A genus of gram-negative, nonmotile bacteria. Characteristic large mucoid colonies are due to production of a large amount of capsular material. Species of Klebsiella are commonly found in soil and water, on plants, and in animals and humans. Harmless strains of Klebsiella are beneficial because they fix nitrogen in soil. Pathogenic species include K. pneumoniae, K. rhinoscleromatis, and K. ozaenae, also known as K. pneumoniae subspecies pneumoniae, rhinoscleromatis, and ozaenae. Klebsiella pneumoniae is the second most frequently isolated colon-related bacterium in clinical laboratories. The carbohydrate-containing capsule of Klebsiella promotes virulence by protecting the encased bacteria from ingestion by leukocytes; nonencapsulated variants of Klebsiella do not cause disease. Capsular types 1 and 2 cause pneumonia; types 8, 9, 10, and 24 are commonly associated with urinary tract infections. Escherichia Pneumonia Klebsiella accounts for a large percentage of hospital-acquired infections, mostly skin infections (in immunocompromised burn patients), bacteremia, and urinary tract infections. It is also the most common contaminant of intravenous fluids such as glucose solutions and other medical devices.Hospital infections Klebsiella may produce E. coli-like enterotoxins and cause acute gastroenteritis in infants and young children. Enteric illnesses due to Klebsiella are more predominant where populations are more crowded and conditions less sanitary. Other virulence factors of Klebsiella include a relatively high ability to survive and multiply outside the host in a variety of environments, and its relatively simple growth requirements. Endotoxin Klebsiella rhinoscleromatis causes rhinoscleroma, a chronic destructive granulomatous disease of the upper respiratory tract that is most common in eastern Europe, central Africa, and tropical South America. Klebsiella ozaenae is one cause of chronic rhinitis (ozena), a destructive atrophy of the nasal mucosa, and is infrequently isolated from urinary tract infections and bacteremia. Medical bacteriology | 
