A. Yeh1, B. Firek1, J. Holder-Murray1, M. J. Morowitz1 1University Of Pittsburgh,Department Of Surgery,Pittsburgh, PA, USA
Introduction:
Wound infections after colorectal surgery occur at a rate of 5 to 30%. A potential contributor for which there is no published literature is the wound microbiome. This study will analyze the role of the skin microbiota in the development of wound infections after colorectal surgery. We will define the temporal and spatial changes of the skin microbiota in the peri-operative period and determine if specific bacterial populations or patterns of microbial diversity are predictive of wound infections.
Methods:
Peri-operative samples were obtained from adult patients undergoing colorectal surgery for cancer, diverticulitis, and IBD. Pre-operative samples included a skin swab at the anticipated site of the surgical incision. Intra-operative samples included skin swabs before and after skin preparation, subcutaneous fat of the extraction incision upon opening and prior to closing, and colon specimen contents. Post-operative samples included skin swabs and stool samples daily until discharge and at the post-operative clinic visit. Bacterial 16S rRNA gene sequences in each sample were amplified, sequenced on the Illumina MiSeq, and analyzed with QIIME. Healthy volunteer samples from the American Gut Project (AGP) were analyzed as a control.
Results:
A mean of 14.3 samples were collected from 9 patients. The average hospitalization was 5.1 days. Six, 1, and 2 patients underwent a left-sided resection, right-sided resection, and total colectomy, respectively. Species richness and evenness on the skin gradually decreased from the pre-operative clinic visit to the day of surgery after skin preparation and remained low in the post-operative period. Principal coordinates analysis comparing differences in microbial composition showed a clustering of pre-operative skin samples with healthy AGP volunteers signifying similar composition. Post-operatives skin swabs clustered distinctly from healthy samples signifying instability in microbial composition. Staphylococcus, a bacterium common in wound infections, was more abundant in the skin swabs post-operatively (see figure). Conversely, Corynebacterium, a common healthy bacterium, was decreased. One patient developed an Enterococcus wound infection. Ileostomy and skin samples prior to the wound infection showed dominance by Enterococcus, possibly signifying a predictive value of microbiota monitoring.
Conclusion:
In our preliminary results, the skin microbiota after colorectal surgery undergoes collapse of its microbial diversity and composition. During the post-operative period, pathogens such as Staphylococcus proliferate at the expense of healthy bacteria. Future work will require additional patient recruitment to determine whether these findings increase the risk of wound infections.
