Klebsiella pneumoniae

Gram Stain

• Gram negative bacilli - fermenter

Clinical Significance

These organisms are widely distributed in nature and are part of commensal human gastrointestinal flora.

They are associated with both community and health care associated infections (pneumonia, urinary tract infections, bacteremia, septicemia, meningitis and skin/soft tissue/ bone/joint infections).

K. pneumoniae subsp pneumoniae - associated with necrotizing lobar pneumonia, often in debilitated individuals (especially alcoholics).  

The K1 genotype can cause hepatic abscesses with associated severe ocular and central nervous system complications in previously healthy individuals.

K. pneumoniae subsp ozaneae-  associated with chronic atrophic rhinitis and other chronic respiratory infections.

K. pneumoniae subsp rhinoscleomatis-  associated with a granulomatous infection of the upper respiratory tract typically in immunocompromised individuals.

Usual Susceptibility Pattern

These organisms are resistant to ampicillin.

The number of strains producing extended spectrum beta-lactamases (ESBL) or AmpC cephalosporinases is increasing, resulting in resistance to penicillins, cephalosporins, and beta-lactamase inhibitor combinations.

Carbapenem resistance is significant in certain geographic locations.

Most strains remain susceptible to aminoglycosides, quinolones, and nitrofurantoin.

Susceptibility to TMP/SMX, fosfomycin, and tetracyclines is variable.