The prevention and management of surgical site infections

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By Hilali Noordeen and NS Harshavardhana 

Surgical site infections (SSIs) are the most common type of nosocomial infections acquired after surgery. They can have a significant social and economical impact, and they can reduce quality of life1.

 

Surgical site infections are potentially fatal and, whether fatal or not, a patient developing a SSI can be a demoralising experience for the treating surgeon. At the moment, there is an increasing move towards stratifying SSIs as “never events” (ie, serious, largely preventable events that would not have happened if the correct preventative measures were in place)—this is particularly the case with methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C difficile), which, in the UK, must be reported to the healthcare regulatory bodies (ie, the Department of Health).


The incidence of postoperative SSI varies with type and complexity of surgery, surgical approach, and whether or not instrumentation was used. The reported infection rates for common spinal surgeries are listed in the table below.   

 

Spinal Surgery

Infection rate (%)

Lumbar decompression surgery

0–1

Lumbar fusion surgery

1–3

Lumbar instrumentation surgery

2–6

Cervical spine surgery

1–2

Spinal deformity surgery

1–>15

Adolescent idiopathic scoliosis

1–2

Adult deformity surgery

2–10

Neuromuscular scoliosis

5–>20

Congenital scoliosis

2–4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Risk factors


There is an abundant amount of literature studying risk factors for SSIs, and most of these studies are at the highest level of evidence—IV. However, the data from these studies are conflicting and there is a paucity of solid evidence for robust risk factors that cause SSIs. Furthermore, complex interplay of inter-related factors makes systematic assessment and meta-analysis extremely difficult. That said, most of the published studies have identified a history of previous infection, diabetes, and obesity to be independent risk factors associated with high incidence of developing a SSI
2.


The Spinal Surgical Invasiveness Index (SSII) is a standardised and validated outcome measure developed by the American Association of Orthopaedic Surgeons (AAOS) that takes into account the number of vertebrae decompressed, fused, and instrumented and the approach used (anterior vs. posterior) to determine the risk of developing an SSI
3.


Role of antibiotics


Strict theatre asepsis, sterile prep and drape and prophylactic antibiotics are vital to prevent an SSI. There has been an increasing trend towards individualised antibiotic prophylaxis driven by patients’ unique characteristics than conventional gram positive cocci cover in recent times (eg, penicillin or cephalosporins)
4. With up to 6.7% of patients undergoing spinal surgery having positive urine cultures, gram negative bacilli cover is also increasingly preferred (eg, aminoglycosides). Further topical application of vancomycin powder in the wound prior to closure has been found to be very effective in reducing SSI5


Treatment


Strict vigilance, clinical evaluation and aggressive investigation by lab tests (complete blood count and differential count of white blood cells, erythrocyte sedimentation rate and C-reactive protein) guided by microbiological wound swabs and culture and sensitivity (C/S) result is the cornerstone for managing SSIs. Prolonged administration of antibiotics guided by C/S results usually suffices for the management of superficial or mild infections. However, deep and severe infections require aggressive surgical debridement and washouts and with or without suction irrigation to salvage instrumentation and maintain spinal stability. If these strategies fail, removal of all spinal implants with appropriate long-term IV antibiotics and spinal immobilisation in spica brace or cast is desired to eradicate infection.


Personal series


In a series of 304 surgeries (deformities, 128; instrumented lumbar fusions, 52; cervical spine surgeries, 46; miscellaneous [including revision surgeries], 78) over a 12-month period (July 2011–June 2012), we had three superficial infections, five deep infections, and one late and chronic infection—meaning that we had an early deep infection rate of 1.64%, which is a much lower infection rate than is reported in the literature. All five deep infections grew 
E Coli correlating with a history of faecal contamination in the postoperative period. There were no “superbug” (eg, MRSA) infections. We owe our low infection rate to meticulous soft-tissue handling with haemostasis, water-tight wound closure and individualised antibiotic prophylaxis supported by diligent nursing care by dedicated team at the Royal National Orthopaedic Hospital NHS Trust in Stanmore (UK).


NS Harshavardhana is a clinical spinal fellow and Hilali Noordeen is a consultant spinal surgeon at the Spinal Deformity Unit, Department of Spinal Surgery, Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK


References


1. Horan et al. Control Hosp Epidemiol 1993; 14: 73–80

2. Pull Ter Gunne et al. Spine 2012; [Epub ahead of print] PMID: 22565388.

3. Cizik et al. Journal of Bone & Joint Surgery (Am) 2012; 94:335–42

4. Nunez-Pereira et al. European Spine Journal 2011 (Supp 3): S394–402

5. Molinari RW et al. European Spine Journal 2012 (Supp 4): S476–82

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