Normal human microbial flora & Epidemiology of IDs.pptx

Normal human microbial flora & Epidemiology of IDs

1. NORMAL BACTERIAL FLORA OF THE HUMAN BODY DR RANU SONI MD, DNB, MNAMS ASSISTANT PROFESSOR DEPARTMENT OF MICROBIOLOGY MMCMSR, SADOPUR, AMBALA

2. Learning objectives At the end of the session, the students will be able to Define resident flora and transient flora List common human normal flora Describe beneficial and harmful effects of normal flora

3. NORMAL FLORA OF THE HUMAN BODY Definition; Also called “ indigenous microbiota” Diverse group of microbial population that every human being harbours on his/her skin and mucous membranes

4. Types of Normal Flora Resident flora It includes microbes that are always present at a body site. It promptly re-establishes itself even when removed. It consists of relatively fixed types of microorganisms regularly found in a given area at a particular age.

5. Types of Normal Flora Transient flora It includes organisms that are present for very short time . It consists of non-pathogenic or potentially pathogenic microorganisms. These organisms may be temporarily established due to exogenous factors such as food. Example—transient bacteremia occurs after the brushing of teeth.

6. Factors Determining the Composition of the Normal Flora Nature of the local environment (age, pH, temperature, redox potential, and oxygen, water, and nutrient levels) Local factors such as site of body, peristalsis, saliva, lysozyme secretion, and secretion of immunoglobulins Exogenous factors such as clothing worn, occupation, antibiotic consumption, nutritional status, immunosuppressive, and metabolic disorders

7. Advantages Provides the host with some essential nutrients (e.g., microbial flora of the intestinal tract synthesise vitamin K and several B group vitamins). Aids in the metabolism of indigestible compounds. Provides defence against colonisation by opportunistic pathogens by providing a local barrier against them.

8. Beneficial Effects of Normal Flora

9. Aids the host’s immunity —the immune system is dependent on interactions with the human microbiome, as suggested by recent studies. Helps in the prevention of inflammatory disease during colonisation (as shown by some symbiotic bacterial species); the production of metabolic waste products such as acetic, butyric, and lactic acids by strict anaerobes inhibits the growth of pathogenic bacteria in the large bowel. In newborns, it stimulates the development of the immune system .

10. Disadvantages Some of the normal microbial flora can act as opportunistic pathogens and cause disease in immunocompromised individuals. Normal microbial flora often contaminate clinical samples collected from sterile sites (due to improper collection), causing confusion in laboratory diagnosis.

11. Diseases produced by Normal Flora

12. Site-Specific Normal Flora Human skin : Organisms in the environment, depends on the area of body Face, neck, hands, buttocks : Streptococci, Staphylococci, Candida Nasopharynx: Colonization within 2-3 days of birth Mouth : Anaerobes and Candida - at birth : Micrococci, Streptococci - In 2-5 days , replaced by bacteria from mother and attendant - Within 12hrs of birth , alpha Streptococci in upper respiratory tract Gut flora : anaerobes( Bacteroides, Clostridium, etc ) and coliform bacteria

13. NORMAL FLORA OF THE HUMAN BODY Vaginal flora : depends on pH and enzyme content - At puberty : E.coli, Doderlein’s bacilli, yeast - Pregnancy : S.epidermidis , Doderlein’s bacilli, yeast - Includes G.vaginalis , Bacteroides species, Candida, alpha Streptococci

14. NORMAL FLORA OF THE HUMAN BODY Probiotics : live microorganisms in normal human body, -Inhibits pathogens in gut -Effects on mucosal barrier function and interaction with antigen-presenting dendritic cells - Used in antibiotic associated diarrhoea - Most common: Bifidobacterium, Lactobacillus

15. NORMAL FLORA OF THE HUMAN BODY Figure; longitudinal distribution, frequency of concurrence and densities of bacteria making up the normal flora of the human gastrointestinal tract

16. Sterile Sites in the Body Few bacteria are found in the normal bronchi. The smaller bronchi and the alveoli are normally sterile. Spleen Liver Pancreas Bladder CSF Blood

17. Changes in Normal Flora with Age

18. Changes in Normal Flora with Age

19. Changes in Normal Flora with Age

20. NORMAL FLORA AND THE IMMUNE SYSTEM Normal flora provides minimum stimulation for immune system Implication of alteration of normal bacterial flora Factors causing alteration of flora - Prolonged antibiotic therapy, immunosuppression/ immunodeficiency - pH alteration - Increased virulence of commensals Pseudomembraneous colitis - Due to elimination of normal flora by indiscriminate antibiotic usage - Clostridium difficile multiplies - Results in diarrhea

21. Prevention Rational use of antimicrobial agents should be prioritised and, wherever possible, narrow-spectrum antibiotics should be used at the correct dosage and for the correct duration of time to prevent the suppression of gut flora. Treatment First episode : Oral vancomycin (500 mg/day) is recommended. Initial recurrence : Oral vancomycin—pulse or tapered therapy. In case of three or more recurrences

22. THERAPEUTIC USE OF GUT FLORA Fecal flora for treating chronic GIT ailments Fecal microbiota transplantation Gut bacteria from healthy donor to patient via colonoscope Treatment of irritable bowel syndrome despite treatment with a tapered/pulsed dose oral vancomycin regimen, fecal microbiota transplant (FMT) should be considered

23. Probiotics Probiotics are live microorganisms found in the normal human body. These organisms can have multiple interactions with the host, including competitive inhibition of pathogenic bacteria. When administered in adequate amounts, they confer health benefits to the host.

24. Probiotics Probiotics; Some of their functions are as follows Inhibition of other pathogenic microbes in the gut by rapid colonization. Effects on the mucosal barrier function and interaction with antigen-presenting dendritic cells. They have been successfully used in antibiotic-associated diarrhoea The two most common probiotics are: Bifidobacterium – Lactobacillus

25. Prebiotics Dietary nondigestible fibers which when administered, stimulate the growth and activity of commensal microorganisms and thereby exert beneficiary effect to the host indirectly

26. Quizzing Q.1 Normal microbial flora are also called: Resident flora Commensal flora Transient flora All of these

27. Q.2 All the following are constituents of normal flora except: Gram-positive bacteria Gram-negative bacteria Yeast Viruses

28. Q.3 The major components of the intestinal flora constitute: a) Coliform bacteria b) Clostridium species c) Yeast d) Enterococcus species

29. Q.4 Sterile body sites include all the following EXCEPT: a) Central nervous system b) Nasopharynx c) Lungs d) Liver

30. Q.5 The relationship between a host and the normal flora wherein both co-exist is called: Symbiosis Commensalism Parasitism Opportunistic infection

31. Q.7 Normal flora in the human body, when administered in adequate amounts, confer a health benefit to the host. These organisms are known as: Probiotics Gnotobiotic Symbiotics Prebiotics

32. Q.8 Most common probiotics include: a) Fusobacterium and Lactobacillus b) Bacteroides and Fusobacterium c) Lactobacillus and Bifidobacterium d) Bifidobacterium and Propionibacterium Essentials of Medical Microbiology © 2018, Jaypee Brothers Medical Publishers

33. Q.9 Disturbance to the normal flora can be caused by: a) Prolonged antibiotic therapy b) Alternation of pH in the mucosa c) Immunosuppressive therapy d) All of these

34. Q.10 Which of the following statements is not true? Normal flora cause confusion in the laboratory diagnosis. Clindamycin administration helps in the multiplication of normal flora. Probiotics are used in treating antibiotic-associated colitis. Fecal transplantation is attempted for irritable bowel syndrome

35. 11. Bacteria such as Klebsiella are not easily phagocytosed. This is due to presence of: a) Capsule b) Fimbriae c) Flagella d) Thick cell wall

36. 12. The minimum number of bacteria required to produce clinical evidence of infection is known as: a) Minimum bactericidal dose b) Minimum inhibition dose c) Minimum lethal dose d) Minimum infection dose

37. Q.1 3 . Endemic infection refers to: a) A slow-spreading infection transmitted from person-to-person. b)Infection that affects many persons simultaneously in a geographically defined area. c) Infection that is prevalent within a localised area. d) Infection that spreads worldwide in a short duration

38. Q. 14. Which of the following is correct regarding exotoxins? a) These are heat-stable lipopolysaccharides that form an integral part of the cell wall. b) They are chiefly produced by gram-positive bacteria. c) They cannot be toxoided. d) They are poor antigens.

39. Q. 15. Which of the following statement best describes the definition of iatrogenic infections? a) These are infections that are physician-induced. b) These are infections in which the clinical effects are not apparent. c) These are infections acquired by a patient after 48 hours of stay in the hospital. d) These are infections in which the typical clinical manifestations are not present.

40. 16. Animals that serve to maintain the microbe in their system are known as: a) Biological vectors b) Reservoir hosts c) Mechanical vectors d) Contagion

41. Q.17. The term prosodemic disease refers to: a) An outbreak of disease in bird population b) A disease constantly present at a high incidence c) A disease affecting large numbers of people in a wide geographic area d) A disease which spreads slowly

42. Q.18. Lysozyme is present in all the secretions except: a) Tears b) Saliva c) Sweat d) Mucus

43. Q.19 Cross-infection means: a) Subsequent infection by the same parasite b) A new infection occurring in a patient already suffering from one infection c) Infection by a parasite in a host whose immunity is lowered by a pre-existing disease d) Initial infection in a host by a parasite

44. Q.20 Who is a paradoxical carrier? a) A carrier who acquires the pathogen from a patient b) An individual who is a carrier for less than six months c) A carrier who acquires a pathogen from another carrier d) An individual who is a carrier for more than six months

45. Q.21 Which of the following is a viral zoonotic disease? a) Rabies c) Hydatid disease b) Plague d) Toxoplasmosis