Peel Trisha N, Cole Nicolynn C, Dylla Brenda L, Patel Robin
Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA; Department of Surgery, St Vincent's Hospital Melbourne, University of Melbourne, Melbourne, VIC, Australia.
Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
Diagn Microbiol Infect Dis. 2015 Mar;81(3):163-8. doi: 10.1016/j.diagmicrobio.2014.11.015. Epub 2014 Dec 3.
Identification of pathogen(s) associated with prosthetic joint infection (PJI) is critical for patient management. Historically, many laboratories have not routinely identified organisms such as coagulase-negative staphylococci to the species level. The advent of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) has enhanced clinical laboratory capacity for accurate species-level identification. The aim of this study was to describe the species-level identification of microorganisms isolated from periprosthetic tissue and fluid specimens using MALDI-TOF MS alongside other rapid identification tests in a clinical microbiology laboratory. Results of rapid identification of bacteria isolated from periprosthetic joint fluid and/or tissue specimens were correlated with clinical findings at Mayo Clinic, Rochester, Minnesota, between May 2012 and May 2013. There were 178 PJI and 82 aseptic failure (AF) cases analyzed, yielding 770 organisms (median, 3/subject; range, 1-19/subject). MALDI-TOF MS was employed for the identification of 455 organisms (59%) in 197 subjects (123 PJIs and 74 AFs), with 89% identified to the species level using this technique. Gram-positive bacteria accounted for 68% and 93% of isolates in PJI and AF, respectively. However, the profile of species associated with infection compared to specimen contamination differed. Staphylococcus aureus and Staphylococcus caprae were always associated with infection, Staphylococcus epidermidis and Staphylococcus lugdunensis were equally likely to be a pathogen or a contaminant, whereas the other coagulase-negative staphylococci were more frequently contaminants. Most streptococcal and Corynebacterium isolates were pathogens. The likelihood that an organism was a pathogen or contaminant differed with the prosthetic joint location, particularly in the case of Propionibacterium acnes. MALDI-TOF MS is a valuable tool for the identification of bacteria isolated from patients with prosthetic joints, providing species-level identification that may inform culture interpretation of pathogens versus contaminants.
确定与人工关节感染（PJI）相关的病原体对于患者管理至关重要。从历史上看，许多实验室并未常规将凝固酶阴性葡萄球菌等微生物鉴定到种水平。基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）的出现提高了临床实验室进行准确种水平鉴定的能力。本研究的目的是描述在临床微生物实验室中，使用MALDI-TOF MS以及其他快速鉴定试验，对从假体周围组织和液体标本中分离出的微生物进行种水平鉴定的情况。2012年5月至2013年5月期间，在明尼苏达州罗切斯特市的梅奥诊所，从假体周围关节液和/或组织标本中分离出的细菌的快速鉴定结果与临床发现相关。共分析了178例PJI和82例无菌性失败（AF）病例，分离出770株微生物（中位数为3株/受试者；范围为1 - 19株/受试者）。197名受试者（123例PJI和74例AF）中的455株微生物（59%）采用MALDI-TOF MS进行鉴定，使用该技术鉴定到种水平的比例为89%。革兰氏阳性菌分别占PJI和AF分离株的68%和93%。然而，与感染相关的菌种与标本污染的菌种分布不同。金黄色葡萄球菌和山羊葡萄球菌始终与感染相关，表皮葡萄球菌和路邓葡萄球菌同样有可能是病原体或污染物，而其他凝固酶阴性葡萄球菌更常为污染物。大多数链球菌和棒状杆菌分离株是病原体。一种微生物是病原体还是污染物的可能性因人工关节位置而异，痤疮丙酸杆菌的情况尤其如此。MALDI-TOF MS是鉴定从人工关节患者中分离出的细菌的有价值工具，可提供种水平鉴定，有助于对病原体与污染物的培养结果进行解读。
