Pseudoglutamicibacter cumminsii in outpatient samples: analysis of isolates and antimicrobial susceptibility.

Introduction: Pseudoglutamicibacter cumminsii is an aerobic, Gram-positive coryneform bacterium whose clinical relevance has not yet been clearly established. Although an increasing number of isolates have been documented in clinical settings, its role in human pathogenesis remains uncertain and warrants further characterization.

Methods: We retrospectively analyzed 116 P. cumminsii isolates obtained from symptomatic outpatients in the Rhine-Ruhr metropolitan area (Germany) between January 2021 and February 2023. Clinical and demographic data, specimen types, and co-isolated organisms were recorded. Antimicrobial susceptibility testing (AST) was performed using broth microdilution, and results were interpreted according to EUCAST guidelines.

Results: Most isolates were recovered from urine (58.6%) and wound swabs (30.2%), primarily from older adults. A statistically significant association was found between specimen type and patient sex and age. While P. cumminsii was usually detected in polymicrobial cultures (75%), two pure-culture cases were identified: one in urine and one in synovial fluid. AST revealed high susceptibility to beta-lactams and linezolid, with variable response to fluoroquinolones.

Conclusions: P. cumminsii is a rare opportunistic pathogen with potential clinical relevance in urogenital and wound infections. Its low pathogenicity suggests it is more likely a secondary colonizer or commensal. Further studies are needed to better understand its clinical significance and impact on human health.