Actinotignum spp

• A. sanguinis
• A. schaalii
• A. urinale 

Gram Stain

• Gram positive cocci/bacilli (anaerobic)

Clinical Significance

Actinotignum spp may be part of the urinary microbiota but have been associated with urinary tract infections especially in the elderly and young children.

A. sanguinis - associated with breast abscesses.

A. schaalii - associated with urinary tract infections (including urosepsis) in elderly patients with underlying genitourinary abnormalities.  It has also been implicated in bacteremia, osteomyelitis, prosthetic joint infections, endocarditis, prostatitis, epididymitis, and necrotizing fasciitis.

A. urinale - associated with chronic cystitis in elderly females and has been implicated in septicemia in patients with chronic renal disease.

Usual Susceptibility Pattern

These organisms are usually susceptible to penicillin, amoxicillin, ceftriaxone, tetracycline, and nitrofurantoin. 

Prolonged therapy with beta-lactam antibiotics is often necessary. 

Susceptibility to clindamycin, macrolides, fosfomycin, and TMP/SMX is variable (A. schaalii resistant to TMP/SMX).

They are often resistant to metronidazole and typically resistant to quinolones.