Healthcare Epidemiology, Infection Control, and Pathogenesis

These vocabulary flashcards cover healthcare epidemiology, infection transmission routes, laboratory diagnosis of infectious diseases, and the mechanisms of pathogenesis and host defense based on lecture materials.

Healthcare epidemiology

The study of the occurrence, determinants, and distribution of health and disease within healthcare settings and facilities.

Healthcare-Associated Infections (HAI)

Infections acquired within healthcare facilities, including those that erupt within $14\,\text{days}$ of hospital discharge.

Community-acquired infections

Infectious diseases acquired outside of healthcare facilities.

Iatrogenic infection

An infection that results from medical or surgical treatment, caused by a surgeon, another physician, or some other health care worker.

Contact Transmission

A route of transmission divided into direct (pathogens transferred from one infected person to another without a contaminated intermediate) and indirect (pathogens transferred via a contaminated intermediate object or person).

Droplet Transmission

Transmission via respiratory droplets larger than $5\,\mu m$ that travel from an infectious individual to the mucosal surfaces of a recipient.

Airborne Transmission

Dissemination of airborne droplet nuclei or small particles containing pathogens that are traditionally defined as being less than or equal to $5\,\mu m$ in size.

Medical asepsis

A clean technique involving precautionary measures to prevent the direct or indirect transfer of pathogens; its goal is to exclude pathogens.

Surgical asepsis

A sterile technique involving practices used to render and keep objects and areas sterile; its goal is to exclude all microorganisms.

Fomites

Nonliving, inanimate objects other than food, such as bedding, towels bestowed, or hospital equipment, that may harbor and transmit microbes.

Bacteremia

The presence of bacteria in the bloodstream.

Septicemia

A serious disease involving chills, fever, prostration, and the presence of bacteria or their toxins in the bloodstream.

Toxemia

The presence of toxins in the bloodstream.

$\alpha$-Hemolysis

A green zone around a bacterial colony on a blood agar plate caused by the partial breakdown of hemoglobin.

$\beta$-Hemolysis

A clear zone around a bacterial colony on a blood agar plate caused by the complete destruction (lysis) of red blood cells.

$\gamma$-Hemolysis

The absence of hemolysis, where no green or clear zone appears around the bacterial colony.

Pathogenicity

The ability of a microbe to cause disease.

Pathogenesis

The steps or mechanisms involved in the development of a disease.

Incubation period

The time that elapses between the arrival of the pathogen and the onset of symptoms.

Prodromal period

The time during which the patient feels "out of sorts" but does not yet experience actual symptoms of the disease.

Symptom of a disease

Subjective evidence of disease experienced by the patient, such as aches, pains, nausea, or dizziness.

Sign of a disease

Objective evidence of disease, such as elevated blood pressure, abnormal heart sounds, or abnormal laboratory results.

Latent infections

Infectious diseases that go from being symptomatic to asymptomatic and then later go back to being symptomatic.

Virulence factors

Phenotypic characteristics dictated by an organism's genotype that enable pathogens to attach, escape destruction, and cause disease.

Adhesins

Molecules (ligands) on the surface of pathogens that enable them to recognize and bind to particular host cell receptors.

Exoenzymes

Enzymes released by bacteria, such as coagulase, kinases, and hyaluronidase, that serve as major mechanisms for causing disease.

Endotoxins

Part of the cell wall structure of Gram-negative bacteria that can cause serious physiologic effects such as fever and shock.

Exotoxins

Poisonous proteins, such as neurotoxins or enterotoxins, that are secreted by a variety of pathogens.

Pyrogens

Substances that cause fever.

Active acquired immunity

Immunity acquired in response to the entry of a live pathogen (natural) or in response to vaccines (artificial).

Passive acquired immunity

Immunity acquired when a fetus or infant receives maternal antibodies (natural) or when a person receives antibodies in antisera (artificial).

Attenuated vaccines

Vaccines containing weakened, avirulent mutant strains of pathogens.

Toxoid

An exotoxin that has been inactivated by heat or chemicals and is injected to stimulate the production of antitoxins.

Opsonins

Substances, such as antibodies or complement fragments, that enhance phagocytosis by enabling phagocytes to attach to pathogens.

Anaphylactic reactions

Type I hypersensitivity reactions, which include allergic responses like asthma, hay fever, and life-threatening systemic shock.

Autoimmune diseases

Conditions resulting from the immune system failing to recognize certain body tissues as "self" and attempting to destroy them as "non-self."