A meta-analysis on the distribution of pathogenic Vibrio species in water sources and wastewater in Africa

Vibrio species are waterborne ubiquitous organisms capable of causing diseases in humans and animals and the occurrence of infections caused by pathogenic Vibrio species among humans have increased globally. This reemergence is attributed to environmental impacts such as global warming and pollution. Africa is most vulnerable to waterborne infections caused by these pathogens because of lack of good water stewardship and management. This study was carried out to provide an in-depth inquiry into the occurrence of pathogenic Vibrio species in water sources and wastewater across Africa. In this regard, a systematic review and meta-analysis was conducted by searching five databases: PubMed, ScienceDirect, Google Scholar, Springer Search and African Journals Online (AJOL). The search yielded 70 articles on pathogenic Vibrio species presence in African aquatic environments that fit our inclusion criteria. Based on the random effects model, the pooled prevalence of pathogenic Vibrio species in various water sources in Africa was 37.6 % (95 % CI: 27.7-48.0). Eighteen countries were represented by the systematically assessed studies and their nationwide prevalence in descending order was: Nigeria (79.82 %), Egypt (47.5 %), Tanzania (45.8 %), Morocco (44.8), South Africa (40.6 %), Uganda (32.1 %), Cameroon (24.5 %), Burkina Faso (18.9 %) and Ghana (5.9 %). Furthermore, 8 pathogenic Vibrio species were identified across water bodies in Africa with the highest detection for V. cholerae (59.5 %), followed by V. parahaemolyticus (10.4 %), V.alginolyticus (9.8 %), V. vulnificus (8.5 %), V. fluvialis (6.6 %), V. mimicus (4.6 %), V. harveyi (0.5 %) and V. metschnikovii (0.1 %). Evidently, pathogenic Vibrio species occurrence in these water sources especially freshwater corroborates the continuous outbreaks observed in Africa. Therefore, there is an urgent need for proactive measures and continuous monitoring of water sources used for various purposes across Africa and proper treatment of wastewater before discharge into water bodies.

Prevalence of integrons in multidrug-resistant Escherichia coli isolates from waters and vegetables in Nsukka and Enugu, Southeast Nigeria

Irrigation of fresh produce with poorly treated wastewater or contaminated freshwater sources can lead to produce contamination and foodborne illnesses, as well as the dissemination of antimicrobial resistance determinants. In this study, we assessed the presence of integrons in multidrug-resistant Escherichia coli isolated from the University of Nigeria, Nsukka Wastewater Treatment Plant effluent, tap water, vegetables from irrigated gardens and vegetables sold in selected markets from Nsukka and Enugu cities. E. coli was isolated following standard laboratory procedure and confirmed through beta-glucuronidase (uidA)-targeted polymerase chain reaction (PCR). The antibiotic resistance of the isolates was determined using Bauer-Kirby disk diffusion assay, and multiplex PCR was used to determine the presence of class 1 and 2 integrons. Our result revealed a total of 188 E. coli isolates from WWTP effluent (n = 41), tap water (n = 10) and vegetables from greenhouse (n = 46), farms (n = 55) and market (n = 36). Multidrug resistance was detected in all the isolates, ranging from three-drug resistance in a single isolate to 7-drug resistance patterns in two different isolates. Of the total isolates, class 1 integrons were abundantly detected in 175 (93.1%) and class 2 in 5 (2.7%). All the class 2 integrons were found in isolates that were positive for class 1. The abundance of multidrug-resistant E. coli harbouring class 1 integrons in the effluent and vegetable samples is a potential public health risk. Therefore, the appropriate measures for the safe use of poorly treated wastewater for vegetable farm irrigation are required to be put in place to reduce the microbial load of the discharged effluent. Also, education of farmers and the community on the dangers of wastewater effluent-grown plants and proper methods for cleaning harvested vegetable is recommended.

Assessment of the physicochemical and microbiological status of western Niger Delta soil for crude oil pollution bioremediation potential

The physical, chemical and microbiological characteristics of the soil across the western Niger Delta area of Nigeria were determined to assess its potential for natural remediation of crude oil pollution. The pH (oil-producing area, 6.1 ± 1.1; non-oil producing, 5.9 ± 0.9) and temperature (28-35 °C in both areas) were favourable to natural remediation, while the fluctuating moisture (7.7-45.6 %) and the dominant sandy soil textural classes (70 %) were limitations. The carbon nitrogen phosphorus (CNP) ratio markedly exceeded recommended 100:10:1, while the cation exchange capacity was below acceptable range. Counts of heterotrophic bacteria, fungi and hydrocarbon-utilising and nitrogen-fixing bacteria (mean range log10 3.8 ± 1.5-6.52 ± 0.9 cfu/g) were favourable having markedly exceeded the minimum counts required. Crude oil loss was highest in loam soil, but significantly (P = 0.00) increased in all soil textural classes including sandy soils after amendment with cow dung/poultry dropping and manual aeration in laboratory and 8-month field tests as indicated by two-way ANOVA. Thus, the overall assessment is that while CNP can be viewed as the major limiting factor to natural oil pollution remediation in the western Niger Delta soil, its influence can be minimised by the amendment indicated in the study.