Antibiotic resistance genes are abundant and diverse in raw sewage used for urban agriculture in Africa and associated with urban population density.

A comparative study was conducted to (1) assess the potential of raw sewage used for urban agriculture to disseminate bacterial resistance in two cities of different size in Cameroon (Central Africa) and (2) compare the outcome with data obtained in Burkina Faso (West Africa). In each city, raw sewage samples were sampled from open-air canals in three neighbourhoods. After DNA extraction, the microbial population structure and function, presence of pathogens, antibiotic resistance genes and Enterobacteriaceae plasmids replicons were analysed using whole genome shotgun sequencing and bioinformatics. Forty-three pathogen-specific virulenc e factor genes were detected in the sewage. Eighteen different incompatibility groups of Enterobacteriaceae plasmid replicon types (ColE, A/C, B/O/K/Z, FIA, FIB, FIC, FII, H, I, N, P, Q, R, T, U, W, X, and Y) implicated in the spread of drug-resistance genes were present in the sewage samples. One hundred thirty-six antibiotic resistance genes commonly associated with MDR plasmid carriage were identified in both cities. Enterobacteriaceae plasmid replicons and ARGs found in Burkina Faso wastewaters were also present in Cameroon waters. The abundance of Enterobacteriaceae, plasmid replicons and antibiotic resistance genes was greater in Yaounde, the city with the greater population. In conclusion, the clinically relevant environmental resistome found in raw sewage used for urban agriculture is common in West and Central Africa. The size of the city impacts on the abundance of drug-resistant genes in the raw sewage while ESBL gene abundance is related to the prevalence of Enterobacteriaceae along with plasmid Enterobacteriaceae abundance associated to faecal pollution.

Phytochemical Study of Aqueous Extract of Ochna schweinfurthiana F. Hoffm Powder Bark and Evaluation of Their Anti-Inflammatory, Cytotoxic, and Genotoxic Properties.

Ochna schweinfurthiana has been used in traditional medicine to treat pain, inflammation, and arthritis. It is a rich source of complex dimers of flavonoids with potential use as templates for the development of therapeutic drugs. Hence, the aim of this study was to study the phytochemical content and evaluate the in vitro cytotoxic, genotoxic, and anti-inflammatory activities of the aqueous extract of Ochna schweinfurthiana bark (OSE). Phytochemical study was carried out according to LC-MS procedures, while isolation was carried out using thin layer and column chromatographies. Cytotoxicity was investigated by the mitochondrial viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) method while genotoxicity potential of the extract was ascertained using the Salmonella typhimurium test strains TA98 and TA100. The anti-inflammatory effect of OSE was evaluated by the in vitro inhibition of 15-lipooxygenase enzyme and bovine serum albumin denaturation (BSA) assays. The investigation of compounds extracted from OSE led to the identification and isolation of six known compounds, namely, hemerocallone (9), 6,7-dimethoxy-3'-4'-dimethoxyisoflavone (10), lithospermoside (13), amentoflavone (14), agathisflavone (15), and ß-D-fructofuranosyl-α-D-glucopyranoside (17). In the anti-inflammatory assay, aqueous extracts of the bark showed selective inhibition of 15-lipooxygenase with IC50 value of 32.2 ± 0.36 µg/mL and the result of the bovine serum albumin denaturation assay with IC50 value of 130± 5.78 µg/mL showed moderate activity. The toxicity assay indicated that OSE are noncytotoxic on Vero cell line with LC50 value of 50 mg/mL and nongenotoxic toward Salmonella typhimurium tester strain TA98 and TA100. Result from this study supports the traditional use of the selected medicinal plants in Cameroon for the treatment of inflammatory conditions. Noncytotoxicity and nongenotoxicity of OSE suggest that this plant is safe for use.

Wastewater used for urban agriculture in West Africa as a reservoir for antibacterial resistance dissemination.

State of art metagenomics were used to investigate the microbial population, antibiotic resistance genes and plasmids of medical interest in wastewater used for urban agriculture in Ouagadougou (Burkina Faso). Wastewater samples were collected from three canals near agricultural fields in three neighbourhoods. Assessment of microbial population diversity revealed different microbial patterns among the different samples. Sequencing reads from the wastewaters revealed different functional specializations of microbial communities, with the predominance of carbohydrates and proteins metabolism functions. Eleven pathogen-specific and 56 orthologous virulence factor genes were detected in the wastewater samples. These virulence factors are usually found in human pathogens that cause gastroenteritis and/or diarrhoea. A wide range of antibiotic resistance genes was identified; 81 are transmissible by mobile genetic elements. These included seven different extended spectrum ß-lactamase genes encoding synthesis of four enzyme families, including two metallo-ß-lactamases (blaAIM-1 and blaGES-21). Ten different incompatibility groups of Enterobacteriaceae plasmid replicons (ColE, FIB, FIC, FII, P, Q, R, U, Y, and A/C), and 30 plasmid replicon types from Gram-positive bacteria. All are implicated in the wide distribution of antibiotic resistance genes. We conclude that wastewater used for urban agriculture in the city represents a high risk for spreading bacteria and antimicrobial resistance among humans and animals.