Water safety, antifungal-resistant aflatoxigenic aspergillus flavus and other pathogenic fungi in a community hand-dug wells

J Appl Microbiol. 2022 Aug;133(2):673-682. doi: 10.1111/jam.15559. Epub 2022 May 4.


Aim: To investigate hand-dug well water used for drinking and domestic purposes in a rural community in Southwest Nigeria for water safety and fungal presence as well as to determine the antifungal resistance and aflatoxigenic potentials of isolated fungi.

Methods and results: Water samples were analysed for risk of contamination, bacteriological and mycological parameters using a standard sanitary survey checklist and microbiological culturing. Isolates were identified and subjected to antifungal resistance profiling using the diffusion method for susceptibility testing of filamentous fungi. Multidrug-resistant strains were confirmed with DNA barcoding identification. Fungal isolates were screened for aflatoxigenic potentials by culture methods and confirmed by densitometric analysis. From the 23 hand-dug wells assessed, 56.52% had a high risk of contamination (ROC) score, nitrate >50 mg/L (73.9%), and the presence of total coliforms (100%), Escherichia coli (43.48%) and fungi (91.3%). Spearman rank correlation coefficient gave a positive and strong correlation between Total Fungi and Faecal Coliform (r = 0.701; p = 0.016; n = 23) at 0.05 significance level (2-tailed). Aspergillus sp. (34%), Penicillium sp. (18%) and Rhizopus sp. (17%) were the most dominant fungal genera. Isolates were resistant to fluconazole (76.19%), ketoconazole (73.80%), clotrimazole (92.86%), griseofulvin (88.09%) and nystatin (100%). Penicillium and Aspergillus (50%) were positive for cultural mycotoxin screening. A strain of antifungal-resistant A. flavus produced aflatoxin B1 (752 ppb) and B2 (15 ppb).

Significance of the study: The existence of antifungal-resistant and aflatoxigenic fungi in water used for drinking and domestic purposes shows that filamentous fungi constitute greater threats than previously recognized and this call for a paradigm shift from the perceived safety of untreated hand-dug well-water.

Keywords: aflatoxins; antifungal resistance; drinking water; fungi; hand-dug well water; water safety.

MeSH terms

  • Aflatoxins* / analysis
  • Antifungal Agents / analysis
  • Antifungal Agents / pharmacology
  • Aspergillus
  • Aspergillus flavus / genetics
  • Fungi
  • Penicillium* / genetics
  • Water


  • Aflatoxins
  • Antifungal Agents
  • Water