# Molecular Genetic Analysis of Perioperative Colonization by Infection-Related Microorganisms in Patients Receiving Intraoral Microvascular Grafts

## TL;DR

This study examines how bacteria colonize oral microvascular grafts after surgery and how antibiotic use affects these changes.

## Contribution

The study reveals postoperative microbial shifts and the impact of antibiotic treatment on oral microbiome adaptation.

## Key findings

- Infection-related bacteria like Pseudomonas aeruginosa and Enterobacteriaceae increased post-surgery without causing clinical infection.
- Streptococcus mitis decreased on buccal mucosa but increased on graft surfaces, indicating oral dysbiosis.
- Ampicillin/sulbactam treatment reduced or displaced Streptococcus mitis, promoting other bacteria like Mycoplasma salivarium.

## Abstract

Background/Objectives: In oral and maxillofacial surgery, the reconstruction of defects often involves the transfer of skin tissue into the oral cavity utilizing microvascular grafts. This study investigates postoperative changes in microbial colonization following intraoral microvascular transplantation, as well as potential influencing factors. Methods: In 37 patients undergoing intraoral reconstructions, pre- and postoperative swabs were taken from the donor and recipient regions to quantify the seven selected marker bacteria using TaqMan PCRs. Patient-specific factors and clinical data were also recorded. Results: The infection-associated Acinetobacter baumannii tended to decrease postoperatively, while the infectious pathogens Pseudomonas aeruginosa, Enterococcus faecalis and the family of Enterobacteriaceae showed a postoperative increase without being directly associated with a clinical infection. Streptococcus mitis showed a significant postoperative decrease on buccal mucosa and increase on the graft surface (oral dysbiosis) and was significantly reduced or displaced by other bacteria (e.g., Mycoplasma salivarium, positive selection) when treated with ampicillin/sulbactam. Conclusions: The cutaneous microbiome of the graft adapts to the local intraoral environment. Postoperative shifts in oral bacterial colonization and an increase in infection-relevant bacteria were observed. These perioperative changes in colonization are also influenced by the administration of ampicillin/sulbactam. Consequently, single doses of antibiotics appear to be more beneficial compared to longer-term preventive use.