Human Cellulosimicrobium Infections: A Clinically Oriented Review of Diagnostic and Therapeutic Challenges

Cellulosimicrobium species, formerly classified within the genus Oerskovia, are environmental Gram-positive filamentous bacilli that rarely cause human infection. Their clinical significance may be underestimated because coryneform Gram-positive rods are frequently interpreted as contaminants in routine cultures. Publications on human infections are dominated by case reports and small case series, most often involving bloodstream infection, infective endocarditis, osteoarticular infection, peritoneal dialysis-associated peritonitis, and endophthalmitis. Reported cases commonly occur in patients with immunosuppression, malignancy, renal replacement therapy, prosthetic cardiac valves, central venous catheters, or other foreign material. Cellulosimicrobium cellulans and its former name Oerskovia xanthineolytica account for most described infections. Diagnostic confirmation usually requires careful interpretation of repeated positive cultures, isolation from sterile sites, and reliable identification using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry or 16S ribosomal ribonucleic acid gene sequencing when available. Therapeutic evidence remains limited, but vancomycin and trimethoprim-sulfamethoxazole generally retain in vitro activity, whereas resistance to beta-lactams and clindamycin has been reported. Management should combine species-level identification, susceptibility testing, appropriate antimicrobial therapy, and source control, including removal of infected devices whenever feasible.