Walker J T, Bradshaw D J, Bennett A M, Fulford M R, Martin M V, Marsh P D
CAMR, Porton Down, Salisbury, United Kingdom.
Appl Environ Microbiol. 2000 Aug;66(8):3363-7. doi: 10.1128/AEM.66.8.3363-3367.2000.
Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 10(5) CFU. ml(-1); in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this "viable by BacLight" fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered "cleaner" than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.
牙科设备水系统（DUWS）中存在细菌生物膜，这可能成为病原体的滋生地。本研究的目的是调查普通牙科诊所中DUWS的水微生物负荷以及DUWS管道的生物污垢情况。从英格兰西南部的55个牙科手术室采集了水和管道样本。通过在环境选择性、临床选择性和病原体选择性培养基上的活菌计数来确定污染情况，并使用显微镜和图像分析技术来确定生物污垢情况。微生物负荷范围为500至10⁵ CFU·ml⁻¹；在95%的DUWS水样中，其超过了欧盟饮用水标准，在83%的水样中超过了美国牙科协会的DUWS标准。在可见细菌中，通过BacLight染色显示68%具有活性，但在这一“BacLight染色有活性”的部分中，只有5%在琼脂平板上形成菌落。分别在1个、5个、2个和9个不同的手术室中检测到嗜肺军团菌、分枝杆菌属、念珠菌属和假单胞菌属。分别在4个和1个手术室中检测到推测的口腔链球菌和梭杆菌属，提示存在回吸现象和防回吸装置故障。从未检测到乙型肝炎病毒。去污策略（55个手术室中的5个）显著降低了生物膜覆盖率，但显著增加了水相中的微生物数量（两种情况均为P < 0.05）。使用软水、硬水、去离子水或蒸馏水供水的DUWS或不同类型的DUWS（主供水、水箱供水或瓶装供水）中的微生物负荷没有显著差异。从微生物学角度来看，没有哪个DUWS可以被认为比其他的“更清洁”。DUWS输送给患者的水的微生物水平超过了饮用水安全标准。
