Microbiota (Normal Flora) 2024-2025 PDF

Microbiota (Normal Flora) Presented by: Batch 50  Ali Alshareef 17932  Abdelhadi Bayou 19889  Retaj Alwerfali 17863  Lamya Aljazwi 19955  Noha Abbas 19829 Under supervision: Dr. Ghada A. Abbas 3rd year medical student 2024-2025 ...

Microbiota (Normal Flora) Presented by: Batch 50  Ali Alshareef 17932  Abdelhadi Bayou 19889  Retaj Alwerfali 17863  Lamya Aljazwi 19955  Noha Abbas 19829 Under supervision: Dr. Ghada A. Abbas 3rd year medical student 2024-2025  Inteneded learning outcome 1. Define the microbiota (normal flora). 2. List the types of normal flora. 3. Discus the different sites of normal flora in human body. 4. Describe the conditions that create opportunities for normal microbiota to cause disease. 5. Name the factors affecting on normal flora. 6. Discuss the role of normal flora.  Microbiota (Normal flora)  Definition: Normal flora denotes the population of microorganism that inhabit the skin and mucous membranes of healthy normal people.  Microbiota / Microbiome / Microflora Different names for the same thing.  Advantages of normal flora: 1. Synthesis of vitamins such as vitamin K and B12 in intestine. 2. Produce anti-bacterial chemicals to suppress pathogens.  Disadvantages of normal flora: 1. Normal flora become pathogenic when the immune system is lowered 2. Abnormal multiplication of normal flora leads to diseases  Types of normal microbiota A. Resident flora (fixed microorganism) Allways present. Found in a specific area at agiven age. Re-establishes itself. Causes diseases, if disturbed. B. Transient flora (Temporary) Remains for hours, days, or week. Come from the environment. Non-pathogenic microorganism.  Microbiota (Normal flora)  Total papulation of normal flora in human is 1014 while total number of cells 1013.  Sometimes they cause disease when they leave their origenal site.  Location site of normal flora 1. Skin. 2. Eyes (conjunctiva). 3. Nose (respiratory tract). 4. Mouth. 5. Ear ( external ear). 6. Urogenital tract. 7. Gastrointestinal tract. Sterile sites in the human body 1. Blood 2. CSF 3. Body fluid (peritoneal, pleural) 4. Internal organ and Tissue  Normal flora of skin  Residant flora Staphycoccus epidermis.  Yeast as candida albicans is a member of the normal flora of the skin, when a needle pierces the skin it can reach the blood stream and cause systemic infections.  Normal flora of oral cavity Sterile at birth but is colonized after 4-12hours by Viridance streptococci. Streptococcus sunguis (dental plaque). Streptococcus mutans secreate a biofilm and producing (dental caries). Normal flora of respiratory tract  Upper rispiratory tract (Nose-Oropharynx).  Lower respiratory tract is sterile (Trachea-Bonchi -pulmonary tissue). Normal flora of genitourinary tract (GUT) Gut is sterile except vagina and distal 1 Cm part of urethra. Female genital tract is more heavily colonized than male. Due to: 1. Female urethra being short. 2. Short distance between opening of urethra and anus. 3. Vagina heavily colonized.  Normal flora of gastrointestinal tract Predominant site, colonized with bacteria. In the stomach only a few bactereria are present due to acidic PH. In the Small intestine a few in upper part, while lower part is more abundant. Large intestine 99% in large intestine are bacteriodes species. Conditions where microbiota cause disease 1. Weakened immune system. 2. Changes in the local environment. 3. Disruption of microbiota. 4. Presence of medical device.  1. Weakened immune system: When the immune system is compromised there is a subsequent microbiota overgrowth which causes opportunistic infections (OI). 2. Changes in the local environment: Changes in the habitat such as PH and temperature can lead to overgrowth of microbiota and thus cause OI. 3. Disruption of microbiota: Killing of some microbiota by broad-spectrum antibiotics may allow some commensal bacteria to replicate unchecked and cause disease. 4. Presence of medical devices: Devices like catheters can be colonized by microbiota which forms a biofilm leading to infection.  Role of microbiota 1. Defense against pathogens. 2. Stimulate the immune system. 3. Nutrient synthesis. 4. Maintaining PH.  1. Defense against pathogens:  Normal flora competes with pathogens for nutrient and space, and secret some toxins that eliminate harmful bacteria. 2. Stimulate the immune system:  By inducing the secretion of IgA in mucosal immune system and help in the development of the intestinal humoral system. 3. Nutrient synthesis: Vitamin production: some bacteria in the gut produce vitamin K, which is necessary for blood clotting. Production of bio active compounds: such as Indole-3-propionic acid (IPA) (potent anti-oxidant). 4. Maintaining PH: In the vagina, normal flora (like Lactobacillus species) help maintain an acidic environment, which prevents the growth of harmful bacteria.  Factors affecting normal flora 1. Mode of delivery. 2. Infant feeding. 3. Age. 4. Antibiotic. 5. Medications. 6. Surgery. 7. Hygiene practices. 8. Ph & Oxygen & Temperature.  Factors affecting normal flora 1. Mode of delivery  Infants born by vaginal delivery are exposed to the mother’s bacteria at birth canal, a baby can be infected with bacteria that causes meningitis during birth for example (Group B Streptococci) are part of the normal vaginal flora in 5–30% of women. 2. Infant feeding:  Infant feeding is another important factor for establishing the bacterial community in the gut, Human breast milk contains >700 species of bacteria, such as (Streptococci) and (Staphylococci) are predominant bacterial genera in human milk, transfer of microbiota from mothers to their infants affect infant growth and development. While Formula Milk can contain harmful bacteria such as Salmonella and Cronobacter. Which can be transmitted to the infant, causing disease 3. Age  The composition of normal flora can vary depending on a person's age. For example, infants have a different microbiota compared to adults, and the diversity of bacteria increases as a person grows. 4. Antibiotic therapy  Antibiotic therapy, such as clindamycin, can suppress predominant Normal flora, Thus allowing very rare organism such as )Clostridium difficile found in about 1% of people) to overgrow and cause severe colitis. 5. Medications  That many drugs have an impact on the gut microbiota, including the drugs used to treatment Type 2 DM. 6. Surgery  After tooth extraction or oral surgery often the bacteria streptococci that live in the mouth enter into the blood. The presence of these bacteria in the blood rarely causes harm to healthy people, but causes fatal inflammation when settle on prosthetic heart valves and produce infective endocarditis 7. Hygiene practices  Handwashing regular can help prevent the spread of harmful bacteria and maintain a healthy balance of normal flora.  Reference  Jawetz ،Melnick ،& Adelberg's Medical Microbilogy ،28th_ Edition.  Medical Microbiology & Immunology (3rd education).  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC543960/