CH 14- 16

Symbiotic Relationships

to live together

mutualism

both organisms benefitEx: bacteria in human colon

commenalism

one organism benefits, other organism neither benefits or is harmed (mites in human hair follicles)

ammenalism

one organism is harmed, one organism neither benefits nor is harmed

parasitism

benefits, other organism is harmed

resident microbes

part of the normal microbiota throughout life, mostly commensal

where can resident microbes be found?

upper respiratory tract, digestive tract, female/male urinary and respiratory systems, eyes and skin

transient microbes

remain in the body for short period of time EX- found in same regions of the body

How normal microbes can become pathogenic?

Introduction into a new location, Immune suppression, Changes in normal microbiota, Stress

reservoirs of human infection

sites where pathogens are maintained as a source of infection

types of reservoirs of human infection

animal reservoirs, human carriers, non-living reservoirs

how are zoonose acquired?

direct contact with animal or its waste, eating animals, bloodsucking arthropods

human carriers

asymptomatic infected individuals can be ineffective to others

non-living reservoir

soil, water, food,presence due to contamination of feces or urine

infection

when organisms evades body’s external defenses, multiplies, and becomes established in the body

portals of entry

sites through which pathogens enter the body conjuctiva of eye, nose, mouth, ear, broken skin, insect bite, placenta, vagina, urethra, anus

3 major pathways

skin, mucous membranes, placenta

Protective layers of skin and mucous membranes

outer layer of dead skin cells act as a barrier to pathogens

adhesion

process by which microorganisms attach themselves to cells

Importance of adhesion in infection

required to establish colonies successfully within the host

disease signs

objective manifestations of disease observed or measured

disease

results if invading pathogen alters normal body functions

symptoms

subjective characteristics of disease felt only by the patient

syndromes

symptoms and signs that charcterize a disease or an abnormal condition

asymptomatic/subclinical

infections lack symptoms but may still have signs of infection

etiology

study of the cause of disease disease

hereditary

caused by errors in the genetic code received from parents

congenital

birth defects

degenerative

result from agingnu

nutritional

lack of nutirents in diet

endocrine

due to excess or defenciencies of hormones

mental

emotional or psychosomaticim

immunological

hyperactive or hypoactive immunity

neoplastic

abnormal cell growth

infectious

caused by an infectious agent

iatrogenic

caudes by medical treatment or procedures

idiopathic

unknown causes

exceptions to kochs postulates

some pathogens can’t be cultured in the laboratory, disease caused by a combination of pathogens and other cofactors, ethical considerations prevent applying koch’s postulates to pathogens that require a human host

koch postulates

- germ theory of disease; infections by pathogenic microorganisms cause disease

virulence factors

enzymes, toxins, antiphagocytic factors

enzymes

secreted by the pathogen, dissolve structural chemicals in the body, help pathogen maintain infection, invade, and avoid body defenses important to virulence of the pathogen

toxins

chemicals that harm tissues or trigger host immune responses that cause damage

toxemia

refers to the presence of toxins in the bloodstream, toxins carried beyond the site of infection two

exotoxins

released from cells G- pos, intentionally released

endotoxins

released from destruction of G-neg

antiphagocytic factors

factors prevent phagocytosis by the host’s phagocytic cells

what allows pathogens to remain in a host for longer time?

bacterial capsule, antiphagocytic chemicals

bacterial capsule

composed of chemicals not recognized as foreign, slippery and difficult to engulf

antiphagocytic chemicals

prevent fusion of lysosome and phagocytic vesicles

disease stages

incubation, prodromal, illness, decline, convalescence

incubation

DNA replicates; no signs and symptoms

prodromal

usually when hosts begin to feel sick, vague, general symptoms

illness

most severe signs and symptoms

convalescence

recovering from illness; no signs or symptoms

portals of exit

ear, broken skin, eyes, nose, mouth, skin, mammary glands, vagina, anus, seminal vesicles, urethra

contact transmission

direct, indirect, droplet

indirect contact

pathogens are spread from host to host by fomites
d

droplet transmission

spread of pathogens in droplets of mucus by exhaling, coughing, and sneezing

vehicle transmission

(airborne, waterborne, foodborne) airborne - pathogens travel more than 1m via an aerosol (sneezing, coughing, ac systems, sweeping)

waterborne

f important in the spread of many gastrointestinal diseases

foodborne

spread of pathogens in and on foods

bodily-fluid

such as blood, urine, and saliva can carry pathogens

Vector transmission

(mechanical, biological)

biological

transmit pathogens and serve as host for some stage of the pathogen’s life cycle

mechanical vectors

passively transmit pathogens present on their body to new hosts

acute disease

disease in which symptoms develop rapidly and that runs its course quickly

chronic disease

disease with usually mild symptoms that develop slowly and last a long time

subacute disease

disease whose time course and symptoms range between acute and chronic

asymptomatic disease

disease without symptoms

noncommunicable disease

disease not passed form person to person

local infection

infection confined to a small region of the body

systemic infection

widespread infection in many systems of the body

focal infection

infection site that serve as a source of pathogens for infections at other sites of the body

primary infection

initial infection within a given patient

secondary infection

infections that follow a primary infection

disease incidence

number of new cases of a disease in a given area

disease prevalence

number of total cases of a disease in a given area

endogenous

pathogen arise from normal microbiota within patientia

iatrogenic

results from modern medical procedures

superinfections

use of antimicrobial drugs inhibits some resident microbiota, allowing other microbes to thrive

why healthcare facilities are prone?

presence of microorganisms in hospital environment, immunocompromised patients, transmission of pathogens between staff and patiens

innate immunity

nonspecific, defend anything

first line of defense

skin

physical barrier

epidermis acts like skin barrier

antimicrobial peptides

act against microorganisms

lysozyme

destroy cell wall of bacteria

sebum

keeps hair pliable, secreted by sebaceous glands
m

mucous membranes

thinner barrier - epithelium, secretions - mucus, dendritic cells - below epithelium phagocytize pathogens
de

dendritic cells

below epithelium phagocytize pathogens

Normal microbiome protects in several ways

Nutrient consumption, alter pH, block attachment, bacteriocins - generate antimicrobial compounds

alter PH

create an environment unfavorable to toher microorganisms

block attachment

prevent pathogens from attaching to host cells

bacteriocins

generate antimicrobial compounds
a

antimicrobial peptides

present in skin, mucous membranes, neutrophils, many organs secrete chemicals with antimicrobial properties
s

second line of defense

blood

plasma

mostly water containing electrolytes, dissolved gases, nutrients, proteinsl

leukocytes

white blood cells

platelets

involved in blood clotting

granulocytes

basophils, eosinophils, neutrophils

basophil

stain blue with basic dyeeo