Ubiquitous non-motile, Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule.
Frequent human pathogens, Klebsiella organisms can lead to a wide range of disease states, notably pneumonia, urinary tract infections, septicemia, and soft tissue infections.
Klebsiella species have also been implicated in the pathogenesis of ankylosing spondylitis and other spondyloarthropathies.
Klebsiella pneumoniae is the most common cause of nosocomial respiratory tract and premature intensive care infections, and the second most frequent cause of Gram-negative bacteraemia and urinary tract infections. Drug resistant isolates remain an important hospital-acquired bacterial pathogen, add significantly to hospital stays, and are especially problematic in high impact medical areas such as intensive care units.
Gram-negative, non-motile, encapsulated, lactose-fermenting, facultative anaerobic, rod-shaped bacterium. It is closely related to K. oxytoca from which it is distinguished by being indole-negative and by its ability to grow on both melezitose and 3-hydroxybutyrate.
Found in the normal flora of the mouth, skin, and intestines. Generally, Klebsiella infections are seen mostly in people with a weakened immune system.
Can cause destructive changes to human lungs if aspirated (access is typically gained after a person aspirates colonizing oropharyngeal microbes into the lower respiratory tract).
Clinically, it is the most significant member of the Klebsiella genus of Enterobacteriaceae.
New antibiotic resistant strains of K. pneumoniae are appearing, and it is increasingly found as a nosocomial infection.
Seven species of the Klebsiella genus, with demonstrated similarities in DNA homology are known:
(1) Klebsiella pneumoniae,
(2) Klebsiella ozaenae,
(3) Klebsiella terrigena,
(4) Klebsiella rhinoscleromatis,
(5) Klebsiella oxytoca,
(6) Klebsiella planticola, and
(7) Klebsiella ornithinolytica.
K oxytoca and K rhinoscleromatis have also been demonstrated in human clinical specimens.
In recent years, klebsiellae have become important pathogens in nosocomial infections.
The most common infection caused by Klebsiella bacteria outside the hospital is pneumonia, typically in the form of bronchopneumonia and also bronchitis. These patients have an increased tendency to develop lung abscess, cavitation, empyema, and ural adhesions. It has a high death rate of about 50% even with antimicrobial therapy. The mortality rate can be nearly 100% for persons with alcoholism and bacteremia.
In addition to pneumonia, Klebsiella can also cause infections in the urinary tract, lower biliary tract, and surgical wound sites. The range of clinical diseases includes pneumonia, thrombophlebitis, urinary tract infection (UTI) (Klebsiella ranks second to E. coli for urinary tract infections in older persons), cholecystitis, diarrhea, upper respiratory tract infection, wound infection, osteomyelitis, meningitis, and bacteremia and septicemia.
One of many carbapenem-resistant Enterobacteriaceae (CRE) is Carbapenem-Resistant Klebsiella pneumoniae (CRKP). Over the past 10 years, a progressive increase in CRKP has been seen worldwide. CRKP is resistant to almost all available antimicrobial agents, and infections with CRKP have caused high rates of morbidity and mortality, in particular among persons with prolonged hospitalization and those critically ill and exposed to invasive devices (e.g., ventilators or central venous catheters).
There are a number of mechanisms of Carbapenem Resistance in Enterobacteriaceae. These include:
(1) Hyperproduction of ampC beta-lactamase with an outer membrane porin mutation
(2) CTX-M extended-spectrum beta-lactamase with a porin mutation or drug efflux, and
(3) Carbapenemase production. When Klebsiella pneumoniae bacteria produce the carbapenemase enzyme they are known as KPC-producing organisms or carbapenem-resistant Klebsiella pneumoniae (CRKP).
Klebsiella organisms are often resistant to multiple antibiotics. Current evidence implicates a plasmid as the source of the resistant genes. Klebsiella with the ability to produce extended-spectrum beta-lactamasesESBL are resistant to many classes of antibiotics.
Important considerations: The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions. Generally, the most common agents/regimens are listed first. Listed dosages may need to be adjusted for renal dysfunction.
Klebsiella pneumoniae: Growing worldwide resistance to a broad array of antibiotics. Therapy should be guided by susceptibility testing. Extended spectrum beta-lactamase (ESBL) and carbapenemase production is a growing problem.
Susceptible strains:
Ceftriaxone 1-2 grams IV q24h (range: 1-2 grams q12-24h)
Ciprofloxacin 400mg IV q12h (Severe/complicated: 400mg IV q8h)
Colistimethate (colistin base): 2.5 – 5mg/kg/day in 2-4 divided doses. Max 5 mg/kg/day PLUS [ Meropenem 1 gram IV q8h OR Imipenem500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
