Chapter 13 Flashcards
What is an infection?
A condition in which pathogenic microorganisms penetrate host defenses, enter tissues, and multiply
What constitutes the pathologic state?
- Cumulative effects of infection damage
- Disruption of tissues and organs
- Results in disease
What is the definition of disease?
Any deviation from health
What factors cause disease?
Infections, genetics, aging, malfunctions of systems or organs
What is an infectious disease?
Disruption of tissues/organs caused by microbes or their products
What are normal biota?
Large and diverse collection of microbes living on and in the body
What diseases can be influenced by differences in the gut microbiome?
Crohn’s, obesity, heart disease, asthma, autism, diabetes
What are the benefits of normal biota?
Influence organ development, prevent overgrowth of harmful microbes
What is microbial antagonism?
General antagonistic effect “good” microbes have against intruder microorganisms
What factors weaken host defenses and increase susceptibility to infection?
Age, genetic/acquired defects in immunity, pregnancy, surgery/organ transplants, underlying disease, chemotherapy/immunosuppressive drugs, stress, other infections
What are endogenous infections?
Infections caused by microbiota already in/on the body, which typically occur when normal biota are introduced to a new bodily site
What is a pathogen?
A microbe whose relationship with its host is parasitic, resulting in infection and disease
What are true pathogens?
Pathogens capable of causing disease in healthy persons with normal immune systems
What are opportunistic pathogens?
Pathogens that cause disease when the host’s defenses are compromised or when introduced to a part of the body that is not natural to them
What are biosafety levles?
A system of biosafety categories adopted by the CDC based on the general degree of pathogenicity and relative danger in handling of pathogens
What is virulence?
The degree of pathogenicity, indicated by a microbe’s ability to establish itself in the host and cause damage
What is a virulence factor?
Characteristic or structure of the microbe that contributes to toxin production or induction of an injurious host response
What is the Infectious Dose (ID)?
The minimum number of microbes required for an infection to proceed
What is a portal of entry?
The characteristic route taken by a microbe to initiate infection
What are exogenous infections?
Infections originating from outside the body
How do infectious agents enter the skin?
Through broken skin or by forging pathways via digestive enzymes
How do infectious agents enter the GI tract?
Through food, drink, and other ingested substances
What are the gateways to the respiratory tract?
Oral cavity, nasal cavity
What affects how far into the respiratory tree an agent is carried?
Its size
Which pathogens use urogenital portals of entry?
Those transmitted by sexual means
What is the placenta?
An exchange organ that permits diffusion of dissolved nutrients and gases to the fetus
How can the fetus obtain microbes from the mother?
Spread from the umbilical vein, acquirement while passing through birth canal
What is adhesion?
Process by which microbes gain a more stable foothold on host tissues
What factor affects adhesion?
The specific binding molecules on both the host and pathogen
What is quorum sensing?
Chemical communication between nearby bacteria critical to establishment of infection
What are phagocytes?
White blood cells that engulf and destroy pathogens by means of enzymes and antimicrobial chemicals
What are antiphagocytic factors?
Virulence factors used by pathogens to avoid phagocytes by circumventing some part of the phagocytic process
What are exoenzymes?
Enzymes secreted by microbes that break down and inflict damage on tissues, dissolve host’s defense barriers, and promote microbe spread into deeper tissues
What is a toxin?
A chemical product of microbes, plants, and some animals that is poisonous to other organisms
What is an exotoxin?
Any toxin secreted by a living bacterial cell to the infected tissues
What is endotoxin, or lipopolysaccharide?
A toxin that is shed from the outer membrane of gram-negative bacteria
What is a localized infection?
An infection in which the microbe enters the body and remains confined to a specific tissue
What is a systemic infection?
Infection spreads to several sites and tissue fluids, usually via the bloodstream
What is a focal infection?
Exists when the infectious agent breaks loose from a local infection and is carried to other tissues
What is a mixed infection?
Several agents establish themselves simultaneously at the infection site
What is the primary infection?
The initial infection
What is the secondary infection?
Occurs when a primary infection is complicated by another infection by a different microbe
What are acute infections?
Infections that come on rapidly and have short-lived effects
What are chronic infections?
Infections that progress and persist over a long period of time
What is a sign?
Any objective evidence of disease as noted by an observer; more precise than symptoms
What is a symptom?
Subjective evidence of disease as sensed by the patient
What is a syndrome?
A disease identified or defined by a certain complex of signs and symptoms
What are granulomas/abcesses?
Walled-off collections of inflammatory cells and microbes
What is edema?
Accumulation of fluid in afflicted tissue
What is lymphadenitis?
Swollen lymph nodes
What is leukocytosis?
Increase in WBC levels
What is Leukopenia?
Decrease in WBC levels
What is septicemia?
General state in which microbes are multiplying in the blood and present in large numbers
What is bacteremia?
Presence of small numbers of bacteria in the blood; not necessarily multiplying
What is viremia?
Presence of viruses in the blood
What are asymptomatic infections?
Host is infected but does not manifest the disease; patient experiences no symptoms and does not seek treatment
What is the portal of exit?
Avenue for pathogens to exit the host
What are the various ways that pathogens exit the host?
Secretion, excretion, discharge, sloughed tissue
What is latency?
A dormant state of an infectious agent; microbe can periodically become active and produce recurrent disease
What are sequelae?
Long-term or permanent damage to organs and tissues
What is the incubation period?
Time from initial contact with the infectious agent to the appearance of first symptoms
What is the prodromal period?
When the earliest notable symptoms of infection appear
What is the acute phase?
Infectious agent multiplies at high levels, exhibits its great virulence, and becomes well established in target tissue
What is the convalescent stage?
Patient responds to infection and symptoms decline
What is a reservoir?
Primary habitat in the natural world from which a pathogen originates
What is a source?
Distinct from a reservoir; individual/object from which an infection is acquired
What is a carrier?
An individual who unknowingly shelters a pathogen and can spread it
What are the types of carriers?
Asymptomatic, incubating, convalescent, chronic, passive
What are vectors?
Living animals that transmit an infectious agent from one host to another
What is a biological vector?
A vector that actively participates in pathogen’s life cycle
What is a mechanical vector?
A vector that is not necessary to the pathogen life cycle and merely transports the pathogen
What is a zoonosis?
An infection indigenous to animals but also transmissible to humans
What is a communicable disease?
Occurs when an infected host can transmit the infectious agent to another host
What does it mean for a pathogen/disease to be contagious?
It is highly communicable, especially through direct contact
What is a noncommunicable disease?
Does not arise through transmission of infectious agent from host to host
What is horizontal transmission?
Disease is spread through a population from one infected individual to another, either directly, indirectly, or through a vector
What is vertical transmission?
Transmission from parent to offspring
What is a vehicle?
Any inanimate material commonly used by humans that can transmit infectious agents
What is a fomite?
An inanimate object that harbors and transmits pathogens, but is not a continuous source of infection
What are healthcare-associated infections (HAIs)?
Infectious diseases that are acquired or develop during a hospital or healthcare facility stay
What is medical asepsis?
Practices that lower the microbial load in patients, caregivers, and the hospital environment
What is surgical asepsis?
Ensuring all surgical procedures are conducted under sterile conditons
What is epidemiology?
The study of the frequency and distribution of disease and distribution of disease and other health-related factors in defined populations
What is the prevalence of disease?
Total number of existing cases with respect to the entire population
What is the incidence of disease?
Measures the number of new cases over a certain time
What is the mortality rate?
Measures number of deaths in a population due to a certain disease
What is a point-source epidemic?
One in which the infectious agents came from a single source
What is a common-source epidemic?
Result from common exposure to a single source of infection; can occur over a period of time
What is a propagated epidemic?
Results from an infectious agent that is communicable from person to person; sustained over time in a population
What is a pandemic?
Spread of an epidemic across continents
What is the index case?
The first patient found in an epidemiological investigation
What is an endemic?
An infectious disease that exhibits a relatively steady frequency over a long period of time within a geographic locale
What is a sporadic disease?
Occasional cases are reported at irregular intervals in random locales
