2. Definition
• Micros --- means ‘very small’
• Bios------- means’ life’
Therefore, Microbiology is the study of small
living organisms (things) that cannot be seen
with our naked eyes but with a help of a
Microscope e.g.: Viruses, Bacteria
Fungi, Algae, Protozoans etc.
Microorganisms are those living
things that are too small to be seen
with the naked eye.
3. SUB-GROUPS OF MICROBIOLOGY
• Medical microbiology
This deals with human beings (man). Usually
performed on human blood and body fluids. It is the
study of microorganisms such as:
– Bacteria
– Fungus
– Parasites
– Viruses etc in which most of them can only be
seen with the microscope!
• Industrial microbiology
This deals with chemicals. beer, vitamins, drugs, enzymes
4. • Food and dairy microbiology
This deals with food stuffs.
• Agricultural and Soil microbiology
This deals with Agriculture
• Veterinary microbiology
This is deals with Animals.
• Public Health Microbiology &Epidemiology
This is deals with control and spread of diseases
5. M E D I C A L M I C R O B I O L O G Y
Medical microbiology deals with:
• Human pathogens that affects human beings (man).
• Commensal organisms which on occasions
particularly when outside can cause serious illness in
human beings.
• Animal pathogens that affects human beings.
Medical microbiology is concerned with:
– Etiology-----Causes of infections
– Pathogenesis----mode of infections
– Laboratory diagnosis
– Treatment
– Epidemiology----Science of diseases that affects a
community, study of the spread, distribution,
prevalence and control of diseases in a
community.
6. BRANCHES OF MEDICAL MICROBIOLOGY
• PARASITOLOGY
This is the study of parasites causing diseases in
human beings.
• MYCOLOGY
This is the study of Fungi causing diseases in human
beings.
• IMMUNOLOGY
This is the study of the mechanism involved in the
development of body resistance to Infections.
• BACTERIOLOGY
This is the study of Bacteria causing diseases in
human beings.
7. • GENETICS
The study of heredity and variation of genes.
• Biotechnology:
The use of microorganisms, cells, or cell components
to make a product e. g. Foods, vitamins, enzymes,
antibiotics,
• Recombinant DNA Technology:
– Insertion or modification of genes to produce
desired proteins
• VIROLOGY
This is the study of viruses causing infections in
human beings.
8. SCOPE FOR MICROBIOLOGY
• DIAGNOSTIC
• This means isolation and identification of organisms causing
infections
• PROGNOSIS OF DISEASES
• This means monitoring and evaluation of the progress,
effectiveness and in-effectiveness of disease treatment.eg.
Widal test whereby rising titres in Widal test signifies active
disease (in-effectiveness in treatment) and falling titres shows
effective treatment.
• GUIDENCE IN TREATMENT
• This means setting of drug susceptibility test after culturing of
organisms in a culture media into pure form. The pattern of
drug sensitivity guides the clinician in treatment of the patient.
• SOURCES OF INFECTION
• This is determining the sources of sudden disease outbreaks
9. SOME MILESTONES OF ACHIEVEMENTS IN MICROBIOLOGY
• Before the beginning of humanity, parasites have lived
in or on other living organisms for shelter, protection
and nourishment.
• This is evidenced by the damage caused by them on
bones of mammies and early humans causing
diseases such as Osteomylitis and Syphilis by that
time.
• In the early days in Egypt and China, people kept
themselves clean by washing with water to prevent
disease easily transmittable from one person to
another.
• They had learnt to isolate sick people to prevent
spread of the disease.
10. • In the book of Leviticus chapter 13, there is the
first recording of rules concerning public health
whereby Hebrews were told to practice personal
hygiene by washing and keeping themselves
clean.
• They were told to burry their waste materials
outside their camp sites.
• They were required to isolate those who were
sick e.g. People with Leprosy etc.
• They were prohibited from eating animals died
of natural cause.
11. IN THE EARLY DAYS (REINASSANCE PERIOD)
• During the early days, there were wide spread of
epidemics e.g. syphilis, worm infestations and rabies.
Due to these epidemics, physicians of the time were
alerted to look for the reasons for the contraction and
spread of the disease.
• Most people thought that diseases occurred due to
curses of gods and as a result of that bizarre treatment
were used to drive out the diseases.
12. Brief History Microbiology
1. Lucretius, a Roman philosopher (98-55 B.C.), and Girolamo
Fracastoro (Fransastorius), a physician (1478-1553)
believed invisible creatures were responsible for disease.
They observed that ‘agents of communicable diseases were
living germs that could be transmitted from one person to
another either directly or indirectly when he was doing an
observation on syphilis epidemics.
2. In early 1600s, Franscesco Stelluti observed bees and
weevils using a microscope
13. 3. In (1632-1723), Anton Van Leeuwenhoek described ‘Little
Animals’ which he found in stagnant rain water as he was
examining it under his home-made microscope (50-300X
magnification). He referred them as ‘Animalcules’.
He also demonstrated protozoa and spermatozoa.
He is described as the ‘father of Microbiology’.
4. In (1796), Edward Jenner discovered a vaccine against small
pox.
5. In (1840s), Ignaz Semmelweis discovered hand washing
before surgery.
14. In (1850s), he demonstrated that childbed fever
(puerperal fever), caused by streptococcal infections,
was transmitted to patients by doctor’s hands.
Women giving birth in hospitals by medical students and
physicians were 4x more likely to contract puerperal
fever compared to those by midwives
6. In (1860s), Louis Pasteur:
They came out with a theory of ABIOGENESIS or
spontaneous theory which generally brought a lot of
debate from the other scientists.
15. a. ABIOGENESIS or SPONTANEOUS THEORY
It has a concept that ‘life could originate from non-living or
decomposing matter’. Describes spontaneous appearance
of living creatures in decayed meat, stagnant water (ponds),
fermenting grains and infected wounds. It was debated,
tested, dis-approved and then approved that ‘life must arise
from a pre-existing life’. This is referred to as abiogenesis
This was supported (tested) by the following scientists:
Aristotle in (384-322 BC)
John Needham (1713-1781)
Lazarro Spallanzani (1729-1799)
Felix Pouchet (1859)
Disapproved by:
Francesco Redi (1626-1697)
Schwann, Friedrich Schroder and von Dusch (1830s)
John Tyndall (1820-1893)
16. b. PASTUERIZATION AND STERILIZATION TECHNIQUES.
• In 1822-1895, Louis Pasteur worked on sterilization of
liquids whereby today we have sterilization methods using
Autoclaves at (50-60)0c.This process is referred to as
pasteurization which is being used today to destroy milk
pathogens.
• He also developed Hot air oven and Autoclaves.
C. GERM THEORY OF FERMENTATION
• He described Germ theory of fermentation which states
that; specific micro-organisms causes specific changes
in the substance in which it belongs e. g. Yeast in grape
juice is able to ferment sugars and convert it into Ethyl-
Alcohol (wine) which if not sterilized properly can be
contaminated by bacteria called Acetobacter and forms
Acetic Acid (Vinegar) and spoil the taste of the wine.
17. d. GERM THEORY OF DISEASE
• In 1878, Louis Pasteur described Germ theory of
diseases which states that: Specific diseases were
caused by a specific micro-organism.’ This theory
was proved by isolating organisms like chicken cholera,
Anthrax and rabies.
NB
• In 1888, he established Pasteur school for mass Anti-
rabies vaccination.
• He also developed vaccines from killed bacteria
especially for Anthrax and attenuated or weakened
viruses for rabies.
18. 7. Robert Koch (1843-1910).
In1876 he introduced fixing and staining of bacteria using
dyes (stains).
He also demonstrated isolation of bacteria in pure culture
using culture media.
In 1881, he discovered Vibrio cholera organisms
In 1882, he discovered Tubercle bacilli
In 1890, he came up with Tuberculin test
He also isolated Bacillus anthracis
In the same year, he came up with an experimental
procedure to prove ‘Germ theory of diseases and he
referred it as ‘Koch’s postulates theory’.
Richard Petri, another of Koch’s assistants, developed
the Petri dish
19. KOCH’S POSTULATES GERM THEORY (1870s)
It states that:
• The causative (etiological) agent of a disease must be
present in all affected organisms but absent in healthy
individuals.
• The agent of the disease must be capable of being
isolated and cultured in pure form.
• When the cultured agent of the disease is introduced to
a healthy organism, the same disease must occur.
• The same causative agent of the disease must be
isolated again from the affected host.
20. 9. In 1868, Mr. Hansen described an organism known as
Mycobacterium leprae.
11. In 1879, Mr. Neissers observed organisms in the pus
cells of a patient suffering from Gonorrhea and described
it as Neisseria gonorrhea.
12. In 1881, Mr. Ogston described Streptococci organisms.
13. In 1886, Mr. Fraenkol discovered Pneumococci
organisms.
14. In 1884, Mr. Loffler described Diphtheria organisms.
15. In 1902, Mr. Walter Reed described viruses for Yellow
fever.
16. In 1925, Mr. Flemings described fungi called Penicillium
tertium which can be used in production of drugs such as
Penicillin that destroys Streptococcus organisms.
17. In 1940, Tissue culture systems were introduced for the
diagnosis of viruses.
21. 18. In 1862, Mr. Joseph Lister introduced Antiseptics and
Aseptic techniques. He is the father of aseptic surgery
19. In 1902, Mr. Ronal Ross described transmission and life
cycle of malaria in man and in the year, he was given the
Nobel Prize for his work.
20. In (1851 - 1908), Charles Chamberland identified viruses as
disease-causing agents – Tobacco Mosaic Virus
21. In 1962, Mr. J. D. Watson and F. H. Crick were declared the
Nobel Prize winners for their work on Molecular structure of
DNA.
22. In 1972, G. M. Edelman and R. Porter were declared the
Nobel Prize winners when they put up forward a structure of
an Immuno-globulin.
23. In 1977, Mr. Yallow was declared the Nobel Prize winner for
his work on Radio- Immuno- assays.
24. In 1966, Mr. F. P. Rouis was declared the Nobel Prize winner
for his work on viral etiology (cause) of Cancer.
22. Selected Novel Prizes in Physiology or Medicine
• 1901* von Behring discovered Diphtheria antitoxin
• 1902 Ross discovered Malaria transmission
• 1905 Koch discovered TB bacterium
• 1908 Metchnikoff discovered Phagocytes
• 1945 Fleming, Chain, Florey discovered Penicillin
• 1952 Waksman discovered Streptomycin drug
• 1969 Delbrück, Hershey, Luria discovered Viral replication
• 1987 Tonegawa discovered Antibody genetics
• In 1997 Prusiner discovered Prions
• In 2003 Agre, Mackirron discovered water and ion channels
• 2005 Marshall, Warren discovered Helicobacter and ulcers
• 2008 Hausen discovered Papilloma and viruses
23. 25. In 1697 FRANCISCO RED:
He is referred to as the father of parasitology.
He described the cycle of insects and also showed that
Ascaris developed from ova.
26. GORDON ABERDEN:
In 1795, He showed that puerperal sepsis developed in
women who were visited or delivered by nurses and
doctors who had previously attended either patients
suffering from the same disease. He recommended that
every medical personnel attending patients should wash
hands and change clothes to prevent infections.
24. COMMON TERMINOLOGIES IN MICROBIOLOGY
• BACTERIA
Are small (minute) simple celled organisms that can be
examined with a help of a microscope.
Belong to a Prokaryotic group of organisms or plant
kingdom.
Vary in sizes from (0.1-10) micrometers long.
Multiply by means of Binary fission.
Can be either commensols, sympionts, opportunistic,
parasites, saprophytes or pathogenic organisms.
Saprophytes are organisms living on dead or decaying
organic matters.
Parasites are organisms’ plants or animals living on or in
another organism for its shelter, nourishment, transport
and reproduction purposes. They can be harmful or not.
Pathogens are organisms capable of causing diseases.
25. Commensols are organisms living on another living
organism and do not cause a disease at a particular
site but should it change that site, it may be harmful
and cause a disease.
Symbiosis is a relationship between different species
where both of the organisms in question benefit from
the presence of the other.
Opportunistic organisms are organisms that takes
advantage of certain opportunities to cause disease.
They have a simple cell structure containing both DNA
and RNA nucleic acid materials.
26. • CLASSIFICATION OF MICRO-ORGANISMS
All micro-organisms are classified into two groups
1. Prokaryotic cell groups e.g. Bacteria, Viruses, Chlamydia,
Rickettsia and Mycoplasma
29. Differences Between Cell Types
Prokaryotic Cell
• Are smaller and simpler
• Single circular chromosome
• Can be unicellular (all alone).
• Chromosome found in a
cytoplasmic region called the
nucleoid (Cytoplasmic region
containing genetic material)
• No internal membranes
• Endoplasmic reticulum is
absent
• Golgi apparatus are absent
• Mitochondria is absent
• Lysosomes are absent
Eukaryotic Cell
• Are bigger and more
complicated
• Multiple linear chromosomes
• Can be multicellular (involves
others).
• Chromosomes found in a
membrane-bound nucleus.
• Extensive network of internal
membranes
• Endoplasmic reticulum is
present
• Golgi apparatus are present
• Mitochondria is present
• Lysosomes are absent
30. 1. CELL WALL
• Outer layer of a cell and it is composed of Muco-peptides
called Peptidoglycan which helps in strengthening the cell
wall. It is made up of Amino acids and polypeptides.
Functions
• Provides the bacterial cell with rigidity.
• Protects the bacterial cell against osmotic damage (internal
osmotic pressure of the bacterial cell wall).
• Maintains the characteristic shape of the bacteria.
• Plays an important role in the cell division.
• Offers resistance to harmful effects of the environment.
• Posses bacterial antigens important in virulence and
immunity.
• Helps in classification of bacteria into Gram positive
organisms and Gram negative organisms.
31. DIFFERENCES BETWEEN
GRAM POSITIVE ORGANISMS
• Have (50-90)% Peptidoglycan in
their cell wall
• Have Techoic Acid in their cell wall
• Have less or no fatty substances on
their cell wall (No lipid-A)
• Have high affinity for the basic
stains e.g. Crystal violet, Gentian
violet hence staining Blue in color.
• They produce Exotoxins.
• Do not have Lipo-polysaccharides
GRAM NEGATIVE ORGANISMS
• Have (5-10) % Peptidoglycan
• Lack Techoic Acid on their cell wall
• Have a lot of fatty substances on
their cell wall ( lipid-A)
• Have high affinity for the Acidic
stains e.g. Neutral red hence
staining Red in color.
• They produce Endotoxins
• They have Lipo-polysaccharides
32. 2. CYTOPLASM
Contains the bacterial chromosomes (genome), DNA,
Water Plasmids, Lysosomes, Ribosome’s, Amino
acids, Lipids (granules containing lipids) etc.
Contains both DNA and RNA. DNA determines
hereditable characteristics of bacteria.
Functions
• Gives the bacteria shape.
• Acts as a suspending medium for bacterial materials.
• Provides little mechanical strength to the bacterial cell.
33. 3. NUCLEUS
• It is present in all the cells which do not show the outer
nuclear membranes.
• It is concerned with the genetic information of the bacterial
cell.
4. CAPSULE
• Consists of excreted slim usually of poly-saccharides with
mucoid substances surrounding it.
• Presence of capsule indicates Virulence of the organism
(ability to cause infection) and it is enhanced by high
concentration of sugars and presence of serum in the
medium.
Functions
• Protects the cell from phagocytosis.
• Protects the cell from viruses that might attach themselves to
the cell wall of the bacteria.
34. 5. RIBOSOMES
Are sites of protein production and distributed in the
Cytoplasm (Manufacture proteins). They are composed of
RNA and proteins.
6. CYTOPLASMIC MEMBRANE
• Is a thin and semi-permeable membrane mainly lipo-proteins
surrounding the cytoplasm
Functions
• Contains enzymes which manufactures the bacteria’s
nutrients
• Permits diffusion of water inward or outwards
35. 7. MESOSOMES
• It is made from plasma membrane present in the
cytoplasm.
• Concerned with the respiration, cell division, Sporulation.
8. PILLI (FIMBRIAE)
• Numerous and short thread-like projections, smaller than
flagellum and are born around the bacterial cell.
Functions
• They are organs for adhesion.
• Play a role in the transfer of DNA.
• Act as receptor sites of bacteriophage (viruses that
infects bacteria and cause diseases in the same
bacteria).
36. 9. Lysosomes
• Contain digestive enzymes
Functions
– Aid in cell renewal
– Break down old cell parts
– Digests invaders
10. Vacuoles
• Membrane bound storage sacs
• More common in plants than animals
• Contains
– Water
– Food
– wastes
37. 11. Mitochondria
– They break down fuel molecules (Glucose, Fatty
acids) to release cell’s energy
– the more energy the cell needs, the more
mitochondria it has
12. Golgi Apparatus
• Involved in synthesis of plant cell wall
• Packaging & shipping station of cell
• containing finished cell products
13. Endoplasmic reticulum
– may be smooth: builds lipids and carbohydrates
– may be rough: stores proteins made by attached
ribosomes
38. 14. Cell membrane
– delicate lipid and protein skin around cytoplasm
– found in all cells
15. FLAGELLA
Definition
• Are thread-like appendages that develop from the cell
membrane of the bacterial cell.
• They consist of deity proteins.
Function
• Are usually used for locomotion or movement of bacteria
39. Types of flagella arrangements.
1. Monotrichas flagellum
• Single flagellum on one pole or side of a bacterial cell.
• Example of the organisms:
-Vibrio cholera
-Legionella pneumophilia
40. 2. Amphitrichas flagella
• Are single flagellum in each pole or side of a bacterial cell
e.g. : -Pseudomonas aeroginosa
3. Lophotrichas flagella
• Are a tuft of flagella in one pole or both poles of a bacterial
cell e.g. : -Spirillum Serpens, -Campylobacter jejune
41. 4. Peritrichas flagella
• Are flagella all around the bacterial cell wall e.g. :
Proteus vulgaris, Clostridium spps, Salmonella spps,
Alcaligenes spps.
5. Atrichas flagella
• Are bacteria without flagellum in their cell walls e.g. :
Salmonella pollurum, Bacillus anthracis, Salmonella
gallinarum, Klebsiella
42. NAMING ORGANISMS (NOMENCLATURE)
• Binomial system uses 2 names
• Genus species
• ex. Bacillus subtilis
• ex. Clostridium tetani
• ex. Staphylococcus aureus
Taxonomy
• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• species
43. 3-Domains
• Eubacteria
– true bacteria, Peptidoglycan
• Archaea
– odd bacteria that live in extreme environments, high
salt, heat, etc. (usually called extremophiles)
• Eukarya
– have a nucleus & organelles (humans, animals,
plants)
44. Systemic classification (code of nomenclature or epithets).
Domain--------------------------Eubacteria, Eukarya, Archaea
Kingdom---------------Protista, Fungi, Plantae, Animalia, Algae
Phylum-------------------------- Proteobacteria (Thallophyta or
Protophyta).
Class-----------------------ends with ‘mycetes’ e.g. Schizomycetes
Order-------------------------ends with ‘ales’ e.g. Eubacteriales,
Pseudomonadules, Actinomycetales,
Spirochaetales, Mycoplasmatales,
Chlamydobacteriales, Rickettsiales
Family ----------------ends with ‘aceae’ e.g. Streptococcaceae.
Genus--------------Streptococcus
Species----- Streptococcus pyogenes
45. 1. Naming Microorganisms
1. Binomial (scientific) nomenclature gives each microbe 2
names:
– Genus - noun, always capitalized
– species - adjective, lowercase
• Both italicized or underlined
– Staphylococcus aureus (S. aureus)
– Bacillus subtilis (B. subtilis)
– Escherichia coli (E. coli)
2. Classification and Identification of microorganisms
• Classification: Placing organisms in groups of related
species. Lists of characteristics of known organisms.
• Identification: Matching characteristics of an “unknown”
organism to lists of known organisms.
– Clinical lab identification
46. CLASSIFICATION OF BACTERIA
General characteristics of bacteria
• They have a simple cell structure hence posses a cell
wall
• They multiply by means of binary fission
• They contain both RNA (ribonucleic acid) and DNA
(deoxyribonucleic acid)
• They have ribosome used for protein synthesis
• They are sensitive to antibiotics
• They have variety of active metabolic enzymes
• They belong to prokaryotic organisms.
• They measure between 0.2 to 2.0 μm in diameter and
2 to 10μm in length.
47. Classification of bacteria
Bacterial classification is based on the following;
1. Microscopic morphology (Cell morphology and Staining
reactions)--- according to shape and staining
characteristics of bacteria.
2. Macroscopic morphology (Cultural characteristics ----
Oxygen requirements e.g. Aerobes, Anaerobes and
facultative anaerobes – colony appearance
3. Physiological / biochemical characteristics
4. Chemical analysis (Antigenic structures)
5. Serological analysis
6. Genetic composition using specialized molecular biology
techniques
7. Host resistance or pathogen city (Pathogens, Non-
pathogens and commensals)
48. 1. Cell morphology (according to shape of the bacteria).
Bacteria are classified into two groups:
• Higher bacteria
Are filamentous and form structures called mycelia e.g. L-forms,
Mycoplasma spps, protoplasts, spheroplasts.
• Lower bacteria
Are true bacteria, which are unicellular and grouped on the bases
of their shape as follows;
Cocci (plural), coccus (singular) meaning berries and spherical
Bacilli (rods) singular (bacillus)
• Vibrios singular (Vibrio)
• Spirilla singular (spirillum)
• Spirochetes , singular (spirochete)
Organisms, which show variation in shapes, appearance forms,
are described as pleomorphic
49.
50. 1. Cocci
a. Cocci
b. Doplococci
c. Streptococci
d. Staphylococci
e. Sarcina ( 3D )
f. Gaffkya ( 2D )
51. 1. COCCI
• These are round or oval organisms measuring about (0.5-
1.0) um in diameter. During multiplication period cocci may
be in singles or pairs or chain or clusters.
Diplococi:
They are those cells, which after binary fission the daughter
cells remains attached to the mother cells. They form a
characteristic kidney shape hence referred to as ‘gram
negative diplococci or kidney shaped diplococci. e.g. Neisseria
gonorrhoeae and Neisseria meningitidis etc
52. Lancet shape diplococci.
They are those cells, which after binary fission the daughter
cells moves away from the mother cells. They form a
characteristic pair of connected spears hence referred to as
lancet shaped diplococci or ‘gram positive lancet shaped
Diplococci’ e.g. Streptococcus pneumoniae or Diplococcus
pneumoniae etc.
53. Streptococci:
They are those cells, which after binary fission the daughter
cells occur in singles, pairs or in chains of three (3) or even
more hence referred to as ‘‘gram positive cocci’. e.g.
Streptococcus pyogenes, Streptococcus faecalis,
Streptococcus viridans etc.
Staphylococci :
They are those cells, which after binary fission the daughter
cells occur in singles, pairs or in clusters assuming a
characteristic ‘bunches of grapes’ hence referred to as
‘gram positive cocci’. e.g. Staphylococcus aureus,
Staphylococcus albus etc.
54. Tetracocci:
They are those cells, which after binary fission the daughter
cells occur in four (4) hence referred to as ‘‘gram positive
cocci’. e.g. Gaffikya tetragena.
Sarcina :
They are those cells, which after binary fission the daughter
cells occur in eight (8) hence referred to as ‘gram positive
cocci’. e.g. Sarcina lutea.
Veillonella :
They are cocci smaller than staphylococci hence referred to as
‘gram negetive cocci’. e.g. Veillonella parvula.
55. 2. BACILLI
• They are stick like bacteria or rod- like bacteria with
rounded, square or swollen ends which after binary fission
the daughter cells do not usually remain attached to one
another, but separate.
• They are either gram positive organisms or gram negative
organism measuring (1-10) um in width.
• They can occur in singles, pairs or in chains.
• Those which occur in chain are called Strepto-bacilli.
• The rods with rounded ends are often called Cocco-bacilli
57. Example of gram –ve bacilli
• Gram negative aerobic cocci e.g. Neisseria spps.
• Gram negative aerobic bacilli e.g. Pseudomonas spps.
• Gram negative facultative bacilli e.g. Escherichia spps,
Klebsiella spps, Proteus spps, Salmonella spps, Shigella spps,
Yersinia spps, Bordetella spps, Haemophillis spps, Brucella spps
• Gram negative strict or obligate anaerobic bacilli e.g
Bacteroides spps, Fusobacterium spps.
• Strict anaerobes cocci e.g Peptostreptococci spps,
Peptococcus spps
• Gram negative micro-aerophilic bacilli e. g Campylobacter
spps.
• Gram +ve bacilli e. g Bacillus spps, Clostridium spps, Listeria
spps Corynebacterium spps, Lactobacillus spps,
Mycobacterium spps.
58. 3. VIBRIOS
• These are small slightly curved rods measuring (3-4) um in
length by 0.5um in width.
• Most of Vibrios are motile with single flagellum (monotrichous)
at one end with a darting motility. They are gram negative
coma shaped organisms e.g. Vibrio cholera.
4. SPIRILLA
• They are small, regular coiled, rigid organisms measuring 3-
4um in length each coil measure 1um. They are motile with a
group of flagella (tuft) at both ends. They are gram negative
organism e.g. Spirillum minus.
59. 5. SPIROCHETES
• They resemble Spirilla in shape but they are flexious spiral
filaments which are Gram negative poorly stained. They are
coiled and motile but do not posses flagella e.g. Treponema,
Borrelia spps, Leptospira spps
• Aerobic Spirochetes e.g. Leptospira spps.
• Anaerobic Spirochetes e.g. Borrelia spps and Treponema
spps.
60. 6. RICKETTSIAE
• Although classified as bacteria, they resemble viruses in
that they replicate in living cells.
• They multiply by means of binary fission but in living cell.
• They are un-able to survive as free living organisms.
• Under light microscope, they appear as red particles
when stained with Giemsa stain
General characteristics
• They contain both RNA and DNA nucleic materials
• They have cell wall composed of Peptidoglycan.
• They are sensitivity to antibiotics and antiseptics
61. 7. CHLAMYDIAE
• They are gram-ve organisms measuring 250- 500um
• Multiply in living cells like viruses
• Contain both enzymes.
• Reproduce in two forms
• Infection forms: elementary body and Reticulate body
• Reproduce by binary fission in a living cell
8. Bacteria lacking cell wall
a. MYCOPLASMA
• They do not have cell wall.
• They measure from 0.1-2.0um e.g. Mycoplasma
pneumoniae, Ureaplasma urealyticum
62. b. L-FORMS
• They do not have cell wall.
• Produced in laboratory especially from patients being
treated with penicillin.
• Reproduce in ordinary culture media.
c. PROTOPLASTS
• No cell wall due to action of lysozyme enzyme which
destroys Peptidoglycan.
d. SPHEROPLASTS
• They do not have cell wall due to damaged cell wall by
toxic chemical or antibiotics e.g. penicillin.
63. 2. ACCORDING TO STAINING REACTION
• After staining, bacteria can be classified as:
Gram positive bacteria staining blue or purple in color.
Gram negative bacteria staining red or pink in color
using Gram staining technique (method).
• AAFB (Acid –Alcohol Fast Bacilli) of Mycobacterium
group appears pink or red in color when stained with
Ziehl Neelsen staining technique (method).
• Non-Acid–Alcohol Fast Bacilli which appear blue or green
in color are other bacteria.
64. 3. ACCORDING TO OXYGEN REQIREMENTS
• Aerobes: Are organism that can grow only in presence of
free oxygen (100% presence of oxygen) e.g.
Pseudomonas spps.
• Anaerobes: Are organism that can grow only in presence
of free carbon dioxide (100% presence of carbon dioxide )
e.g. Clostridium spps.
• Facultative anaerobes: Are organism that can grow in
presence of both oxygen and carbon dioxide e.g.
Organisms in the family Enterobacteriaceae.
• Micro-aerophilic organisms: Are organism that can grow
in traces of oxygen e.g. Campylobacter spps.
• Carboxyphilic organisms: Are organism that can grow in
traces of carbon dioxide e.g. Neisseria spps.
65. 4. BACTERIAL COLONY MORPHOLOGY
• This is the appearance of bacterial cell growing as a
single unit (colony) in a given solid media. It forms the
basic identification value of the growing organism.
• Can be described based on:
1. SIZE
• Minute (tinny) colonies (a pin dot)
• Small (pen dot)
• Larger colonies (bigger than a pens dot)
1.
Size
2.
Shape
3.
Appearance
4. Elevation 5. Opacity
6.
Color
7.
Edges
8.
Consistency
9.
Emulsifiability
10.
Biochemical
reaction
66. 2. SHAPE
• Entire (round or Circular), Irregular (shapeless), Crenated
colonies, Undulated colonies, Lobulated colonies, Spindle,
Filamentous, Spreading
3. APPEARANCE
• A bacterial colony can be wet, dry, shinny, smooth. Rough,
glistening, fine and granular
4. ELEVATION
• This is comparing the level of the colonies with the level of the
media e.g. Colony can be: Convex, Concave, Flat, Raised
5.OPACITY
This is the ability of the colony to allow light to pass through them
and be able to see the other side e.g.
• Opaque - colony is dark and cannot allow light to pass through.
• Translucent – colony can allow some light to pass through
• Transparent – colony can allow light to pass through.
67. 6. COLOUR OF COLONIES
The color of colonies can be: Yellow, Golden shiny, light purple,
Pink, Greenish pigmentation, White,, yellow-brown white-gray,
Cream etc.
7. CONSISTENCY OF THE COLONIES
Colonies can be: Mucoid: resembling mucous, Dry: crusty,
brittle, Soft: butter-like consistency
8. EMULSIFIABILITY
Some colonies are easily emulsified while others are not
emulsifiable.
69. 2. CLASSIFICATION OF FUNGI
• Fungi are organisms that are larger than the bacteria.
• They grow by forming hyphae or as rounded bodies (spores).
• Branching filament are referred to as Mycelium.
• They grow best in moist atmosphere and require 02 and other
nutrients.
• They belong to Eukaryotic group of organisms.
• There are four major morphological classes of fungi:
Moulds which form vary in thick hyphae and have asexual
type of reproduction.
Yeast which are single or oval cells reproducing by means
of forming buds.
Yeast-like fungi
Dimorphic fungi
70. • Sexual reproduction
– Spores are formed following fusion of male and female
strains and formation of sexual structure
• Sexual spores and spore-forming structures are one basis for
systemic classification of fungi into:
-Ascomycetes -Phycomycetes –Basidiomycetes -Deuteromycetes
71. 3. CLASSIFICATION OF PROTOZOA
These are unicellular organisms. They are much larger
than bacteria. They have a nucleus that is clearly
differentiated from the protoplasm. Found in soil and water.
They are classified based on the method of motility,
reproduction, and life cycle as:
1. Mastigophora – primarily flagella, motility, some flagella and
amoeboid; sexual reproduction; cyst and trophozoite
2. Sarcodina – primarily ameba; asexual by fission; most are
free-living
3. Ciliophora – cilia; trophozoites and cysts; most are free-
living, harmless
• Apicomplexa – motility is absent except male gametes; sexual
and asexual reproduction; complex life cycle – all parasitic
• Illnesses
– Malaria, -Amebic dysentery, -Trichomoniasis vaginitis
-Leading cause of death in developing countries
72.
73. 4. VIRAL CLASSIFICATION
• They are the smallest known infectious agents with only one
type of nucleic acid surrounded by a protein coat.
• Must live and grow in living cells of other organisms
• multiply within a cell by means of replication
• are extremely small ranging in size (20-300) nm in diameter.
• are either oval, round shaped or complex.
• infect animals, insects, bacteria, fungi, plants, human beings
and protozoa etc.
viruses are classification into two major groups depending on
the type of nucleic acid material they posses.
Those viruses that contain RNA-Nucleic acid are called
Ribo-viruses
Those viruses that contain DNA- Nucleic Acid are called
Deoxy-Ribo Viruses.
74. SPORULATION
Sporulation means formation of spores when condition of the
vegetative cells are unfavorable especially when carbon and
nitrogen elements becomes un-available. Rod like bacteria e.g.
Bacillus, Clostridium spps are able to survive by forming
resistance substances called the endospores which are dense
and thick walled so as to be able to withstand activities of
dehydration, heat, cold and action of disinfectants.
When conditions become favorable each bacterial or fungal
spore will germinate giving rise to a vegetative cell which
undergoes a binary fission to give rise to other vegetative cells.
75. DESCRIPTION OF SPORES
Spore description is based on three aspects
• Diameter b. Position c. Shape
1. DIAMETER
• If the diameter of the spore is greater than that of the host
cell the spore will force the cytoplasmic membrane and the
cell wall to protrude or project out. Such a spore will be said
to be bulging.
• Should the spore diameter be less or equal to that of the
host cell, there will be no projection hence the spore will be
said to be non-bulging.
76. 2. POSITION OF THE SPORE
• Spores can occur anywhere if the cell contains the
cytoplasm, nuclear materials and other inclusions.
• Where the spore occurs at the center of the bacterial cell,
the spore is said to be centrally placed.
• Where the spore occurs between the center and the end
of the cell. It is said to be sub-terminally placed.
• Where the spore occurs at the far end of the bacterial cell,
it is said to be terminally placed.
79. CHARACTERISTICS OF SPORES
• They are resistant to severe effects of the environment.
• Most spores are killed at 1210c but bacterial spore
resists temperatures of up to 2130c.
• Bacterial spores are resistant to chemical e.g.
fungicides, bactericides
• Bacterial spores can remain alive for up to 100yrs.
• Bacterial spores are capable of germinating into
vegetative forms when conditions are favorable.
80. 4. BIOCHEMICAL REACTIONS
• Biochemical reaction are the exhibitions of growing
organisms on the culture medium depending on the
reactions the organism has done on the medium.
• Indicators are added or any other changeable substance
which will help to determine if there has been a reaction.
• The reactions could be as results of enzymes or toxins
produced by microorganisms.
• Two common biochemical reactions are observed.
Carbohydrates fermentation.
Blood cell lyses.
81. a. CARBOHYDRATES FERMENTATION
• Carbohydrates are inco-operated in the culture medium
and a suitable indicator added to detect if fermentation
has taken place.
• Fermentation of carbohydrates results in production of
specific acid which changes the PH of the media and the
color of the indicator added thus changing the color of
the media.
• Final detection of carbohydrates fermentation does not
depend on the carbohydrates fermented but on the
indicator used.
82. COMMON CARBOHYDRATES USED
• The common carbohydrates used are glucose, lactose,
maltose, sucrose..
• Lactose is the commonest carbohydrate used in fermentation
• In fermentation process, two, enzymes are responsible.
Lactosidase enzymes- ferments lactose
Permease enzymes – responsible for penetration of
lactosidase enzymes
• There are three types of fermentation are:
Those organisms that are able to ferment
lactose within 18-24hrs are known as
‘true lactose fermenters’ e.g. Klebsiella
spps, Escherichia coli etc.
They posses both (lactosidase and Permease) enzymes
83. Those organisms that can ferment lactose after 24 hrs
24-48hrs are called ‘late lactose fermenters’ e.g.
Shigella sonnei (posses both enzymes)
Organisms that will not ferment lactose are called ‘Non-
Lactose fermenters’. They lack enzyme lactosidase or
both enzymes e.g. Proteus spps.
Examples of indicators
• Phenol blue – it is blue in alkaline media but turns
yellow in acid media.
• Methyl red – it is red in alkaline media but turns pink in
acidic media
• Bromothymol blue - it is blue in alkaline media but turns
yellow in acidic media
• Neutral red – it is red in alkaline media but turns pink in
acidic media.
84. BLOOD CELL LYSIS
• During bacterial metabolic activities, some organisms will
produce toxic substances or enzymes or both which act on the
blood cells causing red blood cells destruction called
haemolysis.
• This haemolysis can be of three types.
Complete haemolysis (beta haemolysis)
This is characterized by a clear zone around the growing
colonies e.g. Staphylococcus aureus, Streptococcus pyogenes
85. Incomplete (partial) haemolysis (alpha
haemolysis)
• This is characterized by green pigmentation zone around
the growing colonies e.g. Streptococcus pneumoniae,
Streptococcus viridans etc
gamma haemolysis
No cell haemolysis at all around the growing colonies e.g.
Streptococcus faecalis.
