The GOOD, The BAD and The UGLY Microbiology 1 Dr Viv Rolfe

Lecture Outline The GOOD What is a microbe and microbiology? What are the different types of microbe? Microbes that are harmless. The BAD Common types of microbe that cause disease. The UGLY An introduction to infection.

A MICROBE is a tiny organism that has to be viewed under a microscope. MICROBIOLOGY is the branch of biology which studies micro-organisms and their effects on the living host. The MICROSCOPE is the tool used by all microbiologists. What is a Microbe and Microbiology?

Microscopes Basic microscope - simple glass lenses for low power magnification. Confocal microscope and scanning electron microscope - state of the art technology for high power magnification.

Does Size Matter? Microbes are measured in units called MICRONS... Micro = 1 / of a meter = m

Rain drop 10,000  m in DIAMETER Pin Head 2,000  m Amoeba 500  m Fungus spore 30  m Bacteria 1-5  m Smoke particle 0.1  m Virus < 0.05  m

Rain drop 10,000  m in DIAMETER Pin Head 2,000  m Amoeba 500  m Fungus spore 30  m Bacterium 1-5  m Smoke particle 0.1  m Virus < 0.05  m

Penicillin spores- damage bacterial cell walls giving us ANTIBIOTICS. The GOOD

Probiotics - “friendly bacteria” The GOOD

…and where would we be without yeast?

Types of Microbes There are 4 basic groups of microbe which can all cause infectious disease. a. bacteria b. fungi: yeasts and molds c. viruses d. protozoa

A - Bacteria a.There are thousands of bacterial species and many are pathogenic. They cause infections because they are everywhere, multiply quickly and some secrete toxins causing illness. Three basic shapes: coccus rod or bacillus spiral

1) Single coccus Coccus - 4 types 2) Paired diplococci 3) Chains or streptococcus 4) Bunches or staphylococcus

Staphylococcus aureus Releases toxins which cause food poisoning. Big news because its a “super bug”. It is resistant to antibiotics and causes major hospital infection (MRSA). E.g.

Rods / bacillus Rod-shaped bacteria 1) Single bacillus 2) In a chain of bacilli

Single - Escherichia coli (E coli for short) Many different strains of E coli. Some are COMMENSAL and live in your colon. Others cause food poisoning, eg E coli E.g.

Chains - Bacillus anthracis. Causes anthrax - animal infection that can spread to human (a zoonosis). Causes ulcers leading to blood poisoning and can be fatal in humans.

Three forms 1) Basic spiral Spiral Shaped 2) Spirillum (or spelt spirillium) 3) Spirochete - more twisted

A simple way of identifying SOME bacteria is by GRAM STAINING. Results… Bacteria that stain purple are termed gram- positive Bacteria that stain pink are said to be gram- negative Identifying Bacteria

Gram negative (e.g.E coli, Neisseria gonorrhoea) Gram positive (E.g. Staphylococcus, Streptococcus)

B - Fungi Fungi include yeasts and molds. Fungi have a rigid cell wall and absorb nutrients for energy. Over 100,000 known species but only about 100 species are pathogenic (harmful).

Candida Albicans - YEAST Part of our commensal flora. Candida causes in vaginal or skin infection in people who are ill, immuno- suppressed, or on antibacterial therapy. E.g.

Made of a HYPHA - a tubular in structure which form a mass or MYCELIUM. Molds reproduce by forming SPORES which can cause infection. Infection ranges from short term irritation to being death threatening. Fungi - Molds

Penicillin HYPHA

Single spore - can causes allergy and asthma.

C - Viruses Wide range of weird and wonderful shapes. Enveloped

Single cell with no organelles. They reproduce in living cells at a fantastic rate. They can mutate taking on new forms making them hard to treat. Viruses

Most viruses cause ACUTE infection – short duration and rapid recovery Eg respiratory infections (e.g., cold viruses, influenza viruses). Latent viral infection can remain dormant in the host for years. Eg Herpes zoster - causes chicken pox and shingles. HIV. Viral Infection

Unicellular microbes inhabiting mainly soil and water which can cause severe disease. 6% of global disease is caused by poor sanitation. (WHO 2004). D - Protozoa

Protozoa

Entamoeba histolytica Single celled AMOEBA which lives in water. Causes amoebic dysentery if ingested. E.g.

Trichomonas vaginalis Single celled FLAGELLATE (flagella is Latin for WHIP). Causes urinary tract and vaginal infections from sexual contact. E.g.

Commensal Microbes We are only about 10% human!!!! The number of microbes is greater than the number of human cells in the entire body!!!

Commensal microbes Noun1. commensalism - the relationship between two different kinds of organisms when one receives benefits from the other without damaging it. Commensals can live all over and in the body: –Gut - E coli –Reproductive system - Candida albicans –Nose - Staphylococci –Mouth - Streptococcus

Commensal microbes The microbes in your large intestine ferment undigested food such as fibre providing the body with energy…..

…and wind!

If a commensal bacteria is in the WRONG PLACE at the WRONG TIME it can cause infection… E.g. - if the skin is cut, during immuno-suppression, in the elderly or very young. But - Commensals can Cause Infection

The BAD and the UGLY Pathogens and Infection

Pathogens A pathogen is a microbes that cause disease (pathogenicity) by rapidly growing, producing toxins or causing cell damage…. Vibrio cholera - diarrhoea Helicobacter pylori - stomach ulcers Mycobacterium tuberculosis - TB

What is an Infection? Infection is the invasion of the body by microbes which then multiply and cause tissue damage and disease. Can be a COMMENSAL microbe which gets into the wrong place Can be a non-resident PATHOGEN which enters the body

And finally… Guess the Infection Bacterium Virus Fungus Protozoa

Measles - VIRUS

Diarrhoea - BACTERIA, PROTOZOA e.g. vibrio cholera, amoebic dysentery

Cold - influenza VIRUS

Athlete's foot - FUNGUS

Mumps - VIRUS Swelling of salivary glands

Jock Itch or Furuncle - BACTERIA Staphylococcus aureus bacterial infection of hair follicle.

Thrush - YEAST Candida albicans infection of mouth or genitals

Thrush

NOTE! Infections can be caused by another type of organism.

Parasites Parasites - can be microscopic or visible to the eye, and are not covered by the medical subject of microbiology.