HNN227 Study Guide - Final Guide: Sputum, Exudate, Pleurisy
1 Jun 2018
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HNN227
INFECTION AND PNEUMONIA
1
DEFINE THE TERM INFECTION
- Infection: infection occurs when a pathogen (a microorganism that causes disease) invades the
body, begin to multiply and produce disease, usually causing harm to the host.
DESCRIBE THE PATHOPHYSIOLOGY OF THE INFECTIVE PROCESS AND IDENTIFY WHERE IT
MAY OCCUR IN THE BODY
PATHOPHYSIOLOGY OF INFECTION:
Invasion by most microorganisms begins when they adhere to ells i a persos ody. Adheree to the
cell allows microorganism to establish a base from which to invade tissues.
Whether the microorganism creates a severe infection or spreads or not is dependent on whether it
produces toxins/enzymes/other substances or not, whether it develops resistance to antimicrobial drugs,
hether it a lok the odys defee ehaiss ad ho ell the persos iue syste is
functioning.
After invading the body, microorganisms must multiply to cause infection. After multiplication begins, one
of three things can happen:
1. Microorganisms continue to ultiply ad oerhel the odys defees
2. A state of balance is achieved causing a chronic infection
3. The body destroys and eliminates the microorganism
How ateria esape our ody’s defence mechanism:
1.
Interfering with the bodies production of antibodies (T cells)
2.
Being enclosed in protective outer coats (capsules) that prevent WBC from ingesting
microorganisms
3.
Resisting being split open
4.
Producing substances that counter the effects of antibiotics (beta-lactamase)
5.
Produe a layer of slie alled iofil that helps the attah to ells ad reduces their risk of
being killed by antibiotics
How the body defends itself:
PHYSICAL BARRIERS INCLUDE: Skin, mucous membranes, tears and earwax
IMMUNE SYSTEM: uses WBC and antibodies to identify and eliminate microorganisms that get through the
odys physial arriers. It ireases the uer of ertai types of WBC eutrophils ad ooytes,
which engulf and destroy invading microorganisms. The blood carries these to the site of infection.
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The immune system may also produce killer T cells and antibodies. Antibodies attach to an immobilised
microorganism and destroy them.
Inflammation is the next line of defence, and fever is another defence mechanism.
Bacteria or viruses can cause infection. Bacteria can be treated with antibiotics (however antimicrobial
resistance is occurring). Viruses are harder to destroy as they hide in the cells away from antibodies.
Antiviral drugs are infective against only a few viruses (HIV for example).
Infections can be systemic or local.
CHAIN OF INFECTION:
- Aetiological Agent: This is the extent to which any micro-organism is capable of producing an
infectious process depends on the number of micro-organisms present, the virulence and
pathogenicity, the ability of the micro-organism to enter the body, the susceptibility of the host and
the ability of the micro-orgaiss to lie i the hosts ody. E.g.
bacteria, virus, fungi, parasites,
prion
- Reservoir: there are many reservoirs or sources for microorganisms. Common sources are other
huas, the idiiduals o iroorgais, plants, animals and the general environment. E.g
.
Human – back of mouth, Environment – dust, soil, water
- Portal of exit from reservoir: before an infection can establish itself in a host, the microorganisms
must leave the reservoir.
E.g. Respiratory tract, GI tract, skin (open wound).
- Method of transmission:
Contact transmission: Direct contact (person to person), indirect contact (inanimate object eg.
hilds toy), droplet contact (coughing, sneezing)
Common vehicle route: Food, water, drugs, blood – HEP B
Airborne transmission: Droplet nuclei – evaporated droplets that remain suspended in the air,
dust particles containing agent
Vector-borne transmission: Mechanical or biological spread – flies, mosquitoes
- Portal of entry to the susceptible host: before a person can become infected, micro-organisms
must enter the body. The skin is a barrier to infectious agents; however, any break in the skin can
readily serve as a portal of entry.
E.g. Respiratory tract, GI tract, break in skin, trans placental
(mother to baby), conjunctiva
- Susceptible host: ay perso at risk for ifetio. Ipairet of the odys iue syste,
integumentary system and other biological factors increase susceptibility.
WHERE IT MAY OCCUR IN THE BODY:
Respiratory tract, GI tract, breaks in the skin, conjunctiva, brain, bone etc.
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find more resources at oneclass.com
Document Summary
Infection: infection occurs when a pathogen (a microorganism that causes disease) invades the body, begin to multiply and produce disease, usually causing harm to the host. Describe the pathophysiology of the infective process and identify where it. Invasion by most microorganisms begins when they adhere to (cid:272)ells i(cid:374) a perso(cid:374)(cid:859)s (cid:271)ody. Adhere(cid:374)(cid:272)e to the cell allows microorganism to establish a base from which to invade tissues. After invading the body, microorganisms must multiply to cause infection. After multiplication begins, one of three things can happen: microorganisms continue to (cid:373)ultiply a(cid:374)d o(cid:448)er(cid:449)hel(cid:373) the (cid:271)ody(cid:859)s defe(cid:374)(cid:272)es, a state of balance is achieved causing a chronic infection, the body destroys and eliminates the microorganism. Physical barriers include: skin, mucous membranes, tears and earwax. Immune system: uses wbc and antibodies to identify and eliminate microorganisms that get through the (cid:271)ody(cid:859)s physi(cid:272)al (cid:271)arriers. It i(cid:374)(cid:272)reases the (cid:374)u(cid:373)(cid:271)er of (cid:272)ertai(cid:374) types of wbc (cid:894)(cid:374)eutrophils a(cid:374)d (cid:373)o(cid:374)o(cid:272)ytes(cid:895), which engulf and destroy invading microorganisms.
