医院污水源生物气溶胶中耐药菌及耐药基因的季节变化特征

Seasonal changes of antibiotic resistant bacteria and antibiotic resistance genes in bioaerosols sourced from hospital sewage

摘要:

【背景】医院污水中残留着高丰度的致病菌和耐药基因等，它们可随着污水处理过程逸散到空气中，导致传染性疾病的感染和流行。【目的】探究医院污水及其逸散的生物气溶胶中耐药菌及耐药基因的赋存情况及季节变化特征。【方法】使用安德森八级采样器采集生物气溶胶样本，通过药敏试验和PCR检测了大肠杆菌(Escherichia coli)的耐药特性，利用高通量定量PCR检测了污水及空气中耐药基因的丰度和种群结构。【结果】生物气溶胶浓度在夏季最高，生物池空气中细菌浓度[(250±170) CFU/m³]和小粒径(<2.1 μm)细菌气溶胶占比均高于其他采样点。在生物池环境样本中共分离鉴定出7株大肠杆菌，这些菌株对头孢西丁和亚胺培南的耐药率最高(85.71%)，而且parC、bla_TEM和dhps的检出率为100%。生物池空气中耐药基因含量在冬季最高(26.18 copies/m³)，不同季节耐药基因含量的均值为14.82 copies/m³。intI1在春季和秋季空气中的丰度最高，tnpA-05和strB分别在夏季和冬季空气中含量最高。溯源结果表明，生物池污水是空气中耐药基因的重要来源。根据多重抗生素耐药性指数和暴露剂量计算结果显示生物池污水被抗生素污染严重，春冬季生物池空气中耐药基因的暴露剂量相对较高。【结论】医院污水处理站作为潜在的高危抗生素暴露源，应加强管理和防控。

Abstract:

[Background] Hospital sewage contains abundant pathogenic bacteria and antibiotic resistance genes (ARGs), which can escape into the air along with the sewage treatment process and lead to infections and emergence of infectious diseases. [Objective] To investigate the presence and seasonal changes of antibiotic resistant bacteria and ARGs in hospital sewage and the bioaerosols. [Methods] Bioaerosol samples were collected by an Anderson eight-stage sampler, and the antimicrobial susceptibility test and PCR were employed to assess the resistance profile of Escherichia coli. The abundance and structure of ARGs in the sewage and air were examined by high-throughput quantitative PCR. [Results] The bioaerosol concentration was the highest in summer. The air of the biochemical tank had higher bacterial concentration ((250±170) CFU/m³) and higher percentage of small-size (<2.1 μm) bacterial aerosols than that at other sampling sites. A total of seven strains of E. coli were isolated and identified in the samples from the biochemical tank. These strains showed the highest resistance (85.71%) to cefoxitin and imipenem, and the detection rates of parC, bla_TEM, and dhps were 100%. The abundance of ARGs in the air of the biochemical tank was the highest (26.18 copies/m³) in winter, and the mean ARGs abundance in different seasons was 14.82 copies/m³. intI1 had higher abundance in the air in spring and autumn, and tnpA-05 and strB in the air had the highest abundance in summer and winter, respectively. The source tracking results showed that biochemical tank effluent was the main source of ARGs. According to the multiple antibiotic resistance index and exposure dose, the sewage of the biochemical tank was seriously polluted by antibiotics, and the exposure dose of ARGs in the air of the biochemical tank was high in spring and winter. [Conclusion] The hospital sewage treatment stations, as the potential sources with a high risk of antibiotic exposure, should be well managed for the prevention and control of infections.