Klebsiella spp. are gram-negative bacilli belonging to the Enterobacteriaceae family and closely related to the genera Enterobacter and Serratia. Klebsiella spp. are considered dysbiotic in the amount of 3 - 4 +. Klebsiella spp. are widely distributed in nature and in the gastrointestinal tract of humans. In humans, they may colonize the skin, oral cavity, pharynx, or gastrointestinal tract. Regarded as normal flora in many parts of the colon, intestinal tract and biliary tract, the gut is the main reservoir of opportunistic strains.
This bacteria has the potential to cause intestinal, lung, urinary tract, and wound infections, but overgrowth of Klebsiella spp. is commonly asymptomatic.
K. pneumoniae, in particular, may cause diarrhea and some strains are enterotoxigenic. Infection has been linked to ankylosing spondylitis as well as myasthenia gravis (antigenic cross-reactivity), and these patients usually carry larger numbers of the organism in their intestines than healthy individuals.
Klebsiella is a significant nosocomial infectious agent, partially due to the ability of organisms to spread rapidly. Klebsiella accounts for approximately 3-7% of all hospital-acquired infections, placing it among the top eight pathogens in hospitals. Extraintestinal infection typically involves the respiratory or urinary tracts, but may infect other areas such as the biliary tract and surgical wound sites.
K. pneumoniae and K. oxytoca are the two members of this genus responsible for most extraintestinal human infections.
Treatment of these organisms has become a major problem because of resistance to multiple antibiotics and potential transfer of plasmids to other organisms. Proper hand washing is crucial to prevent transmission from patient to patient via medical personnel.
Contact isolation should be used for patients colonized or infected with highly antibiotic-resistant Klebsiella strains. Klebsiella ozaenae and Klebsiella rhinoscleromatis are infrequent isolates that are subspecies of K. pneumoniae; however, each is associated with at unique spectrum of disease.
K. ozaenae is associated with atrophic rhinitis, a condition called ozena, and purulent infections of the nasal mucous membranes. K. rhinoscleromatis causes the granulomatous disease rhinoscleroma, an infection of the respiratory mucosa, oropharynx, nose, and paranasal sinuses. Antibiotics may be indicated if symptoms are prolonged and in systemic infections.
Klebsiella pneumoniae
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