Coghlan M W, Davies M J, Hoyt C, Joyce L, Kilner R, Waters M J
Department of Anaesthesia, St Vincent's Hospital, Melbourne, Victoria, Australia.
Anaesth Intensive Care. 2009 Jan;37(1):66-9.
The incidence of epidural abscess following epidural catheterisation appears to be increasing, being recently reported as one in 1000 among surgical patients. This study was designed to investigate the antibacterial activity of various local anaesthetics and additives, used in epidural infusions, against a range of micro-organisms associated with epidural abscess. The aim was to determine which, if any, epidural infusion solution has the greatest antibacterial activity. Bupivacaine, ropivacaine and levobupivacaine crystals were dissolved and added to Mueller-Hinton Agar in concentrations of 0.06%, 0.125%, 0.2%, 0.25%, 0.5% and 1%. Fentanyl, adrenaline and clonidine were also mixed with agar in isolation and in combination with the local anaesthetics. Using a reference agar dilution method, the minimum inhibitory concentrations were determined for a range of bacteria. Bupivacaine showed antibacterial activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli with minimum inhibitory concentrations between 0.125% and 0.25%. It did not inhibit the growth of Pseudomonas aeruginosa at any of the concentrations tested. Levobupivacaine and ropivacaine showed no activity against Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa, even at the highest concentrations tested, and minimal activity against Escherichia coli (minimum inhibitory concentrations 0.5% and 1% respectively). The presence of fentanyl, adrenaline and clonidine had no additional effect on the antibacterial activity of any of the local anaesthetic agents. The low concentrations of local anaesthetic usually used in epidural infusions have minimal antibacterial activity. While the clinical implications of this in vitro study are not known, consideration should be given to increasing the concentration of bupivacaine in an epidural infusion or to administering a daily bolus of 0.25% bupivacaine to reduce the risk of epidural bacterial growth.
硬膜外导管插入术后硬膜外脓肿的发生率似乎在上升，最近报道在外科手术患者中为千分之一。本研究旨在调查硬膜外输注中使用的各种局部麻醉药和添加剂对一系列与硬膜外脓肿相关微生物的抗菌活性。目的是确定哪种硬膜外输注溶液（如果有的话）具有最大的抗菌活性。将布比卡因、罗哌卡因和左旋布比卡因晶体溶解，并以0.06%、0.125%、0.2%、0.25%、0.5%和1%的浓度添加到穆勒-欣顿琼脂中。芬太尼、肾上腺素和可乐定也分别以及与局部麻醉药联合与琼脂混合。使用参考琼脂稀释法，测定了一系列细菌的最低抑菌浓度。布比卡因对金黄色葡萄球菌、粪肠球菌和大肠杆菌具有抗菌活性，最低抑菌浓度在0.125%至0.25%之间。在任何测试浓度下，它都不抑制铜绿假单胞菌的生长。左旋布比卡因和罗哌卡因即使在最高测试浓度下，对金黄色葡萄球菌、粪肠球菌和铜绿假单胞菌也无活性，对大肠杆菌的活性最小（最低抑菌浓度分别为0.5%和1%）。芬太尼、肾上腺素和可乐定的存在对任何一种局部麻醉药的抗菌活性均无额外影响。硬膜外输注中通常使用的低浓度局部麻醉药具有最小的抗菌活性。虽然这项体外研究的临床意义尚不清楚，但应考虑提高硬膜外输注中布比卡因的浓度或每日推注0.25%布比卡因以降低硬膜外细菌生长的风险。
