Klebsiella pneumoniae bacteria in respiratory tract, computer illustration. K. pneumoniae is one of several bacteria that can cause pneumonia (lung inflammation). It causes a severe form that can be a complication of chronic lung diseases. K. pneumoniae is also a multidrug resistant bacterium that can cause severe hospital-acquired infections. This is a carbapenem-resistant strain of this bacterium. Carbapenem is a broad-spectrum antibiotic.