Chlorhexidine Gluconate Surgical Preparation is Associated with Increases in the Proportion of Streptococcus Species and Enterobacteriaceae Genera in Skin Microbiome
Sifon Ndon, AB1, Jane Xu, BA1, Tyler Rice, BS2, Biraja Dash, PhD1, Michael Alperovich, MD, MSc1, Elizabeth Grice, PhD3, Noah Palm, PhD2, Henry Hsia, MD, FACS1.
1Yale University School of Medicine Department of Plastic and Reconstructive Surgery, New Haven, CT, USA, 2Yale University School of Medicine Department of Immunobiology, New Haven, CT, USA, 3University of Pennsylvania Departments of Dermatology and Microbiology, Philadelphia, PA, USA.
Post-surgical infections are amongst the most common post-surgical complications and can cause significant morbidity and mortality for patients. This study sought to better characterize the effect of surgical skin preparation on the skin microbiome and understand how such changes may be related to surgical site infections.
Surgical site skin swabs were collected from consenting women aged years or older undergoing breast reconstructive surgery over a 2-month period at Yale New Haven Hospital. Swabs were obtained immediately prior to and approximately 1 minute after skin sterilization with ChloraPrep. Surgical sites were swabbed for 15-20 seconds with sterile cotton-tipped swabs soaked in an enzymatic lysis buffer (20mM Tris pH 8, 2nM EDTA, 1.2% Triton X-100). Swabs were placed into 1.5ml sterile Eppendorf tubes and stored at -80C until further processing. DNA was extracted using the Invitrogen Purelink Genomic DNA kit. PCR amplification of bacterial genomic DNA was done with Phusion polymerase using primers targeted to the 16S V1-V3 hypervariable regions. Bacterial genomic sequencing was performed with the Illumina MiSeq platform. A Wilcoxon Signed-Rank test was used to compare pre and post-surgical preparation skin microbiome composition with particular focus on the predominant organisms in normal skin flora.
A total of 36 samples (18 pre-prep and 18 post-prep) from 9 patients were obtained and sequenced. On average, 20 operational taxonomic units (SD 7.4) were found within each sample. In each pre-prep sample, Streptococcus species comprised an average of 1.5% (SD 0.1) and Enterobacteriaceae genera comprised an average of 4.2% (5.7) of the skin microbiome. In each post-prep sample, Streptococcus species comprised an average of 3.7% (SD 3.8) and Enterobacteriaceae genera comprised an average of 14.1% (12.6) of the skin microbiome. Wilcoxon Signed Rank test indicated that post-prep proportions were statistically significantly higher than pre-prep proportions for Streptococcus species (S= 56, p=0.0063) and Enterobacteriaceae genera (S=79.5, p<0.0001). There was no statistically significant pre- and post-prep difference in the proportion of Staphylococcus and Corynebacterium species, which are also known to be components of normal skin flora.
The use of ChloraPrep appears to have differential bactericidal/bacteriostatic effects on certain microorganisms, leading to an increase in the proportion of the overall skin microbiome comprised by Streptococcus species and members of the Enterobacteriaceae genera, both of which have been implicated in surgical site infections. Appropriate perioperative antibiotic dosing should be employed to potentially decrease the risk of such infections.
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