MICROBIOLOGY (1).ppt

MICROBIOLOGY
It’s the branch of science that deals with
the study of minute/very
tinny/microscopic organisms which can
not be seen by our naked eyes but only
by using magnifying instruments like
a lens or a microscope
A microorganism is a microscopic
creature that can either be unicellular or
multicellular and relatively complexed

TYPES OF MICROORGANISMS
1. Bacteria
2. Fungi
3. Virus
4. Protozoa/parasites
5. Protist
Microorganisms live in all parts of
biosphere where there is liquid, soil
springs, oceans, atmosphere and inside
the rock.

IMPORTANCE OF MICRO ORGANISMS
1.They help in recycling other organisms, dead
remains and waste products through
decomposition.
2.Some are important symbiotics e.g eschericia
coli in the stomach which help in vitamin k
processing, lactobacillus accidophillus that help
to keep the vaginal pH acidic
3.They are used in biotechnology during food
and beverage preparations
4. They are used in making soil fertile

HISTORY OF MICROBIOLOGY
It began as a speculation that microorganisms
were existing though it was not yet proved and
this was as early as 6th C by a Roman scholar
called marcus varro who suggested that
possibly diseases were spread by yet the
unseen organisms .it was in the 17th C that the
above speculation was proved by Anton Van
Leuwenheuk who discovered the microscope
which revealed the unseen microbes by
marcus hence being the father of micro
biology.

-Lazarro spallanzani,found out that boiling broth,would
sterlize it and any microbe in it. He also found out that
new microbes could settle in broth if it was left exposed
in air.
-Leus pasteur discovered the process of food preservation
called pasteurisation
-Fednard julius cohn discovered the science of classifying
bacteria.
-Robert koch established that microbes can cause diseases
and they could spread from one infected person to
another. He also introduced sterilization of surgical
instruments. He found out that TB was caused by myco
bacteria tuberclosis. TB is called kochs disease.

Mycology, which refers to the study of fungi.
Virology, the study of viruses.
Serology, which is the study of antibody antigen
reactions.
Parasitology, the study of parasites
Epidemeology, which is the study of disease
outbreak in the community.
Immunology – the science which concerned
with mechanisms of body protection against
pathogenic microorganisms and foreign cells and
substances.
Protozoology – which deals with pathogenic
unicellular animal organisms.

BACTERIOLOGY
It is the study of bacteria. Bacteria are
minute, prokaryotic, unicellular
microscopic organisms that live in each
and every environment or space.
Bacteria differ from plants because they
lack chlorophyll and they reproduce by
binary fission where as cells divide into
two atomically equal parts that have the
same genetic composition and structure
and binary fission process (research)

Cont’d
Bacteria are widely distributed in water, soil,
and air. Bacteria that cause diseases or
infections are called pathogens and those that
donot are called commensals or non
pathogenic organisms
Note; when commensals are distributed or
disrupted to another part of the body or rather
than their specific site, they cause infections
e.g. e coli is a commensal in the alimentary
canal but when it gains entrance in the urinary
tract , it causes urethritis.

Cont’d
All bacteria are pathogenic in blood stream causing a
condition known as septicaemia and when they are found in
CNS they cause meningitis, there is no normal flora in
blood and in CNS
-Normal flora are organisms that do not cause disease in
certain parts or sites of the body but only useful to them.eg
lacto bacilli and e coli
Normal flora may cause infections when immune system of
the person is compromised and these are called
opportunistic infections
Assignment;
1. List examples of normal flora and the parts where they are found
2. Benefits of normal flora to humans

The basic structure of a bacteria cell

CLASSIFICATION OF BACTERIA
Bacteria may be classified in six different
ways i.e.
Basing on shape or cell structure
Basing on staining properties and
reaction
Basing on gas requirement
Basing on biochemical reactions
Basing on temperature dependence
Basing on nutritional requirements

CLASSIFICATION OF BACTERIA BASING ON
MORPHOLOGY
1. COCCI
These are bacteria that are spherical,
round or oval shaped. There are many
forms of cocci bacteria i.e.
(i) Diplococci
Thses appear in a pair e.g. Neisseria
gonorrheae and Diplococci
pneumonaea

(ii)Tetrades
These occur in groups of fours e.g.
micrococcus tetragens

(iii) Sacina
These occur in groups of eight e.g.
sacina ventricuri

(iv)Some cocci are in chains and
are referred to as streptococci e.g.
streptococi pyogens and
streptococci agalantae, streptococci
pneumoneae

(v)Some cocci are in clusters and
are called staphylococci e.g. staph
aureus, staph albus

2. BACILLI/BACILLUS
These are rod or stick shaped
microorganisms e.g.
(i)Coryen bacteria diptheriae,
these look like chinese lettery
formation (palisade)

(ii)Some bacillus are in chains e.g.
mycobacterium tuberculosis

iii)Some bacilli are large and long
with tapering ends e.g. fuso
bacterium fusifome

iv)Some bacillus have spore or club
at their terminals eg clostridium
tetani and clostridium pertringes

v)Some other bacilli are curved and
comma shaped e.g. vibrio cholerae

3. SPILLIRA/SPIROCHAETS
These are spring or coil shaped
bacteria e.g. treponema pallidum
and borellia spp

THE STAINING PROPERTY AND REACTIONS
Staining is the process of subjecting
organisms to different colours or dyes for
proper identification and clarification
Grams staining
This is a staining procedure that is used to
divide or differentiate bacteria into two
groups i.e. gram positive and gram negative
bacteria

Cont’d
This staining process of bacteria was
developed by a scientist called Gram, Gram
prepared a dye i.e. crystal violet dye (purple)
He then subjected it to different organisms
where by some organisms could retain it and
others could not get stained with it
Those that retained the dye he called them
gram positive bacteria and those that failed
he called them gram negative

GRAM POSITIVE BACTERIA
These are bacteria that have a thicker/thickened
peptidoglycan layer(cell wall) that enables
them to retain the purple dye during the grams
stain process.
Examples of gram positive bacteria include;
Staphylococcus aureus . This organism causes
stye, boils, abscesses, food poisoning, UTI in
young females, skin ulcers and septicaemia
Staph saprophyticans .This cause UTI in
young active females

Streptococci pneumoniae. This causes
pneumonia in infants, sinustis, septicaemia,
otitis media and conjuctivitis
Strep agalactiea . This causes pneumonia ,
neonatal septicaemia, meningitis in
neonates and septic abortion
Streptococci pyogens . This causes
pharyngitis, otitis media, impetigo,wound
infection, septicaemia, tensilitis, cellulitis

clostridium difficile . This causes
diptheria
bacillus anthracis. This causes pulmonary
anthrax
Clostridium perfringes. This causes gas
gangrene, food poisoning, septicaemia
Coryn bacterium diptheriae . This causes
diptheria
Clostridium tetani. This causes tetanus

GRAM NEGATIVE BACTERIA
These are bacteria that have a thin or less
peptidoglycan layer that does not enable them to
retain the grams stain (crystal violet, purple dye)
Examples of gram negative bacteria include;
Haemophillus influenzae . This causes
meningitis, pneumonia, otitis media, sinusitis ,
chronic bronchitis, flue
Haemophillus ducreyii. This causes chancroid
Eschericia coli. This causes uti, septicaemia,
wound infection and neonatal meningitis

Shigella spp. These cause shigelosis or dysentry
(bloody stool)
Salmonella spp . These cause enteric fever i.e.
typhoid, food poisoning, septicaemia, abscess of the
spleen
Vibrio cholerae . This causes cholera
Brucella spp eg babortus from cattle and b suis from
pigs, b melitenesis from goats. These cause
brucellosis
Bordetella pertusis . This causes whooping cough
Neisseria meningitidis . This causes meningitis and
septicaemia

Cont’d
Neisseria gonorrheae . This causes gonorrhea,
pelvic inflammatory disese , septic arthritis
listeria monocytogens. This cause still Birth or
miscarriages, and septicaemia
Brucella spp e.g. brucella abortus from cattle and
brucella suis from pigs, brucella melitenesis from
goats. These cause brucellosis
Bordetella pertusis . This cause whooping cough
Neisseria meningitidis . This cause mengitis and
septicaemia

Neisseria gonorrheae . This
causes gonorrhea, pelvic
inflammatory disease , septic
arthritis
Listeria monocytogens. This
causes still birth or miscarriages,
and septicaemia

ZN STAINING PROPERTY/REACTION
This staining procedure was developed by a
scientist called Ziehl Nelseen and it is
used to differentiate between acid alcohol
fast bacillus (AAFBs) from the non
AAFBs
ZN prepared two dyes i.e. strong
carbofuchsin (red) and methlene blue dye

Cont’d
He then subjected these dyes to different
bacilli, those that retained Red dye that
was made of acids and alcohols he called
them AAFBs and those that stained blue
dye he called them non AAFBs
AAFBs include;
oMycobacterium tuberculosis
oMycobacterium lepreae

Non AAFBs include;
 Corynebacterium diptheriae
 Clostridium tetani
 Clostridium difficili
 Bacillus anthracis
 Clostridium pernfringes
 Salmonella spp
 Shigella spp

CLASSIFICATION OF BACTERIA BASING
ON GASEOUS REQUIREMENTS
1. Obligate/strict aerobes
These are bacteria that require plenty of
oxygen for their growth e.g.
M.tuberculosis , Proteus aeruginosa
2. Obligate/strict anaerobes
these are microbes that require an
environment that is free of oxygen e.g.
clostridium. tetani

3. Carboxyphilic bacteria
These are bacteria that require an atmosphere of
5 to 10 % co₂ for their growth e.g. neisseria
gonorrhoea
4. Facultative anaerobes
These are bacteria that can survive in an
environment that has o₂ or not e.g.
e .coli
6. Micro aerophillic organisms
These are microbes that can grow best in an
atmosphere that has a trace of o₂ e.g. h.
influenza

CLASSIFICATION OF BACTERIA BASING
ON TEMPERATURE DEPENDANCE
1. Thermophillic
Thsese are temperature loving bacteria that can
survive to up to a temp of 45c and above
2. Mesothermic bacteria
These survive in a medium temperature of 25-45
3. Hypoctermic bacteria.
These survive at low temperature of 8 and below

NUTRITIONAL REQUIREMENTS
1. Autotrophs
These are bacteria that make or prepare their
own food due to presence of chlophyll like
pigment that can perform photosynthesis eg v.
cholerae
2. Chemoautotrophs
These make their own food by use of energy
obtained from chemical sources. They differ
from autotrophs in that they do not need
sunlight

3. Heterotrophs
These are bacteria which do not make their own
food but obtain it from others ie already made
4. Symbiotics bacteria
These are bacteria which obtain food by living
together with other organism e.g. Rhizobium
bacteria in legumes and Entero bacteria in
intestines
5. Saprophytic bacteria
These bacteria survive by eating on rotten
materials

REQUIREMENTS FOR BACTERIAL GROWTH
These are factors or states that assist in bacterial
growth , these factors are divided into physical
and chemical requirements
Physical requirements
1.Temperature
Bacteria need warmth and moderate temp for
their growth and development
2. Moisture
Many bacteria grow well in moist environment
than in dry areas

3. PH
This is the degree of alkalinity or acidity of the
environment. Most bacteria do grow well in a
neutral ph of 7 though acidophiles require a ph
of 0-5.5 and neultaphiles require a ph of 8.5-
11.5
4.Osmotic pressure
This is the pressure exerted on bacteria by their
surroundings , when this pressure is variated it
affects the bacterial growth

Chemical requirements
oCo₂
oNitrogen
oO₂
oSulphur
oPhosphorus

FACTORS THAT ENABLE BACTERIA TO
CAUSE DISEASES
These are particulars or properties that the bacteria
poses, use to cause diseases or infections to
people and animals
1. Invasiveness property
This is the ability of an organism to enter inside the
hosts tissues .
Pathogenic bacteria have this ability hence enabling
them to cause disease and infections

2. Virulence
This is the ability of an organism to quickly multiply
and effectively destroy body tissues
after inversion into the hosts tissue many bacteria
use this property to spread and cause infections
3. Possession or secretion of capsule
This is a very rough and rigid layer produced by some
bacteria especially in adverse conditions
It acts as a protective barrier, many bacteria produce or
have this coating which protects them from
antibodies, phagocytic cells and chemical reactions
hence being able to cause or spread diseases to
humans e.g. streptococcus pneumoniae

3. Production of toxins
Toxins are poisonous substances produced by some
bacteria that case changes with in the hosts tissues
Some toxins are fetal e.g. tetani produces a
nuerotoxin which usually affects the cells of CNS
systems causing spasms and a disease called
tetanus or lock jaw disease
Endo toxins are toxins produced or released when
the organism is dead while Exo toxins are produce
by live organisms

4. Production of enzymes
Some of the enzymes produced by these
bacteria cause antibody destruction e.g.
collagenase enzymes break down the
collagen fibres found in tendons,
cartilages and in bones; kinase enzyme
breaks the fibrin which is formed by the
host as a protective barrier
lipase
protease

5.Possession of pilli
These are appendages found on the
surfaces of bacterial cells and are used for
attachment to the hosts tissues hence
enabling the bacteria to cause infections
in or the hosts tissues
6. Possession of the flagella
the flagella aids in movement from one
site of the body to another spreading its
toxins and affecting different sites

7. spore formation
Spores are small metabolic dormant
cells with thick walls which can be
destroyed by antibodies and
phagocytic cells. So bacteria that
posses this ability can cause
infections on and over a long period
of time

FACTORS THAT MAKE HOSTS SUSCEPTIBLE
TO INFECTIONS/DISEASES
Malnutrition
Poor hygiene
Immunity
Age
Environment
Life style
Hereditary

INFECTION PREVENTION AND CONTROL
Infection
This is the invasion and multiplication of microbes in
or on the body tissues with or with out signs and
symptoms
CLASSES OF INFECTIONS
Localised infections
These are infections which are confined to a smaller
part or portion of the body
Disseminated infections
These spread widely and affects the body beyond the
usual site of infection

Systemic infections
Infections spread through blood and lymphatic
system
Primary infections
This is the 1st disease noted in an illness e.g. skin
rash, running nose in measles
Secondary infections
This occur when the body weaken by a primary
infection e.g. measles to pneumonia
Mixed infections
This occurs when the disease is caused by two or
more organisms

Zoonoses
are infections that affect animals but
can be transmitted to humans
through direct contact with infected
animals tissues , consumption of
animal products which are affected
and in halation of pathogens e.g.
rabies. Anthrax, marbug, brucelosis
and bovin tuberculosis

TYPES OF INFECTIONS
Urinary tract infection
Respiratory tract infection
STDS
Tropical infections
SOURCES OF INFECTIONS
Human
Environment
Animals
Birds

PHASES FOR INFECTION DEVELOPMENT
1.Entry phase
This is a time when a microbe enters into the
body tissues through invasiveness property
2. Incubation period
is the time between the entry of the microbe
and the appearance of the fast signs and
symptoms of the disease
3. Prodrome phase
is the period when the patient presents with
mild but non specific symptoms that signal the
onset of the disease

4. clinical phase
This is the period when a patient experiences
typical signs and symptoms of the disease. In
this stage the organism is actively destroying
the hosts cells
5. Recovery phase
is the time when symptoms disappears , tissues
heal and the body regains strength i.e.
overcomes the infection

Note.
Asymptomatic patients are people
who do not show signs and
symptoms though they have the
infection
symptomatic patients are people
who show signs and symptoms of
the infection they have

MODE OF TRANSMISION OF THE
INFECTIONS
These are the means by which pathogens pass or
move from the source to a new susceptible
host
1. Contact transmission or transfer
This is divided into two i.e. direct contact e.g.
via hand to hand or body to body and indirect
contact e.g. from clothes, beddings and
communal equipments

2. Air borne transfer
This involves inhalation of organisms Of organisms
which are found in droplets from one individual
to another during kissing, coughing, sneezing
3.Common vehicle/oral transfer
This is through eating and drinking contaminated
food
4.Vector borne transfer
This is via arthropodes e.g. ticks and mosquitoes
5. Blood borne transfer
This is via blood transmission e.g. hepatitis and
syphills

ROUTES OF ENTRY OF
MICROBES/ INFECTIONS TO
HUMAN BODIES
Almentary tract
Skin and mucus membranes
Transplacentally or vertical route
Respiratory tract

CROSS INFECTIONS
These are infections that can be transferred
from one person to another who
originally had no infection of that type
SOURCES OF CROSS INFECTIONS
Unsterilized equipments
Body exudates
Infected patients
Wastes

WAYS OF PREVENTING CROSS
INFECTIONS
Wash hands before and after attending to a
patient
Decontaminating wastes before disposal
Proper segregation of wastes according to
their bins and liners before disposal i.e.
highly infectious materials are put in red
bin, e.g. all anatomic wastes/blood stained
materials

 Infectious material are put in yellow bin
e.g. used gauze/gloves/cotton and
infusions
 All sharps are put in yellow safety box
 All non infectious materials are put in
black bin/green e.g. papers/glass
bottles/food items
 All pharmaceuticals are put in brown
bins

Use of sterile equipments on patients
use of protective wear while attending to
patients and handling samples
Wiping away spillages with suitable
disinfectant
Isolation of patients
Note;
Community acquired infections are
infections obtained from the community

NOSOCOMIAL INFECTIONS
These are infections that are acquired from the
hospital or health care facility when the patient
is admitted for any other reason
The common pathogens that can cause these
infections are
• Staph. Aureus
• Pseudomonas
• E.coli
• Mycobacterium Tb

SOURCES OF HOSPITALACQUIRED INFECTIONS
Acutely ill patients
Asymptomatic patients
Inadequate sterilized equipments
Hospital staff during patient care
FACTORS CONTRIBUTING TO NOSOCOMIAL
INFECTIONS
Failure of health worker to follow infection
Control guidelines
Presence of resistant pathogens which are not
affected by common disinfectants

Increasing number of patients with
weakened immunity
Over crowding of patients in the
hospital
Over use and improper use of catheters
Prolonged and over stay in the hospital
Assignment;
What are the ways of prevention of
Nosocomial infections?

PRINCIPLES OF INFECTION CONTROL
1.Aattacking source of the infection
This includes the following;
• Treatment of the cases and carriers
• Isolation of cases
• Control of reservoir host e.g. stray
dogs

2. Interrupting the route of transmission
through
Observing environmental sanitation,
Personal hygiene and
Behavior changes
Vector control
Immunization
3. Protecting the host
Chemotherapy
Sterilization and disinfection
better nutrition
Personal protection e.g. gloving

This is the study of medically
important parasites and the disease
they cause or spread
A parasite, is an organism that live
on or inside another organism/host
for nourishment or shelter.
A host, is an organism where the
parasite get its nourishment and
shelter

Symbiosis, is a feeding relationship
between two organisms of different
species while parasitism is a form of
symbiotic relationship where one
organism benefits at the expense of the
other
TYPES OF PARASITES
Exo parasites
These live on the surface or superficial
parts of the body e.g. ticks

Endo parasites
These live inside the hosts tissues e.g.
• Ascaris lumblicoid
• Giardia lumbria
• Tunga penetrans
Facultative parasites
These show both parasitic and non parasitic
mode of life e.g. ticks
Obligate /strict parasites
These cant survive without a host

TYPES OF HOSTS
Definitive host
It’s a host in which sexual reproduction
of a parasite take place
Intermediate host
It’s a host that harbors larval stages of
a parasite or where the asexual
development of a parasite takes place
Reservoir host
This stores parasites and act as a
source of transmission to other hosts

CLASSES OF PARASITES
Protozoa
Helminths
Examples of protozoa include
plasmodium spp
toxo plasma spp
trichomonas spp
trypanasoma spp

Examples of helminths include
• Tape warms
• Hook warms
• Ring warms
• Thread warms
• Ascaris lumbricoides
• Filarial warms
Assignment
1. Life cycle of plasmodium/malaria
2.Life cycle of hook warm
3.Life cycle of tape warm

Immunology
This is the study of the body’s
immune system
Immunity. Is the body’s ability to
resist or fight against diseases and
the disease causing germs

The body’s immunity is divided
into two systems, viz
1. Innate/ non specific
immunity
2. Adaptive immunity/specific
immunity

INNATE IMMUNITY/NON-SPECIFIC:
Innate immunity is the non
selective rapid first line body
defense immune system that
involves physical and chemical
body barriers

The physical body barriers against disease
causing germs include
Skin
The skin is very rough and rigid hence avoiding
easy penetration of the microbes into the body
Cilia
These are hair like projection found in the
deferent parts of the body like in the respiratory
system, these help in trapping organisms
preventing them from entering into the body
hence a protection

The chemical barriers are;
Mucus
This is found also in the respiratory system and its
aim is to trap and kill microbes since it contains anti
microbial agents hence providing protection
Hcl
This chemical kills microbes in the stomach that
may have entered the GIT along with the food
Lysol
This chemical component is found in the tears, it
contains ingredients that kill microbes that land in
the eyes

The acidic PH in the vagina which kill the organisms
that may enter the body through that route
Sebum
This is the oily chemical produced by the skin, this oil has
the ability of trapping and killing microbes hence giving
protection
Cellular involvement
The phagocytic cells and the macrophages play a big role
of attacking and destroying any organism that may gain
its way into the body and this is seen in the process of
phagocytosis
Inflammation and protein complement actions
These act as an alarm or signal to the body defenses that
the body has been invaded by a pathogen or an enemy

ADAPTIVE/SPECIFIC IMMUNITY
It’s divided into two and these are;
1. Passive immunity
2. Active immunity
PASSIVE IMMUNITY
This is the type of immunity acquired when
already made antibodies are introduced into the
body to help it fight against a specific antigen.
Therefore this means that the body is not involved
in making and producing these antibodies or
immunity

Passive immunity is further divided into two types
vis
 Natural passive immunity
 Artificial passive immunity
Natural passive immunity is the type of immunity
acquired when already made antibodies are passed on the
baby from the mother through the placenta and breast
milk
Artificial passive immunity is the type of immunity
acquired when the serum/vaccine containing artificially
made antibodies is introduced into some one’s body to
protect him or her from a specific organism or disease
Advantages and disadvantages of passive immunity
(research work)

ACTIVE IMMUNITY
This is the type of immunity that occurs when an
individual’s body is actively involved in making its own
antibody against a specific antigen. This type of
immunity is also further divided into;
1. Natural active immunity
2. Artificial active immunity
Natural active immunity is the type of immunity
acquired after suffering from an infection or disease.
This means that when a person gets an infection, the
body responds by producing antibodies against that
antigen, some of the produced antibodies will be used in
the elimination process and others will remain as
memory antibodies or cells

So when the body is attacked again by
the same antigen, it uses the memory
antibodies to eliminate that antigen
Artificial active immunity
This is the type of immunity acquired
when an antigenic substance has been
introduced into the body through
immunization to provoke or stimulate
it to produce antibodies against that
specific introduced antigen

Merits and demerits of active
immunity(research)
differences between active
and passive immunity

Active immunity Passive immunity
It is produced with the help of
the bodies immune system
The body is not actively
involved in the formation of
the immunity
Immunity developed is long
lasting
Immunity lasts for a short
period of time
Immunity takes time to be
developed
Provides immediate immunity
Immunological memory is
used
Its not used
Its not applicable in immune
suppressed clients
Its applicable

IMMUNISATION AND VACCINATION
Immunization is the process of
creating/introducing immunity against
specific antigen or infection
Or
Is the process of introducing vaccines
in the body to help it fight against
disease causing germs

VACCINES
This refers to the substance that
contains antigenic material and when
introduced in the body it boosts or
stimulates antibody production
the vaccine may contain living or
killed microbes, bacteria, toxoid or
antigenic material

TYPES/CLASSES OF VACCINES
1. Live attenuated vaccines
2. killed/ inactivated vaccines
3. Toxoid vaccine
4. Conjugated vaccines
KILED VACCINES
These are from pathogens that have
been killed with chemicals or heat and
they need multiple doses to induce
adequate immune response

Examples of killed vaccines
Hepatitis vaccine
Influenza vaccine
Rabies vaccine,
Polio vaccine
Pertusis vaccine
Merits
1. They are stable and easy to store
2. They have along duration of potency

Demerits
1. Multiple doses are required in order to
generate adequate immune response
2. May turn into an infection if inactivation
was not completed
LIVE ATTENUATED VACCINES
These are made by weakening the pathogen
using the process of attenuation
the weakened pathogen continues to
multiply inside the human host and

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