Emery Haley, PhD, Scientific Writing Specialist
Klebsiella oxytoca
Clinical Summary
- K. oxytoca is recognized as a classical, urease-positive, gram-negative, biofilm-forming, uropathogen.
- K. oxytoca is primarily associated with recurrent UTIs and complicated UTIs in individuals with risk factors such as such as pregnancy, immunocompromise, multimorbidity, or urinary tract abnormalities.
- In symptomatic UTI patients, K. oxytoca:
- Is not a contaminant (is found in catheter-collected urine specimens).
- Is viable (can grow out on culture).
- Is pathogenic (associated with elevated urine biomarkers of infection).
- Reported severe complications of K. oxytoca UTI include emphysematous cystitis, pyelonephritis, bacteremia, spondylodiscitis, urosepsis, and death.
- Multidrug-resistant K. oxytoca is a significant and global health threat.
Bacterial Characteristics
Gram-stain
Gram-negative
Morphology
Bacillus
Growth Requirements
Non-fastidious (grows well in standard urine culture conditions)
Facultative anaerobe
Nitrate Reduction
Yes
Urease
Positive
Biofilm Formation
Yes
Pathogenicity
Colonizer or Pathobiont
Clinical Relevance in UTI
K. oxytoca is a urease-positive,[1] gram-negative, biofilm-forming, microorganism classically recognized as a uropathogen.
In preclinical studies of UTI, K. oxytoca exhibited the ability to adhere to epithelial cells of the bladder, and this ability was enhanced in the presence of E. coli, E. cloacae, Staphylococcus species, and other Klebsiella species.[2] Persistent and/or recurrent K. oxytoca UTIs are typically attributed to the epithelial adherence and biofilm formation abilities of K. oxytoca coupled with innate and acquired resistance to several antibiotics.[3–5] K. oxytoca is also a frequent cause of complicated UTI in both children and adults with risk factors such as pregnancy, immunocompromise, multimorbidity, or urinary tract abnormalities.[4]
In a study of older adult males and females with clinically suspected complicated UTI, K. oxytoca was detected in both midstream voided and in-and-out-catheter collected specimens indicating that it was truly present in the bladder, not simply a contaminant picked up during voiding.[6] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which K. oxytoca was detected, indicating that the presence of K. oxytoca was associated with an immune response to urinary tract infection.[7–9]
The World Health Organization (WHO) has included third-generation-cephalosporin-resistant and carbapenem-resistant Enterobacterales, including K. oxytoca, in the “critical” group of the 2024 Bacterial Priority Pathogens List (BPPL).[10] Severe reported complications of K. pneumoniae UTI include emphysematous cystitis, pyelonephritis, bacteremia, spondylodiscitis, urosepsis, and death.[11–13]
Together, these findings indicate that K. oxytoca should be seriously considered as a uropathogen and demonstrate the value of detecting this organism in both children and adults experiencing recurrent UTI or with risk factors for complicated UTI, such as pregnancy, immunocompromise, multimorbidity, or urinary tract abnormalities.
Treatment
Evidence of Efficacy (Checkmarks): Amoxicillin/Clavulanate, Ampicillin/Sulbactam, Cefaclor, Cefazolin, Cefepime, Ceftazidime, Ceftriaxone, Ciprofloxacin, Doxycycline, Gentamicin, Levofloxacin, Meropenem, Nitrofurantoin, Piperacillin/Tazobactam, Sulfamethoxazole/Trimethoprim, and Trimethoprim.