This ppt briefly explains the concept of infection and control

1. Infection control Concepts.

2. Introduction:
• As hospital are gathering places for the sick, they are also focal point
for the transmission of disease.
• Infection control key aspect in patient care.
• As a member of health care system it is a professional duty to follow
established infection control policies.
• This will promote the safety of patients, yourself and other members
of health care system.

3. Micro-organisms :
• Living organisms that are too small to be seen with naked eyes.
• Includes- bacteria , viruses , protozoa , prions and fungi.
• Normal flora – lives inside body without causing infections.
• Investigation for underlying abnormalities in specific areas of the body
when bacteria are isolated from normally sterile sites e.g. Escherichia
coli isolation from blood cultures indicates probable intra-abdominal
pathology because Escherichia coli is part of the normal gastrointestinal
flora, or isolation of a Viridans Streptococcus in blood cultures may
indicate infective endocarditis as a result of poor dentition as
Viridans Streptococcus are part of the normal mouth flora

5. Bacteria
• Bacteria are very small , single- celled organisms with a cell wall and
an atypical nucleus , that lacks a membrane .
• Cell wall is essential for survival of the bacterium , making it target for
destruction by some antibiotics.
• Bacteria grow independently and can replicate without a host cell.
• Three distinct shapes : spherical (cocci ),rod- shaped (bacilli),
and spiral (twisted).
• Can be gram positive or gram negative.
• Gram positive if they retain the color after being treated by alcohol .
• Can also be acid-fast or nonacid-fast.

6. Cont..
• Streptococci and staphylococci are gram positive. Escherichia coli is
gram negative and mycobacterium tuberculosis is acid-fast.
• Bacteria are also grouped by their oxygen requirement.
• Obligate Aerobes and anaerobes
• Bacteria that can grow in both condition either aerobic or anaerobic
are called facultative organisms .
• Some type of bacteria can generate endospores.
• Generally endospores are resistant to destruction.

7. Rickettsiae:
• Are also consider bacteria but are atypical , smaller than bacteria and
barely visible in an ordinary light microscope.
• They only grow inside animal cells (e.g. rats, rabbit)
• Do not survive in environment.
• They are transmitted among animal when they are bitten by infected
arthropods such as ticks , lice, fleas and mites.
• Human are only accidental host.
• These cause rocky mountain spotted fever and typhus fever.

8. Viruses :
• Smallest known disease – causing organisms. Must be viewed in
electronic microscope.
• A fully developed viral particle is called as virion, is made up of either
DNA or RNA.
• Is covered by protein coating called the capsid.
• Capsid may be covered by a lipoprotein envelop that has projecting
spikes .
• Enveloped viruses such as influenza , HIV , hepatitis B uses these
spike to attach to the host cell.
• Rhino virus does not posses spikes .Capsid helps in attachment.

9. Cont..
• Viruses can not survive independently.
• They invade the host cell and stimulate it to participate in the
formation of additional virus particles.
• It has been difficult to create antiviral drugs that are not also harmful
to host cell.

11. Corona virus microscopic image .

12. Fungi :
• Fungi occurs as single celled yeasts or as long, branched filament like
structures called molds (many cells).
• Yeast reproduce by forming buds, whereas mold reproduces by
spores.
• Many fungi serves for useful purpose.
• Antibiotic penicillin .
• Helps in decomposition of dead animals and plants.
• In humans fungi causes skin infections , such as athlete's foot and ring
worm.
• Respiratory infections , pharyngeal and esophageal candidiasis.

14. Prions:
• The smallest and least understood among all pathogens.
• Scientists believe that it might be a infectious protein.
• They don’t posses DNA or RNA , their method of replications are also
not fully understood.
• They affect the nerve cells and are resistant to body’s natural defense
system.
• They were first identified as the cause of scrapie, a degenerative
disease affecting the nervous system of sheep.
• Prions are the cause of bovine spongiform encephalopathy (mad cow
disease.)and both classic and variant creutzfeldt –jakob disease in
humans. Causes neurological problems and dementia.

15. Protozoa :
• They are complex single-celled animals that generally exist as free-
living organisms.
• Few are parasite and live within human body.
• May be classified as motile and non- motile.
• They locomot using pseudopods / cilia / flagella.
• Most protozoa produces some type of resistant form , such as cyst to
survive in the environment outside of host.
• Other protozoa have complex life cycles involving alternate residence
in the human body and insect vector . Like malaria.
• They can infect gastrointestinal , genitourinary , circulatory and
respiratory systems.

16. Cont..
• Amebiasis and giardiasis – causes diarrhea.
• Trichomoniasis – affects genitourinary tract. Causes yellow-greenish
discharge from male and female urethra and vagina.
• Toxoplasmosis – affects the blood and lymphatic system .

19. Cycle of Infection:
• The factor involved in the spread of disease are sometimes called the
cycle of infection.
• For infection 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 susceptible individual .

20. Infectious Organisms:
• Microorganisms capable of causing disease are called pathogenic
organisms or pathogens.
• They posses certain properties called virulence factors.
• These factors enable bacteria to destroy or damage host cells and
resist destruction by the host’s cellular defense.
• Each bacterial pathogens has an affinity for a certain type of cell in
the body.
• They attach to this cell and excrete protein substance called toxins.
• Virulence factor assist the pathogens to avoid recognition by the host
cells .

21. Reservoir Of Infection:
• The reservoir or source of infection may be any place where
pathogens can thrive in sufficient numbers to pose a threat.
• Such environments must provide moisture, nutrients , and a suitable
temperature , all of which are found in human body.
• A reservoir of infection might be a patient with hepatitis , a
radiographer with an upper respiratory infection or a visitor with
staphylococcal boils.
• Animals , the reservoir for salmonella.
• Soil , the reservoir for tetanus.
• Food, the reservoir for botulinum.
• Water, the reservoir for typhus.

22. Portal of Exit:
• The portal or exit from the human body may be any route through
which blood, body fluid , excretions, or secretions.
• Example includes the respiratory , urinary and gastrointestinal tracts ,
an infected wound and the bloodstream .

23. Susceptible host :
• Patient who have a reduced natural resistance to infection.
• May develop nosocomial infection.
• For health care workers – occupationally acquired infections.-
hepatitis B and C viruses are the biggest concern.
• Hospital workers , mainly radiographer are exposed to many
pathogens.

24. Portal of Entry:
• It is the route by which microorganisms gain access into the
susceptible host.
• Example: respiratory , urinary and GI tracts, open wound or break in
skin , mucous membranes of eyes, nose and mouth and the blood
stream .

25. Transmission of Disease.
• Direct contact
• Indirect contact
a) Fomites- object that has been in contact with pathogenic organisms
is called a fomite. A contaminated urinary catheter is a typical
example. X-ray table , vertical Bucky , sponges etc.
b) Vectors – vector is an arthropod / insect (infected by infectious
organisms ). Eg: malaria , dengue , plague etc.
c) Vehicles – any medium that transport microorganisms like food,
water , drugs, blood etc.
d) Droplet contamination – Large droplet containing microorganism
and measuring more than 5 micrometer. Does not last in air form
long time and travel short distance around 3 feet . Eg: Influenza,
meningitis , diphtheria , pertussis , streptococcal pneumonia etc.

26. Cont..
e) Airborne Transmission – occurs from dust that contains spores or
droplet nuclei.
- Droplet nuclei are defined as particle of evaporated droplets
containing microorganisms.
- They can remain suspended in air for longer period of time.
- Eg: Tuberculosis , rubeola (Measles), Varicella viruses.

27. Body’s defense against Infections:
• Natural Resistance- intact skin and mucous membranes , cilia of
respiratory tract , lysozyme in tears , acid in stomach , vagina and skin
. 2nd line of defense is inflammatory response and phagocytosis .
Viruses infected cells produce interferons , a small protein molecule
that protects the uninfected cells from invasion by the original virus
as well as others. Produced in labs. for treatment of hepatitis B and C.

28. Acquired Immunity :
• Humans are born with a certain amount of immunity , but most
humans become resistant to disease by becoming infected with a
specific organism.
• Immunity can also be conferred from vaccines made from dead or
weakened strains of microorganisms for a specific infection. –
Acquired Immunity .
• Antibodies are produced against antigens .
• Acquired immunity is long term .

29. Passive Immunity:
• Passive immunity occurs when an individual receives preformed
antibodies from others to provide temporary immunity .
• Eg: immunoglobulin injections to prevent infection after exposure to
certain viruses and the immunity that is passed to infants from their
mothers at birth and in breast milk .

30. • Reference: Patient care in Radiography , 9th edition , Ruth Ann Ehrlich
.
• Online sources.
Thank you !!