Clinical significance of positive cranial bone flap cultures and associated risk of surgical site infection after craniotomies or craniectomies

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The risk of surgical site infection (SSI) after craniotomies or craniectomies in patients in whom contaminated bone flaps have been reimplanted has not been determined. The objectives of this study were to identify the prevalence of bone flaps with positive cultures—especially those contaminated with Propionibacterium acnes—to assess the risk of SSI after reimplanting (either during the initial operation or subsequently) bone flaps with positive cultures, and to identify risk factors for SSI following the initial craniotomies or craniectomies.


The authors conducted a retrospective review of cases in which patients underwent craniotomy/craniectomy procedures between January and October 2007 in the neurosurgery department at the University of Iowa Hospitals and Clinics. They also reviewed processes and procedures and did pulsed field gel electrophoresis of P. acnes isolates to look for a common source of contamination. They then conducted a prospective cohort study that included all patients who underwent craniotomy/craniectomy procedures between November 2007 and November 2008 and met the study criteria. For the cohort study, the authors obtained cultures from each patient's bone flap during the craniotomy/craniectomy procedures. Data about potential risk factors were collected by circulating nurses during the procedures or by a research assistant who reviewed medical records after the procedures. An infection preventionist independently identified SSIs through routine surveillance using the Centers for Disease Control and Prevention's definitions. Univariate and bivariate analyses were performed to determine the association between SSI and potential risk factors.


The retrospective review did not identify specific breaks in aseptic technique or a common source of P. acnes. Three hundred seventy-three patients underwent 393 craniotomy/craniectomy procedures during the cohort study period, of which 377 procedures met the study criteria. Fifty percent of the bone flaps were contaminated by microorganisms, primarily skin flora such as P. acnes, coagulase-negative staphylococci, and Staphylococcus aureus. Reimplanting bone flaps that had positive culture results did not increase the risk of infection after the initial craniotomy/craniectomy procedures and the subsequent cranioplasty procedures (p = 0.80). Allowing the skin antiseptic to dry before the procedures (p = 0.04, OR 0.26) was associated with lower risk of SSIs. Female sex (p = 0.02, OR = 3.49) was associated with an increased risk of SSIs; Gliadel wafer implants (p = 0.001, OR = 8.38) were associated with an increased risk of SSIs after procedures to treat tumors.


Operative factors such as the way the skin is prepared before the incision rather than the skin flora contaminants on the bone flaps may play an important role in the pathogenesis of SSIs after craniotomy/craniectomy. Gliadel wafers significantly increased the risk of SSI after procedures to treat tumors.

Abbreviations used in this paper: CHG = chlorhexidine gluconate; CoNS = coagulase-negative staphylococci; SSI = surgical site infection; UIHC = University of Iowa Hospitals and Clinics.

Article Information

Address correspondence to: Jeremy D. W. Greenlee, M.D., Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa 52242. email:

Please include this information when citing this paper: published online March 4, 2011; DOI: 10.3171/2011.1.JNS10782.

© AANS, except where prohibited by US copyright law.



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    Flow chart describing information obtained in the study population. *The risk of SSI after the initial craniotomies/craniectomies when bone flaps were reimplanted immediately (16 [5.4%] of 297) was not significantly different from the risk of SSI when bone flaps were banked (4 [5.0%] of 80) (p = 1.00, Fisher exact test). †Twenty SSIs occurred in 20 patients after the initial craniotomy/craniectomy procedures. ‡Follow-up information through 11/30/2009 is provided for the 80 procedures (79 patients) for which bone flaps were banked (beneath the broken line). However, risk factors for SSIs were assessed only for the initial craniotomy/craniectomy procedures (above the broken line), not for delayed cranioplasty procedures. §These 2 SSIs were not included in the study of risk factors for SSIs. One of the 2 patients also acquired an SSI after the initial craniotomy/craniectomy; this initial SSI was included in the risk factor study.



Attenello FJMukherjee DDatoo GMcGirt MJBohan EWeingart JD: Use of Gliadel (BCNU) wafer in the surgical treatment of malignant glioma: a 10-year institutional experience. Ann Surg Oncol 15:288728932008


Brem HLanger R: Polymer-based drug delivery to the brain. Sci Med 3:52611996


Centers for Disease Control and Prevention Division of Healthcare Quality Promotion National Center for Infectious Diseases: The National Healthcare Safety Network (NHSN) Manual: Patient Safety Component Protocol AtlantaCenters for Disease Control and Prevention2008. 3439


Cronquist ABJakob KLai LDella Latta PLarson EL: Relationship between skin microbial counts and surgical site infection after neurosurgery. Clin Infect Dis 33:130213082001


Darouiche ROWall MJ JrItani KMOtterson MFWebb ALCarrick MM: Chlorhexidine-alcohol versus povidoneiodine for surgical site antisepsis. N Engl J Med 362:18262010


Dohmen PM: Influence of skin flora and preventive measures on surgical site infection during cardiac surgery. Surg Infect (Larchmt) 7:Suppl 1S13S172006


Edwards JRPeterson KDAndrus MLDudeck MAPollock DAHoran TC: National Healthcare Safety Network (NHSN) Report, data summary for 2006 through 2007, issued November 2008. Am J Infect Control 36:6096262008


Guzel AOzekinci TOzkan UCelik YCeviz ABelen D: Evaluation of the skin flora after chlorhexidine and povidoneiodine preparation in neurosurgical practice. Surg Neurol 71:2072102009


Kamble RPant SSelby GBKharfan-Dabaja MASethi SKratochvil K: Microbial contamination of hematopoietic progenitor cell grafts-incidence, clinical outcome, and cost-effectiveness: an analysis of 735 grafts. Transfusion 45:8748782005


Klein MAKadidlo DMcCullough JMcKenna DHBurns LJ: Microbial contamination of hematopoietic stem cell products: incidence and clinical sequelae. Biol Blood Marrow Transplant 12:114211492006


Korinek AMGolmard JLElcheick ABismuth Rvan Effenterre RCoriat P: Risk factors for neurosurgical site infections after craniotomy: a critical reappraisal of antibiotic prophylaxis on 4,578 patients. Br J Neurosurg 19:1551622005


Larson E: Guideline for use of topical antimicrobial agents. Am J Infect Control 16:2532661988


Mangram AJHoran TCPearson MLSilver LCJarvis WR: Guideline for prevention of surgical site infection, 1999. Hospital Infection Control Practices Advisory Committee. Infect Control Hosp Epidemiol 20:2502801999


McGovern PCLautenbach EBrennan PJLustig RAFishman NO: Risk factors for postcraniotomy surgical site infection after 1,3-bis (2-chloroethyl)-1-nitrosourea (Gliadel) wafer placement. Clin Infect Dis 36:7597652003


Nasser RMHajjar ISandhaus LMHall GSAvery RKBolwell BJ: Routine cultures of bone marrow and peripheral stem cell harvests: clinical impact, cost analysis, and review. Clin Infect Dis 27:8868881998


Owens CDStoessel K: Surgical site infections: epidemiology, microbiology and prevention. J Hosp Infect 70:Suppl 23102008


Padley DJDietz ABGastineau DA: Sterility testing of hematopoietic progenitor cell products: a single-institution series of culture-positive rates and successful infusion of culture-positive products. Transfusion 47:6366432007


Patah PAParmar SMcMannis JSadeghi TKarandish SRondon G: Microbial contamination of hematopoietic progenitor cell products: clinical outcome. Bone Marrow Transplant 40:3653682007


Pfaller MAChromosomal restriction fragment analysis by pulsed field gel electrophoresis–application to molecular epidemiology. Isenberg HD: Essential Procedures for Clinical Microbiology WashingtonAmerican Society for Microbiology1998. 651657


Prince HMPage SRKeating ASaragosa RFVukovic NMImrie KR: Microbial contamination of harvested bone marrow and peripheral blood. Bone Marrow Transplant 15:87911995


Shinoura NYamada ROkamoto KNakamura O: Early prediction of infection after craniotomy for brain tumours. Br J Neurosurg 18:5986032004


Uchino MIkeuchi HMatsuoka HTsuchida TTomita NTakesue Y: Risk factors associated with surgical site infection after ileal pouch-anal anastomosis in ulcerative colitis. Dis Colon Rectum 53:1431492010


van Ek BBakker FPvan Dulken HDijkmans BA: Infections after craniotomy: a retrospective study. J Infect 12:1051091986


Vanneaux VFoïs ERobin MRea Dde Latour RPBiscay N: Microbial contamination of BM products before and after processing: a report of incidence and immediate adverse events in 257 grafts. Cytotherapy 9:5085132007


Whyte WHambraeus ALaurell GHoborn J: The relative importance of routes and sources of wound contamination during general surgery. I Non-airborne. J Hosp Infect 18:931071991




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