Where does Klebsiella (K.) pneumoniae grow?

Where Does Klebsiella pneumoniae Grow?

Klebsiella pneumoniae primarily grows in the human gastrointestinal tract (especially the small intestine and colon) and respiratory tract, as well as in various environmental reservoirs including water, soil, sewage, and vegetation. 1, 2

Human Colonization Sites

• K. pneumoniae commonly colonizes the human gastrointestinal tract, which serves as the primary reservoir for transmission and subsequent infection 2
• The small intestine is often the initial site of colonization, with later transition to the colon over time 2
• K. pneumoniae also colonizes the nasopharynx and respiratory tract, which can lead to pneumonia in susceptible individuals 3
• The urinary tract is another common site where K. pneumoniae can grow, causing urinary tract infections 4

Environmental Reservoirs

• K. pneumoniae is ubiquitous in nature, found in surface waters, soils, sewage, and vegetation 1
• Polluted waters and soils are particularly common habitats for K. pneumoniae 1
• Environmental K. pneumoniae strains have been found to possess similar virulence potential as clinical isolates, explaining their ability to cause opportunistic infections 4

Hospital and Healthcare Settings

• K. pneumoniae can contaminate hospital environments and medical devices 5
• The bacteria can survive on environmental surfaces (e.g., door knobs, hand rails) in healthcare settings, facilitating transmission 5
• Medical equipment such as catheters and ventilators can become colonized, serving as sources for nosocomial infections 5

Factors Promoting Colonization and Growth

• Capsule polysaccharide is necessary for K. pneumoniae colonization of the large intestine 2
• The type VI secretion system contributes to colonization across the gastrointestinal tract 2
• Fimbriae, lipopolysaccharide, and siderophores are important virulence factors that facilitate growth in various host environments 3
• Antibiotic treatment disrupts normal gut microbiota, allowing for increased K. pneumoniae colonization and potential dissemination to other tissues 2

Clinical Significance of Growth Sites

• Gastrointestinal colonization is considered a prerequisite for subsequent infection 2
• Asymptomatic colonization can progress to invasive infection, particularly in immunocompromised patients or following antibiotic treatment 2, 3
• K. pneumoniae can spread from its colonization sites to cause bacteremia, liver abscesses, and infections at other sterile sites 3
• Carbapenem-resistant K. pneumoniae (CRKP) can spread between patients in healthcare settings, particularly in units like hematology/oncology where patients may be immunocompromised 5

Transmission and Spread

• K. pneumoniae can spread through contaminated water sources and environmental surfaces 5
• In healthcare settings, transmission can occur via healthcare workers' hands or contaminated equipment 5
• The plasmid-carrying New Delhi metallo-beta-lactamase (NDM) is highly transmissible to other bacteria, facilitating the spread of antibiotic resistance 5
• K. pneumoniae can colonize the gastrointestinal systems of humans for prolonged periods, creating reservoirs for ongoing transmission 5

Human Microbiologist