Microbiology
Microbiology is the
study of micro-organisms - usually only visible under a microscope. It is
important to know about these as some may cause disease.
Pathogenic micro-organism
A micro-organism
which causes disease
Non-pathogenic micro-organism
A micro-organism
which does not cause disease, live with us as commensals
Organisms which do
not cause disease in one location may cause disease in another place. Eg. Coliforms are commensal in the colon but
pathogenic in the bladder or blood
Eg. Escherichia coli may cause cystitis or choleycystitis
Forms of micro-organism
Prion, Virus, Mycoplasma,
Bacteria, Protozoa, Fungi, Helminths
Prions are self replicating rogue protein molecules
Viruses may use DNA
or RNA as their genetic material, they are about 20 – 80 nm in size
Mycoplasma are small simple bacteria and do respond to antibiotics
Bacteria are about 1
micrometer in size and are prokaryotic
Protozoa are
eukaryotic
Arrange the following infectious diseases under the aetiological
organism
Tuberculosis,
Smallpox, Measles, Mumps, Gastro-enteritis, German measles, Athletes foot,
Monilia, Meningitis, Pneumonia, Cold sores, Leprosy, Colds, Influenza, Wound
infection, Cystitis, Conjunctivitis, Osteomylitis, Chicken pox, Diphtheria,
Whooping cough (pertussis), AIDS, Herpes cold sores, Peptic ulcers, Syphilis,
Gonorrhoea, Malaria, Hepatitis, Sore throat, Candida, Pneumocystis, Cholera,
Creutzfeld Jakob Disease
Rubella Diptheria
Herpes
zoster Whooping
cough
Staining of bacteria
Bacteria need to be
stained so they may be seen under the microscope
Gram positive - holds blue stains
Gram negative - does
not hold blue stains, these are usually stained red
Shapes of bacteria
Bacteria may be
classified by their shape
Cocci -
spherical
Bacilli -
rod shaped
Vibrio -
curved bacteria
Groups of bacteria
Staphylococcus - grow in clusters
Streptococcus - grow in chains
Diplococcus
Bacteria and oxygen
Aerobic -
need oxygen to survive
Anaerobic - are poisoned by
oxygen
Treatments
Virus -
no treatments for most infections
Bacteria -
antibiotics for most infections
Fungi -
local and systemic anti-fungal drugs
Spread of infection
Vector -
any organism which transmits infection
Fomite -
any object which transmits infection
Direct contact
Indirect contact
Droplet
Insects
Animals
Body fluids
Faecal-oral
Food and drinks
Terms
Epidemic -
increase in incidence of a disease
Pandemic -
world wide epidemic
Endemic -
a disease which is always present
Bacterial growth requirements
Temperature –
most pathogens like a temperature of 37`C
Water – lack of
water can cause spore formation
Substrates
Oxygen for aerobes
Bacterial growth medium
Bacterial reproduction
Bacteria reproduce by
simple cell division, (binary fission)
In optimum conditions
bacteria may divide every 20 minutes
Opportunist
infections
MICROBIOLOGY
Virus
Bacteria
Mycoplasm
Protozoa
Fungi
List common diseases caused by each of the above microorganisms
Define a pathogenic microorganism
Differentiate between:
Cocci
and bacilli
Gram
negative and positive bacteria
Aerobic
and anaerobic organisms
Staphylococcus
and streptococcus
Briefly outline the treatment options for viral,
bacterial and fungal infections
State what a vector and a fomite are
Describe the possible means of mirco-organisms
between individuals
Discuss what a good bacterial growth medium
consists of
State how frequently bacterial numbers can
increase given good conditions.
Microbiology is the study of micro-organisms –
usually they are so small that they are
only visible with the aid of a microscope. It is important to know about
these as some may cause disease.
Pathogenic micro-organism
Non-pathogenic micro-organism
A
micro-organism which does not cause disease
It
is important to know that organisms which do not cause disease in one location may
cause disease in another place. Eg.
Coliforms are commensal in the colon but pathogenic in the bladder or
blood
Micro-organisms that usually
populate the human body are called the normal flora; they are commensals, do not harm their host and may even be
beneficial.
CLASSIFICATION OF MICRO-ORGANISMS
A EUCARYOTES - microsopic animals
1.
Protozoa (unicellular)
amoeba, malarial parasites
2.
Helminths
(multicellular) tapeworms, flukes, roundworms
B EUCARYOTES - microsopic plants
1.
Fungi, e.g. yeasts and moulds
2.
Algae (all non-pathogenic) green, brown, red algae
C PROKARYOTES
1.
Bacteria (true bacteria) e.g. staphylococci
2.
Actinomycetes
(filamentous bacteria) e.g. Streptomyces
3.
Rickettsias
(parasitic intracellular bacteria
a.
Rickettsias,
e.g. typhus fever
b.
Chlamydias
e.g. psittacosis
4.
Mycoplasm
(bacteria without cell walls e.g. Mycobacterium pneumoniae
5.
Phototrophic bacteria (produce oxygen in
sunlight)
a.
Cyanobacteria
e.g. blue-green algae
b.
Photosynthetic e.g. purple and purple
sulphur bacteria
D VIRUSES - non-cellular
micro-organisms, e.g. influenza and poliomyelitis
Reference:
Watson,
R. (Ed) (1999) Essential Science for Nursing Students,
Micro-organisms inhabit almost every type of environment, even the most
hostile. Some micro-organisms are very
useful.
A few micro-organisms can cause disease. We can now effectively treat most
infectious disease, we can vaccinate to prevent many others.
PROKARYOTIC cells are small and far less complex than eucaryotic cells.
They have no internal skeletal structure, instead the shape of the cell
is determined by a rigid cell wall.
Bacterial cells have two
main shapes:
Spehiral (cocci)
Rod
shaped (bacilli)
A few species are shaped
like curved rods or spirals
Arrange the following infectious diseases under the aetiological
organism, use the headings in the workbook, adding 1 more heading - prion
Tuberculosis, Smallpox,
Measles, Mumps, Gastro-enteritis, German measles, Athletes foot, Monilia, Meningitis, Pneumonia, Cold sores, Leprosy, Colds,
Influenza, Wound infection, Cystitis, Conjunctivitis, Osteomylitis, Chicken
pox, Diphtheria, Whooping cough, AIDS, Herpes cold sores, Peptic ulcers,
Syphilis, Gonorrhea, Malaria, Hepatitis, Sore throat,
Candida, Pneumocystis, Cholera, Creutzfeld
Jakob Disease
MICROBIOLOGY WORKBOOK
1.
Define
a pathogenic micro-organism
Virus
Contain
genetic material and are able to reproduce.
So
tiny can only be seen with an electron microscope
Smallest
known infectious agent.
They
can grow only within the living cell of the host
Viruses
are not usually susceptible to antibiotics.
Influenza (various strains)
Cold sores
HIV (Human immunodeficiency virus) causes AIDS (Acquired immune deficiency
syndrome)
Chickenpox (Varicella zoster virus) and shingles (herpes zoster)
Hepatitis
Glandular fever (Infectious mononucleosis)
Measles
Mumps
Poliomyelitis
Rabies
Rubella
Viral encephalitis
Warts and gential warts (HPV – human
papillomaviruses)
Bacteria - 1 celled
organisms that are a primitive life form.
Staining there cells helps make their structure more visible and reveals
information about their properties.
Found everywhere, their requirements vary greatly.
Can produce spores, resitant forms
that can tolerate long periods of dryness or other adverse conditions.
Spores are easily airborne and are resistant to ordinary
methods of disinfection, particularly dangerous.
Some bacteria can swim rapidly by having flagella.
Reproduce by binary fusion (simple cell division)
Cause damage in 2 ways:
by producing poisons or toxins
and by entering the body tissues and
growing within them.
Cholera
Dental caries
Brucellosis
Anthrax
Acute bacterial conjunctivitis
Diphtheria
External otitis
Gastritis
Gonorrhoea
Legionnaires’s disease
Chlamydia trachomatis
Menigitis – several different bacteria
Psitticosis
Pelvic inflammatory disease
Whooping cough (Pertussis)
Pneumonia
Rheumatic fever
Salmonella
Shigella, dysentery
Staphylococcal infections
Syphillis
Tetanus
Toxic shock syndrome (Staphylococcus aureus strains)
Trachoma (Chlamydial conjunctivitis)
Typhoid
Mycoplasm
Found in soil, water, moist grass, mud
puddles, the sea.
Sporozoa
grow in a host, Malaria caused by Plasmodium are carried by a type of mosquito,
cause serious illness in the tropis, resulting in up
to 3 million deaths each year.
Some protozoa are opportunistic infections
e.g. in AIDS
Amoeba (dysentry)
Malaria (Anopheles mosquito)
Toxoplasmosis (cat faeces and undercooked meat)
Trichomoniasis (urogenital infection)
Sleeping sickness (tsetse fly)
Fungi (also
called mycotic conditions)
True
fungi are a large group of simple plantlike
organisms.
Only
a few are pathogenic.
Larger
and more complicated than bacteria, still a simple life form.
Fungi
grow best in the dark.
Reproduce
in several ways, cell division, producing spores
Blastomycosis
Candidiasis
Histoplasmosis
Mycosis (any disease cause by fungi)
Tinea (tinea pedis - athletes foot, tinea cruris – jock itch, tinea corporis –ringworm
Prion
Creutzfeld Jakob Disease
Parasitic
Round worms,
hookworms,
flatworms
4. Differentiate between:
Cocci and
bacilli
Shapes of bacteria
Bacteria may be classified by their shape
Cocci -
spherical
Bacilli -
rod shaped
Vibrio -
curved bacteria
Gram
negative and positive bacteria
Staining of bacteria
Bacteria need to be stained so they may be seen under the microscope
Gram positive - holds
blue stains
Gram negative - does not hold blue stains, these are usually stained red
Aerobic and
anaerobic organisms
Bacteria and oxygen
Aerobic - need
oxygen to survive
Anaerobic - are poisoned by oxygen
Staphylococcus and streptococcus
Groups of bacteria
Staph - grow in clusters
Strep - grow in chains
5. State what a vector and
a fomite are:
Spread of infection
Vector -
any organism which transmits infection
Fomite - any object which
transmits infection
6. Describe
the possible means of spread of mirco-organisms
between individuals:
Direct contact
Indirect contact
Droplet
Insects
Animals
Body fluids
Faecal-oral
Food and drinks
Diagram
from OHP – The chain of infection
7. What does a good
bacterial growth medium consists of:
Bacterial growth requirements
Temperature
Water
Substrates
Oxygen for aerobes
8. State how frequently
bacterial numbers can increase given good conditions.
Bacterial reproduction
Bacteria reproduce by simple cell division
In optimum conditions bacteria may divide every 20 minutes
9. Briefly
outline the treatment options for viral, bacterial and fungal infections
Treatments
Virus -
no treatments for most infections
Bacteria -
antibiotics for most infections
Fungi -
local and systemic anti-fungal drugs
MICROBIOLOGY WORKBOOK
1.
Define a pathogenic
micro-organism
Virus
Bacteria
Mycoplasm
Fungi
4. Differentiate between:
Cocci and
bacilli
Gram
negative and positive bacteria
Aerobic and
anaerobic organisms
Staphylococcus
and streptococcus
5. State what a vector and
a fomite are:
6. Describe
the possible means of spread of mirco-organisms between
individuals:
Diagram
from OHP – The chain of infection
7. What does a good
bacterial growth medium consists of:
8. State how frequently
bacterial numbers can increase given good conditions.
9. Briefly
outline the treatment options for viral, bacterial and fungal infections