o Hospital acquired infection: Infections acquired during hospital stays o Pathgen: A microorganism capable of causing sisease Nonpathogen: a microorganism that does not cause disease; may be part of the normal flora o Opportunistic pathogen: An agent capable of causing disease only when the host's resistance is impaired (ie, when the patient is"immunocompromised) o Pathogenicity: The ability of an infectious agent to cause disease o Virulence: The quantitative ability of an agent to cause disease. Virulent agents cause disease when introduced into the host in small numbers. Virulence involves invasion and toxigenicity LD so(age/sex/health /route of entry, etc o LD50: The number of pathogens required to cause lethal disease in half of the exposed hosts is called an Ldso ID50: The number of pathogens required to cause disease(or, at least, infection) in half of the exposed hosts is called the ID o Adherence(adhesion, attachment) the process by which bacteria stick to the surfaces of host cells Once bacteria have entered the body, adherence is a major initial step in the infection process. The terms adherence, adhesion, and attachment are often used interchangeabl o Invasion: The process whereby bacteria, animal parasites, fungi, and viruses enter host cells or tissues and spread in the body Toxigenicity: The ability of a microorganism to produce a toxin that contributes to the development of disease⚫ Hospital acquired infection:Infections acquired during hospital stays. ⚫ Pathgen: A microorganism capable of causing sisease. ⚫ Nonpathogen: A microorganism that does not cause disease; may be part of the normal flora. ⚫ Opportunistic pathogen: An agent capable of causing disease only when the host’s resistance is impaired (ie, when the patient is “immunocompromised”). ⚫ Pathogenicity: The ability of an infectious agent to cause disease ⚫ Virulence: The quantitative ability of an agent to cause disease. Virulent agents cause disease when introduced into the host in small numbers. Virulence involves invasion and toxigenicity. LD 50 (age /sex /health /route of entry, etc ) ⚫ LD50: The number of pathogens required to cause lethal disease in half of the exposed hostsis called an LD50. ⚫ ID50: The number of pathogens required to cause disease (or, at least, infection) in half of the exposed hosts is called the ID50 ⚫ Adherence(adhesion, attachment): the process by which bacteria stick to the surfaces of host cells. Once bacteria have entered the body, adherence is a major initial step in the infection process. The terms adherence, adhesion, and attachment are often used interchangeably. ⚫ Invasion: The process whereby bacteria, animal parasites, fungi, and viruses enter host cells or tissues and spread in the body. ⚫ Toxigenicity: The ability of a microorganism to produce a toxin that contributes to the development of disease