Microbiology
A branch of biology that studies
organisms
that can only be seen with a
microscope
Historical Overview
• Fossil evidence dating back 3.5 million
years (Burton & Egelkirk 1999)
• Early civilizations isolate...
Historical Overview (Cont’d)
• 1546 Girolamo Fracastorius – suggests
disease is cause by living germs
• 1667 Antony van Le...
Types of micro-organisms
Non-pathogen(ic)
Pathogen(ic)
Non disease
causing
Commensal
Disease causing
Types of micro-organisms
bacteria
parasites
viruses
fungi
Bacteria
 Single celled organisms
 Structure:
- rigid cell wall enclosing cytoplasm
- nuclear body but no nuclear membra...
Requirements of bacteria
Oxygen:
variable
•aerobic
•anaerobic
pH:
Most neutral/sl.alkaline
Some highly acid
Some highly al...
Properties of bacteria
Spore formation
Toxin production
Bacterial spores formation
Protective mechanism developed by
some bacteria to survive in adverse
conditions
Highly resista...
ANTHRAX
Production of toxins
2 types:
Exotoxins:
Living bacteria
released into and
cause damage to
surrounding
tissues
Endotoxins:...
Classification of bacteria
1. Staining properties
Gram positive
bacteria:
retain
violet
colour
Gram negative
bacteria:
ret...
Classification by shape
Round: cocci
diplococci
streptococci
staphylococci
Rod:
bacilli
Spiral:
spirilla
vibrio
Corkscrew:...
Cocci diseases (singular =
coccus)
 meningococci - meningococcal
meningitis
(diplococci)
 streptococcus pyogenes - tonsi...
Bacilli diseases
Examples include:
 Clostridium tetani - tetanus
 Corynebacterium diphtheriae -
diphtheria
 Escherichia...
Bacterial disease examples:
spiral shaped
Spirilla:
Spirilla minus - rat bite fever
Vibrio:
Vibrio cholerae - cholera
Spir...
CHOLERA
Specialised bacteria
Rickettsiae and chlamydiae
o smaller than most bacteria
o can only reproduce in living cells - are
th...
Specialised bacteria
Mycoplasma
• ultramicroscopic bacteria
• do not have a cell wall
Diseases caused:
• certain respirato...
Viruses
• ultramicroscopic
• no cell structure
• no rigid cell wall
• are intracellular parasites
• can only reproduce wit...
VIRUS
Viruses
DNA viruses
 Herpes virus - herpes simplex, herpes zoster
 Adenovirus - conjunctivitis, URTI
 Poxvirus - variol...
“BIRD FLU” VIRUS
SMALLPOX VIRUS
VIRUS
Fungi
• Plant organisms: mainly moulds
and yeasts
• Do not contain chlorophyll
• Present in soil, air, water
• Multiply by...
Pathogenic fungi (mycoses)
Superficial:
skin, mucous
membranes,
hair,
nails
Intermediate:
subcutaneous
tissue
Systemic:
de...
Fungi
Diseases caused
Dermatophytes:
o Tinea pedis - athlete’s foot
o Tinea unguium – toenail infections
Candidiases (moni...
TINEA PEDIS
Parasites
• Survival requirements depend on a
living organism – the host
• Parasite-host effects variable: from
little dam...
Pathogenic parasites
o Trematodes (flukes) : liver, lungs or
intestinal infestation
o Nematodes – round worm infestation
o...
PEDICULI CAPITUS
PEDICULI
Prevention
• Immunisation
• Cleaning processes: environment &
equipment
• Health status of staff, visitors etc
• Provision...
Prevention
• PPE
• Management of waste and body
fluids
• Handwashing
Transmission modes
 the mode of movement of pathogen from exit point to new
host
Airborne:
droplets
dust particles
Contac...
ENTRY POINT
 ways in which pathogen
enters the body
ingestion
inhalation
broken skin/
mucous
membranes
trans-
placental
EXIT POINT
 the point from which pathogens emerge to enable
entry to a new site of residence
 human exit points include:...
Prevention
• Handwashing
• Isolation
• Cleaning systems: environment
and equipment
• Use of appropriate PPE
SUSCEPTIBLE HOST
o Degree of resistance an individual has
to a pathogen
o Resistance to disease influenced by
such factors...
Prevention
• Procedures to manage indwelling
lines: catheters, IV
• Aseptic techniques for wound
care
• Handwashing
• Immu...
Lunch
• Please return in 45 min
BODY DEFENCES AGAINST INFECTION
External mechanical and chemical barriers
First line of defence
Inflammatory response
Seco...
External mechanical and chemical
barriers
 intact skin and mucous membranes:
acid mantle, sweat, sebum, normal
flora
 ga...
Inflammation
 second line of body defence
 is non-specific: occurs whenever body
tissues are injured
 classic clinical ...
Inflammatory response
Tissue injured
Release of chemicals
(e.g. histamine, kinins)
Blood vessels to dilate
Capillaries t...
Inflammation
Heat and redness
due to vasodilation
resulting in increased
blood supply to injured
area
Tenderness/Pain
caus...
Pus
Mixture of:
-dead or dying neutrophils
-broken down tissue cells
-dying and living pathogens
If area not completely cl...
Other non-specific defences
• Complement fixation
- 22 plasma proteins
- attach to foreign cells
• Interferons
- proteins ...
Phagocytosis
• Ingestion of microbes or any foreign
particulate matter by cells called
phagocytes
• Two major types of pha...
Mechanism of Phagocytosis
• Three phases:
– Chemotaxis – activated complement proteins
cause chemical attraction of phagoc...
Immune Response
o Third line of body defence
o Response is specific, systematic
and has a memory
o Cells of the immune sys...
Immune response
o Two kinds – closely allied
o Both triggered by antigens
o Cell-mediated (cellular) immune
responses (CMI...
Formation of T Cells and B Cells
• Both develop from haemopoietic
stem cells in red bone marrow
• B cells complete maturit...
Immune system cells
B lymphocytes:
-produce antibodies
(immunoglobulins)
T lymphocytes:
-non-antibody
producing
Macrophage...
Immunity
Any substance capable
of
stimulating the
immune system and
causing an
immune response
Are immunoglobulins
(Igs)
p...
Functions of Antibodies
• Neutralizing antigen
• Immobilization of bacteria
• Agglutination and precipitation of
antigen
•...
Immunity
Innate
(genetic, inborn)
Acquired
Naturally acquired Artificially acquired
Active
Protection acquired by
getting ...
Immunological Memory
• Memory for certain antigens triggers
immune responses
• Immune responses are much quicker
and more ...
References
• Burton, G., and Engelkirk, P., (1999).
Microbiology for the Health Sciences, Lippincott
Williams & Wilkins, P...
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Microbiology 2009

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Microbiology 2009

  1. 1. Microbiology A branch of biology that studies organisms that can only be seen with a microscope
  2. 2. Historical Overview • Fossil evidence dating back 3.5 million years (Burton & Egelkirk 1999) • Early civilizations isolated infected persons • Soiled dressings were burned (Burton & Egelkirk 1999) • Causes believed to be the action of gods • Early treatments – leeches, bleeding
  3. 3. Historical Overview (Cont’d) • 1546 Girolamo Fracastorius – suggests disease is cause by living germs • 1667 Antony van Leeuwenhoek – first light microscope – sees and describes microbes • 1876 Robert Koch – develops culture plates • 1890’s Louis Pasteur – developed methods of sterilization, pasteurisation.
  4. 4. Types of micro-organisms Non-pathogen(ic) Pathogen(ic) Non disease causing Commensal Disease causing
  5. 5. Types of micro-organisms bacteria parasites viruses fungi
  6. 6. Bacteria  Single celled organisms  Structure: - rigid cell wall enclosing cytoplasm - nuclear body but no nuclear membrane - some develop a capsule for protection - some have flagellae for propulsion - some have fimbriae enabling attachment to other cells
  7. 7. Requirements of bacteria Oxygen: variable •aerobic •anaerobic pH: Most neutral/sl.alkaline Some highly acid Some highly alkaline Carbon: require a small amount for cell structure Temperature: Optimum – 37 C Wide range from 5-60 C Food and water: required by all
  8. 8. Properties of bacteria Spore formation Toxin production
  9. 9. Bacterial spores formation Protective mechanism developed by some bacteria to survive in adverse conditions Highly resistant to: - high temperatures - freezing - sunlight - disinfectants Some spores (e.g. anthrax) have been found to be active after 100 years of being in inactive form
  10. 10. ANTHRAX
  11. 11. Production of toxins 2 types: Exotoxins: Living bacteria released into and cause damage to surrounding tissues Endotoxins: Remain in bacterial wall released on death of bacterium
  12. 12. Classification of bacteria 1. Staining properties Gram positive bacteria: retain violet colour Gram negative bacteria: retain red colour Acid fast bacteria: stain unable to penetrate due to waxy envelope Reactions of bacteria to a staining technique
  13. 13. Classification by shape Round: cocci diplococci streptococci staphylococci Rod: bacilli Spiral: spirilla vibrio Corkscrew: spirochaete
  14. 14. Cocci diseases (singular = coccus)  meningococci - meningococcal meningitis (diplococci)  streptococcus pyogenes - tonsillitis, pharyngitis, cellulitis  staphylococcus aureus - boils, carbuncles  pneumococci - pneumonia (diplococci) Examples:
  15. 15. Bacilli diseases Examples include:  Clostridium tetani - tetanus  Corynebacterium diphtheriae - diphtheria  Escherichia coli (E.Coli) – urinary tract infections  Pseudomonas aeruginosa - infected wounds
  16. 16. Bacterial disease examples: spiral shaped Spirilla: Spirilla minus - rat bite fever Vibrio: Vibrio cholerae - cholera Spirochaete: Treponema pallidum - syphilis Corkscrew shaped
  17. 17. CHOLERA
  18. 18. Specialised bacteria Rickettsiae and chlamydiae o smaller than most bacteria o can only reproduce in living cells - are therefore parasites o rickettsiae often carried by fleas, ticks, lice (vectors) Disease examples:  Rickettsia australis - Queensland tick typhus  Chlamydia trachomatis - trachoma, salpingitis
  19. 19. Specialised bacteria Mycoplasma • ultramicroscopic bacteria • do not have a cell wall Diseases caused: • certain respiratory and genital tract diseases
  20. 20. Viruses • ultramicroscopic • no cell structure • no rigid cell wall • are intracellular parasites • can only reproduce within a host cell • composed of either DNA or RNA but not both • can lie dormant in cells with activation occurring at a later time
  21. 21. VIRUS
  22. 22. Viruses DNA viruses  Herpes virus - herpes simplex, herpes zoster  Adenovirus - conjunctivitis, URTI  Poxvirus - variola (smallpox) RNA viruses  Paramyxovirus - colds, measles, mumps, croup  Piconavirus - infectious hepatitis A & B, polio. Retroviruses  Human immunodeficiency virus (HIV) - AIDS  Human T lymphotropic virus (HTLV) - lymphoma
  23. 23. “BIRD FLU” VIRUS
  24. 24. SMALLPOX VIRUS
  25. 25. VIRUS
  26. 26. Fungi • Plant organisms: mainly moulds and yeasts • Do not contain chlorophyll • Present in soil, air, water • Multiply by producing spores • Most non-pathogenic • A few are pathogenic
  27. 27. Pathogenic fungi (mycoses) Superficial: skin, mucous membranes, hair, nails Intermediate: subcutaneous tissue Systemic: deep tissues organs 3 types of mycotic infections
  28. 28. Fungi Diseases caused Dermatophytes: o Tinea pedis - athlete’s foot o Tinea unguium – toenail infections Candidiases (moniliasis): o Candida species - oral thrush, skin infections o Aspergillus - aspergillosis (respiratory disease)
  29. 29. TINEA PEDIS
  30. 30. Parasites • Survival requirements depend on a living organism – the host • Parasite-host effects variable: from little damage to death • Classification includes: helminths – multicellular animals (worms) e.g. flatworms (platyhelminths) : roundworms (nematodes) : flukes (trematodes) protozoa - single celled animal organisms transmitted to humans by insects
  31. 31. Pathogenic parasites o Trematodes (flukes) : liver, lungs or intestinal infestation o Nematodes – round worm infestation o Echinococcus granulosis (dog tapeworm) – hydatid cysts o Protozoa – malaria, toxoplasmosis
  32. 32. PEDICULI CAPITUS
  33. 33. PEDICULI
  34. 34. Prevention • Immunisation • Cleaning processes: environment & equipment • Health status of staff, visitors etc • Provision of clean water, food & sanitation
  35. 35. Prevention • PPE • Management of waste and body fluids • Handwashing
  36. 36. Transmission modes  the mode of movement of pathogen from exit point to new host Airborne: droplets dust particles Contact: direct indirect Ingestion: infected food/ water/utensils/ objects hands Vectors: Flies, rats, mosquitos
  37. 37. ENTRY POINT  ways in which pathogen enters the body ingestion inhalation broken skin/ mucous membranes trans- placental
  38. 38. EXIT POINT  the point from which pathogens emerge to enable entry to a new site of residence  human exit points include: - breaks in skin and mucous membranes : discharging wounds - gastro-intestinal tract : faeces, vomitus, bile, drainage tube - respiratory tract : sneezing, coughing, expectorating sputum - urinary tract : infected urine - blood : bleeding wounds - reproductive tract : semen, vaginal discharge
  39. 39. Prevention • Handwashing • Isolation • Cleaning systems: environment and equipment • Use of appropriate PPE
  40. 40. SUSCEPTIBLE HOST o Degree of resistance an individual has to a pathogen o Resistance to disease influenced by such factors as: - healthy nutrition - adequate rest and sleep - effective management of stress - effective hygiene practices - adequate exercise
  41. 41. Prevention • Procedures to manage indwelling lines: catheters, IV • Aseptic techniques for wound care • Handwashing • Immunisation • Treat disease processes • Encourage mobility, self care
  42. 42. Lunch • Please return in 45 min
  43. 43. BODY DEFENCES AGAINST INFECTION External mechanical and chemical barriers First line of defence Inflammatory response Second line of defence Immune response Third line of defence Non-specific defences Specific defences
  44. 44. External mechanical and chemical barriers  intact skin and mucous membranes: acid mantle, sweat, sebum, normal flora  gastro-intestinal tract: mucous membranes, normal bowel flora, saliva, stomach acidity, bile alkalinity  respiratory tract: mucous membranes, cilia, nasal secretions  eyes: tears  urinary tract: acidity of urine
  45. 45. Inflammation  second line of body defence  is non-specific: occurs whenever body tissues are injured  classic clinical manifestations: - redness - heat - swelling - pain/tenderness - restricted movement  pus formation occurs when injured area becomes infected
  46. 46. Inflammatory response Tissue injured Release of chemicals (e.g. histamine, kinins) Blood vessels to dilate Capillaries to leak Activation of pain receptors cause
  47. 47. Inflammation Heat and redness due to vasodilation resulting in increased blood supply to injured area Tenderness/Pain caused by pressure on underlying sensory nerve receptors from swelling. Send impulses to spinal cord to brain Swelling (oedema) results from capillary leakage into surrounding tissues
  48. 48. Pus Mixture of: -dead or dying neutrophils -broken down tissue cells -dying and living pathogens If area not completely cleared of infection, remnants become walled off to form an abscess Surgical drainage may be necessary before healing occurs
  49. 49. Other non-specific defences • Complement fixation - 22 plasma proteins - attach to foreign cells • Interferons - proteins secreted by virus infected cells • Natural Killer Cells – Lymphocytes that destroy infectious microbes plus certain spontaneously arising tumour cells • Fever - temperature rise may kill certain pathogens
  50. 50. Phagocytosis • Ingestion of microbes or any foreign particulate matter by cells called phagocytes • Two major types of phagocyte: – Neutrophils (white blood cells) – Macrophages (scavenger cells derived from monocytes)
  51. 51. Mechanism of Phagocytosis • Three phases: – Chemotaxis – activated complement proteins cause chemical attraction of phagocytes to a particular location – Adherence – attachment of the plasma membrane of the phagocyte to the surface of the foreign material. – Ingestion – the cell membrane of the phagocyte extends projections that engulf the micro-organism
  52. 52. Immune Response o Third line of body defence o Response is specific, systematic and has a memory o Cells of the immune system are: - B lymphocytes - T lymphocytes - Macrophages
  53. 53. Immune response o Two kinds – closely allied o Both triggered by antigens o Cell-mediated (cellular) immune responses (CMI) o T cells proliferate into “killer” cells and directly attack the invading antigen o Antibody-mediated (humoral) immune responses (AMI) o B cells transform into plasma cells which synthesize and secrete specific proteins called antibodies or immunoglobulin's
  54. 54. Formation of T Cells and B Cells • Both develop from haemopoietic stem cells in red bone marrow • B cells complete maturity in bone marrow • T cells leave as pre-T cells and migrate to the thymus gland to mature
  55. 55. Immune system cells B lymphocytes: -produce antibodies (immunoglobulins) T lymphocytes: -non-antibody producing Macrophages: -engulf foreign particles Humoral (antibody mediated) immunity Cell mediated and humoral immunity Cell-mediated (cellular) immunity
  56. 56. Immunity Any substance capable of stimulating the immune system and causing an immune response Are immunoglobulins (Igs) produced in the body in response to Antigens Five classes: -IgM, IgA, IgD, -IgG, IgE Antigens: (Ags) Antibodies: (Ab)
  57. 57. Functions of Antibodies • Neutralizing antigen • Immobilization of bacteria • Agglutination and precipitation of antigen • Activation of complement • Enhancing phagocytosis • Providing foetal and newborn immunity
  58. 58. Immunity Innate (genetic, inborn) Acquired Naturally acquired Artificially acquired Active Protection acquired by getting the disease Passive Antibodies passively cross from mother to baby via placenta or breast milk Active Protection acquired by immunisation with vaccine that stimulates body to actively produce own antibodies Passive Protection acquired by direct injection of antibodies (immunoglobulins)Ref: Tabbner, 2005, p.331 (Adapted from Herlihy and Maebius: 2000, p.354)
  59. 59. Immunological Memory • Memory for certain antigens triggers immune responses • Immune responses are much quicker and more intense after a second exposure to an antigen • Basis for immunization
  60. 60. References • Burton, G., and Engelkirk, P., (1999). Microbiology for the Health Sciences, Lippincott Williams & Wilkins, Philadelphia • TAFE Frontiers, (2003). Learners Resource: Microbiology and Wound Management, Dept. of Education, Employment and Training. Victoria • Marieb, E., (2006). Essentials of Human Anatomy & Physiology (8E). Pearson. San Francisco • Tortora, G. J., & Grabowski, S., (1996). Principles of Anatomy and Physiology (8 E). Harper Collins. New York

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