Bacterial shedding in common spine surgical procedures: Headlamp/loupes and the operative microscope

STUDY DESIGN. Simulated discectomy was performed using 1) headlamp/loupes, 2) the operative microscope, or 3) neither; and bacterial shedding was assessed using air sampler/settle plate techniques. OBJECTIVES. To determine the potential contribution of these 2 commonly used systems of magnification/ illumination to postoperative infection by using a controlled, experimental setting to limit confounding factors. SUMMARY OF BACKGROUND DATA. Postoperative infections following surgery on the degenerative lumbar spine generally range from 0.6% to 6%. Headlamp/loupes and the operative microscope may contribute to potential infection, but, to date, the contribution to shedding rates while using these tools has not been assessed. METHODS. Seventy samples from simulated discectomies within the usual sterile operative setting were collected using a 2-stage air sampler/settle plate technique. Group 1 (30 samples) used the operative microscope, Group 2 (30 samples) used headlamp/loupes, and Group 3 (10 samples) used neither as a control. Collected samples were examined for bacterial growth using blood agar plates and were assessed qualitatively and quantitatively. RESULTS. Greater than half of the collected samples in Groups 1 and 2 demonstrated bacterial growth with coagulase negative Staphylococcus being found in nearly all positive samples and secondary species being common. No statistical differences between the 2 groups were noted for number of samples with growth, species of bacterial growth, number with growth of secondary species, or colony counts. Both groups demonstrated significantly greater number of samples with growth relative to the control Group 3. CONCLUSIONS. The use of headlamp/loupes or the operative microscope is associated with bacterial shedding. Proper techniques of cleaning, storage, and draping should be used to minimize their contribution to potential postoperative infection. No significant difference was noted between the 2 test groups, suggesting that infection risk should not come into play when choosing techniques of illumination/ magnification.