O'Donnell M J, Tuttlebee C M, Falkiner F R, Coleman D C
Microbiology Research Unit, Department of Oral Surgery, Oral Medicine and Oral Pathology, School of Dental Science & Dublin Dental Hospital, University of Dublin, Trinity College, Lincoln Place, Dublin 2, Republic of Ireland.
J Hosp Infect. 2005 Apr;59(4):348-60. doi: 10.1016/j.jhin.2004.10.001.
Within six months of opening of the new Dublin Dental Hospital in September 1998, areas of corrosion were observed on many of the baseplates of the hospital's 103 dental chair units (DCUs) at the site of attachment of the suction hoses. The corroded areas were heavily contaminated with Pseudomonas spp. and related genera posing a risk of cross-infection, particularly for immunocompromised patients. These species were used as marker organisms to investigate the source of the contamination. P. aeruginosa was the predominant species recovered from 41 selected DCU baseplates (61% prevalence), whereas P. putida (46% prevalence) and P. aeruginosa (43% prevalence) were predominant at the attachment ends of 37 selected high-volume suction hoses. Forty-one selected isolates of P. aeruginosa from 13 DCU baseplates, 16 high-volume suction hoses and 12 coarse filter housings (another suction system site) from 19 separate DCUs were serotyped to determine the similarity of isolates at each site. The majority of isolates (68.3%) belonged to serotype O:10, while the remainder belonged to serotypes O:6 (7.3%), O:11 (7.3%), O:14 (9.8%) and O:5/O:16 (7.3%). Of the isolates from DCU baseplates, additional isolates with the same serotype were recovered from other suction system sites in 10/13 (77%) cases. Isolates of only one serotype were recovered from each of the 19 DCUs investigated. Forty-one serotyped isolates were also subject to computer-assisted analysis of SpeI-generated DNA fingerprint profiles, and similarity coefficient (S(AB)s) values were calculated for each pairwise combination of isolate profiles. The data obtained showed that the isolates consisted of two distinct main populations, each containing separate clades corresponding to specific serotypes. Serotype O:6 (three isolates), O:11 (three isolates) and O:5/O:16 (three isolates) belonged to a single strain in each case. Serotypes O:14 (four isolates) and O:10 (28 isolates) belonged to two strains in each case. The two serotype O:10 strains, termed fingerprint groups I (four isolates from three DCUs) and II (24 isolates from 10 DCUs), were the most distantly related of all the strains identified. These findings demonstrated that the hospital DCUs had become colonized with a small number of P. aeruginosa strains, one of which (serotype O:10, fingerprint group II) predominated. These results also confirmed that DCU baseplate contamination was most likely to be due to leakage from suction system hoses at the baseplate attachment sites, probably due to loosening during use. Replacement hose connectors that firmly retained the suction hoses in the attachment sites so that they could not be loosened by movement of the suction hoses solved this problem, and eliminated further contamination of the DCU baseplates.
1998年9月新的都柏林牙科医院开业后的六个月内，在医院103个牙科治疗椅单元（DCU）的许多底板上，于吸引软管连接处发现了腐蚀区域。这些腐蚀区域被假单胞菌属及相关菌属严重污染，存在交叉感染风险，尤其是对免疫功能低下的患者。这些菌种被用作指示生物来调查污染来源。铜绿假单胞菌是从41个选定的DCU底板中分离出的主要菌种（流行率61%），而恶臭假单胞菌（流行率46%）和铜绿假单胞菌（流行率43%）是在37个选定的大容量吸引软管连接处的主要菌种。从19个不同DCU的13个DCU底板、16个大容量吸引软管和12个粗滤器外壳（另一个吸引系统部位）中选取的41株铜绿假单胞菌分离株进行血清分型，以确定每个部位分离株的相似性。大多数分离株（68.3%）属于血清型O:10，其余属于血清型O:6（7.3%）、O:11（7.3%）、O:14（9.8%）和O:5/O:16（7.3%）。在从DCU底板分离出的分离株中，10/13（77%）的病例在其他吸引系统部位发现了相同血清型的额外分离株。在所调查的19个DCU中，每个DCU仅分离出一种血清型的分离株。41株血清分型的分离株还进行了SpeI产生的DNA指纹图谱的计算机辅助分析，并计算了每个分离株图谱两两组合的相似系数（S(AB)s）值。所获得的数据表明，分离株由两个不同的主要群体组成，每个群体包含对应特定血清型的单独分支。血清型O:6（三株分离株）、O:11（三株分离株）和O:5/O:16（三株分离株）在每种情况下都属于单一菌株。血清型O:14（四株分离株）和O:10（28株分离株）在每种情况下都属于两个菌株。这两个血清型O:10菌株，分别称为指纹组I（来自三个DCU的四株分离株）和II（来自10个DCU的24株分离株），是所有鉴定出的菌株中亲缘关系最远的。这些发现表明，医院的DCU已被少数铜绿假单胞菌菌株定植，其中一种（血清型O:10，指纹组II）占主导。这些结果还证实，DCU底板污染很可能是由于吸引系统软管在底板连接处泄漏，可能是由于使用过程中松动所致。更换能将吸引软管牢固固定在连接部位从而使其不会因吸引软管移动而松动的软管连接器解决了这个问题，并消除了DCU底板的进一步污染。
