ABSTRACT
The genus Klebsiella is a gram-negative bacterium belonging to the family of Enterobacteriaceae. Named after German microbiologist Edwin Klebs, Klebsiella covers nonmotile, rod-shaped organisms with a prominent polysaccharide outer layer. This outer layer encloses the entire cell surface that accounts for the larger appearance of the bacteria on Gram stain and reportedly provides resistance against several host defense mechanisms. Due to its high resistance property, Klebsiella has been well known as a predominant cause of community-acquired bacterial pneumonia, particularly in chronic alcoholics. 1 This infection induces characteristic radiographic abnormalities that are attributed to severe pyogenic reaction, 2 and often requires hospitalization. As opportunistic pathogens, Klebsiella spp. chiefly target the immunocompromised individuals who are hospitalized due to severe diabetes mellitus or chronic pulmonary obstruction. The most common nosocomial Klebsiella infection is caused by Klebsiella pneumoniae, a clinically significant species among the genus. To a lesser extent, Klebsiella oxytoca is also implicated in human infection. Klebsiella spp. account for 3%–7% of nosocomial bacterial infections, and hence rank as the second most important infectious pathogens in hospitals. 3–5 Table 33.1 summarizes the most significant nosocomial infections caused by Klebsiella spp.
