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Mwapasa T, Chidziwisano K, Mphasa M, Cocker D, Rimella L, Amos S, Feasey N, Morse T. Key environmental exposure pathways to antimicrobial resistant bacteria in southern Malawi: A SaniPath approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 945:174142. [PMID: 38906299 PMCID: PMC11234251 DOI: 10.1016/j.scitotenv.2024.174142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 06/12/2024] [Accepted: 06/17/2024] [Indexed: 06/23/2024]
Abstract
Antimicrobial resistance (AMR) poses a severe global health threat, yet the transmission pathways of AMR within communal public environments, where humans and animals interact, remain poorly explored. This study investigated AMR risk pathways, prevalence, and seasonality of extended-spectrum β-lactamase (ESBL) producing E. coli and K. pneumoniae, and observed practices contributing to environmental contamination within urban, peri-urban, and rural Malawi. Using the SaniPath tool, in August 2020, transect walks across three Malawian study sites identified potential AMR exposure pathways, including drains, standing water, soil, and areas of communal hand contact. Subsequently, from September-2020 to August-2021, 1440 environmental samples were collected at critical points along exposure routes (n = 40/month from each site). These underwent microbiological analysis using chromogenic agar techniques to detect the presence of ESBL E. coli and ESBL K. pneumoniae. Results showed the highest ESBL prevalence in urban environments (68.1 %, 95%CI = 0.64-0.72, p < 0.001) with a higher ESBL presence seen in drains (58.8 %, 95%CI = 055-0.62, p < 0.001) and soil (54.1 %, 95%CI = 0.46-0.62, p < 0.001) compared to other pathways. Environmental contamination was attributed to unavailability and poor condition of sanitation and hygiene infrastructure based on key informant interviews with community leaders (n = 9) and confirmed by independent observation. ESBL prevalence varied between seasons (χ2 (2,N = 1440) = 10.89, p = 0.004), with the highest in the hot-dry period (55.8 % (n = 201)). Prevalence also increased with increased rainfall (for ESBL E.coli). We highlight that community environments are likely to be a crucial component in AMR transmission, evident in the abundance of ESBL bacteria in identified exposure pathways. Additionally, poor sanitation infrastructure and practices coupled with seasonal dynamics further affect the presence of ESBLs in communal environments. Therefore, a context appropriate whole system approach that tackles infrastructure and behavioural factors, supported by effective surveillance is required to impact AMR and a range of aligned development challenges in these settings.
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Affiliation(s)
- Taonga Mwapasa
- Centre for Water, Sanitation, Health, and Appropriate Technology Development (WASHTED), Malawi University of Business and Applied Sciences, Blantyre, Malawi.
| | - Kondwani Chidziwisano
- Centre for Water, Sanitation, Health, and Appropriate Technology Development (WASHTED), Malawi University of Business and Applied Sciences, Blantyre, Malawi; Department of Environmental Health, Malawi University of Business and Applied Sciences, Blantyre, Malawi
| | - Madalitso Mphasa
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Derek Cocker
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; David Price Evans Global Health and Infectious Disease Group, University of Liverpool, Liverpool, United Kingdom
| | - Lorenzo Rimella
- Department of Mathematics and Statistics, University of Lancaster, Lancaster, United Kingdom
| | - Stevie Amos
- Centre for Water, Sanitation, Health, and Appropriate Technology Development (WASHTED), Malawi University of Business and Applied Sciences, Blantyre, Malawi
| | - Nicholas Feasey
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Tracy Morse
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, United Kingdom
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Jago C, Robins P, Howlett E, Hassard F, Rajko-Nenow P, Jackson S, Chien N, Malham S. Trapping and bypassing of suspended particulate matter, particulate nutrients and faecal indicator organisms in the river-estuary transition zone of a shallow macrotidal estuary. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170343. [PMID: 38280583 DOI: 10.1016/j.scitotenv.2024.170343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/19/2024] [Accepted: 01/19/2024] [Indexed: 01/29/2024]
Abstract
Hydrodynamic controls of the transport of suspended particulate matter (SPM), particulate nutrients and faecal indicator organisms (FIOs) in the river-estuary transition zone (RETZ) of a shallow macrotidal estuary were studied on tidal and seasonal timescales. The RETZ was found to be a conduit for SPM rather than a zone of particle accumulation during spring tides, with complex size fractionation and biogeochemical exchanges of particulate nutrient/FIO compositions. The downstream RETZ was characterised by flood-dominant currents, but with ebb-dominant turbulence due to the suppression of flood tide turbulence by salinity stratification created by lateral convergence; this produced a net seaward mass transport of SPM. Without lateral convergence in the narrower upstream RETZ, flood-dominant currents and flood-dominant turbulence were experienced. Hence the RETZ exported SPM landwards from its upper end and seawards from its lower end - a process observed throughout the year during spring tides and low-to-mean river flows. During neap tides when SPM concentrations were reduced, the RETZ became a zone of minor particle accumulation as its lower end imported SPM landwards from the estuary and its upper end imported SPM seawards from the river. During a river flood event, net SPM flux was significantly increased and was seawards throughout the RETZ. SPM mass concentration and carbon, nitrogen, phosphorous, and FIO concentrations peaked due to local resuspension and advection of an ephemeral estuarine turbidity maximum (ETM). The ETM formed on the advancing flood tide due to entrainment of material from intertidal flats. Flocculation and settling occurred at high slack water. The ETM was reconstituted by entrainment on the ebb and was composed of larger flocs than on the flood. Particulate nutrients and FIOs were associated with flocs in the 10-200 μm range but not with smaller or larger flocs. SPM concentrations in the resuspension component and ETM exceeded microbial water quality standards, emphasising the need for monitoring practices that consider tidal dynamics. The results from this study showing periodic SPM export from, rather than prolonged accumulation in, the RETZ and the influence of particle size fractionation on biogeochemical fluxes in the RETZ, are likely to be transferable to many other embayment-type estuaries on macrotidal coasts.
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Affiliation(s)
- Colin Jago
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK
| | - Peter Robins
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK.
| | - Eleanor Howlett
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK; Natural Resources Wales, Maes y Ffynnon, Penrhos Rd, Penrhosgarnedd, Bangor LL57 2DW, UK
| | - Francis Hassard
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK; Cranfield University, College Way, Bedford MK43 0AL, UK; Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Johannesburg, South Africa
| | - Paulina Rajko-Nenow
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK
| | - Suzanna Jackson
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK; Natural Resources Wales, Maes y Ffynnon, Penrhos Rd, Penrhosgarnedd, Bangor LL57 2DW, UK
| | - Nguyen Chien
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK
| | - Shelagh Malham
- School of Ocean Sciences, Bangor University, Marine Centre Wales, Menai Bridge LL59 5AB, UK
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