Is Cutibacterium acnes early surgical site infection rate related to the duration of antibiotic prophylaxis in adolescent idiopathic scoliosis surgery?

Cutibacterium acnes (C. acnes) is a gram-positive anaerobic bacillus located in pilosebaceous glands, usually responsible for late postoperative surgical site infections (SSI). A recent study performed in our institution highlighted an unexpected emergence of C. acnes early SSI. One potential explanation was the change of the perioperative antibioprophylaxis (ATB) protocol, which switched from 48 h postoperative cefamandole to intraoperative only cefazoline. The aim of this study was therefore to investigate the influence of the ATB duration on the occurrence of C. acnes early SSI, by comparing the incidence rates during 3 consecutive ATB protocols. Between January 2007 and September 2017, all patients who underwent posterior fusion for AIS were retrospectively reviewed. Early C. acnes SSI were reported and compared between 3 periods, during which the ATB protocols were modified. January 2007-February 2012: Intraoperative Cefamandole continued 48 h (protocol 1) March 2012-August 2016: Single shot of intraoperative Cefazoline (protocol 2) September 2016-September 2017: Intraoperative Cefazoline continued 48 h (protocol 3). Fifty-three early SSI (7.2%) were reported among the 732 posterior AIS fusions included. Global incidence of C. acnes infection was 2.9%. The incidence of C. acnes in early SSI increased from 0 to 4.9% between protocol 1 and 2, but was reduced to 1.7% with protocol 3. Early C acnes SSI can be explained by the difficulty to eradicate this pathogen with current skin preparation procedures and some Beta-lactam antibiotics tolerance. Longer duration antibioprophylaxis is preferable to prevent from early C. acnes SSI.