KLEBSIELLA SPP. AS NOSOCOMIAL PATHOGENS - EPIDEMIOLOGY, TAXONOMY, TYPING METHODS, AND PATHOGENICITY FACTORS

Bacteria belonging to the genus Klebsiella frequently cause human noso comial infections. In particular the medically most important Klebsiel la species, Klebsiella pneumoniae, accounts for a significant proporti on of hospital-acquired urinary tract infections, pneumonia, septicemi as, and soft tissue infections. The principal pathogenic reservoirs fo r transmission of Klebsiella are the gastrointestinal tract and the ha nds of hospital personnel. Because of their ability to spread rapidly in the hospital environment, these bacteria tend to cause nosocomial o utbreaks. Hospital outbreaks of multidrug-resistant Klebsiella spp., e specially those in neonatal wards, are often caused by new types of st rains, the so-called extented-spectrum-beta-lactamase (ESBL) producers . The incidence of ESBL-producing strains among clinical Klebsiella is olates has been steadily increasing over the past years. The resulting limitations on the therapeutic options demand new measures for the ma nagement of Klebsiella hospital infections. While the different typing methods are useful epidemiological tools for infection control, recen t findings about Klebsiella virulence factors have provided new insigh ts into the pathogenic strategies of these bacteria. Klebsiella pathog enicity factors such as capsules or lipopolysaccharides are presently considered to be promising candidates for vaccination efforts that may serve as immunological infection control measures.