Oral microbiology third lecture.pdf

1. Dr.Iman Qoraan Spring 2020 The Resident Oral Microflora

2. Diversity of resident flora Synergic metabolic interactions by microorganisms Dental plaque biofilms Diversity of nutrients supplied

3. Microbial classification schemes Conventional Morphological and Physiological Chemical properties : enzymes , carbohydrate , amino acid, etc... Serological : antigen- antibody reactions Molecular 16S ribosomal RNA gene amplification

4. -Simple -Quantitative -Sensitivity tests -Rapid(serological tests) -Some tests can be done directly on clinical samples (other than culture) -Pure culture is needed -Not all microorganisms can be cultured(e.g: treponema) Conventional Identification Methods Advantages Disadvantages

5. Around 700 microorganism present in the oral cavity Only 50% can be cultured

6. Molecular Identification Methods *Accurate *Rapid *Sensitive *Provide information about non culturable microorganisms *Data sequences is limited *Antimicrobial sensitivity is not possible Pros Cons

7. Oral Microorganisms Bacteria Gram positive (cocci, bacilli) Gram negative (cocci, bacilli) Obligate anaerobes Mycoplasma Fungi Protozoa Archea Viruses

8. Gram Positive Cell Wall

9. A. Mutans streptococcus Group Mutans(different shapes): cocci, coccobacilli,bacilli Extracellular soluble/insoluble glucan, mutan (insoluble glucan), fructan ,and intracellular polysaccharides Release signaling molecules that induce genetic transformation and acid tolerance Facultative anaerobic , acidophilic,acidogenic AntigenI/II subunit vaccine

10. 1. S. mutans c,e,f,k human serotypes Favors hard non shedding surfaces (teeth, denture) Opportunistic (dental caries, endocarditis)

11. Streptococcus mutans Gram stain Colonies on blood agar

12. 2. S. sobrinus Inhibited by bacitracin d,g serotypes are human specific AntigenI/II is also present (SpaA) Associated with dental caries Produce extracellular and intracellular polysaccharides

13. B. Anginosus Group S.anginosus • Isolated from purulent infections like maxillofacial and other body sites • Don’t produce extracellular polysaccharides S.intermedius • Produce intermedilysin affect neutrophil function in abscess formation • Don't produce extracellular polysaccharides • isolated from brain and liver abscesses S.constellatus • Derived from purulent infections • Don’t produce extracellular polysaccharides

14. Anginosus Group S. anginosus may be B-hemolytic or none

15. • Isolated from vestibular mucosa of mouth • Produce urease and H2O2 which inhibit competing bacteria • Do not produce extracellular polysaccharides • Opportunistic endocarditis and bacteremia S.vestibularis • Colonize mucosal surfaces mainly the tongue ,rarely cause disease • Produce extracellular fructan, glucan and levanase • Levan (extracllular fructan) make mucoid colonies on sucrose containing agar S. salivarius C. Salivarius group

16. D.Mitis group S.sanguinis Colonize tooth surface Produce extracellular glucan Cleave arginine and generate ammonia Produce IgA prtoease S.gordonii Colonize tooth surface Produce extracellular glucan Cleave arginine and generate ammonia Cleave starch using salivary alpha amylase(binding to amylase protect it from host) defenses- host mimicry S.oralis produce neuraminidase enhance adherence by cleaving sialic acid from mucin Produce IgA protease Competent for natural genetic transformation S.mitis Opportunistic pathogen misidentified as S.pneumoniae Cause infective endocarditis Competent for natural genetic transformation

17. Nutritionally variant streptococci ØGranulicatella adiacens(S.adiacens): ü Require cysteine ,pyridoxal(vitamin B6) for growth ü Exhibit satellitism with other bacteria that provide cofactors ØAbiotrophia defectiva

18. Other Gram positive cocci Ø Enterococcus faecalis : isolated from immunocompromised patients, treatment failed periodontal pocket Ø S.pyogenes: isolated from saliva of patients with sore throat Ø Staphylococcus and Micrococci: Transient flora, isolated from denture plaque Ø Peptostreptococcus stomatis: anaerobic,isolated from dental abscesses,infected pulp chambers,root canals and advanced forms of periodontal disease

19. Gram Positive Rods and Filaments

20. A. Actinomyces A.naeslundii Major portion of dental plaque, colonize mouth at infant age produce fructan, urease,neuraminidase have fimbriae for coaggregation and cell-surface interaction A.israelii opportunistic pathogen cause actinomycosis produce protective granules that help bacteria evade immune system and antibiotic treatment and disseminate into body A.odontolyticus form red pigment colonize mouth at infant age

21. B. Eubacterium Gram variable,filamentous , obligate anaerobe, non culturable Asaccharolytic Form dentoalveolar abscesses

22. C. Lactobacillus species Some species are cocci Acidogenic and acid tolerant There salivary levels are useful to monitor patient's dietary behavior (carbohydrate intake) and cariogenic potential of a mouth Isolated from advanced caries lesions

23. Lactobacillus

24. Other Gram Positive Rods qPropionibacterium spp.:obligate anaerobic, found in dental plaque qBifidobacterium dentium:isolated from dental plaque qRothia mucilaginosa: produce extracellular polysaccharides,isolated exclusively from the tongue qCorynebacterium matruchutii: short fat cell and long filament growing out( whip-handle cell) Corynebacterium matruchutii

25. Gram Negative Cell Wall and Stain

26. Gram Negative Cocci Neisseria • Consume oxygen creating anaerobic environment during plaque formation Moraxella catarrhalis • opportunistic pathogen • B-lactamase producer Veillonella • Strict anaerobic • unable to metabolize carbohydrates • Convert lactic acid to weaker acid preventing enamel dissolution

27. Gram Negative Rods q Haemophilus Ø H.parainfluenzae: Require NAD (nicotinamide adenine dinucleotide ) q Aggregatibacter Ø A.actinomycetemcomitans Ø Capnophilic (require 5-10% CO2) Ø Opportunistic pathogen produce collagenase, IgG protease Ø Cause aggressive periodontitis in adults

28. Obligately Anaerobic Genera qBlack pigmented anaerobes: Ø Prevotella and Porphyromonas Ø Produce brown-black pigment on Blood agar Ø Require X-factor (hemin) Ø Isolated from subgingival sites of dental plaques qFusobacterium Ø Pleomorphic,long filamentous Ø Asaccharolytic Use amino acids as energy source Ø Some species isolated from normal gingival crevice others are associated with periodontal disease

29. Black pigmented anaerobes

30. Fusobacterium

31. Obligately Anaerobic Genera qHelicobacter pylori Ø Associated with gastritis, peptic ulcers and gastric cancer Ø Transiently found in the mouth following reflux from the stomach

32. Obligately Anaerobic Genera qSpirochaetes Ø Isolated from subgingival plaque Ø Their number is diagnostic for necrotizing ulcerative periodontitis Ø Characterized by endoplasmic flagella(axial filaments) Ø Difficult to be cultured, need dark field microscope, molecular methods Ø Treponema denticola ü Proteolytic: degrade collagen and gelatin ü Can be cultured

33. Spirochetes Cell wall and Gram stain

34. Fungi Present in small proportion Imperfect yeast (divide asexually) like candida are common flora Perfect (divide sexually) yeast are transient in healthy individuals Perfect molds like Aspergillus , Mucor, Geotrichum present in AIDS patients

35. 1. Candida albicans is the main oral fungal flora 2. C. glabrata, C. krusei, C. tropicalis, C.guilliermundii, Rhodotorulla, Saccharomyces are present 3. Isolated mainly from dorsum of the tongue and increased with presence of intra-oral devices like dentures or orthodontic appliances 4. Carriage rate increases at middle and old age Fungi

36. Mycoplasma Disease associated M.orale, M. salivarium associated with salivary gland hypofunction Isolation mucosal surfaces RT,UT Saliva M.salivarium M.pneumonaie Oral mucosa M.buccale M. orale Growth media Need enriched media with protein Elevated CO2 Shape and size Lack cell wall Gram negative pleomorphic Smallest free growing cells<1um

37. Mycoplasma structure

38. Viruses 1. Herpesviridae Herpes simplex virus type1 (HSV1) • Most virus isolated from saliva and orofacial areas • Persist within oral tissues • Cause cold sores • Remains latent in trigeminal nerve ganglion • Reactivated by stress or UV light • Mainly recovered by molecular methods Cytomegalovirus(CMV) • Isolated from saliva • Latent • persistent • Portal entry to oral cavity is unknown

39. Cytomegalovirus infection

40. Viruses 2. Coxakievirus A Coxakievirus A serotypes 2,4,5,6,8,9,10,16 isolated from oral epithelium and saliva Disease Herpangina( hand,foot,mouth disease)

41. Coxakievirus

42. Viruses 3.Human papilloma virus(HPV) more than 100 type 2,4,6,11,16 detected in oral lesions of AIDS Isolated from tissues with hyperplastic warty like lesions (verruca vulgaris)

43. Viruses Hepatits B &HIV HBV Present in saliva of carriers Cross infection threat HIV Present in saliva Cross infection threat(rare)

44. Hepatitis B HIV

45. Other Viruses qMumps and measles in oral lesions qBacteriophage ü Viruses for which bacteria are the natural hosts ü Bacteriophage specific for S.mutans, Lactobacillus, Actinomyces, Veillonella and Aggregatibacter sp. ü Isolated from saliva and dental plaque samples

46. Protozoa microscopic unicellular eukaryotes Their life cycle consist of trophozoite the motile, feeding form) and cyst (protective form) Some are motile by flagella , cilia or pseudopodia while others are non motile Reproduce asexually by binary fission, (apicomplexa reproduce sexually

47. Protozoa Trichomonas tenax Commensal in oral cavity Heterotrophic (acquire carbon through ingestion of other microorganisms , organic matter and leucocytes) Motile by flagella and undulating membrane Increase in patients with periodontal disease Entamoeba gingivalis First ameobae isolated from human Heterotrophic Motile by pseudopodia found in the gingival pocket(abnormal depth of the gingival sulcus

48. Trichomonas tenax

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