Related Experiment Video
Updated: Aug 16, 2026
In Vivo Mouse Model of Spinal Implant Infection
Published on: June 23, 2020
Propionibacterium acnes wound contamination at the time of spinal surgery
Gregory C McLorinan1, Josephine V Glenn, Michael G McMullan
1Department of Microbiology, School of Medicine, Queen's University, The Royal Victoria Hospital, Belfast, UK.
Unlabelled:
Bacteria of the normal skin microbiota such as Propionibacterium acnes and coagulase-negative staphylococci often are dismissed as contaminants when detected in clinical samples. Propionibacterium acnes is described as a cause of spinal infection and more recently has been linked to sciatica. To date no researchers formally have examined the incidence of bacterial wound contamination during spinal surgery. Surgical specimens were removed from 79 patients having spinal surgery for analysis using agar culture detection, broth enrichment, and immunofluorescence microscopy. Bacteria were identified in 29.1% of skin samples, 21.5% of tissue samples and 16.5% of washings retrieved from operative wounds. Propionibacterium acnes was identified more frequently than Staphylococcus spp in each of the three sample types. Bacteria were detected using enrichment in 9 (11%) patients and using fluorescence microscopy in 15 (19%). The results of immunofluorescence microscopy suggest that Propionibacterium acnes detected in wounds originates from patient skin. Bacteria from contaminated wounds appeared as single cells using fluorescence microscopy; however previous work shows that bacteria from infected hip prosthesis are observed as large aggregates. Therefore, it is suggested that immunofluorescence microscopy is a useful tool to help discriminate between surgical contamination and infection.
Level Of Evidence:
Diagnostic study, Level I (prospective study). See the Guidelines for Authors for a complete description of levels of evidence.
Insights
Bacterial contamination is common in spinal surgery wounds, with Propionibacterium acnes frequently found. Immunofluorescence microscopy can help distinguish contamination from infection by observing bacterial cell patterns.
Area of Science:
- Microbiology
- Surgical Infections
- Diagnostic Techniques
Background:
- Normal skin bacteria like Propionibacterium acnes are often overlooked as contaminants in clinical samples.
- Propionibacterium acnes is implicated in spinal infections and sciatica.
- The incidence of bacterial wound contamination during spinal surgery has not been formally studied.
Purpose of the Study:
- To investigate the incidence of bacterial contamination in surgical wounds during spinal surgery.
- To determine the types of bacteria commonly found in these wounds.
- To evaluate the utility of immunofluorescence microscopy in differentiating contamination from infection.
Main Methods:
- Prospective diagnostic study involving 79 patients undergoing spinal surgery.
- Analysis of surgical specimens (skin, tissue, washings) using agar culture, broth enrichment, and immunofluorescence microscopy.
- Comparison of bacterial detection methods and morphological characteristics (single cells vs. aggregates).
Main Results:
- Bacteria were detected in 29.1% of skin samples, 21.5% of tissue samples, and 16.5% of wound washings.
- Propionibacterium acnes was identified more frequently than Staphylococcus spp. across all sample types.
- Immunofluorescence microscopy detected bacteria in 19% of samples and suggested skin origin, with single cells indicating contamination.
Conclusions:
- Bacterial contamination is a significant finding in spinal surgery wounds.
- Propionibacterium acnes is a prevalent contaminant originating from the patient's skin.
- Immunofluorescence microscopy shows promise as a tool to differentiate surgical wound contamination from infection based on bacterial morphology.
