Chapter 12,14,15 Review

health care epidemiology

primary focus is on infection control and the prevention of healthcare associated infection

two categories of infectious disease

• healthcare associated infections

• community acquired infections

Pneumonia 

disease causes the greatest number of deaths from HAIs

4 most prevalent bacterial pathogens most often involved in HAI

• clostridium difficile

• staphylococcus aureus

• Klebsiella pneumoniae

• Escherichia coli

 3 major factors that contribute to causing HAIs

• increasing number of drug-resistant pathogens

• failure to follow infection control guidelines

• increased number of immunocompromised patients

Handwashing

is the single most important measure to reduce the risks of transmitting pathogens from one patient to another or from one anatomic site to another.

asepsis

any actions taken to prevent infection 

 Joseph Lister

pioneer of antiseptic techniques and antiseptic surgery 

medical asepsis

precautionary measures necessary to prevent direct transfer of pathogens 

 surgical asepsis

practices used to render and keep objects and areas sterile 

Chemical sterilants

kill bacterial spores with prolonged exposure times

*l*n the classification system which items confer a high risk if contaminated and must be sterile?

critical items

Noncritical items

needs low level disinfectants 

standard precautions

applied to ALL patients regardless of any diagnosis or admission reason 

 transmission based precautions

• used for patients who are known or suspected to be infected with highly transmissible pathogens

• used in addition to standard precautions

three types of transmission based precautions

• contacts precautions

• droplet precaution

• airborne precautions

AIIR (airborne infection isolation room)

• Airborne infection isolation room

• negative pressure

• air evacuated from an AIIR passes through (HEDA) filter

protective environment

• patients who are especially vulnerable to infection

• the room is under positive pressure air entering the room passes through HEPA filters

 pathogenicity

the ability to cause disease 

infection

means colonization by a pathogen; pathogen may or may not go on to cause disease 

Incubation period

time between arrival of pathogen and illness; pathogen is multiplying 

Prodromal period

time during which patient has general symptoms that are not specific to disease 

Period of illness

patient has typical symptoms associated with disease 

Convalescent period

time during which patient recovers and returns to normal function 

Localized infection

confined to one area of the bod or the original site of infection 

systemic infection

infection spreads throughout the body (generalized infections) 

acute

rapid onset, usually followed by a relatively rapid recovery 

chronic

has a slow onset and lasts a long time 

subacute disease

comes on more suddenly than a chronic disease, but less suddenly than an acute disease 

symptoms

• evidence of a disease that is experienced by the patients

• subjective= say

signs of disease

• objective evidence of a disease

• specific test or something that is measurable

latent infection

• disease that is dormant

• a stress can as a trigger that allows disease to become active

primary disease/infection

first disease

secondary disease/infection

resulting disease from primary

virulence factors

• attributes that enable pathogens to attach, escape destruction, and or cause disease

• phenotypic characteristics

adhesins

enable pathogens to recognize and bind to particular host cell receptors

Fimbriated E.Coli 

type of E. coli anchors to the bladder and can cause cystitis

Intraleukocytic pathogens

are obligate intracellular pathogens that live within white blood cells.

facultative intracellular pathogens 

type of pathogen is capable of both an intracellular and extracellular existence

capsules

protects bacteria; phagocytes are unable to attach and ingest them 

flagella

enable flagellated bacteria to invade aqueous area of the body 

2 major mechanisms by which pathogens cause disease

exoenzymes or toxins they produce 

Necrotizing enzymes

exoenzymes that destroy tissues 

Collagenase

breaks down collagen enabling pathogen to invade tissues 

Hemolysin

cause damage to host’s red blood cells 

endotoxin

part of the cell wall structure of gram-negative bacteria 

Neurotoxins

are the most potent exotoxins and affect the CNS

Scarlet fever

is caused by erythrogenic toxin

the role mucus from mucous membranes has in the first line of defense:

contains substances that can kill bacteria or inhibit growth 

role does the second line of defense serve

usually destroys pathogens able to penetrate the first line 

transferrin

glycoprotein from the liver that has a high affinity for iron and binds to it thus depriving pathogens of it. 

Pyrogens

stimulate the production of fever.

 process of initiating fever

Leukocytes produce Il-1, IL-1 then stimulates hypothalamus to produce prostaglandins which cause the increased temperature 

Interferons

antiviral proteins produced by virus infected cells that interfere with viral replication

Complement system

30 different proteins interacting in the “complement cascade” to assist in destroying pathogens

Opsonization

process by which phagocytosis is facilitate by the deposition of opsonins 

Cytokines

chemical mediators that enable cells to communicate with each other 

3 major events in acute inflammation

• vasodilation which increases blood flow to site

• increased permeability of the capillaries

• accumulation of leukocytes at the site

4 primary purposes of inflammation

• localized an infection

• prevent the spread of microbial invaders

• neutralize any toxins

• aid in the repair of damaged tissue

granulocyte

names for the prominent cytoplasmic granules they posses 

basophils

are involved in allergic and inflammatory reactions

macrophages

immune system cell develops from monocytes during inflammatory responses

 4 steps of phagocytosis

1. chemotaxis

2. attachment

3. ingestion

4. digestion

ingestion

once ingested the object is contained within a membrane bound vesicle called a phagosome 

digestion

the phagosome fuses with a lysosome to form a digestive vaculoe

Chediak Higashi Syndrome 

syndrome causes failure of phagolysosome formation

leukocidin

some bacteria produce an exoenzyme which kills phagocytes 

leukopenia

an abnormally low number of circulating leukocytes