Klebsiella pneumoniae is a Gram-negative rod that is part of the normal gut flora. It can cause a number of infections in humans including pneumonia (typically following aspiration) and urinary tract infections.

Features of Klebsiella pneumonia

• more common in alcoholic and diabetics
• may occur following aspiration
• 'red-currant jelly' sputum
• often affects upper lobes

Prognosis

• commonly causes lung abscess formation and empyema
• mortality is 30-50%

A human neutrophil interacting with Klebsiella pneumoniae (pink), a multidrug-resistant bacterium that causes severe hospital infections. Credit: NIAID