1. Introduction to Microbiology (Micro-organisms)

2. Bacteria Size = MICROSCOPIC Apart from the plasmid, what seem to be the differences between the bacterial cell and a human cell? Bacterial cells have CELL WALLS Bacterial cells don’t have A NUCLEUS

3. Special Features Prokaryotic - lacks a clearly differentiated NUCLEUS Mostly UNICELLULAR Rigid CELL WALL (protection from bursting) Some bacteria have a Mucilaginous CAPSULE (protection)

4. Special Features Some have FLAGELLA for movement Where might pseudomonas be found? PILI help attachment to host

5. Common examples of bacteria Clostridium welchii (gas gangrene), Staphylococcus aureus, Streptococcus, Escherichia coli StreptococcusE.Coli

6. Classification Shape: CoccusBacillus VibriosSpirochaetes

7. Patterns and Staining Patterns: StaphylococciStreptococci Diplococci Staining: e.g. gram positive or gram negative

8. Growth Requirements: Water and Nourishment Water is required for chemical reactions and gaseous exchange Clinical relevance? Most bacteria are chemotrophs (derive their energy from the oxidation of chemical compounds) May only need glucose and a few inorganic ions or they may only grow in a living organism. Clinical relevance?

9. Growth Requirements: Respiration and pH Anaerobe - clostridium tetani - grows in the absence of oxygen deep in the body Aerobe - pseudomonas - needs oxygen Facultative anaerobes e.g. staph or strep - use oxygen for respiration when it is available Clinical relevance? pH Most pathogenic bacteria prefer slight alkalinity Clinical relevance?

10. Growth Requirements: Temperature Some can form spores - these have very thick walls and they can survive dryness and temperature changes (E.g. clostridium tetani can form spores) Clinical relevance?

11. Reproduction Can be cultured in a cell-free medium Reproduction is mainly Asexual (binary fission) May divide every 20 minutes or so 1  2  ?  8  16  ?  64  ?  256  ?

12. Reproduction Draw a graph plotting time against population size : Clinical relevance? Time Population 20m1hr1.402.203hr4hr 500 400 300 200 100

13. Hospital Acquired Infection In some species ‘sex’ facilitates biological variation Most Hospital Acquired Infection (H.A.I.) due to bacteria LIST EXAMPLES SEEN IN CLINICAL PRACTICE

14. VIRUSES Different from other micro-organisms because they consist only of NUCLEIC ACID (either DNA or RNA) surrounded by a protein CAPSULE Size Smallest infectious agents

15. Viruses Possible cause of some CANCERS (oncogenic viruses) The human papilloma virus (HPV) is a common virus. HPV types 1, 2 and 4 are associated with the common warts. Some HPV types can lead to abnormal changes in the cells of the cervix. Common examples of viruses Hepatitis B, Herpes, Coryza Classification: Type of nucleic acid (DNA or RNA) Size and shape

16. Viruses - Growth Requirements and Reproduction Viruses can only reproduce inside a living cell (intracellular microbe) Viruses have a poor rate of survival outside living cells although some remain viable in droplets and are spread via air

17. Viral Replication Virus fastens to host cell Nucleic acid injected into cell, protein capsule left on the outside 1 2

18. Viral Replication New virus particles are liberated Viral nucleic acid links up with cell’s genes and the infected host cell manufactures new viruses using the instructions contained in the viral nucleic acid. 3 4 Most community illnesses are due to viruses

19. FUNGI Structurally more complicated than bacteria and have a nucleus Different types Candida albicans, tinea pedis (athlete’s foot) Do you recognize the condition above?!

20. Classification of Fungi Moulds (filamentous) - tinea (ringworm) True yeasts Yeast-like - candida (THRUSH) Dimorphic

21. Fungi Growth Requirements Fungi make spores that can survive drying Problems A fungal disease is called a MYCOSIS (superficial or deep mycoses) Candida albicans is responsible for ‘thrush’ (this is an opportunistic infection especially after patients have received antibiotics)

22. Other Types of Microorganisms Protozoa e.g. Mycoplasms e.g. Ricketsiae Chlamydiae Look up an example of the above (preferably one that you have heard of)

23. Helminths (worms) E.g. Roundworm, Threadworm, Tapeworms

24. Terminology Antiseptic Disinfectants applied to the skin or living tissue Aseptic Method developed to prevent contamination of wounds (or other susceptible sites) by ensuring only sterile objects or fluids will make contact with these sites and that the risks of airborne contamination are minimized BactericidalBacteria killers BacteriostaticInhibit bacterial growth, but may not kill

25. Terminology CarrierBeing infected but not having any symptoms Commensals Found in normal body flora. Benefit host by not allowing pathogens to colonize. Cause disease if they get in to an abnormal site (e.g. E.coli causing cystitis) Cross infectionInfection acquired from other people - either patients or staff (may be contact or airborne)

26. Terminology DisinfectantChemical compound which can destroy vegetative micro-organisms DisinfectionTreatment which achieves killing of non-sporing or vegetative micro- organisms Endogenous Source of infection - organisms that the person carries Exogenous Source of infection - organisms not normally present in the person, but coming from outside Incubation Period from arrival of microbe to onset of symptoms Opportunistic Cause disease in weak or debilitated e.g. pseudomonas NosocomialHospital acquired (from another patient, staff or the environment)

27. Terminology Pathogens Will cause disease (depending on host factors such as age, nutrition, immune status, genetics, drug treatment) Resident organismNot removable by washing Saprophytes Found in environment (soil for example). Recycle organic compounds. Do not normally cause disease

28. Terminology SepsisPresence of inflammation, pus formation etc SterilizationTreatment which achieves the complete killing or removal of al types of micro-organisms, including spores of tetanus and gas gangrene, which are resistant to most disinfectants Transient organismCan be removed by appropriate hand washing Virulent Easily able to attack host