Normal Flora
Normal “flora” Flora – microorganisms that are usually found associated with healthy body tissue.Microbes and humans
Very few microbes arealways pathogenic
Many microbes are
potentially pathogenic
Most microbes are
never pathogenic
Normal Flora
Advantages Protection against pathogen germs. Acid production (Stomach, Vagina). Metabolism (vitamin B and K, Enzymes) e.g. E. coli & Bacteroids produce Vitamin K in the gut which is available for use by host. Stimulation of the immunsystem.Normal flora - Oral cavity
Ecology and developmental stages Birth: sterile mouth, but within 4-12 hours (Lactobacilli, Streptococci) Neonate (Streptococcus salivarius, Staphylococci, Neisseriae, Moraxella catarrhalis. Teeth appear (Streptococcus mutans, Streptococcus parasanguis) Gingival crevice area (Anaerobic species, yeasts) Puberty (Bacteroides, Spirochetes).Normal flora - Oral cavity
Actinomyces species are normally present in tonsilar tissue and on the gingival areas in adults Yeasts (Candida albicans) occur in the mouth 108 bacteria/ml of saliva, potentially >700 speciesNormal Flora
A-Gram-positive cocciGenus Streptococcus(viridans ).Gram-positive Cocci In chains Non-motile Facultative anaerobes;Variable haemolysis but ∂-haemolysis most common.1- mutans group Main species: 1-Streptococcus mutans serotypes c, e, f. 2- S. sobrinus serotypes d, g. 3- S. cricetus serotype a. 4-S. ratus; serotype b.
2- Salivarius group.• Main species: Streptococcus salivarius. S. Vestibularis.3- Anginosus groupMain species: S. intermedius. S. anginosus.
4- mitis group• Main species: Streptococcus mitis.S. sanguis.S. oralis.
5-Anaerobic streptococci• Main species: Peptostreptococcus anaerobius. Micromonas micros.C- Gram-positive rods and filaments These organisms are common isolates from dental plaque and include: Actinomycetes, Lactobacilli, Eubacteria and Propionibacteria.
1-Genus Actinomyces. Short, Gram-positive • Main species: Actinomyces israelii, A. myeri. The most important human pathogen is: A. israelii is distinguished by its anaerobic or microaerophilic growth and its non acid fast staining
2- Genus Lactobacillus. G+ bacilli. Main species: Lactobacillus caseii, L. acidophilus arranged in pairs or short chains . Grow in facultative anaerobic condition or obligate anaerobic. Non motile, Non spore forming. Catalase ( - ) . Fermentation of many CHO and forming acids.
3- Genus PropionibacteriumGram-positive bacilli.catalase negative• Main species: Propionibacterium acnes,Cultural characteristics: strict anaerobe; produces propionic acid from glucose,Main intra-oral sites and infections: root surface caries, plaque
D. Gram-negative cocci. 1- Genus Neisseria Gram-negative diplococci. Main species: Neisseria mucosa; N sicca. Cultural characteristics:facultative anaerobes. Main intraoral sites and infections: tongue, saliva.
2- Genus Veillonella Gram-negative cocci, small cells. Main species: Veillonella parvula,V. atypica. Cultural characteristics: Strict anaerobes; selective medium Rogosa vancomycin agar. unable to metabolize Carbohydrates Main intraoral sites and infections: tongue, saliva and plaque.
E- Gram-negative rods - facultative anaerobic
1- Genus Haemophilus Gram-negative coccobacilli. Main species: Haemophilus haemolyticus H. segnis H. parahaemolyticus.-Cultural characteristics: All isolates are facultative anaerobes. growth is enhanced on heated blood agar(chocolate), requires (X factor) and (V factor) for growth. Main intraoral sites and infections: plaque, saliva.
2- Actinobacillus Gram-negative coccobacilli, microaerophilic Produces many virulence factors: leukotoxin, epitheliotoxin, collagenase, Main intraoral sites and infections: periodontal pockets
F- Gram negative rods –obligate anaerobicGenus 1-FusobacteriumGram-negative rods with rounded ends Slender, cigar-shaped anaerobicaly grow on blood agar,colonies are nonhemolytic.Main species: Fusobacterium nucleatum; F. planti• Main intraoral sites and infections: gingival area, tonsils
Spirochaetes: Are diverse group of spiral motile organisms comprising five genera. Only three genera are human pathogens. Treponema Borrelia Leptospira
Genus Treponema Motile Gram-negative helical cells. Main species: Treponema denticola; T. macrodentium; characteristics: all are strict anaerobes, and difficult to culture. Require enriched media with serum. Found in the gingival crevice; closely associated with acute ulcerative gingivitis. periodontal disease.