Emery Haley, PhD, Scientific Writing Specialist
Klebsiella pneumoniae
Clinical Summary
- K. pneumoniae is recognized as a classical, urease-positive, gram-negative, biofilm-forming, uropathogen.
- K. pneumoniae is primarily associated with recurrent UTIs and complicated UTIs in individuals with risk-factors such as indwelling catheters, immunocompromising comorbidities, or urinary tract abnormalities.
- In symptomatic UTI patients, K. pneumoniae:
- 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. pneumoniae UTI include pyelonephritis, bacteremia, urosepsis, and death.
- Multidrug-resistant K. pneumoniae is a significant and well-studied 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. pneumoniae is a urease-positive,[1]gram-negative, biofilm-forming, microorganism classically recognized as a common uropathogen. K. pneumoniae is capable of invading epithelial cells of the urinary tract, forming intracellular reservoirs presumed responsible for persistent and recurrent K. pneumoniae UTIs.[2–4] K. pneumoniae is also a common cause of complicated UTIs among individuals who are immunocompromised or who have risk factors such as urinary tract abnormalities. [4–7] Lastly, K. pneumoniae is associated with hard-to-treat multidrug-resistant catheter-associated UTIs (CAUTIs) and hospital-acquired UTIs (HAUTIs).[8–10] Indeed, K. pneumoniae is one of the six so-called “ESKAPE pathogens” identified as critical multi-drug resistant bacteria requiring urgent development of effective therapeutics.[11]
In preclinical studies of UTI, uropathogenic K. pneumoniae exhibits virulence factors including type 1 pili and adhesins promoting adherence to bladder epithelial cells and a capsule that promotes immune evasion.[12] In preclinical models, K. pneumoniae invaded bladder epithelial cells[13] and also exhibited antagonism with Enterococcus species, E. coli, and P. mirabilis.[14]
In a study of older adult males and females with clinically suspected complicated UTI, K. pneumoniae 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.[15] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which K. pneumoniae was detected, indicating that the presence of K. pneumoniae was associated with an immune response to urinary tract infection.[16–18]
Severe reported complications of K. pneumoniae UTI include pyelonephritis, bacteremia, urosepsis, and death.[7,9,19,20] Together, these findings indicate that K. pneumoniae should be seriously considered as a uropathogen and demonstrate the value of detecting this organism, particularly in individuals with indwelling catheters, urinary tract abnormalities, immunocompromise, or other risk factors for complicated or experiencing recurrent UTI.
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.