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Bacilos Gram-positivos

Corynebacterium urealyticum

Short Gram-positive bacilli in palisades

Identification & Growth

Identification

  • Strongly urease-positive within minutes; lipophilic, slow-growing

Growth Conditions

  • Blood agar for 48–72 h — urine plates discarded at 24 h miss this organism

Clinical Significance

  • Encrusted cystitis and pyelonephritis with alkaline urine and struvite stones

Intrinsic Resistance

  • Multidrug-resistant, including beta-lactams and quinolones

Bench Alerts

  • Persistently alkaline urine with a 24 h 'negative' culture: reincubate up to 72 h

Clinical Notes

Clinical presentations

  • Causes alkaline-encrusted cystitis and pyelonephritis associated with struvite stone formation, due to strong urease activity.
  • Associated with urinary tract infections in renal transplant and immunocompromised patients.
  • Can cause bacteremia in patients with long-term urinary catheters.

Specimens and collection

  • Midstream or catheterized urine is the specimen of choice, with quantitative urine culture.
  • Alkaline urinary pH (>8) in the setting of dysuria should prompt extended culture specific for this organism.
  • Extended incubation (48–72h) is required due to slow growth on standard culture media.

Epidemiology and at-risk populations

  • Colonizes the skin and urinary tract of hospitalized patients with prior broad-spectrum antimicrobial use.
  • Renal transplant patients and those with prior urologic instrumentation are the classic risk group.
  • Prolonged hospitalization and indwelling bladder catheter use increase colonization and infection risk.

Resistance and therapeutic implications

  • Multidrug-resistant to most antimicrobials commonly used for urinary infection, including beta-lactams and fluoroquinolones.
  • Vancomycin is generally active and considered the treatment of choice for confirmed infection.
  • Urinary acidification and removal of encrusted calculi are important adjuncts to antimicrobial treatment.

Bench and reporting notes

  • Strong urease activity is a key biochemical feature for presumptive identification.
  • Slow-growing, lipophilic Gram-positive bacillus, similar to other diphtheroid corynebacteria.
  • Report should flag typical multidrug resistance, guiding empiric vancomycin therapy pending susceptibility results.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Corynebacterium urealyticum in the lab?

Corynebacterium urealyticum is identified through strongly urease-positive within minutes; lipophilic, slow-growing.

What are the intrinsic resistances of Corynebacterium urealyticum?

This organism is naturally resistant to multidrug-resistant, including beta-lactams and quinolones. These drugs should not be reported as susceptible.

Where is Corynebacterium urealyticum commonly found?

It is typically associated with encrusted cystitis and pyelonephritis with alkaline urine and struvite stones.

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