Joshi Purvi, Bhattacharjee Rohit, Sahu Muskan, Gajjar Devarshi
Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
Sci Rep. 2025 May 2;15(1):15375. doi: 10.1038/s41598-025-00457-w.
Most hospital-acquired urinary tract infections are the result of implanted urinary catheter, with majority of studies focused on a single species colonisation, but recently polymicrobial colonisations are being reported. In this study, indwelling urinary catheters were collected from ICU patients and the colonising microbiome was isolated and identified by the traditional; culturing method and metagenomics. It was observed that majority of catheters were colonised by polymicrobial biofilms, containing both bacterial and fungal isolates making them diverse and complex. However, the metagenomics results were quite surprising showing the presence of multiple organisms of which only 1or 2 showed growth when cultured. Later, in vitro assays were performed by selecting 6 combinations, with each combination containing one Candida spp. - C. albicans or C. tropicalis with one bacteria K. pneumoniae, P. aeruginosa or E. coli. It was observed that polymicrobial biofilms were stronger than mono-microbial biofilms, suggesting their increased surface adhesion. Furthermore, to simulate the dynamic environment in which cells are exposed to a certain level of fluid movement, a flow system was established to imitate the flow generated in colonized urinary catheter. We have observed changes in biofilm architecture, adhesion and thickness under flow conditions compared with static conditions, with a uniformly adhered biofilm with increased thickness of polymicrobial biofilms as compared to mono-species biofilms. The biofilm formed under flow was more viable than the static biofilm with higher number of live cells in flow condition.
大多数医院获得性尿路感染是由留置导尿管引起的，大多数研究集中在单一菌种的定植上，但最近有报道称存在多种微生物定植的情况。在本研究中，从重症监护病房（ICU）患者中收集留置导尿管，并通过传统培养方法和宏基因组学对定植的微生物群落进行分离和鉴定。观察到大多数导尿管被多种微生物生物膜定植，其中包含细菌和真菌分离株，使其具有多样性和复杂性。然而，宏基因组学结果相当令人惊讶，显示存在多种生物体，而在培养时只有1种或2种显示生长。后来，通过选择6种组合进行体外试验，每种组合包含一种念珠菌属——白色念珠菌或热带念珠菌与一种细菌肺炎克雷伯菌、铜绿假单胞菌或大肠杆菌。观察到多种微生物生物膜比单一微生物生物膜更强，表明它们的表面附着力增加。此外，为了模拟细胞暴露于一定水平流体流动的动态环境，建立了一个流动系统来模拟定植导尿管中产生的流动。我们观察到与静态条件相比，流动条件下生物膜结构、附着力和厚度的变化，与单一物种生物膜相比，多种微生物生物膜形成的均匀附着生物膜厚度增加。在流动条件下形成的生物膜比静态生物膜更具活力，流动条件下活细胞数量更多。
