Related Experiment Video
Updated: May 20, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
Published on: February 9, 2011
Effect of local anesthetic on microorganisms in a murine model of surgical site infection
Valerie G Sams1, Christy M Lawson, Patricia Coan
1Department of Surgery, University of Tennessee Medical Center, Knoxville, Tennessee, USA. vsams@utmck.edu
Background:
Surgical site infections are common, with an incidence of 1.5% to 5% for all types of surgery. In vitro studies suggest an antimicrobial effect of local anesthetic. We hypothesized that subcutaneous infiltration of local anesthetic before surgical incision would reduce the incidence of postoperative wound infection.
Methods:
In a wound infection model using 4- to 6-week-old female mice, Staphylococcus aureus and Escherichia coli were inoculated in surgical wounds infiltrated with local anesthetic or saline. On day 5, the mice were killed and tissues were evaluated for viable bacterial numbers, presence of bacteria histologically, and degree of inflammation on a scale of 0 to 3 based on number and types of inflammatory cells and presence of necrosis.
Results:
A one-way between-subjects analysis of variance with Tukey honestly significant difference post hoc comparisons showed no statistically significant difference in the degree of inflammation in mice infiltrated with lidocaine, lidocaine mixed with bupivacaine, or saline (p = 0.994, p = 0.337, and p = 0.792, respectively). A Tukey honestly significant difference post hoc analysis demonstrated that the saline (p = 0.038) and lidocaine mixed with bupivacaine (p = 0.006) had significantly lower degrees of inflammation than did the lidocaine group. A Bonferroni post hoc test demonstrated that those in the lidocaine (p = 0.003) and lidocaine mixed with bupivacaine (p = 0.008) groups had significantly higher inflammation than those in the saline group after controlling for the condition of the inocula.
Conclusions:
Infiltrate, whether saline, lidocaine, or lidocaine mixed with Marcaine, did not result in significantly different bacterial presence or higher degree of inflammation when controlling for experimental condition of bacterial inocula. Thus, subcutaneous infiltration of local anesthetic before a surgical incision is made does not reduce the incidence of bacterial growth or influence the degree of inflammation which alters infection rates.
Insights
Pre-surgical local anesthetic infiltration did not reduce bacterial presence or inflammation in mouse wound models. This suggests it may not lower the incidence of postoperative wound infections.
Area of Science:
- Surgical infection research
- Anesthesiology
- Microbiology
Background:
- Surgical site infections (SSIs) affect 1.5%–5% of surgeries.
- In vitro studies suggest local anesthetics possess antimicrobial properties.
- Hypothesis: Local anesthetic infiltration before incision reduces SSIs.
Purpose of the Study:
- To investigate the effect of subcutaneous local anesthetic infiltration on bacterial presence and inflammation in a surgical wound infection model.
- To determine if pre-incisional local anesthetic administration impacts postoperative wound infection rates.
Main Methods:
- A mouse wound infection model was used, inoculating wounds with Staphylococcus aureus and Escherichia coli.
- Wounds were infiltrated with local anesthetic (lidocaine, or lidocaine with bupivacaine) or saline.
- Bacterial counts, histological presence of bacteria, and inflammation (0–3 scale) were assessed on day 5.
Main Results:
- No significant difference in bacterial presence was observed across groups.
- Inflammation levels varied: lidocaine alone showed higher inflammation than saline.
- Lidocaine with bupivacaine showed higher inflammation than saline, but lower than lidocaine alone.
Conclusions:
- Subcutaneous infiltration of local anesthetics did not reduce bacterial presence in surgical wounds.
- Local anesthetic infiltration did not significantly alter the degree of inflammation when controlling for bacterial inocula.
- Findings do not support the hypothesis that pre-incisional local anesthetic reduces bacterial growth or influences inflammation to alter infection rates.
Related Concept Videos
01:12Local Anesthetics: Adverse Effects
Once absorbed into the systemic circulation, local anesthetics can affect the organs that depend on the functioning of sodium...
01:13Local Anesthetics: Pharmacokinetics
01:25Clinical Significance of Antibiotic Resistance
01:30Local Anesthetics: Clinical Application as Surface, Infiltration, and Conduction Block Anesthesia