Water Research and Technology Center, University of Carthage, P.O. Box 273, 8020, Soliman, Tunisia.
Laboratory of Microorganisms and Active Biomolecules, Faculty of Sciences of Tunis, University of Tunis El Manar, LR03ES03, Tunis, Tunisia.
Environ Sci Pollut Res Int. 2023 Feb;30(10):26596-26612. doi: 10.1007/s11356-022-23802-2. Epub 2022 Nov 12.
Urban sewage sludge (USS) is increasingly being used as an alternative organic amendment in agriculture. Because USS originates mostly from human excreta, partially metabolized pharmaceuticals have also been considered in risk assessment studies after reuse. In this regard, we investigated the cumulative effect of five annual USS applications on the spread of antibiotic-resistant bacteria (ARB) and their subsequent resistance to toxic metals in two unvegetated soils. Eventually, USS contained bacterial strains resistant to all addressed antibiotics with indices of resistance varying between 0.25 for gentamicin to 38% for ampicillin and azithromycin. Sludge-amended soils showed also the emergence of resistome for all tested antibiotics compared to non-treated controls. In this regard, the increase of sludge dose generally correlated with ARB counts, while soil texture had no influence. On the other hand, the multi-antibiotic resistance (MAR) of 52 isolates selected from USS and different soil treatments was investigated for 10 most prescribed antibiotics. Nine isolates showed significant MAR index (≥ 0.3) and co-resistance to Cd, As and Be as well. However, events including an extreme flash flood and the termination of USS applications significantly disrupted ARB communities in all soil treatments. In any case, this study highlighted the risks of ARB spread in sludge-amended soils and a greater concern with the recent exacerbation of antibiotic overuse following COVID-19 outbreak.
城市污水污泥（USS）越来越多地被用作农业中的替代有机肥料。由于 USS 主要来源于人类排泄物，因此在重新使用后，部分代谢药物也被认为是风险评估研究中的一个因素。在这方面，我们研究了每年应用 5 次 USS 对两种无植被土壤中抗生素耐药细菌（ARB）传播及其对有毒金属随后耐药性的累积影响。最终，USS 中含有对所有研究抗生素均具有耐药性的细菌菌株，其耐药指数在 0.25（庆大霉素）至 38%（氨苄西林和阿奇霉素）之间变化。与未经处理的对照相比，污泥处理的土壤中也出现了所有测试抗生素的耐药组。在这方面，污泥剂量的增加通常与 ARB 数量相关，而土壤质地没有影响。另一方面，我们从 USS 和不同土壤处理中选择了 52 株分离株，研究了它们对 10 种最常开处方的抗生素的多抗生素耐药性（MAR）。其中 9 株分离株表现出显著的 MAR 指数（≥0.3），并对 Cd、As 和 Be 具有协同耐药性。然而，包括极端突发洪水和 USS 应用终止在内的事件，显著破坏了所有土壤处理中的 ARB 群落。无论如何，本研究强调了在污泥处理的土壤中 ARB 传播的风险，以及在 COVID-19 爆发后，抗生素过度使用情况加剧，这应引起更大的关注。
