Key Words Pathogen Invasiveness/spread Opportunistic pathogen Extracellular bacteria Normal microbiota Intracellular bacteria Pathogenicity Exotoxin Virulence Endotoxin Opportunistic infection Toxoid Nosocomial infection Antitoxin Microeubiosis Carrier microdysbiosis Compromised host Transmission Bacterial biofilmKey Words Invasiveness/spread Extracellular bacteria Intracellular bacteria Exotoxin Endotoxin Toxoid Antitoxin Carrier Compromised host Bacterial biofilm Pathogen Opportunistic pathogen Normal microbiota Pathogenicity Virulence Opportunistic infection Nosocomial infection Microeubiosis microdysbiosis Transmission