/mL (stem). The bactericidal or bacteriostatic properties of the extracts varied depending on the part of the plant and the microorganism considered. Against E. coli, the leaves, stem and roots extracts were bacteriostatic whereas seeds extract was bactericidal. Against S. aureus, the seeds, stem and roots extracts were bacteriostatic whereas leaves extract was bactericidal

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