sink drain biofilms in intensive care units

In hospitals, the transmission of antibiotic-resistant bacteria (ARB) may occur via biofilms present in sink drains, which can lead to infections. Despite the potential role of sink drains in the transmission of ARB in nosocomial infections, routine surveillance of these drains is lacking in most hospitals. As a result, there is currently no comprehensive understanding of the transmission of ARB and the dissemination of antimicrobial resistance genes (ARGs) and associated mobile genetic elements (MGEs) via sink drains. This study employed a multifaceted approach to monitor the total aerobic bacterial flora as well as the presence of carbapenemase-producing Enterobacterales (CPEs), the microbiota and the resistome of sink drain biofilms (SDBs) and hospital wastewater (WW) of two separate intensive care units (ICUs) in the same healthcare facility in France. Samples of SDB and WW were collected on a monthly basis, from January to April 2023, in the neonatal (NICU) and the adult (AICU) ICUs of Grenoble Alps University Hospital. In the NICU, sink drain disinfection with surfactants was performed routinely. In the AICU, however, routine disinfection is not carried out. No CPEs were isolated from either unit's SDBs by bacterial culture. Culture-independent approaches revealed an overall distinct microbiota composition of the SDBs in the two units. The AICU SDBs were dominated by potential Gram-negative bacterial pathogens including Pseudomonas, Stenotrophomonas, Staphylococcus, and Klebsiella, while the NICU SDBs were dominated by the Gram-negative genera Achromobacter, Serratia, and Acidovorax, as well as the Gram-positive genera Weisella and Lactiplantibacillus. In contrast, the resistome of the SDBs exhibited no significant differences between the two units, indicating that the abundance of ARGs and MGEs is independent of microbiota composition and disinfection practices. Investigation of the WW that connected to the respective ICUs revealed that the WW from the AICU exhibited a more diverse aerobic flora than the WW from the NICU. In addition, the AICU WW yielded 15 CPEs, whereas the NICU WW yielded a single CPE. The microbiota of the NICU and AICU WW samples differed from their respective SDBs and exhibited distinct variations over the four-month period. It is noteworthy that the WW from the AICU contained a greater number of genes conferring resistance to quinolones and integron integrase genes, whereas the NICU exhibited a higher abundance of streptogramin resistance genes. The results of our study demonstrated that the resistome of the hospital SDBs in the two ICUs of the investigated healthcare institute is independent of the microbiota, the environment, and the local disinfection measures. However, a difference was observed in the prevalence of CPEs in the WW pipes collecting the waste from the investigated drains. These findings offer valuable insights into the resilience of resistance genes in SDBs in ICUs, underscoring the necessity for innovative strategies to combat antimicrobial resistance in clinical environments.

在医院环境中，抗生素耐药菌（antibiotic-resistant bacteria, ARB）可通过水槽排水口处的生物膜传播，进而引发感染。尽管水槽排水口在医院获得性感染的ARB传播中可能发挥关键作用，但多数医院尚未对这类排水口开展常规监测。因此，目前学界尚未全面明确通过水槽排水口传播的ARB、抗菌耐药基因（antimicrobial resistance genes, ARGs）及相关可移动遗传元件（mobile genetic elements, MGEs）的扩散情况。本研究采用多维度方法，对法国格勒诺布尔阿尔卑斯大学医院同一医疗设施内两个独立重症监护病房（intensive care units, ICUs）的水槽排水口生物膜（sink drain biofilms, SDBs）及医院废水（hospital wastewater, WW）的总需氧菌菌群、产碳青霉烯酶肠杆菌目（carbapenemase-producing Enterobacterales, CPEs）分布、菌群组成与耐药组（resistome）进行监测。2023年1月至4月，研究人员按月采集新生儿重症监护病房（neonatal intensive care unit, NICU）与成人重症监护病房（adult intensive care unit, AICU）的SDB与WW样本。其中NICU常规采用表面活性剂对水槽排水口进行消毒，而AICU未开展常规消毒操作。细菌培养未从两个病房的SDB中分离到任何CPE。非培养依赖方法则显示，两个病房的SDB菌群组成存在显著差异：AICU的SDB以潜在革兰氏阴性病原菌为主，包括假单胞菌属（Pseudomonas）、寡养单胞菌属（Stenotrophomonas）、葡萄球菌属（Staphylococcus）与克雷伯菌属（Klebsiella）；而NICU的SDB则以革兰氏阴性菌无色杆菌属（Achromobacter）、沙雷菌属（Serratia）、食酸菌属（Acidovorax），以及革兰氏阳性菌魏斯氏菌属（Weisella）和植物乳杆菌属（Lactiplantibacillus）为优势类群。相比之下，两个病房SDB的耐药组未表现出显著差异，表明ARGs与MGEs的丰度与菌群组成及消毒措施无关。对对应重症监护病房的连接废水进行分析后发现，AICU的废水需氧菌群多样性高于NICU的废水。此外，AICU的废水中共分离出15株CPE，而NICU的废水仅分离到1株。NICU与AICU的废水菌群组成既不同于各自对应的SDB，也在四个月的采样周期内呈现出明显的动态变化。值得注意的是，AICU的废水中携带更多喹诺酮类耐药基因与整合子整合酶基因，而NICU的废水中链阳菌素耐药基因的丰度更高。本研究结果表明，所调研医疗设施内两个重症监护病房的医院SDB耐药组与菌群组成、环境因素及当地消毒措施均无关联。但在收集对应排水口废水的管道中，CPE的检出率存在差异。上述发现为深入理解重症监护病房水槽排水口生物膜内耐药基因的留存特性提供了重要参考，也凸显了在临床环境中制定新型抗菌耐药防控策略的必要性。