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Involvement of resistant bacteria in the severity of refractory osteonecrosis of the jaw

Junya Kusumoto1,2, Yumi Muraki3, Eiji Iwata3,4

  • 1Department of Oral and Maxillofacial Surgery, Kobe University Graduate School of Medicine, Kobe, Japan. chivalry_2727@dent.kagoshima-u.ac.jp.

Clinical Oral Investigations
|September 16, 2025
PubMed
Abstract

Insights

This study identified bacteria in osteonecrosis of the jaw (ONJ), finding similar microbes to odontogenic infections but more gram-negative rods. Ampicillin-resistant bacteria, like Enterobacter spp., are linked to severe ONJ cases.

Area of Science:

  • Oral and Maxillofacial Surgery
  • Infectious Diseases
  • Microbiology

Background:

  • Osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ) are challenging conditions with unclear bacterial associations.
  • A lack of consensus exists regarding the specific bacteria contributing to the development of refractory ORN and MRONJ.

Purpose of the Study:

  • To identify bacteria associated with refractory osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ).
  • To investigate bacterial factors contributing to severe cases of ORN and MRONJ.

Main Methods:

  • Bacterial cultures were obtained from deep tissue samples of patients undergoing surgery for osteonecrosis of the jaw.
  • Severe ORN and MRONJ cases were classified using established staging systems (Lyon's stage IV and AAOMS stage III, respectively).
  • Demographic data, clinical features, antimicrobial use, and detected bacteria were analyzed to identify factors associated with disease severity.

Main Results:

  • 311 bacterial strains were identified in 100% of the 77 analyzed patients (22 ORN, 55 MRONJ).
  • Streptococcus spp. (37.0%) and anaerobes (33.8%) were the most prevalent bacteria. Antimicrobial-resistant bacteria were detected in 78.4% of cases.
  • Ampicillin resistance and malignancy were significantly associated with severe MRONJ (OR 8.74 and 13.5, respectively). Enterobacter spp. were exclusively found in severe cases.

Conclusions:

  • The bacterial composition in osteonecrosis of the jaw mirrors common odontogenic infections but exhibits a higher prevalence of gram-negative rods.
  • Ampicillin-resistant bacteria, notably Enterobacter spp., play a role in the pathogenesis of severe osteonecrosis of the jaw.
Keywords:
AmpicillinAntimicrobial resistanceGram-negative rodMedication-related osteonecrosis of the jawMicroorganismOsteoradionecrosis of the jaw

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