2024 C1 B Human Microflora PDF

HUMAN MICROFLORA (including their use as Prebiotics, Probiotic and Synbiotics) DR UBLENI EMANGHE DEPT OF MEDICAL MICROBIOLGY& PARASITOLOGY FACULTY OF BASIC CLINICAL SCIENCES UNIVERSITY OF CALABAR, CALABAR  INTRODUCTION Micro-organisms ar...

HUMAN MICROFLORA (including their use as Prebiotics, Probiotic and Synbiotics) DR UBLENI EMANGHE DEPT OF MEDICAL MICROBIOLGY& PARASITOLOGY FACULTY OF BASIC CLINICAL SCIENCES UNIVERSITY OF CALABAR, CALABAR  INTRODUCTION Micro-organisms are ‘ómnipresent’-water, soil, air Normal flora are defined as Microorganisms that live on another living organism (human or animal) without causing disease. OR Permanent or fixed micro-organisms in particular anatomic sites in healthy human body: Aka Normal flora/microbiota or microbiome; OR Population of micro-organisms that inhabit skin/mucous membranes of healthy persons, OR Diverse microbial flora is associated with skin and mucous membrane of every healthy human being from shortly after birth until death-The human body is not sterile. Approximately one hundred trillion bacteria form the normal flora of our bodies. Human microbiota is likened to an ‘ecosystem’-Out-number the approx. 40.0 (37.2) trillion body cells. The Normal flora helps to prevent us becoming colonized with potentially infection-causing bacteria or pathogens.  INTRODUCTION 2 The normal human body has a profuse bacterial flora: this consists of commensal bacteria which, although parasitic, exist in a symbiotic equilibrium with the host. Many of the commensals are potential pathogens if they leave their normal sites, there is a breach of the body defenses, resulting in an infection. The normal flora is physiologically static, although it is subject to constant change.  INTRODUCTION 3 Characteristically: Found at sites that communicate with the exterior- skin, mucous membranes of the nose and mouth and intestine and urogenital tracts The NF is relatively stable, specific genera populate specific body sites NF mostly of bacterial species, some fungi Viruses and parasites are not considered members non-commensals and do not aid the host! Always pathogenic!!  CHARACTERISTICS 2 NF is acquired rapidly during and shortly after birth, remain stable throughout life Composition can be altered by: Local environment (pH, temperature etc), age/hormones, mode of birth, dietary/cultural habits, antimicrobial use, lifestyle (eg smoking/lysozyme secretion, douching), etc Other circumstances can change normal flora, e.g. normal flora of the human body begins to change after admission to a hospital or long-term care facility From about day 4 of admission-from hospital environment, personnel, even devices within patients (intravenous, intra-urinary) etc-Hospital Acquired Infection!  MAIN TYPES OF HUMAN BODY FLORA The Resident/Normal flora The Transient flora Reside within the stratum corneum, skin surface-Staphylococcus epidermidis, Consists of non-pathogenic or potentially pathogenic microorganisms that inhabit the skin or mucous Staphylococcus hominis, Malassezia species membranes for hours, days or weeks etc: it is derived from the environment, does not establish itself permanently on the surface and does not relatively fixed/permanent types of produce disease microorganisms regularly found in a given area acquired during HCWs contact with patients/beds etc, patient secretions-HCWs hands colonized with at a given age pathogenic Staphylococcus aureus, some Gram Negative bacteria, yeasts promptly re-establishes itself when disturbed-eg easily removed by routine surgical hand washing, hand hygiene mouth washing, skin scrubbing can cause disease when found outside their usual site eg dental extraction/infective endocarditis, non-intact skin/soft tissue infection, phlebitis examples  Relationships of NF and host MICROORGANISMS which colonize our bodies maintain a symbiotic relationship with our cells- healthy situation! Mutualism-both benefit : Escherichia coli in gut receive nutrients and produce useful vitamin K Commensalism-where one partner benefits, other neither benefits nor harmed In disease situation: Opportunism-taking “advantage” of the other. A commensal turning into a pathogen!  Advantages of NF (NF in health) Serve as ‘ecological niches’ by fending off entry of pathogenic micro- organisms via‘bacterial interference’, competition for receptors/binding sites etc. The presence of the normal flora prevents other more pathogenic bacteria from gaining a foothold in the body. More efficient in competing for micronutrients than pathogens. The gut bacteria seem to be responsible for the normal structure and function of the intestine: they degrade mucins, epithelial cells and carbohydrate fibre and Their metabolism produces vitamins, especially vitamin K and the B group.  Advantages of NF (NF in Health) Evoke production of antibodies which cross-react with pathogens with related or shared antigens Liberation of endotoxins which help host defenses Some NF colonies have harmful effects on pathogens by the production of bacteriocins  Disadvantages (NF in disease) Mainly from transposition from normal sites: Arise with spread to previously sterile parts (opportunism)/ acting as pathogens rather than commensals of the body NF in one site but pathogen in another! Intestinal perforation-abscess collections, peritonitis NF in intestine BUT as UTI pathogen in the genitourinary tract Broken skin- soft tissue infections During tooth extraction-Rheumatic heart disease/Infective Endocarditis Synergism with potential pathogen- provide vitamin/growth factors to pathogen  Disadvantages (NF in disease) Difficulties in laboratory result interpretation!!! Opportunistic due to Immunosuppression (radiotherapy, chemotherapy, malignancy etc) candida in the blood stream in severely immunocompromised person; Bacterial vaginosis due to decrease vaginal acidity  Host Infection by Elements of the Normal Flora A breach in skin and mucosal surfaces often results in infection of the host by members of the normal flora. Caries, periodontal disease Abscesses, foul-smelling discharges Endocarditis Peritonitis Urinary infection are hallmarks of infections with members of the normal human flora.  Distribution of the Normal flora With the exception of the alimentary tract, the internal organs of other systems are sterile in health, e.g. the bladder and kidneys, the bronchi and lungs, the CNS. Effective local defense mechanisms exist to maintain the sterility of these sites: in addition, chemical substances in serum and tissue fluids e.g. complement, antibody, promote the powerful phagocytic activity of the polymorphonuclear leucocytes  COMMON ANATOMIC SITES OF THE NORMAL FLORA SKIN Largest body organ, most and constant exposure to environment. Moist and occluded areas (axilla, perineum, toe webs) has higher pop than less occluded areas (face, trunk, upper arms, legs). the skin has a rich resident bacterial flora (estimated at 10²-104 organisms per cm2). Low pH, fatty acids from sebaceous glands and lysozymes help to eliminate non-resident organisms. Most common is Staph. epidermidis and Diphtheroids (GPB), propionibacterium acnes (anaerobic GPB), corynebacterium, Micrococcus Less common Peptostreptococcus spp, Streptococcus viridans, Staphylococcus aureus (up to 50% in normal adults), Candida spp, Enterococcus, coliforms Coliforms often found in moist areas-axilla, groin. Anaerobic organisms –in areas with much sebaceous glands where anaerobic conditions prevail.  EYE/CONJUNCTIVA EYE/CONJUNCTIVA Relatively free from bacteria due to the presence of lysozyme in tears and mechanical flushing. Predominant organisms of the eyes are: Moraxella spp, Diphtheroids, Staph epidermidis and the nonhaemolytic streptococci. NOSE AND NASOPHARYNX. The nasopharynx of the infant is sterile at birth but in 2-3 days acquires flora from mother and attendants. Harbours pathogenic organisms usually responsible for infections of nose, throat and lungs. Diphtheroids, staphylococcus, streptococcus, haemophilus, moraxella  ORAL CAVITY THE MOUTH: The mouth of infant inhabits organisms found in mother’s birth canal The mouth contains micrococci, gram positive aerobic spore bearing bacilli, coliforms, proteus and lactobacilli. The gums pockets between the teeth and crypts of the tonsils have a wide spectrum of anaerobic flora like fusiform bacilli, treponemes, lactobacilli, etc. Candida is also found.  UPPER RESPIRATORY TRACT NF take hold within 12 hours of birth. Mouth- Streptococcus mitis and other streptococci, Trichomonas, Candida Similar mouth flora in Oropharynx, Pharynx, Trachea Such as Alpha- and β- hemolytic Streptococci, Neiserria species, Diphtheroids and H.influenzae Smaller bronchi and alveoli are normally sterile. Nose- Staph. aureus, Staph. epidermidis, Diphtheroids, Streptococci.  GASTROINTESTINAL TRACT Sterile in-utero, colonized shortly after birth Lactobacilli, Enterococcus, coliform bacilli Changes with food type/diet Stomach: Low Ph. Low (10³-10⁶ orgs/g of content) and transient Duodenal: Sparse (0-10³); Ileum: moderate, mixed (10⁶-10⁸ organisms/g): Enterococcus Small intestine (Less bacteria than large intestine): Lactobacilli, Streptococci, Clostridium, Candida, Entamoeba, Enterobacteriaceae etc Large intestine: Dense 10⁹-10¹¹ Bacteriodes, E.coli, Strep. faecalis, Fusobacterium spp Organisms in colon useful in bile acid conversion and production of vitamin K and ammonia.  GENITOURINARY TRACT Male and female genitalia habour Mycobacterium smegmatis, Mycoplasma and ureaplasma Urethra (external): Staphylococcus epidermidis, Streptococcus faecalis, Diphtheroids Vagina: Change with age: Before puberty- Staphylococci, Streptococci, Diphtheroids, E. coli. Subsequently Lactobacillus aerophillus (vaginal pH, hormone levels). Transient Candida spp causing vaginitis Lactobacillus gatekeeper of vaginal ecosystem-maintains pH 4.5 +/- 0.5. Absence of lactobacillus=Bacterial vaginosis  Knowledge of the normal flora of the human body Prediction of the pathogens causing infection as bacteria tend to grow in specific body sites e.g. Streptococcus pneumoniae from the upper respiratory tract causing pneumonia Staphylococcus aureus from the skin causing intravenous cannula infections Investigation for underlying abnormalities in specific areas of the body when bacteria are isolated from normally sterile sites e.g. Escherichia coli isolation from blood cultures indicates probable intra- abdominal pathology because Escherichia coli is part of the normal gastrointestinal flora, For isolation of a Viridans Streptococcus in blood cultures may indicate infective endocarditis as a result of poor dentition as Viridans Streptococcus are part of the normal mouth flora  Knowledge of the normal flora of the human body Knowing normal sites of bacteria helps diagnosis when found in the ’wrong’ place Guides empirical treatment-allows for the prediction of the likely causes of disease and hence the choice of a suitable antibiotic Knowing what factors affect normal flora Opportunistic infection-allows predictions to be made as to what the flora will become under the influence of extraneous factors or antibiotic overuse e.g. colitis due to C.difficile; Bacterial vaginosis  Current utility of Normal flora microorganisms in health ‘’Let food be thy medicine and medicine be thy food”-Hippocrates The crucial role of food to our health and well-being by the father of modern Medicine! Russian scientist, Ilyich Mechnikov (Eli Metchnikoff), Russian Nobel prize winner –useful role of some bacteria in human GIT Credited with the concept of probiotics Enhance health or prevent chronic diseases Drew link of longevity among peasant Bulgarians and their staple diet of fermented milk (lactobacillus-rich milk).  Probiotics, Prebiotics and Synbiotics Strong relationship between gut flora and health/disease in the 21st century Modulation or restoration of gut microbiota most commonly known in human health Micro-organisms now used for treatment and prevention of illnesses/diseases Probiotic (good bacteria), prebiotics (growth stimulators), synbiotics (combination of the 2) As food supplements or functional foods Alter, modify or modulate, reinstate the pre-existing intestinal NF General role: Gut health Immune-modulation Cancer prevention Inflammatory bowel disease etc  PROBIOTICS Pro=‘’for life’’ (Greek) Main organisms used are lactobacilli, bifidobacterium species, yeasts etc Commercialized as supplements Now as prophylactic treatment! A preparation or product that contains live micro-organisms which when taken in adequate amounts alter t, he gut microflora and confer health benefit on the host-FDA/WHO definition. Inhibit growth and attachment of harmful bacteria (via their antibacterial chemicals) against these bacteria in the gut epithelium. Useful in diseases within the intestine such as Irritable bowel disease( Crohn’s dx, Ulcerative colitis, Lactose intolerance) as well as many extra-intestinal diseases such as obesity, Type 2 DM, allergy, peptic ulcer, fatigue, aging, osteoporosis, autism etc.  PREBIOTICS Prebiotics composed of non-digestible fibre-like food substances-pectin, inulin carbohydrate substances Substances that induce growth or activity of micro-organisms(bacteria and fungi) that contribute to the well-being of the host They change the proportions or activities of resident flora Selectively stimulate growth of one or group of bacteria (lactobacilli, bifidobacteria) in colon Ideal prebiotic properties: Be resistant to action of stomach acid, bile salts, other hydrolyzing intestinal enzymes Not absorbed in the upper GIT Easily fermented by the beneficial micro-organisms  SYNBIOTICS Syn=synergism Probiotics and prebiotics synergistically-acting Concept of mixtures of probiotics and prebiotics that beneficially affect the body by improving the survival and implantation of live microbes in the gut By definition are products that contain both probiotics and prebiotics The prebiotic also selectively favour the probiotic in a synergistic manner Uses: Cancer treatment adjunct Lipid control-Hypercholesteraemia  LAST TAKE!! 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