Microbiology Chapter 14

pathology

the study of disease

etiology

the cause of a disease

etiological agent

the thing that causese the disease

pathogenesis

the manner in which a disease develops

normal microbiota

permanently colonize the host and do not cause disease under normal condition. The distribution and composition of this is determined by nutrients, physical and chemical factors, mechanical factors, body’s defenses against microbes, age, diet, nutritional status, geography, personal hygiene, living conditions, occupation and lifestyle

transient microbiota

microbes that may be present for days, weeks or months, then disappear

compromised host

a person whose body defenses are weakened, making them more likely to get an infection

microbial antagonism

aka competiive exclusion, competition between microbes. can protect the host by competeting with invading microbes for nutrients, producing substances harmful to invading microbes, affecting pH and available oxygen

koch’s postulates

purpose is to show that a certain microbe causes a certain disease. Steps: 1. pathogen must be present in every case of the disease 2. must be isolated from disease host, grown in pure culture 3. the pathogen from pure culture must cause the disease when inoculated into a heatlhy lab animal. 4. the pathogen must be isolated from the inoculated animal and must be shown to the original organism

symbiosis

a relationship between organisms in which at least one organism is dependent on the other

commensalism

one organism benefits and the other is neither helped or harmed

mutualism

both organisms benefit

parasitism

one organism benefits and the other (host) is harmed, is usually a disease causing microorganism

opportunistic pathogens

normal microbiota that usually don’t cause disease but can cause infection if the host becomes weakened. causes disease in a compromised host (not normally healthy)

signs

objective changes in a body that can be measured or observed as a result of disease

symptoms

subjective changes in body funcctions that are felt by a patient as a result of disease, not apparent to an observer

incidence

number of people who develop a disease during a particular time period, the new cases

prevalence

the total number of cases, all cases total

endemic

a disease constantly present in a population, like h

epidemic

a disease acquired by many people in a given area

pandemic disease

worldwide epidemic

acute

symptoms develop rapidly but has a short duration

chronic

symptoms develop slowly, likely to last for a long period

subacute

intermediate between acute and chronic

latent disease

causitive agient is inactive for a time but then activates and produces symptoms (herpes, cold sores, chicken pox, shingles)

local infection

pathogens are limited to a small area of the body

systemic (generalized) infection

an infection spread throughout the body by the blood and lymph

sepsis

toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection

septicemia

blood poisoning, growth of bacteria in the blood, bacteria are proliferating in the blood

primary infection

acute infection that causes initial illness

secondary infection

opportunistic infection after primary (pre-disposing) infection

incubation period, prodromal period, period of illness, period of decline, period of convalescence

stages of disease

incubation period

interval betweeen initial infection and first signs and symptoms

prodromal period

short period after incubation, early, mild nonspecific symptoms

period of illness

disease is most severe

period of decline

signs and symptoms subside

period of convalescence

body returns to its prediseased state; recovery

reserviors of infection

natural habitats where pathogens live, grow, and multiply before infecting a new host.

human reservoirs

people carry infections, people with sigsn and symptoms or carriers may have inapparent infections

animal reservoirs

animals can carry infections, zoonoses

zoonoses

disease primarily in wild and domestic animals that can be transmitted to humans

nonliving reservoirs

pathogens can survive in soil, water, foods

contact transmission

a way that infectious diseases spread from one person (or reservoir) to another through direct or indirect contact. It’s one of the main modes of disease transmission.

direct contact transmission

requires close association between the infected and susceptible host

indirect contact transmission

spreads to a host by a nonliving object called a fomite

droplet transmission

transmission via airborne droplets less than one meter

vehicle transmission

transmission by an inanimate reservoir: airborne, waterborne, food borne

vectors

arthropods, especiallly fleas, ticks and mosquitos

mechanical transmission

arthropod caorries pathogen on its feet

biological transmission

pathogen reproduces in the vector, transmitted via bites or feces

Healthcare- Associated Infections (HIA) 

result from microorganisms in the hospital environment

direct contact transmission

from hospital staff to patient or patient to patient

indierect contact

through fomites and hospital ventilation system

universal precautions

designed to reduce the transmission of microbes in healthcare and long term care settings, protect patients, residents, staff, visitors from contact with pathogens

standard precautions

basic minimum practices. applied to every person, every time, all levels of healthcare: hand hygiene, personal protective equipment, environmental cleaning and disinfection, safe infection practices, patient placement

transmission-based precautions

supplemental to standard precautions; designed for known or suspected infections that are highly transmissible or involve epidemiologically important pathogens

emerging infectous disease

disese that are new or changing, increasing in incidence, or showing a potetinal to increase in the near future. most are zoonotic

contributing factors

genetic recomination between organisms, evolution of exisiting organisms, widespread use of antibiotics and pesitcides, inherent genetic instability of osme microbes, changes in global climate modern transportation, war, expandind human settlements, animal control measures,

epidemiology

the study of where and when diseases occur and how they are transmitted in populations

descriptive epidemiology

collection and analysis of data

analytical

analyzes a particular disease to determine its porbable cause or risk factors

experimental

involves a hypothesis and controleld experiments

mortality

deaths from notifiable diseases

morbidity

incidicene of specific notifible disease