establishment and evaluation of a mouse catheter-related infection model

建立 白色念珠菌相关导管相关感染的小鼠模型

In recent years, with the development and application of biomedical materials, implant-related infections are emerging as difficult clinical problems1,2. With the wide application of medical catheters in clinics, the number of related infections and deaths is huge every year3,4. The common infection routes of a catheter-related infection (CRI) include: (1) pathogens on the surface of the skin infiltrate into the body and adhere to the outer surface of the catheter5,6,7; (2) improper aseptic operation-derived pathogens invade, adhere and colonize on the catheter; (3) pathogens in the blood circulation adhere and colonize on the catheter; (4) drugs contaminated by pathogenic microorganism.
Candida is the third most common reason for CRI8,9. It is very likely to cause bloodstream infection and other life-threatening invasive candidiasis after biofilms are formed on the surface of the implant. The prognosis is poor, and the mortality rate is high2. It is reported that biofilms are formed on the surface of the catheter within 2 weeks after central venous insertion and in the lumen of the catheter a few weeks later10,11.
Candida albicans (C. albicans) biofilms formed on medical catheters exhibit a double-layer network composed of yeast, stroma, and mycelium12,13. The formation of C. albicans biofilms is not only a key for drug resistance and immune evasion13 but also vital to produce disseminated spores, which leads to further hematogenous infection2,12 and results in more serious and even life-threatening consequences. C. albicans-associated CRI is a major cause of clinical fungal bloodstream infections7,14, and more than 40% of patients with C. albicans infection in the central venous catheter will develop into bacteremia15.
According to the Infectious Disease Society of America, the recommended treatment of Candida CRI includes (1) removal of the infected catheter; (2) subjecting the patients to a 14 days-systemic antifungal therapy8; (3) reimplanting a new catheter4. However, in clinical applications, catheters cannot be fully removed sometimes. Some patients can only be treated with systemic antibiotics and antimicrobial lock therapy, accompanied by strong side effects16,17.
Existing animal models of C. albicans, such as the oropharyngeal candidiasis model, vaginal candidiasis model, and invasive systemic infection model caused by candidiasis18,19 cannot correlate well with the clinical CRI. Therefore, in this study, a C. albicans-associated CRI model in mice was established. Clinical commonly used polyethylene catheters were used as subcutaneous implants20,21, and C. albicans were inoculated on the skin surface to simulate the adhesion of C. albicans to the medical catheters and the formation of biofilms.
This model has been successfully used in our laboratory to screen the anti-biofilm effect of different therapeutics22. In addition, due to the lag detection of C. albicans after catheter infection, a C. albicans strain containing enhanced green fluorescent protein (EGFP) was constructed and inoculated in mice to facilitate the intuitive observation of the colonies and biofilms of C. albicans on the implanted catheter.

作者聚焦：使用荧光蛋白标记增强导管感染中的白色念珠菌检测 

小鼠导管相关 白色念珠菌 感染模型

Our research aims to establish a mouse model of Candida albicans associated catheter-related infection, in which biofilm forms on the catheter. This model is helpful for correlating with the clinical CRI and the interaction between Candida albicans and host. The existing animal models of Candida albicans, such as the oropharyngeal candidiasis model, vaginal candidiasis model, and invasive systemic infection model caused by candidiasis cannot correlate well with the clinical CRI.To improve Candida albicans detection in catheter infections, our protocol employed a stain with enhanced green fluorescein protein. This allowed for clear visualization of Candida albicans colony and biofilms on catheters in mice, and in timely detection.

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Establishment and Evaluation of a Mouse Catheter-Related Infection Model  

小鼠导管相关感染模型的建立与评估

首先，将30只小鼠分成三组，分别标记为对照组，导管组和模型组。将麻醉的小鼠置于手术台上的俯卧位。剃掉动物的背部，然后用碘水对手术部位进行消毒。对于导管组中的小鼠，将一毫升无菌注射器针头插入手术部位以打孔。然后取出注射器针头，将一根一厘米长的导管插入孔中。对于模型组中的小鼠，将200微升白色念珠菌悬浮液液移到手术部位。悬浮液被皮肤吸收后，将一毫升无菌注射器针头插入该部位。然后将导管插入针头形成的孔中。将 20 微升白色念珠菌沿导管悬浮到组织。然后用胶带和纱布固定导管，然后将它们放回笼子喂食。三天后，从安乐死小鼠的背部收集导管和皮肤组织样本。将导管固定在4%多聚甲醛中，温度为4摄氏度48小时。然后用荧光显微镜记录484纳米的酵母生物膜图像。在此之后，分析组织病理学染色的皮肤组织的图像以了解变化。在导管组的聚乙烯导管表面未观察到明显的荧光。在模型组的导管表面上可以看到贴壁白色念珠菌细胞发出的强荧光。对照组和导管皮肤组织的厨师高碘站立显示不存在白色念珠菌。在模型组中观察到少量阳性白色念珠菌细胞。念珠菌感染导致表皮层增厚和延伸，模型组中可见炎症浸润。对照组和导管组均具有完整的表皮层、真皮层、皮脂腺、毛囊和其他结构。

establishment-evaluation-mouse-catheter-related-infection

Research

JoVE Journal

Immunology and Infection

Establishment and Evaluation of a Mouse Catheter-Related Infection Model

316 次观看.  Xi’an Jiaotong University. 首先，将30只小鼠分成三组，分别标记为对照组，导管组和模型组。将麻醉的小鼠置于手术台上的俯卧位。剃掉动物的背部，然后用碘水对手术部位进行消毒。对于导管组中的小鼠，将一毫升无菌注射器针头插入手术部位以打孔。然后取出注射器针头，将一根一厘米长的导管插入孔中。对于模型组中的小鼠，将200微升白色念珠菌悬浮液液移到手术部位。悬浮液被皮?...

视频: Establishment and Evaluation of a Mouse Catheter-Related Infection Model  

A Catheter-Related Candida albicans Infection Model in Mouse

Catheter-related infection (CRI) is a common nosocomial infection caused by candida albicans during catheter implantation. Typically, biofilms are formed on the outer surface of the catheter and lead to disseminated infections, which are fatal to patients. There are no effective prevention and treatment management in clinics. Therefore, it is urgent to establish an animal model of CRI for the preclinical screening of new strategies for its prevention and treatment. In this study, a polyethylene catheter, a widely used medical catheter, was inserted into the back of the BALB/c mice after hair removal. Candida albicans ATCC MYA-2876 (SC5314) expressing enhanced green fluorescent protein was subsequently inoculated on the skin's surface along the catheter. Intense fluorescence was observed on the surface of the catheter under a fluorescent microscope 3 days later. Mature and thick biofilms were found on the surface of the catheter via scanning electron microscopy. These results indicated the adhesion, colonization, and biofilm formation of candida albicans on the surface of the catheter. The hyperplasia of the epidermis and the infiltration of inflammatory cells in the skin specimens indicated the histopathological changes of the CRI-associated skin. To sum up, a mouse CRI model was successfully established. This model is expected to be helpful in the research and development of therapeutic management for candida albicans associated CRI.

We establish a mouse model of C.albicans-associated catheter-related infection (CRI), in which biofilm forms on the catheter, and the interaction between C.albicans and host correlates well with the clinical CRI. This model helps screen therapies for C.albicans biofilm-associated CRI, laying a foundation for clinical transformation.

Catheter-related infection (CRI) is a common nosocomial infection caused by candida albicans during catheter implantation. Typically, biofilms are formed ...