Vertebral osteomyelitis caused by the novel pathogen Cutibacterium modestum: a case report

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Clinical Diagnostics

Background:

• Cutibacterium modestum is one of five species within the Cutibacterium genus.
• While Cutibacterium acnes is a known pathogen in bone and joint infections, C. modestum's clinical role remains largely uncharacterized.
• This report presents the first clinical case of C. modestum infection.

Observation:

• An 82-year-old male presented with fever and worsening lower back pain, indicative of vertebral osteomyelitis.
• Initial antibiotic treatment was ineffective, and Gram-positive rods were detected late in anaerobic blood and pus cultures.
• Diagnostic imaging revealed vertebral bone destruction at L4-L5 and intervertebral disc lesions.

Findings:

• The patient was diagnosed with vertebral osteomyelitis caused by Cutibacterium modestum.
• Identification was achieved through a combination of MALDI-TOF MS, biochemical tests, and 16S rRNA gene sequencing.
• The isolate demonstrated high susceptibility to ampicillin (MIC 0.016 μg/mL).

Implications:

• Cutibacterium modestum can cause significant bone and joint infections.
• Accurate identification of C. modestum requires specialized techniques beyond standard aerobic cultures.
• This case highlights the importance of considering unusual pathogens and utilizing advanced diagnostics for difficult-to-identify microorganisms.