[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/) › Other coryneforms and Cutibacterium

# Other coryneforms and Cutibacterium

- Bacterium

## Gram-positive?

Thick peptidoglycan wall: stains purple.

- Exam priority: medium

Skin and environmental bacteria shaped like clubs; usually harmless, they infect catheters, prosthetic joints and immunocompromised patients.

Updated Nov 13, 2026

Also called: Corynebacterium jeikeium, Corynebacterium striatum, Corynebacterium ulcerans, Cutibacterium acnes (formerly Propionibacterium acnes), Rhodococcus equi

## Quick facts

**Type**
Bacterium · [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

**Gram / shape**
Gram-positive · Club-shaped or pleomorphic rods in V shapes

**Spread**
C · Rhodococcus

**Causes**
Catheter-related bacteraemia · Acne vulgaris

**Treatment**
C

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Diphtheroids in blood are usually contamination, but C. jeikeium and C. striatum in a neutropenic patient with a catheter are real.
- C. jeikeium and C. striatum: multidrug-resistant; vancomycin is the reliable drug.
- Prosthetic shoulder infection years after surgery: Cutibacterium acnes; hold cultures up to two weeks.
- C. ulcerans from pets can make diphtheria toxin.
- HIV with an upper-lobe cavity and weakly acid-fast rods from soil with horse manure: Rhodococcus equi.

## At a glance

**Gram**
Gram-positive

**Shape**
Club-shaped or pleomorphic rods in V shapes and palisades

**Oxygen**
Corynebacterium and Rhodococcus aerobic or facultative; Cutibacterium anaerobic and slow-growing

**Family**
Corynebacteriaceae, Propionibacteriaceae, Nocardiaceae (Rhodococcus)

**Stain**
Rhodococcus can be weakly acid-fast

## Morphology

- Non-spore-forming Gram-positive rods arranged like Chinese letters or palisades
- Rhodococcus equi: coccoid to rod forms with salmon-pink mucoid colonies
- Cutibacterium acnes: slow-growing anaerobic rod that may need up to two weeks of culture

## Transmission

- Endogenous skin flora entering through catheters, surgery or prosthetic material
- C. ulcerans: contact with pets (dogs, cats) or farm animals and raw milk
- Rhodococcus: inhalation of soil contaminated with horse or other herbivore manure

**Reservoir:** Human skin and mucous membranes (C. jeikeium, C. striatum); sebaceous skin of the shoulder, face and back (C. acnes); Dogs, cats and cattle (C. ulcerans); Soil and herbivore manure (Rhodococcus)

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Biofilm on catheters and prosthetic joints
- C. ulcerans can carry the diphtheria toxin gene
- Rhodococcus survives and multiplies inside macrophages
- C. acnes drives inflammation in blocked sebaceous follicles

## Diseases it causes

- Catheter-related bacteraemia in patients with blood cancers and neutropenia (C. jeikeium, C. striatum) [Febrile neutropenia →](https://durgical.com/en/conditions/febrile-neutropenia/)
- Prosthetic valve and device endocarditis [Infective endocarditis →](https://durgical.com/en/conditions/infective-endocarditis/)
- Indolent prosthetic shoulder and joint infection after surgery (C. acnes) [Surgical site infection →](https://durgical.com/en/conditions/surgical-site-infection/)
- Acne vulgaris (C. acnes) [Acne vulgaris →](https://durgical.com/en/conditions/acne-vulgaris/)
- Diphtheria-like illness of throat or skin from toxigenic C. ulcerans [Diphtheria →](https://durgical.com/en/conditions/diphtheria/)
- Cavitary pneumonia in people with advanced HIV or transplants (Rhodococcus equi) [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Clinical picture

- Often dismissed as contaminants; repeated positive cultures with signs of infection mean true infection
- Prosthetic shoulder infection: pain and stiffness months or years after surgery, with normal blood markers
- Rhodococcus: subacute upper-lobe cavity that can resemble tuberculosis

## Diagnosis

- Two or more positive blood cultures drawn from separate sites support true bacteraemia
- Species identification by MALDI-TOF mass spectrometry and susceptibility testing
- Several periprosthetic tissue samples with anaerobic culture held 10–14 days for C. acnes
- Toxin testing of C. ulcerans at a reference laboratory
- Rhodococcus: weakly acid-fast stain and pink colonies from sputum or blood

## Treatment

C. jeikeium and C. striatum are often multidrug-resistant and are treated with vancomycin (linezolid as an alternative) plus catheter removal; C. acnes prosthetic infection needs surgery plus a beta-lactam such as penicillin; toxigenic C. ulcerans is managed like diphtheria (penicillin or erythromycin, antitoxin when indicated); Rhodococcus needs combination therapy (for example vancomycin or a carbapenem with rifampicin, a macrolide or a fluoroquinolone).

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Vancomycin](https://durgical.com/en/pharmacology/vancomycin/)
- [Linezolid](https://durgical.com/en/pharmacology/linezolid/)
- [Benzylpenicillin (penicillin G)](https://durgical.com/en/pharmacology/benzylpenicillin/)
- [Erythromycin](https://durgical.com/en/pharmacology/erythromycin/)
- [Rifampicin](https://durgical.com/en/pharmacology/rifampicin/)
- [Doxycycline](https://durgical.com/en/pharmacology/doxycycline/)

## Prevention

- Catheter care bundles and skin antisepsis before surgery
- Diphtheria toxoid vaccination also protects against toxin from C. ulcerans
- Antiretroviral therapy prevents Rhodococcus disease in HIV

**Vaccine:** No vaccine for these organisms; diphtheria toxoid vaccines (in Colombia's PAI schedule) protect against toxin-mediated disease from toxigenic C. ulcerans.

## Memory aid

«The cousins of diphtheria»: J for jeikeium and Junk drugs (resists almost all), S for striatum and the Ship of catheters, A for acnes and the Arthroplasty shoulder, U for ulcerans and the Uncle's dog, R for Rhodococcus and the Riding stable.

## Test yourself

Think of the answer, then tap the question to see it.

## Which coryneform is a classic multidrug-resistant cause of catheter bacteraemia in neutropenic patients?

Corynebacterium jeikeium (and C. striatum); vancomycin is the reliable drug.

## Why should cultures for prosthetic shoulder infection be kept for up to two weeks?

Cutibacterium acnes grows slowly and anaerobically, so short incubation misses it.

## Which coryneform transmitted by pets can produce diphtheria toxin?

Corynebacterium ulcerans.

## Which organism causes cavitary pneumonia in advanced HIV and is linked to horse manure?

Rhodococcus equi, a weakly acid-fast rod with pink colonies.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/other-coryneforms-and-cutibacterium/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 4

- [Corynebacterium diphtheriae](https://durgical.com/en/microbiology/corynebacterium-diphtheriae/)
- [Staphylococcus epidermidis](https://durgical.com/en/microbiology/staphylococcus-epidermidis/)
- [Nocardia](https://durgical.com/en/microbiology/nocardia/)
- [Mycobacterium tuberculosis](https://durgical.com/en/microbiology/mycobacterium-tuberculosis/)

## Related conditions 6

- [Febrile neutropenia](https://durgical.com/en/conditions/febrile-neutropenia/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)
- [Surgical site infection](https://durgical.com/en/conditions/surgical-site-infection/)
- [Acne vulgaris](https://durgical.com/en/conditions/acne-vulgaris/)
- [Diphtheria](https://durgical.com/en/conditions/diphtheria/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

[← Back to the group: Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Clinical Characteristics of Corynebacterium Bacteremia Caused by Different Species, Japan, 2014–2020](https://wwwnc.cdc.gov/eid/article/27/12/21-0473) (Emerging Infectious Diseases (CDC), 2021); [Notes from the Field: Toxigenic Corynebacterium ulcerans in Humans and Household Pets — Utah and Colorado, 2022–2023](https://www.cdc.gov/mmwr/volumes/73/wr/mm7323a3.htm) (MMWR (CDC), 2024); [A Literature Review of Cutibacterium Acnes: From Skin Commensal to Pathogen in Shoulder Surgery](https://pmc.ncbi.nlm.nih.gov/articles/PMC11478100/) (Cureus, 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/other-coryneforms-and-cutibacterium/