| Organism | Gram stain | Catalase | Colony morphology | Infection sites | Normal habitat |
| Corynebacterium | Straight or irregular shaped Gram-positive (GP) rods in single, pairs, V-shapes, or “Chinese letters” | Positive | Various smooth to rough, dry to sticky most are cream, white, or pale yellow | Have been implicated in multiple sterile sites and chronic wounds or ulcers | Human microbiota, some have animal or soil reservoirs |
| Arcanobacterium | Slender, irregular, GP rods become granular with age | Negative (distinguishing feature) | A. haemolyticum is β-hemolytic, small, white, growth enhanced in CO2 | Smooth colonies found in wounds and rough colonies found in respiratory infections | Human microbiota |
| Arthrobacter | GP rod to cocci with age | Positive | Whitish, gray some species may be yellow to dark rose-red | Urine, wounds, and blood | Soil, raw milk, eggs, and ready to use vegetables |
| Brevibacterium | Irregular GP rods | Positive | Small, opaque, can produce colors from cream to dark red | Catheter-associated bloodstream infections, endocarditis, surgical site infections | Found most often in cheese |
| Cellulomonas | Small, thin GP rod (may appear Gram-negative) | Positive | Small yellow | Sepsis, cholecystitis | Can break down cellulose found primarily in soil |
| Cellulosimicrobium | GP coryneform occasional branching | Positive | Glistening yellow, penetrates into agar | Device associated infections, endocarditis | Found in soil also used to treat soybean meal to make it easier to digest |
| Dermabacter | GP short rods to coccoid | Positive | White, creamy, or dry may resemble coagulase-negative Staphylococcus | Associated with hospital-acquired infections, blood, abscesses, wounds | Human microbiota found primarily on skin and GI tract |
| Leifsonia | GP short rods | Positive | Yellow pigmented, oxidase-positive and can be motile | Hemodialysis patients with bacteremia | Associated with water |
| Microbacterium | Slender, irregular GP rods | Positive | Opaque, glistening often yellow to orange | Catheter-associated bloodstream infections, eye infections due to trauma | Found in soil and cheese |
| Oerskovia | GP branching filaments that fragment into motile rods | Positive | Glistening, small, yellow | Infections due to indwelling devices primarily in immunosuppressed, endocarditis, or infections following traumatic injury | Soil, water, decaying plants |
| Rothia (not mucilaginosa) | GP coccoid, can be filamentous | Positive | Creamy white, rough or smooth colonies | Endocarditis, periodontal disease, pneumonia in immunocompromised | Often found in oral cavity |
| Trueperella | GP coccobacillary to short rods | Negative (distinguishing feature) | Smooth, glassy colonies | Blood and abscess infections | May be found in human respiratory tract, some are zoonotic |
| Turicella | Irregular, long diphtheroid GP rods | Positive | White to cream colonies (strong CAMP positive) | Middle ear infections and bacteremia | Found also in healthy middle ear fluid |
