Barbeau J, ten Bokum L, Gauthier C, Prévost A P
Département de stomatologie, Faculté de médecine dentaire, Université de Montréal.
J Hosp Infect. 1998 Dec;40(4):303-11. doi: 10.1016/s0195-6701(98)90308-5.
It has been postulated that evacuation systems used in dentistry could be a source of cross-contamination between patients through backflow of bacteria dislodged from the saliva ejector tubings. The bacterial microflora associated with these systems was characterized using transmission electron microscopy (TEM) and microbiological cultures. The potential for backflow was investigated by a study of pressure differentials in evacuation system tubing and by the presence of bacteria in backflow samples. Evacuation lines were coated with microbial biofilms in which microcolonies of Gram-positive cocci and Gram-negative bacilli predominated, embedded in an extensive polysaccharide matrix. Most bacteria were metabolically active. Occasionally, buccal material such as collagen, fibrin and eukaryotic cell debris was observed. In other experiments, flow reversal was detected several times during saliva ejector use though each of these events was brief (less than 0.1 s). Aspiration of saliva, or occlusion of the mouthpiece opening by the oral mucosa, were the major factors leading to backflow episodes. Bacteria associated with backflow were found in almost 25% assays, with counts ranging from 1-300 cfu/occurrence. The majority of the bacteria isolated from biofilm or backflow samples were staphylococci, micrococci and non-fermentive Gram-negative rods. Pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus were also isolated from backflow fluids. No oral streptococci could be recovered from biofilms in the tubing beyond 15 min from the last saliva ejector use however, suggesting that these species did not survive in the biofilms. These data suggest, although without direct proof of cross-contamination, the possible existence of an infectious risk associated with oral evacuation systems, as potential pathogens may be shed from tubing biofilms following backflow. Even if the risk of cross-contamination between patients is considered to be low, the necessity for regular disinfection of these systems must be stressed, since biofilms can serve as a reservoir for pathogens or harbor potentially infectious material.
据推测，牙科使用的抽气系统可能会因唾液排出管中细菌回流而成为患者之间交叉污染的源头。利用透射电子显微镜（TEM）和微生物培养对与这些系统相关的细菌微生物群落进行了表征。通过研究抽气系统管道中的压力差以及回流样本中细菌的存在情况，对回流可能性进行了调查。抽气管道上覆盖着微生物生物膜，其中革兰氏阳性球菌和革兰氏阴性杆菌的微菌落占主导地位，嵌入广泛的多糖基质中。大多数细菌具有代谢活性。偶尔会观察到颊部物质，如胶原蛋白、纤维蛋白和真核细胞碎片。在其他实验中，在使用唾液排出器期间多次检测到逆流，不过每次事件都很短暂（不到0.1秒）。唾液抽吸或口腔黏膜堵塞吸嘴开口是导致回流事件的主要因素。在近25%的检测中发现了与回流相关的细菌，每次出现的菌落数为1 - 300 cfu。从生物膜或回流样本中分离出的大多数细菌是葡萄球菌、微球菌和非发酵革兰氏阴性杆菌。也从回流液中分离出了铜绿假单胞菌和金黄色葡萄球菌等病原体。然而，在最后一次使用唾液排出器15分钟后，管道生物膜中未能回收口腔链球菌，这表明这些菌种在生物膜中无法存活。这些数据表明，尽管没有直接证据证明交叉污染，但与口腔抽气系统相关的感染风险可能存在，因为回流后潜在病原体可能从管道生物膜中脱落。即使认为患者之间交叉污染的风险较低，也必须强调定期对这些系统进行消毒的必要性，因为生物膜可作为病原体的储存库或容纳潜在感染性物质。
