Airborne Precautions

The chain of infection is a fundamental model for understanding how infections develop and spread, comprising six interconnected links: the infectious agent (pathogen), the reservoir where the pathogen lives and multiplies, the portal of exit through which the pathogen leaves the reservoir, the mode of transmission to a new host, the portal of entry into the new host, and the susceptible host whose immune defenses cannot effectively resist the pathogen. Transmission-based precautions are implemented in addition to standard precautions when patients are known or suspected to be infected with pathogens requiring extra measures, such as contact precautions involving gown and gloves for organisms like MRSA and VRE. Invasive devices, including urinary catheters, central venous catheters, endotracheal tubes, and surgical drains, serve as direct portals of entry for pathogens, increasing infection risk. When assessing infections, wound culture and sensitivity testing involves collecting a specimen from the wound bed—not surface drainage—using sterile technique to identify the pathogen and determine effective antibiotics. Laboratory markers such as C-reactive protein (CRP), a nonspecific inflammatory marker, and procalcitonin, which is more specific for bacterial infection, are...