Chapter 4 – NORMAL FLORA & HOST PARASITE RELATIONSHIP

1. Chapter 4 – NORMAL FLORA & HOST PARASITE RELATIONSHIP Miss RashidahHjIberahim MIC342 - Miss Rashidah Hj Iberahim

2. Types of Pathogens • Primary Pathogens • Cause disease upon infection, not normally associated with host • Plague (Yersiniapestis), • influenza virus • Opportunistic Pathogens • Cause disease under some circumstances, sometime members of normal flora • Pseudomonas, • Candida albicans

3. Progression of Disease • Transmission: infectious dose from 10-106 organisms • Incubation period: few days (common cold)-weeks (hepatitis A)-months (rabies) • Convalescence: • Clearing (Strep throat, S. pyogenes) • Latency (Chicken pox, tuberculosis, cold sores)

5. Koch’s Postulates • Proposed by Robert Koch • Conclude that a microbe causes a particular disease • Must fulfill four postulates • Microorganism must be present in every case of the disease • Organism must be grown in pure culture from disease hosts • Produce the same disease from the pure culture • Organism recovered from experimentally infected hosts

6. Molecular Postulates • Describe virulence factors • Four postulates • 1. Virulence gene or its product must be present • 2. Virulence gene must transform a non-pathogen into a pathogen • 3. Virulence gene must be expressed during disease process • 4. Antibodies against gene products are protective

7. Establishing an Infection • 1. Encounter: • fecal-oral (cholera) • human-human (tuberculosis) • animal-human (rabies) • vector-borne (plague, lyme disease) • environmental contact (anthrax)

8. Establishing an Infection • 2. Adherence • Prevents early clearance • Often bind host tissues via pili • Specificity can determine host range of pathogen

9. Establishing an Infection • 3. Colonization: multiplication and maintainance • Competition with normal flora • Resist: • bile • stomach acid • peristalsis • skin secretions • IgA (mucosal antibodies) • compete with host for iron

10. Establishing an Infection 4. Molecule Delivery • Affects target cell structure and host response

11. Invasion:Breaching Anatomical Barriers • Find new niche with few competitors • Gain access to rich nutrient supply 1. Skin: tough barrier, rely on wounds or insect vectors 2. Crossing mucous membrane (e.g. intestinal epithelial cells)

12. Definition of normal flora • m/org that normally found in particular area that do not cause harm to host cell and body system • Also known as microflora

13. Harmful • *microorganism in perianal area enter the urinary tract (UT) causing infection in internal UT Can prevent infection by: • Medical asepsis – personnel and hospital environment should be clean from pathogens • Surgical asepsis – instrument used should be sterile and including the surgical room • What did you implement in daily life? MIC341 - Miss Rashidah Hj Iberahim

14. Normal Flora • More bacterial than human cells in the body • provide some nutrients (vitamin K) • stimulate immune system, immunity can be cross-reactive against certain pathogens • Prevent colonization by potential pathogens (antibiotic-associated colitis, Clostridium difficile)

15. Normal flora of body system Skin Gram positive org: • Staphylococcus sp, • Micrococcus, • Coryneform bacteria/Demodexfolliculorum (opening glands – eyebrows) Urogenital • M. smegmatis, • Lactobacili, • Streptococci, • Staphylococcus, • E.coli

16. Body system w/out normal flora • Lower respiratory tract • Systemic and cardiovascular • Nervous system

17. Skin Flora MIC342 - Miss Rashidah Hj Iberahim

18. Oils production • Different area consist of different microflora. Example armpits vs forehead. • Moisture area will support larger populations; nutrients from oils and sweat • Those normal flora might have capability to produce oils that known as fatty acid providing an acidic condition of particular area • Initiating host defense against infection in the 1st line stage • But, excess of oils production might resulting an odour of unpleasant smell to the body MIC341 - Miss Rashidah Hj Iberahim

19. Sweating • Beside oils, the 2nd line of host defends is the sweat that are salty • However, in opposite situation, there are bacteria that able to live in salty area such as Staphylococcus sp. • Majority of the skin flora – Gram +ve : Staphylococcus, Micrococcus and Corynebacterium • Hair follicles inhabitants – mite Demodexfolliculorum MIC341 - Miss Rashidah Hj Iberahim

20. Skin shedding • 3rd line defends is regarding the keratin-degrading fungi • It helps in rapid and continuous shedding of skin cells replacing layer by layer • Removing of skin cell together with group of m/org on the skin MIC341 - Miss Rashidah Hj Iberahim

21. Normal flora Gram positive org. • Staphylococcus sp • Micrococcus • Coryneform bacteria • Demodexfolliculorum (opening glands – eyebrows) MIC341 - Miss Rashidah Hj Iberahim

22. Urogenital Flora MIC342 - Miss Rashidah Hj Iberahim

23. Urogenital • Al parts are sterile except urogenital opening • Urine collection should have ‘clean catch’ technique • E.coli and Lactobacillus are common flora = 100,000 bact/ml of urine • Collection during direct puncture (suprapubic) = sterile sample • Acid pH, high salt and urea concentration leads to high m/org growth • Urine sample should be refrigerated during transportation if delay – high multiplication if stir in RT MIC341 - Miss Rashidah Hj Iberahim

24. Cont. • Mycobacterium smegmatis (acid fast staining bacili) live in external genitalia of female and male • Esp under penis of uncircumsized male – smegma • If included in the sample, might leads to confusion wt the tuberculosis patient which actually having M. tuberculosis • In male, 1/3 of deep are for genital area don’t have normal flora MIC341 - Miss Rashidah Hj Iberahim

25. In female.. Due to hormonal changes.. • Child-bearing – lactobacili numerous in vagina (eating glycogen) • Glycogen in vaginal cell will be fermented become lactic acid and pH decrease to 4.7 • Childhood and after menopause, lactobacili absent coz no glycogen –replaced by streptococci and staphylococci due to alkaline pH in vagina MIC341 - Miss Rashidah Hj Iberahim