Description of infection , it's types ,sources of infection and mode of transmission of infection.

1. Bsc nursing 1 year
Microbiology
Unit :- 3 (infection)
BY:- PRAGYA TIWARI

2. Terminology:-
 Disinfection:- Distraction of all pathogenic microorganism.
 Disinfectant:- A substance destroy bacteria except spore and it’s used for the
cleaning.
 Antisepsis:- Prevention of infection by inhibiting the growth of microorganism or
bacteria.
 Antiseptic :- chemical disinfectant that can be safely applied on skin or mucous
members and are used to prevent infection by inhibiting the growth of bacteria.
 Bacteriostage :- A chemical agent that inhibit tht bacterial growth. (Stage – to
stop or inhibit the growth)
 Cleaning :- Process of removal of dirt, oiland other visible substance from a
surface during cleaning microorganism are also reduced in number.
 Decontamination :- Removal of hazardous substance, microorganism chemicals,
radioactive substance

3. Infection:-
Infection:- The lodgement and multiplication of organisms in the tissue of host constitute classification
of infection :- these are following –
 Primary infection:- Initial infection with organism in host is called primary infection.
 Reinfection :- subsequent infection by same organism in a host is called reinfection.
 Secondary infection:- when in a host whose resistance is lower by pre-existing infectious disease, a
new organism may set up an infection called secondary infection.
 Focal infection/ localised infection:- It is a condition where due to a infection act localised sites like –
tonsils, is called focal infection.
 Cross infection :- When a patient suffering from a disease and few infection setup another host or
external source is called cross infection.
 Nosocomial infection :- Cross infection occurring in hospital is called nosocomial infection.

4. Source of infection :-
Source of infection:-
1. In men :- Men is himself a common source of infection from a patient to carrier. Health carrier is
a person harbouring pathogenic organism, without causing any disease to him. A convalescent
carrier, one who has recovered from disease but continuous to harbor the pathogen in his body.
2. In animal:- Infectious disease transmitted from animals to men are called Zoonosis. Zoonosis
amy be bacterial (eg- plague) , from rat, viral(eg- rabbies from dog).
3. Insect :- The disease caused by insect are called arthropod born disease. Insect like –
mosquitoes, flies, that transmitte are called vector eg-female anopheles mosquito in maleria,
agent Plasmodium .
4. Soil:- soil may serve as source of parasitic infection like – roundworm, hookworm.
5. Water:- Vibrio cholerae, infective hepatitis virus (hepatitis A may be found in water )

5. Mode of transmission of infection:-
Variety of machenism. These includes –
1. Contact direct contact – such as sexually transmitted diseases.
2. Indirect contact – It may be through the agency of formites which are inanimate
(lifeless) object such as clothing, pencil or toys. Which may be contaminated by a
pathogen from one person and act as a vehicle for its transmission to another.
@ Inhalation :- Respiratory infection such as common cold and tuber closes etc,
are acquired by inhalation.
@ Injestion :- Intestinal infection are generally acquired by the injestion of food
and drink contaminated by pathogen.
@ Inoculation :- The disease agent inoculate direct into the skin or mucous eg-
rabbige virus deposited Subcutaneously by dog bite.
@ Congenital :- some pathogen are able to cross the placenta barrier and reach.
The fetus in uterus, disease knows as the vertical transmission (at the time of birth).

6. Chain of infection:-
Chain of infection :-
 infectious agent :- these are any microorganism that can causes a disease such
as bacteria, virus or fungus, parasite. Any organism capable of causing infection
if all the link (component are present)
 Reservoir :- (Where germs live ) It is a place where microorganism resides and
reproduce i.e food, water, toilet human feces, respiratory secretion.
 Portal of exist :- How germs get out. It is a where microorganism leave the
reservoir such as a respiratory tract (nose,mouth) , intestinal track (rectum via
stool) , urinary track, blood and other body fluids

7. Chain of infection :-
 Mode of transmission:- (germs gets around) It means by which an organism
transfer from one carrier to another by either direct or indirect transmission
 Portal of entry:- (how germs get in the host body ) The opening where
infectious disease inters the host body such as mucous member, open wound or
tube inserted in body .
 Susceptible host :- (sick person) It is a person who is at risk for developing an
infection from disease eg- babies – children- elderly people with a weak
immune system, unimmunese people, any one.

8. Chain of infection:-

9. Asepsis:-
Asepsis :-
It is absence of pathogenic organism. It is divided into 2 categories.
 Medical asepsis
 Surgical asepsis
Medical asepsis :-
It consist of technique that inhibits the growth and spread of microorganism.
Medical asepsis is also known as clean technique. It is used in many activities. They
include hand washing, Bathing, cleaning environment, glowing, Gowning, mask
bearing disinfecting articles are used of antiseptic, changing patients bed
linens(bedsheets,pillow cover, clothes etc).

10. Surgical asepsis :-
It destroy all microorganism and their spore. It is
known as sterile technique and it is used I’m
specialized areas or skills, such as care of surgical
wound, urinary catheter insertion, invasive
procedures and surgery.