Cutibacterium acnes remains within the dermis of the scalp after use of standard prophylactic measures among patients undergoing cranial neurosurgical intervention, investigators reported in a study published in the Journal of Clinical Neuroscience.

The prospective, observational study included consecutive patients at a center in Australia who received 2 g of intravenous cefazolin 30 minutes before skin incision. The skin was prepared with 200 mL of alcoholic betadine solution, which was allowed to dry for 5 minutes before surgery.

The patients had 3 swabs taken—1 before prepping the skin with alcoholic betadine (pre-prep), 1 after prepping the skin (post-prep), and a dermal swab after the skin was incised.


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A total of 73 patients (mean age, 57 years [range, 18-81]; 37men) were included from October 2019 to March 2021. Of the cohort, 66 patients had a primary cranial intervention and 7 had a revision surgery.

C acnes was cultured from 127 of 219 samples—83.5% of patients in the pre-prep group, 16.5% of patients the post-prep group, and 27.4% from dermal swabs.

C acnes dermal swabs were positive in 71.2% of the primary cranial intervention patients and in 85.7% of the revision surgery patients. A significant reduction of positive skin cultures was observed after application of the surgical preparation (12 positive from 61, P <.00001).

Among the 86.9% of patients with a positive pre-prep swab, 53 had C acnes in the dermal swab and 77.4% had a positive pre-prep swab with a negative post-prep swab followed with a positive dermal swab. A nonsignificant reduction of positive cultures was found in the dermal swabs after skin preparation (53 positive from 61, P =.109).

The primary study limitation was the absence of long-term follow-up in the participants.

“After prophylactic antibiotic administration and preparation of skin with an alcoholic betadine solution, there is a significant reduction in the rate of positive C. acnes cultures from the skin surface,” stated the researchers. “However, viable C. acnes is still frequently found within the dermis of the scalp despite these prophylactic measures. Whether a change in prophylactic antibiotics would reduce the amount of positive dermal swabs and reduce the risk of C. acnes infections in cranial surgery should be investigated in a prospective randomized trial.”

Reference

Nowicki J, Mills M, Van Der Veken J, Pantelis I, Daniels S, Poonnoose S. The effectiveness of prophylactic antibiotics and betadine skin preparation on cranial cutaneous Cutibacterium acnes—a prospective study.