This blood agar plate (BAP) grew colonies of Gram-negative, small rod-shaped and facultatively anaerobic Klebsiella pneumoniae bacteria.K. pneumoniae bacteria are commonly found in the human gastrointestinal tract, and are often the cause of hospital acquired, or nosocomial infections involving the urinary and pulmonary systems.
genus Klebsiella
The genus was originally divided into 3 main species based on biochemical reactions. Today,
7 species with demonstrated similarities in DNA homology are known.
These are:
(1) Klebsiella pneumoniae
(2) Klebsiella ozaenae
(3) Klebsiella rhinoscleromatis
(4) Klebsiella oxytoca
(5) Klebsiella planticola
(6) Klebsiella terrigena
(7) Klebsiella ornithinolytica
K.pneumoniae is the most medically important species of the group.
K.oxytoca and K.rhinoscleromatis have also been demonstrated in human clinical specimens. In recent years, klebsiellae have become important pathogens in nosocomial infections.
The most frequent bacterial cause of urinary tract infection (UTI) in adult women is Escherichia coli, which is part of the normal gut flora. This organism accounts for approximately 85% of community-acquired UTIs and 50% of hospital-acquired UTIs. Other common organisms include Klebsiella pneumoniae.
K. pneumoniae has been a recognized pulmonary pathogen since its discovery >100 years ago. The classic clinical presentation is dramatic: toxic presentation with sudden onset, high fever, and hemoptysis (currant jelly sputum). Chest radiographic abnormalities such as bulging interlobar fissure and cavitary abscesses are prominent. However, the incidence of community-acquired Klebsiella pneumoniae has apparently declined in the United States. In studies from the 1920s to the 1960s, K. pneumoniae was considered an important cause of community-acquired pneumonia; however, in the last decade K. pneumoniae accounted for <1%>
A striking clinical finding concerning a new manifestation of community-acquired K. pneumoniae infections has been documented. An unusual invasive presentation of K. pneumoniae infection, primary bacteremic liver abscess, has been described by numerous investigators in Asia; >900 patients with Klebsiella liver abscess have been reported from Taiwan in the last 10 years. In addition, case reports and small series from Korea, Singapore, Japan, India, and Thailand have been published. The Taiwanese patients with K. pneumoniae liver abscess have no history of hepatobiliary disease. Seventy percent of such patients have diabetes mellitus; 11% to 12% of the reported patients with Klebsiella liver abscess have other septic metastatic lesions, including pulmonary emboli or abscess, brain abscess, pyogenic meningitis, endophthalmitis, prostatic abscess, osteomyelitis, septic arthritis, or psoas abscess.
