Backgrounds: Surgical site infections (SSIs) represent one of the most common and potentially preventable sources of morbidity and healthcare cost escalation associated with skin cancer surgery. There is a lack of data reporting organisms cultured from SSIs in skin surgery, with guidelines for antibiotic prophylaxis based on common skin pathogens rather than actual cultured organisms. In this study, we sought to define the cultured microbiology of SSIs specific to skin cancer surgery and test these against empiric treatment guidelines. Methods: All consenting patients presenting to the Auckland regional skin cancer treatment centre over a 6-month period were included. Patients receiving any form of antibiotics within a week prior to surgery were excluded. All wounds were assessed postoperatively, with clinically significant infections identified as those with a standardized wound infection score of 4 (range 0-7) and/or prescribed post-operative antibiotics within 3 weeks of surgery. Wound cultures were recorded. Results: About 104 clinically significant SSIs were identified from 333 lesions treated, with cultures available in 27%. Cultured organisms included MSSA (79%), MRSA (14%), coagulase-negative Staphylococci (11%), and 'skin flora' (14%). Empiric guidelines inaccurately predicted effective treatment in 14% of cases, exclusively due to MRSA. Conclusion: To our knowledge this is the first comprehensive report of SSI microbiology following skin cancer surgery. The overwhelmingly predominant organisms were Staphylococcus sp. (76%), with the rate of MRSA approaching prevalence warranting empiric firstline treatment. These data help inform effective rationalized empiric antibiotic treatment, when indicated, for optimal outcome following skin surgery.

ImportanceSurgical site infections (SSIs) represent a costly and preventable complication of cutaneous surgery. However, there is a paucity of randomized clinical trials investigating antibiotic prophylaxis for reducing SSIs in skin cancer surgery, and evidence-based guidelines are lacking. Incisional antibiotics have been shown to reduce the rate of SSIs before Mohs micrographic surgery, but this represents a small subset of skin cancer surgery.ObjectiveTo determine whether microdosed incisional antibiotics reduce the rate of SSIs before skin cancer surgery.Design, Setting, and ParticipantsIn this double-blind, controlled, parallel-design randomized clinical trial, adult patients presenting to a high-volume skin cancer treatment center in Auckland, New Zealand, for any form of skin cancer surgery over 6 months from February to July 2019 were included. Patient presentations were randomized to one of 3 treatment arms. Data were analyzed from October 2021 to February 2022.InterventionsPatients received an incision site injection of buffered local anesthetic alone (control), buffered local anesthetic with microdosed flucloxacillin (500 µg/mL), or buffered local anesthetic with microdosed clindamycin (500 µg/mL).Main Outcomes and MeasuresThe primary end point was the rate of postoperative SSI (calculated as number of lesions with SSI per total number of lesions in the group), defined as a standardized postoperative wound infection score of 5 or more.ResultsA total of 681 patients (721 total presentations; 1133 total lesions) returned for postoperative assessments and were analyzed. Of these, 413 (60.6%) were male, and the mean (SD) age was 70.4 (14.8) years. Based on treatment received, the proportion of lesions exhibiting a postoperative wound infection score of 5 or greater was 5.7% (22 of 388) in the control arm, 5.3% (17 of 323) in the flucloxacillin arm, and 2.1% (9 of 422) in the clindamycin arm (P = .01 for clindamycin vs control). Findings were similar after adjusting for baseline differences among arms. Compared with lesions in the control arm (31 of 388 [8.0%]), significantly fewer lesions in the clindamycin arm (9 of 422 [2.1%]; P < .001) and flucloxacillin (13 of 323 [4.0%]; P = .03) arms required postoperative systemic antibiotics.Conclusions and RelevanceThis study evaluated the use of incisional antibiotics for SSI prophylaxis in general skin cancer surgery and compared the efficacy of flucloxacillin vs clindamycin relative to control in cutaneous surgery. The significant reduction in SSI with locally applied microdosed incisional clindamycin provides robust evidence to inform treatment guidelines in this area, which are currently lacking.Trial Registrationanzctr.org.au Identifier: ACTRN12616000364471

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