An opportunistic pathogen is a microbe that takes advantage of weakened or vulnerable individuals to cause an infection. But there are many alternative terms used to describe these pathogens. They're often called "hospital-acquired infections" because they tend to occur in healthcare settings. Some other terms that can be used to describe opportunistic pathogens include "infectious agents," "disease-causing organisms," or "pathogenic bacteria." Other terms used to describe specific types of opportunistic pathogens include "pneumocystis carinii," which causes pneumonia in people with weakened immune systems, or "fungal infections," which can be caused by several different types of fungi that thrive in warm, moist environments. No matter what term is used, however, it's important to recognize these pathogens for what they are and take appropriate measures to prevent infection and control their spread.