Profiles of ARGs and their relationships with antibiotics, metals and environmental parameters in vertical sediment layers of three lakes in China.

Antibiotic resistance is a global health problem, and the role of antibiotics and metal pollution in antibiotic resistance in sediment biocenosis is limited. The occurrence and relationship between antibiotic resistance genes (ARGs), antibiotics, metals and environmental parameters were investigated in vertical layers of sediments in rural and urban lakes. Generally, the total concentrations of seven antibiotics were significantly higher in the rural lake (Lake Taihu = 96%) than in the urban lakes (Xuanwu = 0.3%, Wulongtan = 3%), while similar concentrations were observed for metals (Taihu (34%), Xuanwu (33%) and Wulongtan (33%)). The concentration of metals and antibiotics were mostly higher in the surface sediment layers than the deeper ones (for antibiotics; surface layers = 89%, deeper layer = 11%, for metals; surface = 65%, deep = 35%). The ARGs showed no significant difference between surface and deeper sediments (surface = 48%, deep = 52%, p < 0.05). The potential ecological risk index of Ni, Cu, Zn, Cr, Mn, As, Cd, and Pb contamination showed that Lake Taihu and Wulongtan had moderate ecological risks while Lake Xuanwu had a low ecological risk. Pearson coefficient and network analysis showed that direct and indirect relationship existed among antibiotics, metals, environmental parameters, and ARGs, and the relationship was linked by key environmental components. tetA, blaTEM, SDZ, TOC, OFL, Cd, OTC, NOR, Ni, sulA, AUR, TC, DOX and TN were the major factors that influence the distribution of resistance genes, forming a complex network mechanism of antibiotic resistance. Our study revealed that antibiotics and heavy metals are widely distributed in the surficial sediments and the proliferation of ARGs are influenced by some key environmental components.

Efficacy and safety of steroid in the prevention of esophageal stricture after endoscopic submucosal dissection: A network meta-analysis.

BACKGROUND AND AIM: Even though endoscopic submucosal dissection is an important endoscopic resection technique for gastrointestinal neoplasms, there are chances that postoperative esophageal stricture might take place as a side effect. Steroid applications were reported to be effective for the prevention of stricture formation. Therefore, this study aims to evaluate the efficacy and safety of different steroid applications. METHODS: Eligible studies published on PubMed, the Cochrane Library, Embase, Web of Science, and Chinese Biomedical Literature Database before August 2018 were reviewed. The preventions were divided as placebo/no treatment, long-term oral steroid (LOS), median-term oral steroid, short-term oral steroid, single-dose steroid injection, multiple-dose steroid injection, topical superficial steroid, steroid injection combined with oral steroid, and preemptive endoscopic balloon dilatation. The primary outcomes were postoperative esophageal stricture rate and endoscopic balloon dilatation sessions required. Complications were also analyzed. RESULTS: A total of 19 studies were included. The network meta-results illustrated that compared with the placebo, all kinds of steroid interventions were associated with lower rates of postoperative esophageal stenosis and less number of endoscopic balloon dilatation sessions. Moreover, combined therapy was no better than single regimen therapy. No significant differences between various steroid applications in the incidence of complications were spotted during this study. Based on the results of the network and clustered ranking, LOS might be the superior prevention for postoperative stricture with satisfying efficacy. CONCLUSION: The present study showed that LOS appears to be the optimal prevention method for postoperative stricture formation.

Distribution and relationship between antimicrobial resistance genes and heavy metals in surface sediments of Taihu Lake, China.

Heavy metals, pharmaceuticals, and other wastes released into the environment can significantly influence environmental antibiotic resistance. We investigated the occurrence of 22 antimicrobial resistance genes (ARGs) and 10 heavy metal concentrations, and the relationship between ARGs and heavy metals in surface sediment from seven sites of Lake Taihu. The results showed significant correlations (p < 0.05) between sediment ARG levels, especially for tetracycline and sulfonamides (e.g., tet(A), tet(D), tet(E), tet(O), sul1, sul2 and int-1) and specific heavy metals (Fe, Mn, Cr, Cu, Zn, among others) in the Lake. In the surface sediments, heavy metals showed an interaction with resistance genes, but the strength of interaction was diminished with increasing depth. For most of the heavy metals, the concentration of elements in the top sediments was higher than that in other depths. Tetracycline resistance genes (tet(A), tet(B), tet(D), tet(E) and tet(O), ß-lactam resistance genes (SHV, TEM, CTX, OXA and OXY) and sulfonamide resistance genes (sulA, sul1, sul2, sul3 and int-1) were detected. They showed a trend which inferred a statistically significant increase followed by decreases in the relative abundance of these ARGs (normalized to 16S rRNA genes) with increasing depth. This study revealed that tet(A), tet(O), TEM, OXY, int-1, sul1 and sul3 were widespread in surface sediments with high abundance, indicating that these genes deserve more attention in future work.

Adaptation to urbanization impacts on drainage in the city of Hohhot, China.

This study presents a quantitative assessment of urbanization effects on hydrological runoff and drainage network in the city of Hohhot, China. The evolution of urban spatial morphology for the historical years (1987-2010) and projected year (2020) is described by changes in geographic information system (GIS)-based land use maps and further represented in hydrological parameters in the Storm Water Management Model (SWMM) simulation. The results show the levels of service of historical drainage were too low to have dominant impacts on flood risks, and hence a significant upward trend in catchment runoff response was observed over time. Comparisons with changes in system overloading indicate that the relative increase in flood risk is greatest at the early stage of urbanization with relatively low levels of development. The proposed adaptation measures based on a cost-effective optimal approach was found feasible to significantly improve the drainage performance and mitigate the increasing flooding impacts.

Antibiotic concentration and antibiotic-resistant bacteria in two shallow urban lakes after stormwater event.

Stormwater runoff is generally characterized as non-point source pollution. In the present study, antibiotic concentration and antibiotic susceptibilities of cultivable heterotrophic bacteria were investigated in two small shallow urban lakes before and after strong storm event. Several antibiotics, lactose-fermenting bacteria and cultivable heterotrophic bacteria concentrations increased in surface water and/or surface sediment of two small urban lakes (Lake Xuanwu and Wulongtan) after strong storm event. In general, the frequencies of bacteria showing resistance to nine antibiotics increased after storm event. Based on the 16S rRNA genes of 50 randomly selected isolates from each water sample of two lakes, Aeromonas and Bacillus were dominant genera in samples from two lakes, while genera Proteus and Lysinibacillus were the third abundant genera in Lake Xuanwu and Wulongtu, respectively. Presences of nine antibiotic resistance genes (ARGs) in the 100 isolates were detected and most of these isolates harbored at least two ARGs with different functions. The detection frequency of ARGs in Gram-negative isolates was higher than that in Gram-positive isolates. The most prevalent integron in 100 isolates was int(II) (n = 28), followed by int(I) (n = 17) and int(III) (n = 17). Our results indicate that strong storm events potentially contribute to the transfer of ARGs and antibiotic-resistant bacteria from land-sewer system to the urban Lakes.