Modeling microbial survival in buildup biofilm for complex medical devices
Modeling microbial survival in buildup biofilm for complex medical devices
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DOI：
10.1186/1471-2334-9-56
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发表时间：
2009-05-08
影响因子：
3.7
通讯作者：
Howie, Rosemarie
中科院分区：
文献类型：
--
作者：
Alfa, Michelle J.;Howie, Rosemarie
背景：柔性内窥镜要经过反复的病人使用和再处理。一些证据表明，随着时间的推移，内窥镜通道中会出现有机物质的积累或积聚。这种“积聚生物膜”(BBF)是在使用和再加工过程中周期性暴露于湿相和干相的结果。本研究探讨了生物膜基质是否比传统的生物膜(TBF)对消毒效果和微生物清除提出了更大的挑战。传统生物膜是指表面不断浸泡在液体中形成的。方法：利用最小生物膜根除浓度(MBEC)系统，开发了一种独特的模拟方法来评估干燥、消毒剂暴露和再暴露于试验微生物的重复循环形成的生物膜中微生物的存活。该模型模拟了后处理协议对柔性内窥镜的累积影响。用戊二醛(GLUT)和加速过氧化氢(AHP)对TBF和BBF中微生物的杀灭进行了评价。结果：有机基质和乙醛消毒相结合可迅速产生保护性BBF，促进高水平的生物存活。在高营养条件下形成的交联型BBF，最大菌落形成单位(CFU)接近6Log(10)CFU/peg。然而，如果使用氧化剂进行消毒，如果有机含量保持在较低水平，生物体就不会存活。一个关键的发现是，一旦建立，通过过量暴露形成的BBF的微生物负荷比在TBF中积累的速度更快。由BBF中粪肠球菌和铜绿假单胞菌的最大Log(10)CFU/初始Log(10)CFU确定的高级消毒(HLD)后生物膜存活率分别为10和8.6；与TBF中每种微生物的存活率接近2相比，有显著差异。来自间接生长测试的数据第一次证明了基质中存在有机体存活。当过量使用时，TBF和BBF都有存活的生物体。对于AHP，BBF的存活率低于TBF。结论：该BBF模型首次证明了BBF中确实存在多种微生物的存活，且比TBF生长得更快。与AHP相比，当使用过剩时，这一点最为明显。这些数据支持对再处理的内窥镜进行仔细清洗的必要性，因为有机材料和微生物的存在阻碍了在使用过剩和AHP时进行有效的消毒。然而，当有BBF时，像Glut这样的交联剂就不那么有效了。来自BBF的MBEC模型的数据表明，对于重复使用和再加工的柔性内窥镜，如果BBF在渠道内发展，有效的高水平消毒的保证可能会降低。
Background: Flexible endoscopes undergo repeated rounds of patient-use and reprocessing. Some evidence indicates that there is an accumulation or build-up of organic material that occurs over time in endoscope channels. This "buildup biofilm" (BBF) develops as a result of cyclical exposure to wet and dry phases during usage and reprocessing. This study investigated whether the BBF matrix represents a greater challenge to disinfectant efficacy and microbial eradication than traditional biofilm (TBF), which forms when a surface is constantly bathed in fluid.Methods: Using the MBEC (Minimum Biofilm Eradication Concentration) system, a unique modelling approach was developed to evaluate microbial survival in BBF formed by repetitive cycles of drying, disinfectant exposure and re-exposure to the test organism. This model mimics the cumulative effect of the reprocessing protocol on flexible endoscopes. Glutaraldehyde (GLUT) and accelerated hydrogen peroxide (AHP) were evaluated to assess the killing of microbes in TBF and BBF.Results: The data showed that the combination of an organic matrix and aldehyde disinfection quickly produced a protective BBF that facilitated high levels of organism survival. In cross-linked BBF formed under high nutrient conditions the maximum colony forming units (CFU) reached similar to 6 Log(10) CFU/peg. However, if an oxidizing agent was used for disinfection and if organic levels were kept low, organism survival did not occur. A key finding was that once established, the microbial load of BBF formed by GLUT exposure had a faster rate of accumulation than in TBF. The rate of biofilm survival post high-level disinfection (HLD) determined by the maximum Log(10)CFU/initial Log(10)CFU for E. faecalis and P. aeruginosa in BBF was 10 and 8.6 respectively; significantly different compared to a survival rate in TBF of similar to 2 for each organism. Data from indirect outgrowth testing demonstrated for the first time that there is organism survival in the matrix. Both TBF and BBF had surviving organisms when GLUT was used. For AHP survival was seen less frequently in BBF than in TBF.Conclusion: This BBF model demonstrated for the first time that survival of a wide range of microorganisms does occur in BBF, with significantly more rapid outgrowth compared to TBF. This is most pronounced when GLUT is used compared to AHP. The data supports the need for meticulous cleaning of reprocessed endoscopes since the presence of organic material and microorganisms prevents effective disinfection when GLUT and AHP are used. However, cross-linking agents like GLUT are not as effective when there is BBF. The data from the MBEC model of BBF suggest that for flexible endoscopes that are repeatedly used and reprocessed, the assurance of effective high-level disinfection may decrease if BBF develops within the channels.