腰椎インストゥルメンテーション手術後のMRSAによる手術部位感染に対する抗菌治療―インプラント抜去回避のために

Antibiotic Treatment for Surgical Site Infection due to MRSA/MRCNS Following Spinal Instrumentation Surgery to Avoid Implant Removal

　腰椎インストゥルメンテーション手術後のMRSA（MRCNSを含む）による手術部位感染（SSI）に対する化学療法の治療成績を分析し，インプラント抜去を回避しうる治療法を検討した．1998～2000年の274手術例では，第1・2世代セフェムによる予防的抗菌薬投与（AMP）が数日間行われた．この群のSSI発生率は4.0％で起因菌は全例MRSA，2.2％は感染鎮静化のためにインプラント抜去を余儀なくされた．2001～2003年の289手術例では，MRSAにもある程度の抗菌力を有するアンピシリン合剤によるAMPを行った．その結果，SSI発生率は2.8％に減じたものの，完全阻止はできなかった．起因菌はすべてMRSAであった．一方，SSI治療に関しては，起因菌ターゲットの絞り込み，バイオフィルム対策，早期診断，適切な抗菌治療を行うことにより，インプラント抜去率を0.7％にまで減じせしめた．

　The purpose of this study was to establish antimicrobial management which does not require implant removal in treatment of deep incisional surgical site infection (SSI) due to methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase-negative staphylococci (MRCNS) following instrumentation surgery in the lumbar spine. In the first term of this study between 1998 and 2000, 274 patients with posterior lumbar interbody fusion (PLIF) underwent antimicrobial prophylaxis (AMP) using first-or second-generation cephalosporins for postoperative several days. The incidence of SSI was 4.0％ (11 of 274 patients) and the SSI pathogens in all 11 patients were MRSA or MRCNS. Six (2.2％) out of the 274 patients underwent implant removal for infection control. In 289 patients who underwent PLIF or transforaminal lumbar interbody fusion (TLIF) in the second term of this study between 2001 and 2003, sulbactam/ampicillin (SBT/ABPC) or ampicillin/cloxacillin (ABPC/MCIPC) with sensitivity against MRSA and MRCNS was used for AMP to prevent SSI due to MRSA or MRCNS. As a result of AMP modification, although the incidence of SSI was reduced to 2.8％ (8 of 289 patients), SSI could not be controlled completely. Additionally, all SSI pathogens were MRSA or MRCNS. Regarding treatment for established SSI, implant removal was significantly reduced from 2.2％ to 0.7％ by narrowing down target SSI pathogens for spinal instrumentation surgery, the use of antibiofilm disease agent, early diagnosis, and adequate administration of antimicrobial agent for MRSA/MRCNS.