Abstract
Aim
To test the hypothesis that surface skin swabs taken after skin preparation with alcoholic povidone iodine (APVPI) would not grow bacteria, whereas full thickness biopsies taken from the line of surgical incision would grow bacteria.
Method
Informed consent was obtained from 44 patients undergoing primary hip (n=13) and knee (n=31) arthroplasty. Each received antimicrobial prophylaxis before skin preparation with APVPI under laminar flow. After the APVPI had dried, a skin swab and a full thickness 8mm x 4mm elliptical skin biopsy were taken from the line of incision. The skin swab was rolled in 5mL anaerobe basal broth to inactivate the APVPI, incubated at 37 degrees and checked for growth for 2 weeks. One half of the skin biopsy was snap frozen and used for gram and nitroblue tetrazolium staining. The other half was placed into 5mL of anaerobe basal broth, incubated at 37 degrees and monitored for growth for 2 weeks.
Results
Forty-four skin biopsy samples and 42 corresponding swabs were collected. Fourteen of 42 surface swabs were positive for bacteria (5 Staphylococcus epidermidis, 6 Propionibacteria acnes, 1 S. aureus, 1 S. capitis, 1 S. epidermidis and P. acnes, and 1 S. warneri and P. acnes).
Fifteen of 44 skin biopsies were positive for bacteria (7 P. acnes, 3 S. epidermidis, 1 S. aureus, 1 S. capitis, 1 Psuedomonas spp, 1 P. acnes and S. epidermidis, 1 S. edidermidis and S. capitis).
Gram positive bacteria were seen in all gram stained sections of skin and all sections of skin were positive for live bacteria when stained with nitroblue tetrazolium.
Discussion
This study shows that skin preparation with APVPI does not completely remove viable bacteria from the skin. Surgeons need to be aware of this and to adapt their surgical technique to avoid coming into contact with the patient's skin, including cut edges, when performing surgery involving implants.
