Comorbidity

Medical comorbidities are associated with an increased risk for superficial and deep infection. As well as the individual comorbidities associated with the specific illness, limited mobility, inability to sit, recurrent respiratory infections, copious secretions, and urinary and bowel incontinence all adversely affect infection rates. Patients with poor social care and community support are also at increased risk for infection. These risk factors are more prevalent in patients with syndromic and neuromuscular scoliosis, who remain at higher risk for infection than those with idiopathic scoliosis, even after preoperative optimization.

Coagulase-negative Staphylococcus is the most common colonizing organism overall in pediatric patients undergoing deformity surgery. However, in patients with neuromuscular disease, Pseudomonas, Escherichia coli, and Enterococcus are more prevalent. Propionibacterium acnes, a gram-positive rod associated with acne, is increasingly recognized as another infecting organism. P. acnes grows slowly, and extended culture (≥6 days) is often required.

Poor Nutrition

Patients who are undernourished have a decreased immune capability and are predisposed to infection. A patient’s height and weight should be plotted on a growth chart preoperatively. For patients whose weight is in a low centile, pre- and postoperative nutritional support should be considered. Patients with a high body mass index and significant adipose tissue also have an increased risk of infection.

Multiple Surgical Procedures

Multiple surgical procedures, such as are required in patients with growing rods, expose patients to an increase risk for surgical site infection because of sequential exposures, wound healing, and scarring. Techniques that minimize the number of surgical procedures should be associated with a reduced infection rate. Prominent implants, poor soft tissue repair, and inadequate coverage all predispose to infection.

Antibiotics

Perioperative antibiotics reduce the risk for infection. Antibiotics are routinely administered at the induction of anesthesia and continued for 24 hours. In patients with syndromic and early onset scoliosis, microbiological prophylaxis may need to be modified to cover the different organisms encountered. The use of topical antibiotics in the surgical field is becoming more widespread in spine surgery, but currently the evidence of its effectiveness is not clear.

Skin Preparation

Surgical skin preparation and bio-occlusive drapes impregnated with iodine appear to reduce skin site infection. The effectiveness of the use of topical glues to reduce bacterial load at the skin edges remains unproven.

Laminar Flow

Operating theaters with laminar flow and a high rate of air exchange have lower bacterial counts than do conventional theaters. Reducing operating room traffic, staff numbers, and turnover reduces bacterial counts in the airflow.

Bleeding and Hematoma Formation

Significant bleeding and hematoma formation make the soft tissues susceptible to secondary bacterial infection. Whether suction drainage reduces infection rates by reducing hematoma formation or increases infection rates by acting as a contaminating source of infection of deep spinal metalwork by superficial skin flora is controversial.

Recognition

Larger curves (both preoperatively and postoperatively), greater blood loss, longer procedures, allogeneic transfusions, skin breakdown, and poor healing are all associated with higher infection rates. The differentiation between a superficial and a deep wound infection is important in all aspects of management. Should deep contamination be suspected, then urgent intervention is required. Inflammatory markers are raised in the postoperative period, but persistently raised markers or increasing levels of markers are indicative of infection. Spinal imaging studies, such as ultrasound, may show collections of fluid in the surgical field. Magnetic resonance (MR) imaging and computed tomography (CT) are both affected by implants but again may show collections and abscess formation. CT scans will often identify implant loosening, which can be challenging for MR imaging.