Actinomyces in infected osteoradionecrosis--underestimated?

Area of Science:

• Oral and Maxillofacial Surgery
• Infectious Diseases
• Oncology

Background:

• Infected osteoradionecrosis (IORN) is a serious complication following radiation therapy for head and neck cancers.
• Irradiated bone is susceptible to infection, primarily by Candida species and cariogenic bacteria, with limited data on Actinomyces involvement.
• IORN can lead to fractures and necessitate jaw resection.

Purpose of the Study:

• To investigate the prevalence and characteristics of Actinomyces in patients with infected osteoradionecrosis.
• To determine the association of Actinomyces with clinical and histopathological findings in IORN.

Main Methods:

• Histological examination using multiple staining techniques (hematoxylin-eosin, Gram, Grocott, PAS) was performed on tissue samples from 31 IORN patients.
• Semi-nested polymerase chain reaction (PCR) targeting the 16S ribosomal RNA gene was used to detect Actinomyces DNA.
• Clinical and radiological signs of IORN were assessed in all participants.

Main Results:

• Actinomyces colonies were identified in 64.5% (20/31) of patients, predominantly in the mandible (16/20).
• Actinomyces were consistently found attached to necrotic bone.
• PCR confirmed the presence of Actinomyces DNA, including Actinomyces israelii.

Conclusions:

• Actinomyces is significantly more prevalent in IORN than previously recognized.
• The study suggests Actinomyces plays a role in the chronic inflammation and purulent discharge characteristic of IORN.
• Histopathological detection of Actinomyces is crucial due to its association with prolonged treatment duration and potential involvement in osteolytic mechanisms.