Produced by the National Institute of Allergy and Infectious Diseases (NIAID), this digitally-colorized scanning electron micrograph (SEM) depicts a blue-colored, human white blood cell (WBC) known specifically as a neutrophil, interacting with two pink-colored, rod-shaped, multidrug-resistant (MDR) Klebsiella pneumoniae bacteria, which are known to cause severe hospital-acquired, nosocomial infections. Please see the Flickr link below for additional NIAID photomicrographs of various bacteria. Klebsiella is a type of Gram-negative bacteria that can cause different types of healthcare-associated infections, including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis. Increasingly, Klebsiella bacteria have developed antimicrobial resistance, most recently to the class of antibiotics known as carbapenems. Klebsiella bacteria are normally found in the human intestines (where they do not cause disease). They are also found in human stool (feces). In healthcare settings, Klebsiella infections commonly occur among sick patients who are receiving treatment for other conditions. Patients whose care requires devices like ventilators (breathing machines) or intravenous (vein) catheters, and patients who are taking long courses of certain antibiotics are most at risk for Klebsiella infections. Healthy people usually do not get Klebsiella infections.