Okonkwo, V., Cholet, F., Ijaz, U. Z. , Koottatep, T., Pussayanavin, T., Polpraset, C., Sloan, W. T. , Connelly, S. and Smith, C. J. (2023) intI1 gene abundance from septic tanks in Thailand using validated intI1 primers. Applied and Environmental Microbiology, 89(11), e01071-23. (doi: 10.1128/aem.01071-23) (PMID:37874304) (PMCID:PMC10686061)
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Abstract
Antimicrobial resistance (AMR) poses a serious global health threat, and wastewater treatment (WWT), including septic tanks, is a source of AMR. In Thailand, antibiotics are unregulated, and septic tanks are commonly used. Yet, their impact on the spread or mitigation of AMR is unknown. We monitored household and healthcare conventional septic tanks (CST) and household solar septic tanks (SST) in Thailand using the class 1 integron-integrase (intI1) gene abundance as a proxy for AMR. A systematic review of the literature found 65 intI1 primers. We evaluated the coverage and specificity of each, including a new MGB TaqMan primer-probe, against clinical and environmental intI1, intI1-like, and non-intI1 databases. The three best primers were selected, laboratory validated for DNA and mRNA quantification, and used to quantify septic tank intI1 gene abundance. No primer set could distinguish between intI1 and intI1-like sequences. While primer choice did not affect gene abundance of the same sample (P-value > 0.05), sometimes when comparing the same samples quantified by different primers, statistical differences were observed for one but not the other primer set. This may lead to different interpretations of AMR risk. Irrespective of primers or reactor type intI1 gene abundance was greatest in influent > effluent > sludge. intI1 gene abundance was lowest in the effluent of the SST-household < CST-household < CST-healthcare. 31% to 42% of intI1 was removed by the CST-household tank, indicating while septic tanks remove some intI1 they remain a source to the surrounding environment. Toward the goal of achieving standardization across studies, we recommend the F3-R3 primer for intI1 quantification.
| Item Type: | Articles |
|---|---|
| Additional Information: | We gratefully acknowledge the support of the following funders: VO was supported through a University of Glasgow College of Science and Engineering Doctoral studentship and CS by a RAEng of Engineering-Scottish Water Research Chair (RSF1718943). The project was funded through EPSRC awards EP/VO30515/1 and EP/P029329/1. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Cholet, Dr Fabien and Smith, Professor Cindy and Connelly, Dr Stephanie and Sloan, Professor William and Ijaz, Dr Umer and Okonkwo, Mr Valentine |
| Creator Roles: | Okonkwo, V.Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Writing – original draft, Writing – review and editing Cholet, F.Formal analysis, Investigation, Methodology, Visualization, Writing – review and editing Ijaz, U.Formal analysis, Methodology, Writing – review and editing Sloan, W.Funding acquisition, Resources, Writing – review and editing Connelly, S.Funding acquisition, Methodology, Resources, Writing – review and editing Smith, C.Conceptualization, Funding acquisition, Investigation, Resources, Validation, Writing – original draft, Writing – review and editing |
| Authors: | Okonkwo, V., Cholet, F., Ijaz, U. Z., Koottatep, T., Pussayanavin, T., Polpraset, C., Sloan, W. T., Connelly, S., and Smith, C. J. |
| College/School: | College of Science and Engineering > School of Engineering > Infrastructure and Environment |
| Journal Name: | Applied and Environmental Microbiology |
| Publisher: | American Society for Microbiology |
| ISSN: | 0099-2240 |
| ISSN (Online): | 1098-5336 |
| Published Online: | 24 October 2023 |
| Copyright Holders: | Copyright © 2023 Okonkwo et al. |
| First Published: | First published in Applied and Environmental Microbiology 89(11):e01071-23 |
| Publisher Policy: | Reproduced under a Creative Commons license |
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