Because hospitals are gathering places for the sick, they are also focal
points for the transmission of disease. Anyone with a health problem
is more susceptible to infection, and therefore infection control is of
critical importance in patient care.
As a member of the health care team, it is your professional duty to
follow established infection control policies. This will promote the
safety of patients, yourself, and other members of the health care
team. The emergence of new diseases, the return of old ones, and
the development of hospital-acquired, multidrug-resistant infections
make it even more important for these policies to be followed and for
everyone to play a role in preventing the spread of infection.
Infection is the invasion and multiplication of microorganism in body
tissues which may be clinically in apparent or result in local cellular
injury due to competitive metabolism,toxins,in the cellular replication
or antigen-antibody response
is an establishment and growth of micro organisms in or on the host
Microorganisms are living organisms that are too small to be seen
with the naked eye.
They include bacteria, viruses, protozoa, prions, and fungi. Most
microorganisms do not cause infection or disease and are essential
for our well-being
Microorganisms that live on or inside the body without causing
infections or diseases are referred to as normal microbial flora
They aid in skin preservation and digestion and protect us from
harmful organisms that can cause infections or diseases.
Microorganisms that cause infections and diseases are called
pathogens, and their harmful effects will be discussed later.
Bacteria are very small, single-cell organisms with a cell wall and an
atypical nucleus that lacks a membrane. The cell wall is essential for
survival of the bacterium, making it the target for destruction by
Bacteria grow independently and can replicate without a host cell.
They are classified according to shape, and most have one of three
spherical, called cocci;
rod-shaped, called bacilli;
and spiral, classified as either spiral or spirochetes
• may be further classified based on how the cells are grouped. They
may exist singly, in groups of two, in long chains, or in clusters.
• occur as single cells, in pairs, or in chain
By using staining processes, bacteria can be sub classified;
as Gram-positive or Gram-negative,
and as acid-fast or nonacid-fast
Following the Gram-stain process, bacteria are identified as Gram-
positive if they retain the dye when treated with alcohol. If the alcohol
washes out the dye, they are called Gram-negative
• To determine if bacteria are acid-fast, a different staining process is
used. The bacteria are stained, heated, and treated with an acid
alcohol to remove the color.
If the bacterium resists decolonization, it is classified as acid fast
positive, indicating that acid-fast bacteria are present.
If decolonization occurs, the bacterium is acid-fast negative
Streptococci and staphylococci are Gram- positive. Escherichia coli, a
bacillus, is Gram-negative,
Mycobacterium tuberculosis, a bacillus, is acid-fast positive, often
simply called "acid fast.
Bacteria are also grouped based on their oxygen requirements. Some
require oxygen to grow and are called obligate aerobes,
while others will not grow in the presence of oxygen and are called
anaerobes. Bacteria that can adapt and grow under either aerobic or
anaerobic conditions are called facultative organism.
Bacteria are able to adapt to new conditions and are also able to
mutate, allowing them to resist and survive in the presence of
are subcellular organisms and are among the smallest known
disease-causing organisms. Because of their small size, they must be
viewed with an electron microscope.
A fully developed viral particle, called a virion, is made up of genetic
material, deoxyribonucleic acid (DNA) or ribonucleic acid (RNA),
which is protected by an outer protein coating called the capsid. The
capsid may be covered by a lipoprotein envelope that has projecting
Enveloped viruses, such as influenza, human immunodeficiency
virus (HIV), and hepatitis B, use these spikes to attach to host cells.
Viruses cannot survive independently. A virus invades a host cell for which
it has specificity, stimulating it to participate in the formation of additional
virus particles. For example, the hepatitis virus attaches to receptor sites
on a liver cell. Because viruses reside in and use the host cell to replicate, it
has been difficult to create antiviral drugs that are not also harmful to the
host cell. Only a few antiviral agents exist, and these are useful against only
a limited number of virus.
Other common viruses include the Epstein-Barr virus, which causes
infectious mononucleosis, and varicella, which causes chicken pox and
are complex single-celled animals that generally exist as free-living
organisms; a few are parasitic and live within the human body.
They may be classified as motile (moving) or nonmotile.
If motile, they are further classified by their method of motility. Some
move by changing their shape to form pseudopods (false "feet");
others move using flagella, whip like formations that move the cell, or
cilia, fine, hair like projections that propel the organism.
Most parasitic protozoa produce some type of resistant form, such
as a cyst, to survive in the environment outside the host. Other
protozoa have complicated life cycles involving alternate existence in
the human body and an insect vector. This is true of the protozoan
that causes malaria.
Fungi (singular, fungus) occur as single-celled yeasts or as long,
branched, filament-like structures called molds that are composed of
Some fungi can exist in either form, depending on the environment.
Yeasts reproduce by forming buds, while molds reproduce by spore
CYCLE OF INFECTION
The factors involved in the spread of disease are sometimes called the
cycle of infection. For infections to be transmitted, there must be
an infectious organism,
a reservoir of infection,
a portal of exit,
a susceptible host, a portal of entry,
and a means of transporting the organism from the reservoir to the
RESERVOIR OR SOURCE OF INFECTION
The reservoir or source of infection may be any place where
pathogens can thrive in sufficient numbers to pose a threat. Such an
environment must provide moisture, nutrients, and a suitable
temperature, all of which are found in the human body.
Because some pathogens live in the bodies of healthy individuals
without causing apparent disease, a person may be the reservoir for
an infectious organism without realizing it. These persons are called
The portal of entry is the route by which microorganisms gain access
into the susceptible host. Examples include the respiratory, urinary,
and gastrointestinal tracts; an open wound or break in the skin; the
mucous membranes of the eyes, nose, or mouth; and the
TRANSMISSION OF DISEASE
The most direct way to intervene in the cycle of infection is to prevent
transmission of the infectious organism from the reservoir to the susceptible
To accomplish this, you must understand the six main routes of transmission:
The first route is direct contact. This transmission mode requires that the host is
touched by an infected person and that the organisms are placed in direct contact
with susceptible tissue.
For example, syphilis and HIV infections may be contracted when infectious
organisms from the mucous membrane of one individual are placed in direct
contact with the mucous membrane of a susceptible host.
Also, skin infections often occur among hospital workers because of the frequent
contact with patients who have staphylococcal and streptococcal disease
The five other principal routes of transmission are indirect and
involve transport of organisms by way fomites, vectors, vehicles,
airborne means, and droplet contamination.
An object that has been in contact with pathogenic organisms is
called a fomite
A contaminated urinary catheter is a typical example. Other fomites
in the radiology department might include the x-ray table, vertical
Bucky, image receptors, positioning sponges contaminated with
infectious body fluids, or perhaps your contaminated glove
A vector is an arthropod in whose body an infectious organism
develops or multiplies before becoming infective to a new host.
Some examples of vectors are mosquitoes that transmit malaria or
dengue fever, fleas that carry bubonic plague, and ticks that
spread Lyrne disease or Rocky Mountain spotted fever.
A vehicle is any medium that transports microorganisms. Examples
include contaminated food, water, drugs, or blood.
Airborne contamination occurs either by dust that contains spores or
by droplet nuclei, which are particles of evaporated droplets
measuring 5 microns (micrometers, ym, 0.001 mm) or smaller
containing microorganisms that remain suspended in the air for long
Droplet contamination often occurs when an infectious individual
coughs, sneezes, speaks, or sings in the vicinity of a susceptible host.
Droplet transmission involves contact of the mucous membranes of
the eyes, nose, or mouth of a susceptible person with large droplets
(greater than 5 ym) containing microorganism
PREVENTING DISEASE TRANSMISSION
Standard Precautions are designed to reduce the risk of transmission
of unrecognized sources of blood borne and other pathogens in
health care institutions. Standard Precautions apply to:
All body fluids
Secretions and excretions (except sweat), regardless of whether they
contain visible blood
Standard Precautions also reduce the risk of transmission from
recognized sources of infection by including precautions for three
modes of transmission:
airborne, droplet, and contact. These transmission based precautions
are discussed later in Isolation Technique.
You must decide when to take the extra time to protect both yourself
and your patients. How you assess these risks and respond to them
will vary with the setting and your level of experience. As a beginning
student, your level of precautions should be very high.
Although you may observe more experienced workers taking fewer
precautions, do not think that you must Follow their example. At this
stage in your education, it is far better to take too much precaution
than to use too little. Remember that the key to effective protection is
using a consistent approach to all contact Substances of all patients at
Medical asepsis deals with reducing the probability of infectious
organisms being transmitted to a susceptible individual. The healthy
human body has the ability to overcome a limited number of
infectious organisms, but this resistance can be overwhelmed by a
On the other hand, reduced resistance caused by disease, cancer
chemotherapy, immunosuppressant's, or extremes in age may result
in infection after only minimal exposure. The fewer organisms to
which a patient is exposed, the more likely it is that he or she will
The process of reducing the total number of organisms is called
microbial dilution and can be accomplished at several levels.
First, simple cleanliness measures, such as proper cleaning, dusting,
linen handling, and hand hygiene techniques, can reduce the
transmission of microorganisms.
The second level is disinfection and Involves the destruction of
pathogens by using chemical materials.
The third level is surgical asepsis, or sterilization. his involves treating
items with heat, gas, or chemicals to make them germ-free. The
sterile items are then stored in a manner that prevents
Hand hygiene refers to decontamination of the hands using soap and water,
an antiseptic hand wash, or an alcohol-based hand rub
Medically aseptic handwashing is an easy and effective method to control
the transmission of infections
Unfortunately, evidence shows that most physicians, nurses, and other
health care workers do not wash their hands often enough or well enough.
There are several reasons attributed to the poor adherence to regular
handwashing in health care facilities: inaccessibility to sinks, lack of time in
between patients, lack of role models, and the concern that handwashing
is irritating to the skin and causes drying
Use of an alcohol-based hand rub requires about 15 seconds of time versus
about a minute to walk to a sink and another 30 to 60 seconds to complete
the handwashing procedure. An alcohol based hand rub is more accessible
than a sink because it can be carried in the health care worker's pocket or
is located at the patient's bedside.
Additionally, it has been found to be more efficacious than soap and water
in reducing nosocomial infections. Alcohol-based hand rubs are also less
irritating to the skin, especially when skin-conditioning agents are added to
They are very effective against many microorganisms (Gram-negative,
Gram-positive, M. tuberculosis, fungi, and some viruses) including
multidrug-resistant organisms. However, it will not destroy bacterial spores
Handwashing with soap and water is still recommended to physically
remove spores from the surface of contaminated hands.
Alcohol-based hand rubs should not replace handwashing with soap
and water when hands are visibly soiled or contaminated with blood
or body secretions or excretions.
Gloves should always be worn to prevent contact with the patient's
blood or other body fluids. Following removal of the gloves, the
hands should be decontaminated through use of an antiseptic hand
rub or antiseptic hand wash to reduce bacterial count
HANDLING AND DISPOSAL OF
CONTAMINATED ITEMS AND WASTE
Objects or linens soiled with body secretions or excretions are
considered contaminated and may serve as fomites even when no
stains are apparent.
Any linen used by patients should be handled as little as possible. To
prevent airborne contamination, fold the edges of linens to the
middle without shaking or flapping, and immediately place loosely
balled linens in the hamper.
DISPOSAL OF CONTAMINATED WASTE
A modern hospital uses many disposable items, from simple objects such
as paper cups and tissues to more complex items such as catheterization
sets. Disposable items are designed to be used only once and then
discarded. The only exception to this rule involves the immediate reuse of
an unsterile item (for example, emesis basin) by the same patient.
Each hospital has a protocol for discarding disposable items. Some
separate glass, plastic, and paper into covered containers, while others
place everything together. Follow the procedure for your institution.
Regulations demand that objects contaminated with blood or body fluids
be discarded in a suitable container and marked with the biohazard
Used needles and syringes are placed in special containers designed to
receive the syringe without recapping it
Some provide a sheath that slides forward to shield the contaminated
needle, and others have a retractable needle.
The health care worker can retract the needle into the syringe after
removing the needle from the vein.
It is important to use these safety features to prevent accidental
needle sticks. A needleless system provides the greatest protection
from needle sticks and should be used to introduce medications and
contrast media after initial venous access is established
These are techniques that prevent the transforms of pathogens from
one person to another, their aim is to contained pathogens by
establishing aseptic barrier around the client and personnel.
The most commonly used barriers are:
ii. Gowns, gloves, private rooms
iii. Labelling and bagging of the contaminated equipment and
iv. Water proof disposable bags for linen
v. Control air flow into sterile areas and out of contamination.
Reverse barrier nursing
This is method used to patient who has very low immunity.
Example; severely burnt client/patient so that he is protected from
LOCATION IN CARRYING OUT
BARRIER/REVERSE BARRIER NURSING
Single room is very much recommended
A cubicle or corner bed in the ward may be chosen
Corner bed should be screened across the foot of the bed
A clearly written “NO ENTRY” should be displayed at the entrance
Elements to follow in barrier nursing
Hand washing on entering and leaving the room
Used of gowns,masks,gloves.gown could be disposable after use or
those which can be disinfected and laundered.
Decontamination before rinsing soiled articles with blood to protect
yourself from spray of droplets (soaking of the article in chlorine
prepared from pharmacy)
Each client to have his own bedpan and urinals
Eating utensils must be washed and boiled for 10 minutes.
Each client should be mapped with disinfectant 1:20
Furniture should be cleaned with disinfectant
All charts clients files and x-ray films should be kept the barrier area
to avoid contamination.
CARE OF INFENCTIOUS PATIENT ARRIVING AT
THE X- RAY DEPARTMENT
If possible the infectious patient should not be allowed to come to
the x-ray department, but should be examined in the word by means
of a mobile x-ray.
If he/she is brought to the x-ray department then he should stay
there for the shortest time consistent with an efficient examination.
An infectious patient should be attended at the x-ray department
when the department is not busy and there are no patients present
Examining the patient at such a period will make it easier to ensure
the isolation of the infectious patient
If it is not possible to examine him lately then he must be x-rayed as
soon as he arrives in the department taking priority over other
For drying hands, use disposable paper towels
The x-ray rooms and changing rooms should be well ventilated and
must be kept clean and tidy.
Accessories such as the pads head clamps, angle boards and
protractors should be kept in closed cupboards where they are more
likely to escape dust
The top of the x-ray table and the front surface of the erect potter-
Bucky stand should be cleaned with a suitable stand should be
cleaned with a suitable antiseptic solution.
Aerosol sprays are useful since they allow quick, easy and hygienic
application of the cleansing agent.
Patient should wear a clean gown and have a clean cubicle in which
to undress. This is to maintain hygiene for the patient and thus cross
infection is well controlled.
oChemotherapy – treatment of disease by chemical agents
oDisinfectant – chemicals used to free an environment from
pathogenic organisms or to render such organism inert.
oFomite – is an inanimate object that has been in contact with an
oHost – animal or plant that harbors or nourishes another organism.
oIatrogenic – resulting from the activities of physicians
oImmunity – security against a particular disease
oNosocomial – pertaining to or carrier that harbors pathogenic
organism, without injury to itself and serves as a source from which
other individuals can be infected.
oVector – carrier especially an animal (usually arthropod)that transfers
an infective agent from one host another
oCarrier – a person who serves as a reservoir; is an infection individual
who does not display the disease symptoms.