莱州湾近岸海域中典型抗生素与抗性细菌分布特征及其内在相关性

为了揭示海陆衔接区环境中抗生素与抗性细菌分布特征及其内在相关性,以莱州湾及其主要入海河流为研究区域,利用HPLC-MS/MS分析样品中15种磺胺类抗生素(SAs)和6种喹诺酮类抗生素(QNs)的浓度,并通过改良的Method 1604(US EPA)评估海水与沉积物中2种典型水传病原微生物大肠杆菌(E.coli)与金黄色葡萄球菌(S.aureus)的抗生素抗性水平,进而探讨该区域水体中抗性菌株的分布特点以及微生物抗性率与相应抗生素浓度的相关性。结果显示,莱州湾水体与沉积物中普遍存在磺胺与喹诺酮类抗生素残留及抗性污染问题。两大类抗生素在水体中平均残留浓度分别为3.89 ng·L~(-1)(SAs)和234.68ng·L~(-1)(QNs),在沉积物中分别为0.91 ng·g~(-1)(SAs)和49.37 ng·g~(-1)(QNs),且分布特征基本呈现自河流向海洋逐渐递减的趋势,说明河流输入是莱州湾抗生素污染的主要来源。在水体中,具有磺胺类抗性的E.coli和S.aureus平均检出量分别达到2 018和4 683 CFU·L~(-1),抗性率范围分别在0%~37.3%和10.6%~45.8%之间;而2种喹诺酮类抗性病原微生物的平均检出量则相对较低,分别为1 315 CFU·L~(-1)(E.coli)和1 461 CFU·L~(-1)(S.aureus),抗性率分别为0%~50.0%和0%~20.8%;此外,相比于E.coli,S.aureus为沉积物中的主要抗性病原微生物,磺胺与喹诺酮类抗性S.aureus检出率均高于80%,平均检出量分别为24CFU·g~(-1)和18 CFU·g~(-1)。相关性分析表明,莱州湾近岸海域水体中磺胺类抗生素浓度与磺胺类抗性微生物总量之间具有良好的线性关系,然而其与微生物抗性率之间并未表现出相似的规律,说明近岸海洋环境中抗生素的残留量不是影响抗性菌株丰度的唯一因素。

Distribution and Correlation of Typical Antibiotics and Antibiotic-Resistant Bacteria in the Coastal Marine Environment of Laizhou Bay, China

To study the distribution and correlation of antibiotics and antibiotic-resistant bacteria in the coastal adjacent land environment, 15 kinds of sulfonamides (SAs) and 6 kinds of quinolones (QNs) in water and sediment were analyzed by a multi-residue chemical analysis methodology, using solid phase extraction coupled with liquid chromatography tandem mass spectrometry, sampled from the rivers discharging to the Laizhou Bay and the seawater of the bay. Furthermore, the resistant levels of E. coli and S. aureus in the water and sediment were assessed by the improved Method 1604 (EPA). Results showed that antibiotic residues and resistance pollution problems were widespread in water and sediment of Laizhou Bay. The mean concentrations of SAs and QNs were 3.89 ng·L^-1 and 234.68 ng·L^-1 in water, and 0.91 ng·g^-1 and 49.37 ng·g^-1 in sediment. For further analysis, a gradually decreasing trend of antibiotics distribution showed from the river to the sea, which indicated that river was a statistically significant source of antibiotics. Meanwhile, high prevalence of antibiotic resistance bacteria was found in the Laizhou Bay. The levels of resistance to SAs were 0%~37.3% (E. coli) and 10.6%~45.8% (S. aureus) in water. The mean concentrations of SAs-resistant E. coli (S-Re-E. coli) and SAs-resistant S. aureus (S-Re-S. aureus) were high up to 2 018 and 4 683 CFU·L^-1. Moreover, the mean concentration of QNs-resistant E. coli (Q-Re-E. coli) and QNs-resistant S. aureus (Q-Re-S. aureus) were 1 315 and 1 461 CFU·L^-1 in water. The resistant levels of the E. coli and S. aureus were 0%~50.0% and 0%~20.8%. Moreover, S. aureus was the main resistant bacteria in sediment, and the detection rate of the S-Re-S. aureus strains and Q-Re-S. aureus strains were all above 80%. The mean concentration of S-Re-S. aureus and Q-Re-S. aureus were 24 and 18 CFU·g^-1, and the resistant levels were 0%~ 54.5% and 0%~33.3% in sediment. Correlation analysis showed that a good linearity between the concentrations of SAs and the abundance of SAs-resistant bacteria in water. Nevertheless, no significant correlations were found between antibiotic concentrations and resistant levels, which indicated that antibiotic residues were not the only factor to affect the abundance of antibiotic-resistant bacteria in the coastal adjacent land environment.