From the Research
Actinobaculum shaalii, now reclassified as Actinotignum schaalii, is a gram-positive, rod-shaped bacterium that should be considered a potential urinary tract pathogen, particularly in elderly patients and those with underlying urological conditions, and treated with beta-lactam antibiotics, such as amoxicillin, as first-line therapy. This bacterium is part of the normal human flora, primarily found in the genitourinary tract, and can cause urinary tract infections, bacteremia, and occasionally more serious infections like endocarditis or abscess formation 1. Diagnosis is challenging as it requires special culture conditions, growing slowly and requiring extended incubation in an anaerobic or CO2-enriched environment, which can lead to underdiagnosis if not properly considered by clinicians 2.
Some key points to consider when dealing with suspected A. schaalii infections include:
- The bacterium is generally susceptible to penicillins but may show resistance to ciprofloxacin and trimethoprim 1
- Treatment typically involves beta-lactam antibiotics, with amoxicillin or amoxicillin-clavulanate being first-line choices at standard doses for 7-14 days depending on infection severity 1
- Alternatives include cephalosporins, fluoroquinolones, or trimethoprim-sulfamethoxazole, but the choice of antibiotic should be guided by susceptibility testing when possible 3
- Clinicians should communicate with the microbiology laboratory to ensure appropriate culture techniques and consider this pathogen in recurrent or treatment-resistant urinary tract infections, especially in elderly or immunocompromised patients 2, 1
The incidence of A. schaalii infections may be higher than previously reported, particularly in elderly populations, and it is essential to be aware of its potential as a cause of urinary tract infections and other more severe infections 3. By considering A. schaalii as a potential pathogen and using appropriate diagnostic and treatment strategies, clinicians can improve outcomes for patients with this infection.