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By David R Telles, DDS Diplomate of the American Board of Oral and Maxillofacial Surgery Bacteria can be distinguished from one another by their morphology (size, shape, and staining characteristics) via: ◦ Metabolic ◦ Antigenic ◦ genetic characteristics Difficult to differentiate by size, but do have different shapes Examples ◦ Spherical bacterium (e.g. Staphylococcus): coccus ◦ Rod-shaped bacterium (E. coli) : is a bacillus; and the snakelike treponeme is a spirillum. ◦ Branched filamentous (e.g. Nocardia and Actinomyces): similar to fungi. ◦ Aggregates grapelike clusters of Staphylococcus aureus diplococcus observed in Streptococcus or Neisseria species. Prok vs. Eukaryotes Differentiated based on morphology Gram Negative vs. Gram Positive Gram staining Bacterial Classification Host defenses against bacterial infection Bacterial chromosome = dsDNA, circular contained in the nucleoid Plasmids - smaller, circular, extrachromosomal DNA ◦ commonly found in GN bact ◦ selective advantage via resistance to one or more antibiotics. GP vs. GN bacterial ribosome = 30S + 50S subunits, forming a 70S ribosome -- unlike the eukaryotic 80S (40S + 60S) ribosome. Cyto membr: no steroids in all spp. except mycoplasma A. GP: thick peptidoglycan layer ◦ teichoic ◦ lipoteichoic acids. B. GN bacterium ◦ thin peptidoglycan layer ◦ outer membrane w/ LPS Phospholipids Proteins ◦ peri-plasmic space transport, degradative, and cell wall synthetic proteins ◦ Membranes joined to the cytoplasmic membrane at adhesion points and is attached to the peptidoglycan by lipoprotein links. Thick, multilayered cell wall Peptidoglycan (150 to 500 Å) surrounding the cytoplasmic membrane ◦ meshlike exoskeleton similar fxn to exoskeleton ◦ sufficiently porous -- diffusion of metabolites ◦ essential for: structure, replication, and survival Upon infection peptidoglycan interferes with: ◦ phagocytosis -- mitogenic (stimulates mitosis of lymphocytes) ◦ pyrogenic enzymes that catalyze the reaction: 1) D-alanine 2) D-alanine transpeptidase-carboxypeptidases. are the targets of β-lactam antibiotics and are called penicillin-binding proteins. Peptidoglycan ◦ Susceptible to lysozyme Found in human tears/mucus Lysozyme degrades glycan backbone of the peptidoglycan ◦ W/o peptidoglycan succumb osmotic pressure differences + lyse Other Cell Wall Components ◦ Teichoic - water-soluble polymers of polyol phosphates, which are covalently linked to the peptidoglycan Important factors in virulence ◦ Lipoteichoic acids - fatty acid and are anchored in the cytoplasmic membrane common surface antigens that distinguish bacterial serotypes and promote attachment to other bacteria and… specific receptors on mammalian cells (ADHERENCE) endotoxic-like ◦ Complex polysaccharides (AKA C polysaccharides). ◦ Proteins e.g. M protein of streptococci + R protein of staphylococci Teichoic Acid structure More complex than GP CWs 2 layers external to the cytoplasmic membrane External to the cytoplasmic membrane ◦ thin peptidoglycan layer -- only 5% to 10% of CW by weight ◦ no teichoic or lipoteichoic Outer membrane ◦ unique to GN bacteria Periplasmic space – ◦ hydrolytic enzymes - important to cell bkdwn of macromolecules for metabolism. ◦ proteases, phosphatases, lipases, nucleases, and carbohydrate-degrading enzymes ◦ lytic virulence factors e.g.: as collagenases, hyaluronidases, proteases, and β-lactamase are in the periplasmic space. ◦ sugar transport systems and other binding proteins to facilitate the uptake of different metabolites and other compounds. ◦ binding proteins -- chemotaxis system senses external environment of the cell. Outer membrane maintains ◦ ◦ ◦ Lipopolysaccharide (LPS). -- AKA endotoxin ◦ ◦ ◦ ◦ ◦ interleukin-1, interleukin-6, tumor necrosis factor, fever + possibly cause shock follows the release of large amounts of endotoxin into the blood stream. Porins ◦ ◦ ◦ Found on outer leaflet amphipathic molecule (hydrophobic /hydrophilic ends) a powerful stimulator of immune responses activates B cells + induces macrophage and other cells to release “Shwartzman reaction” (DIC) ◦ bacterial structure/permeability barrier to large molecules protection from adverse environmental conditions proteins which traverse the lipid bilayer -- transmembrane proteins. allow the diffusion of hydrophilic molecules <700 Da in mass through the membrane. ********allow passage of metabolites and small hydrophilic antibiotics, Outer membrane conn. to the cyto. membr at adhesion sites and is tied to the peptidoglycan by lipoprotein ◦ ◦ lipoprotein -- covalently attached to the peptidoglycan + anchored in the outer membrane Route for the delivery of newly synthesized outer membrane components to the outer membrane. The lipopolysaccharide of the gramnegative cell envelope. A. Segment of the polymer showing the arrangements of the major constituents. B. Stucture of lipid A of Salmonella typhimurium. C. Polysaccharide core. D. Typical repeat unit (S. typhimurium). Outer Membr is held together by ◦ divalent cation (Mg+2 and Ca+2) linkages ◦ between P on LPS molecules + hydrophobic interactions between LPS + proteins. ◦ stiff, strong membrane ◦ disrupted by antibiotics (e.g., polymyxin) removal of Mg and Ca ions (chelation EDTA). Capsule ◦ (in GP or Gngram) loose polysaccharide or protein layers ◦ If loosely adherent + nonuniform in density = slime layer. ◦ AKA glycocalyx ◦ Bacillus anthracis exception to this rule produces a polypeptide capsule ◦ capsule is hard to see in a microscope but can be visualized by the exclusion of India ink Porphymonas spp. Pseudomonas spp. Capsule ◦ ◦ ◦ ◦ ◦ Flagella ◦ ◦ ◦ ◦ poorly antigenic and antiphagocytic major virulence factor (e.g., Streptococcus pneumoniae) a barrier to toxic hydrophobic molecules Promote adherence to other bacteria or to host tissue surfaces E.g. Streptococcus mutans = dextran and levan capsules -- means by which the bacteria attach to the enamel ropelike propellers composed of helically coiled protein subunits anchored in the bacterial membranes through hook and basal body motility (chemotaxis) toward food and away from poisons. express antigenic and strain determinants. Fimbriae (pili) (Latin for “fringe”) ◦ ◦ ◦ ◦ ◦ ◦ ◦ hairlike structures on the outside of bacteria protein subunits (pilin) smaller in diameter (3 to 8 nm versus 15 to 20 nm[flagella]) + not coiled in structure. Typically peritrichously (uniformly) over the entire surface of the bacterial cell. promote adherence to other bacteria or to the host AKA: adhesins, lectins, evasins, and aggressins important virulence factor for E. coli colonization and infection of the urinary Neisseria gonorrhoeae F pili (sex pili) ◦ ◦ promote the transfer of large segments of bacterial chromosomes between bacteria. encoded by a plasmid (F). Spores ◦ Some GP but never GN ◦ Bacillus + Clostridium spore formers ◦ harsh environments bacteria convert from vegetative state to a dormant state (spore) ◦ Basis of autocalving testing ◦ The bacterial cell-wall proteoglycan can be attacked by lysozyme. ◦ Bacteria release peptides which are chemotactic for polymorphs. ◦ Polymorphs and macrophages use receptors for bacterial sugars to bind and slowly phagocytose them. ◦ Bacteria induce macrophages to release inflammatory cytokines such as interleukins 1 and 6 and tumour necrosis factor α (TNFα). ◦ Bacterial lipopolysaccharides and endotoxins activate the alternative complement pathway, generating opsonizing C3b and iC3b on the bacterial surface. The membrane attack complex (MAC) can lyse Gram-negative but not Gram-positive bacteria. ◦ Bacterial polysaccharides (e.g. pneumococcal) with multiple repeated epitopes may activate B cells independently of T helper cells because of their ability to cross-link Bcell receptors (BCRs). The resultant mainly IgM antibodies efficiently agglutinate bacteria and activate the classical complement pathway. ◦ Exogenous processing of phagocytosed bacteria by macrophages results in presentation of peptide epitopes in the context of MHC-II to TH1 cells. These induce macrophage activation for efficient bacterial killing. ◦ Processing of bacterial antigens by B cells induces TH2 responses and high-affinity antibody production: IgG antibodies neutralize soluble bacterial products such as toxins; IgA antibodies protect mucosal surfaces from bacterial attachment. Immune complexes activate the classical complement pathway. Phagocytic uptake of bacteria coated with C3b/iC3b and antibody is rapid and efficient. Gram Staining Bacterial Shapes A powerful test that -- to distinguish between the Gram Positive and Gram Negative Bacterium The Process: GP = purple ◦ heat-fixed or otherwise dried onto a slide stained with crystal violet ◦ Stain ppted with Gram iodine + excess stain removed via washing with the acetone-based decolorizer. ◦ Counterstain = safranin added to stain any decolorized cells red. ◦ Takes <10 minutes. ◦ Stain is trapped in thick, cross-linked peptidoglycan layer GN = thin peptidoglycan ∴ no retention of CV counterstained safranin turns red Mnemonic “P-Purple-Positive.” NOTE: Not a dependable test for mycobacteria ◦ Due to waxy outer shell ◦ distinguished w/ acid-fast stain Staphylococcus ◦ Gram-positive cocci ◦ arranged in grape-like clusters. ◦ more than 15 different species medical importance: S. aureus, S. epidermidis and S. saprophyticus. ◦ Variety of infections: abscesses of organs Endocarditis gastroenteritis (food poisoning) toxic shock syndrome ◦ Infrequently isolated from oral cavity ◦ Higher proportions of S. aureus found in the saliva of healthy subjects >70yrs. S. aureus ◦ Habitat and transmission ◦ Toxins and enzymes produced Characteristics ◦ human skin esp. anterior nares + perineum. Domesticated animals Transmission route: hands, fomites - Disseminated through air and dust and always present in the hospital environment. Gram-positive cocci in clusters (cluster formation is due to their ability to divide in many planes) non-spore forming non-motile some are capsulated Coagulase Positive Pathogenicity various pyogenic infections (eg, endocarditis, septic arthritis, and osteomyelitis) Food poisoning TSS one of the most common causes of hospital-acquired Pneumonia Septicemia surgical-wound infections. Superficial infections: common agent of boils, carbuncles, pustules, abscesses, conjunctivitis and wound infections; Rarely causes oral infections; Angular cheilitis (together with the yeast Candida) at the angles of the mouth Deep infections; osteomyelitis, endocarditis, septicaemia, pneumonia. Predisposing factors for infection are minor and major breaks in the skin, foreign bodies such as sutures, low neutrophil levels, and injecting drug abuse S. aureus ◦ Culture and identification Grows aerobically as yellow or gold colonies on blood agar Catalase-positive Staphylococcus aureus coagulates dilute human serum or rabbit plasma (i.e. it is coagulase-positive), whereas S. epidermidis does not (coagulase-negative). Protein A — latex agglutination test - synthesized by almost all strains of special affinity to the Fc fragment of immunoglobulin G (IgG). latex particles coated with IgG (and fibrinogen) are mixed with emulsified suspension of S. aureus on a glass slide, visible agglutination of the latex particles occurs no reaction w/ S. epidermidis S. aureus ◦ Treatment and Prevention vast majority (> 80%) of strains resistant to β-lactam drugs and other antibiotics. Multiresistance common w/ strains isolated from hospitals hospital (nosocomial) infection. Penicillin resistance due to β-lactamase encoded by plasmids. Antibiotics active against S. aureus: Flucloxacillin (stable against β-lactamase) Erythromycin Fusidic acid (useful for skin infections) Cephalosporins Vancomycin. Cleanliness, hand-washing and aseptic management of lesions reduce the spread of staphylococci. S. epidermidis ◦ ◦ ◦ ◦ ◦ GP cocci clusters Catalase +, Coagulase – Adhesion polysaccharide promotes adhesion to medical devices Novobiocin sensitive Clinical Presentation: Infection of indwelling medical devices (IV, Foley, prosthetic valve) ◦ Pathobio: Bacteria of normal skin flora capsule allows adherence to device inoculation to internal site infection ◦ Treatment and Prevention Vancomycin (since most strains resistant to PCN/Cephalosporins) Removal of device S. saporphyticus ◦ ◦ ◦ ◦ ◦ GP cocci clusters Catalase +, Coagulase – Adhesion polysaccharide promotes adhesion to medical devices Novobiocin resistant Clinical Presentation: Urinary tract infection, Cystitis ◦ Pathobio: Bacterial entry via sexual activity infection/inflam. of UT spread to bladder resulting in cystitis ◦ Treatment and Prevention TMP-SMX Streptococci Catalase-negative spherical or oval cocci in pairs and chains 0.7–0.9 μm in diameter ◦ Culture - Hemolytic reactions are produced on blood agar α-haemolysis: partial haemolysis and green (viridans) discoloration around the colony β-hemolysis: wide, clear, translucent zone of complete haemolysis around the colony, e.g. Streptococcus pyogenes no hemolysis (γ-haemolysis), e.g. non-haemolytic streptococci. ◦ Serology Currently 20 Lancefield groups are recognized (A–H and K–V) but not all are equally important as human pathogens. The following are worthy of note: Group A includes the important human pathogen Streptococcus pyogenes Group B contains one species, S. agalactiae, an inhabitant of the female genital tract; it causes infection in neonates Group C mainly causes diseases in animals Group D includes the enterococci (S. faecalis, etc.) and ranks next to group A in causing human disease. Streptococcus pyogenes (group A) ◦ Habitat and transmission human upper respiratory tract and skin; it may survive in dust for some time Transmission: airborne droplets + contact. ◦ Characteristics commensal in the nasopharynx more commonly (about 10%) in children β- haemolytic Some strains produce mucoid colonies as a result of having a hyaluronic acid capsule -- contribute to virulence -- resistance to phagocytosis. ◦ Exotoxins and enzymes Streptokinase: a proteolytic enzyme which lyses fibrin Hyaluronidase: attacks the material that binds the connective tissue, thereby causing increasing permeability (hence called the ‘spreading factor') DNAases (streptodornases): destroy cellular DNA Hemolysins (streptolysins, leucocidins): phage-mediated and are responsible for the characteristic erythematous rash in scarlet fever. β-haemolytic colonies (e.g. Streptococcus pyogenes) produce complete translucence of blood agar, whereas α-haemolytic colonies (e.g. Streptococcus pneumoniae) do not. Streptococcus pyogenes (Group A) ◦ Pathogenicity tonsillitis and pharyngitis peritonsillar abscess (now rare) scarlet fever mastoiditis and sinusitis otitis media (middle-ear infection) wound infections leading to cellulitis and lymphangitis impetigo (a skin infection). ◦ Complications. *****After an episode of infection some patients develop complications -- rheumatic fever/glomerulonephritis/erythema nodosum - -longlasting effects Cellulitis - hyaluronidase mediates subcutaneous spread of infection erythrogenic toxin causes the rash of scarlet fever post-streptococcal infection, manifesting as rheumatic fever, is caused by immunological cross-reaction between bacterial antigen + : human heart tissue acute glomerulonephritis immune complexes bound to glomeruli ◦ Tx of Choice: Penicillin All: Erythromycin Streptococcus agalactiae (Group B) ◦ Habitat and transmission Found in the human vagina; sometimes anorectal carriage occurs. Babies acquire infection from mother during delivery/nursing. ◦ Characteristics Gram-positive cocci in chains. ◦ Culture and identification β-haemolytic ◦ Pathogenicity No toxins or virulence factors have been identified. This species causes neonatal meningitis and septicaemia Associated with septic abortion and gynaecological sepsis. ◦ Treatment and prevention Penicillin is the drug of choice ALL: erythromycin Prophylactic antibiotics may be given to neonates if the mother is culture-positive. Oral Streptococci (“Viridans Streptococci”) ◦ Found mainly in oropharynx ◦ mixed group of organisms ◦ typically α-haemolytic some strains are non-haemolytic /β-haemolytic ◦ Four main ‘species groups’: salivarius group anginosus group mitis group. Strep Recognized species of oral streptococci Oral Streptococci ◦ Habitat and transmission Large portion of resident oral flora ¼ of the total cultivable flora from supragingival/gingival plaque and half of the isolates from the tongue and saliva are streptococci. vertically transmitted Infective endocarditis (loosely “viridans streptococci”) is generally a result of their entry into the bloodstream. ◦ Culture and identification Gram-positive cocci in chains α-haemolytic Catalase negative Not inhibited by bile or optochin ◦ Pathogenicity major agents of dental caries ability to produce sticky, extracellular polysaccharides in the presence of dietary carbohydrates binding of the organisms to enamel and to each other important agents of infective endocarditis and some 60% of cases Streptococcus pneumoniae (pneumococcus) ◦ Habitat and transmission ◦ Characteristics ◦ α-haemolytic colonies - appear typically as ‘draughtsmen’ due to central indentation sensitivity to optochin and solubility in bile The latex agglutination test for capsular antigen in spinal fluid can be diagnostic. Pathogenicity ◦ Gram-positive ‘lancet-shaped’ cocci in pairs (diplococci) or short chains often capsulate α-haemolytic on blood agar catalase-negative facultative anaerobe Culture and identification ◦ normal commensal in human URT 4% of the population carry this bacteria in small numbers Transmission : respiratory droplets. pneumonia meningitis otitis media and sinusitis in children induces an inflammatory response polysaccharide capsule retards phagocytosis Vaccination with antipolysaccharide vaccine helps provide type-specific immunity Other common diseases caused: lobar pneumonia, acute exacerbation of chronic bronchitis, otitis media, sinusitis, conjunctivitis, meningitis and, in splenectomized patients, septicaemia. Treatment and prevention Penicillin or erythromycin S. pneumoneae ◦ Virulence factors Peptostreptococcus ◦ Gram-positive anaerobic cocci ◦ often be isolated from dental plaque female genital tract carious dentin subgingival plaque dentoalveolar abscesses advanced periodontal disease ◦ Found in “mixed anaerobic infections”-◦ Pathogenic role unclear. Spp. P. anaerobius P. magnus P. micros ◦ For example, peptostreptococci and viridans streptococci [oral flora] -- found in brain abscesses following dental surgery Peptostreptococcus magnus + Peptostreptococcus anaerobius frequently isolated. Corynebacterium ◦ ◦ ◦ ◦ Gram-positive bacilli, non-spore forming rod Pleomorphism (i.e. coccobacillary appearance) non-sporing / non-capsulate/non-motile. In common w/ Mycobacterium+Nocardia spp -- a CW containing mycolic acid ◦ Imp human pathogens + commensals ◦ Fatal upper respiratory tract infection of childhood -diphtheria Corynebacterium diphtheriae ◦ Habitat and transmission Human throat and nose, occasionally skin carry toxigenic organisms up to 3 months after infection Transmission: respiratory droplets. Pleomorphic, non-fastidious, facultative anaerobe Gram-positive Club-shaped (tapered at one end) bacilli 2–5 μm in length, arranged in palisades Divide by ‘snapping fission’ Rods have a beaded appearance Granules stain metachromatically with special stains such as Neisser methylene blue stain (i.e. the cells are stained with blue and the granules in red). ◦ Characteristics ◦ Culture and identification Grows well at 37°C Blood tellurite agar produce distinctive grey-black colonies after 48 hours' incubation at 35°C. Preliminary identification is helped by the shape and size of the colonies on tellurite agar Identification via biochemical reactions + demonstration of toxin production. Toxin production Some are non-toxigenic (and hence non-virulent) + normal skin or throat commensals Corynebacterium diphtheriae ◦ Toxin production exotoxin responsible for virulence Diphtheria toxin -- exotoxin produced by strains carrying bacteriophages with the tox gene — inhibits protein biosynthesis in eukaryotic cells two components: subunit A -- ADP ribosylating activity subunit B -- binds the toxin to cell surface receptors toxin blocks protein synthesis of host cells by inactivating an elongation factor. Macroscopically Rxn is to respiratory mucosa production of a grey, adherent pseudomembrane comprising bacteria, fibrin and epithelial and phagocytic cells obstruct the airway + patient may die of asphyxiation. If into bloodstream affects motor nerves of the myocardium + nervous system Corynebacterium diphtheriae ◦ Pathogenicity Affects the mucosa of the upper respiratory tract, sometimes skin Skin infections usually mixed infections w/ Staphylococcus aureus and/or Streptococcus pyogenes ◦ Treatment and prevention Acute phase maintain the airway is critical Antitoxin given to neutralize the toxin + penicillin to kill the organisms Antibiotics little effect once toxin has spread. Immunization highly effective in preventing diphtheria. Schick test -- used to demonstrate immunity. Here, the circulating level of antibody after immunization (or clinical/subclinical infection) is assessed by inoculating a standardized dose of the toxin. Lactobacillus ◦ ◦ ◦ ◦ ◦ GP, non-spore forming, aerobe, rod saprophytes in vegetable and animal material (e.g. milk) Some spp. common animal/human commensals inhabiting oral cavity and other parts of the body Acidophilic - associated with the carious process. Two main groups: ◦ Homofermenters -- produce mainly lactic acid (65%) from glucose fermentation (e.g. Lactobacillus casei) Heterofermenters -- produce lactic acid as well as acetate, ethanol and carbon dioxide (e.g. L. fermentum). Lactobacillus casei and L. rhamnosus, L. acidophilus and the newly described species L. oris - common in the oral cavity Habitat and transmission Lactobacilli are found in the oral cavity, gastrointestinal tract and female genital tract. In the oral cavity they constitute less than 1% of the total flora. Transmission routes are unknown. ◦ Characteristics ◦ Culture and identification ◦ Ferment carbohydrates to form acids (i.e. they are acidogenic) + survive well in acidic milieu (aciduric) Grow under microaerophilic conditions in the presence of carbon dioxide and at acidic pH (6.0) Media enriched with glucose or blood promote growth Selective medium, tomato juice agar (pH 5.0), promotes the growth of lactobacilli while suppressing other bacteria. Identification is by biochemical reactions. Pathogenicity isolated from deep carious lesions where pH = acidic lactobacillus count - indication of an individual's caries activity. Although this test is not very reliable, it is useful for monitoring the dietary profile of a patient because the level of lactobacilli correlates well with the intake of dietary carbohydrate. Nocardia ◦ Physiology and Structure Gram-positive, non-spore forming rod, Aerobe, Filamentous Partially acid-fast, filamentous bacilli Cell wall with mycolic acid. Strict aerobe capable of growth on most nonselective bacterial media; however, prolonged incubation (7 days or more) required for recovery of most isolates. ◦ Virulence Specific factors not well-characterized. Opportunistic pathogen. Bronchopulmonary disease. Primary or secondary cutaneous infections (e.g., mycetoma, lymphocutaneous infection, cellulitis, subcutaneous abscesses). Secondary CNS infections (e.g., brain abscesses). ◦ Diseases ◦ Diagnosis Microscopy is sensitive and relatively specific when branching, partially acid-fast organisms are seen. Culture is slow, requiring incubation for up to 1 week. Selective media (e.g., BCYE agar) may be required for isolating Nocardia in mixed cultures. ◦ Treatment, Prevention, and Control Infections are treated with antibiotic therapy with sulfonamides or antibiotics with proven in vivo activity, and proper wound care. Exposure cannot be avoided because nocardia are ubiquitous. Mycetoma caused by Nocardia brasiliensis. Actinomycetes Diseases of Selected Pathogenic Actinomycetes Anctinomyces ◦ ◦ ◦ ◦ ◦ ◦ GP, non-spore forming rod, facultative anaerobe, filamentous not acid-fast produce chronic, slowly developing infections form delicate filamentous forms or hyphae Inhibited by penicillin Spp: Actinomyces israelii Actinomyces meyeri Actinomyces naeslundii Actinomyces odontolyticus Actinomyces viscosus …responsible for most human infections Anctinomyces ◦ Pathogenesis and Immunity Colonize: upper respiratory tract gastrointestinal tract female genital tract ***not normally present on the skin surface Cause disease only when the normal mucosal barriers are disrupted by: trauma, surgery, or infection. “Actinomycosis” development of chronic granulomatous lesions suppurative and form abscesses connected by sinus tracts Macroscopically: colonies of sulfur granules because they appear yellow or orange -- masses of filamentous organisms bound together by calcium phosphate Regions of suppuration are surrounded by fibrosing granulation tissue, which gives the surface overlying the involved tissues a hard or woody consistency. Anctinomyces ◦ Treatment and Prevention combination of surgical debridement of the involved tissues + prolonged administration of antibiotics Uniformly susceptible to penicillin as well as to erythromycin and clindamycin Most spp resistant to metronidazole and the tetracyclines Good oral hygiene + antibiotic prophylaxis when mouth or GI tract is penetrated can lower the risk of these infections. Diseases associated with Peptostreptococcus, Actinomyces, Propionibacterium, and Mobiluncus, which are all anaerobic, non-sporeforming, gram-positive bacilli. Bacillus ◦ GP, Spore forming rod, aerobe ◦ Soil saprophytes ◦ Bacillus anthracis Anthrax ◦ B. cereus Bacillus anthracis Physiology and Structure Virulence The capsule is present in virulent stains. Virulent strains also produce three exotoxins that combine to form edema toxin (combination of protective antigen and edema factor) and lethal toxin (protective antigen with lethal factor). Spores can survive in soil for years. Epidemiology Spore-forming gram-positive bacilli. Facultative anaerobe. Nonfastidious growth of nonhemolytic colonies that are firmly adherent to the agar surface. Polypeptide capsule consisting of poly-D-glutamic acid observed in clinical specimens. B. anthracis primarily infects herbivores with humans as accidental hosts. Rarely isolated in developed countries but is prevalent in impoverished areas where vaccination of animals is not practiced. Individuals at risk include people in endemic areas in contact with infected animals or contaminated soil, people who work with animal materials imported from endemic areas, and military and nonmilitary people exposed to infectious aerosols. There is significant concern that the spores will be used in bioterrorism. Diseases Cutaneous anthrax is the most common form. Inhalation anthrax is the most deadly form. Gastrointestinal anthrax is a rare but commonly fatal disease. Diagnosis Treatment, Prevention, and Control Isolation of the organism from clinical specimens (e.g., papule or ulcer, blood). Ciprofloxacin is the drug of choice; penicillin, doxycycline, erythromycin, or chloramphenicol can be used if susceptible), but the bacteria are resistant to sulfonamides and extended-spectrum cephalosporins. Vaccination of animal herds and people in endemic areas can control disease, but spores are difficult to eliminate from contaminated soils. Animal vaccination is effective, but human vaccines have limited usefulness. Bacillus cereus ◦ Physiology and Structure ◦ ◦ Virulence ◦ Ubiquitous in soils throughout the world. People at risk include those who consume food contaminated with the bacterium (e.g., rice, meat, vegetables, sauces), those with penetrating injuries (e.g., to eye), and those who receive intravenous injections. Diseases ◦ Heat-stable enterotoxin. Heat-labile enterotoxin. Spores can survive in soil. Tissue destruction is mediated by cytotoxic enzymes, including cereolysin and phospholipase C. Epidemiology ◦ Spore-forming gram-positive bacilli. Facultative anaerobe. Nonfastidious growth requirements. Infections include emetic (vomiting) and diarrheal forms of gastroenteritis; ocular infection following trauma to eye; and other opportunistic infections. Diagnosis Isolation of the organism in implicated food product or nonfecal specimens (e.g., eye, wound). Treatment, Prevention, and Control Gastrointestinal infections are treated symptomatically. Ocular infectious or other invasive diseases require removal of foreign bodies and treatment with vancomycin, clindamycin, ciprofloxacin, or gentamicin. Gastrointestinal disease is prevented by proper preparation of food (e.g., foods should be consumed immediately after preparation or refrigerated). Clostridium ◦ anaerobic, spore-forming, gram-positive rods ◦ Four medically important species: Clostridium Clostridium Clostridium Clostridium tetani botulinum perfringens difficile. Propionibacteria ◦ ◦ ◦ ◦ ◦ ◦ small gram-positive bacilli that short chains or clumps found on: skin, conjunctiva, external ear, oropharynx, female genital tract Anaerobic or aerotolerant, nonmotile, catalase-positive, ferment carbohydrates propionic acid major byproduct Common spp. Propionibacterium acnes and Propionibacterium propionicus. ◦ P. acnes acne (as the name implies) in teenagers and young adults opportunistic infections in patients with prosthetic devices (e.g., artificial heart valves or joints) or intravascular lines (e.g., catheters, cerebrospinal fluid shunts) Contamination with bacteria on the skin at the phlebotomy site. Tx: Topical application of benzoyl peroxide and antibiotics. Antibiotics such as erythromycin and clindamycin have proved effective. Cocci Bacilli Spirochetes ◦ Aerobes: Neisserie ◦ Anaerobes: Veillonelle ◦ Aerobes: Pseudomonas ◦ Aerobes/ or facultative Parvobacteria Enterobacteria Vibrios Legionella Pasteurellaceae -- Actinobacillus ◦ Anaerobes Bacteroides Prevotella Porphymonas Fusobacterium ◦ Aerobes: Leptospira ◦ Anaerobes: Treponema Cocci ◦ Aerobes: Neisserie Neisseria gonorrhoeae and Neisseria meningitidis -strictly human pathogens Remaining species commonly present on mucosal surfaces of the oropharynx and nasopharynx Aerobic, gram-negative cocci typically arranged in pairs (diplococci) “coffee bean” appearance Non-motile, no endospores oxidase-positive Most produce catalase Neisseria gonorrhoeae Physiology and Structure Gram-negative diplococci with fastidious growth requirements.. Oxidase- and catalase-positive; acid produced from glucose oxidatively. Diseases See table on last slide Diagnosis Gram stain of urethral specimens is accurate for symptomatic males only. Culture is sensitive and specific but has been replaced with molecular probe techniques in many laboratories. Treatment, Prevention, and Control Ceftriaxone, cefixime, ciprofloxacin, or ofloxacin can be administered in uncomplicated cases. In vitro susceptibility should be determined in cases unresponsive to therapy, because antibiotic resistance is increasing. Penicillin should be avoided, because resistance is common. Doxycycline or azithromycin should be added for infections complicated by Chlamydia. For neonates, prophylaxis with 1% silver nitrate; ophthalmia neonatorum is treated with ceftriaxone. Prevention consists of patient education Effective vaccines are not available. Neisseria meningitidis ◦ Physiology and Structure ◦ Gram-negative diplococci with fastidious growth requirements. Grows best at 35°C to 37°C in a humid atmosphere. Oxidase- and catalase-positive; acid produced from glucose and maltose oxidatively. Outer surface antigens include polysaccharide capsule, pili, and lipooligosaccharides (LOS) Virulence Capsule protects bacteria from antibody-mediated phagocytosis. Specific receptors for meningococcal pili allow colonization of nasopharynx. Bacteria can survive intracellular killing in the absence of humoral immunity. Endotoxin mediates most clinical manifestations. ◦ Transmission ◦ Diseases ◦ See table on neisseria slide Diagnosis ◦ Person-to-person spread occurs via aerosolization of respiratory tract secretions. Gram stain of cerebrospinal fluid is sensitive and specific but is of limited value for blood specimens (too few organisms are generally present except in overwhelming sepsis). Culture is definitive, but organism is fastidious and dies rapidly when exposed to cold or dry conditions. Tests to detect meningococcal antigens insensitive and nonspecific. Treatment, Prevention, and Control Breast-feeding infants have passive immunity (first 6 months). Treatment is with penicillin (drug of choice), chloramphenicol, ceftriaxone, and cefotaxime. Chemoprophylaxis for contacts is with rifampin or sulfadiazine (if isolated organism is susceptible). For immunoprophylaxis, vaccination is an adjunct to chemoprophylaxis; it is used only for serogroups A, C, Y, and W135; no effective vaccine is available for sero-group B. Polysaccharide vaccines conjugated with protein carriers offer protection for infants younger than 2 years Cocci ◦ Anaerobes: Veillonelle obligate anaerobic Gram-negative cocci Freq. isolated from oral samples. Three oral species are recognized: Veillonella parvula V. dispar V. atypica. Veillonella parvula Gram-negative, small anaerobic cocci Found in human oral cavity -- in dental plaque ‘benevolent organisms’ in relation to dental caries metabolize the lactic acid reduce ability to solubilize enamel No known pathogenic potential. Bacilli ◦ Aerobes: Pseudomonas GN, aerobe, rods Peudomonas aerugenosa ◦ ◦ Physiology and Structure Small gram-negative bacilli. Strict aerobe. Non-fermenter. Simple nutritional requirements. Mucoid exopolysaccharide capsule. Ubiquitous in moist environmental sites in the hospital (e.g., flowers, sinks, toilets, respiratory and dialysis equipment) as well as in nature. No seasonal incidence of disease. Can transiently colonize the respiratory and gastrointestinal tracts of hospitalized patients, particularly those treated with broad-spectrum antibiotics, exposed to respiratory therapy equipment, or hospitalized for extended periods. Epidemiology ◦ ◦ ◦ Diseases Pulmonary infections (common in patients with cystic fibrosis). Burn wound infections and other skin and soft tissue infections (can be life-threatening). Urinary tract infections (primarily in catheterized patients). External otitis (varying from mild “swimmer's ear” to malignant otitis externa). Eye infections (commonly associated with contaminated contact lens cleaning fluids). Readily grow on common laboratory media. P. aeruginosa is identified by colonial characteristics (e.g., hemolytic, green pigment, grapelike odor) and simple biochemical tests (e.g., positive oxidase reaction). Diagnosis Treatment, Prevention, and Control Combined use of effective antibiotics (e.g., aminoglycoside and β-lactam antibiotics) frequently required. Mono therapy is generally ineffective and can select for resistant strains. Hyperimmune globulin and granulocyte transfusions may be beneficial in selected infections in immunocompromised patients. Hospital infection control efforts should concentrate on preventing contamination of sterile medical equipment and nosocomial infections. Unnecessary use of broad-spectrum antibiotics can select for resistant organisms such as P. aeruginosa Virulence factors assocaited w/ Pseudomonas aeruginosa Bacilli ◦ Aerobes/ or facultative Parvobacteria Haemophilus Brucella Bordetella Pasteurella Eikenella Haemophilus ◦ ◦ Physiology and Structure Virulence ◦ ◦ ◦ H. influenzae type b is clinically most virulent (with PRP, [polyribitol phosphate] in capsule). Haemophilus adhere to host cells via pili and nonpilus structures. Patients at greatest risk for disease are those with inadequate levels of protective antibodies, those with depleted complement, and those who have undergone splenectomy. Diseases ◦ Small, pleomorphic, gram-negative bacilli or coccobacilli. Facultative anaerobes, fermentative. Most species require X and/or V factor for growth. H. influenzae subdivided serologically (types a to f), biochemically (biotypes I to VIII), and clinically (biogroup aegypticus). H. influenzae is responsible for meningitis, epiglottitis, cellulitis, arthritis, otitis, sinusitis, lower respiratory tract disease, conjunctivitis, and Brazilian purpuric fever. H. ducreyi is responsible of the ulcerative genital infection chancroid. Diagnosis Microscopy is a sensitive test for detecting H. influenzae in CSF, synovial fluid, and lower respiratory specimens. Culture is performed using chocolate agar. Antigen tests for H. influenzae type b are less useful following the introduction of vaccination for this organism. Treatment, Prevention, and Control Haemophilus infections are treated with broad-spectrum cephalosporins, azithromycin, or fluoroquinolones; many strains are resistant to ampicillin. Active immunization with conjugated PRP vaccines prevents most H. influenzae type b infections. Rifampin prophylaxis is used to eliminate carriage of H. influenzae in children at high risk for disease. Bacilli ◦ Aerobes/ or facultative Parvobacteria Eikenella commensals of the human oral cavity + intestine linked to periodontal diseases Eikenella corrodens capnophilic, Gram-negative, short coccobacillary On non-selective media -- corrode the agar surface Human infection results from predisposing factors trauma to a mucosal surface may cause extraoral infections brain /abdominal abscesses Peritonitis Endocarditis osteomyelitis Meningitis Also associated with human bites or fist-fight injuries. Bacilli ◦ Aerobes/ or facultative Enterobacteria Yersinia Salmonella Escherichia coli Shigella Escherichia coli ◦ Physiology and Structure ◦ ◦ ◦ Gram-negative bacilli, Facultative anaerobe, fermenter, oxidase negative. Outer membrane makes the organisms susceptible to drying. Lipopolysaccharide consists of outer somatic O polysaccharide, core polysaccharide (common antigen), and lipid A (endotoxin). Virulence Endotoxin. Permeability barrier of outer membrane. Adhesins (e.g., colonization factor antigen, Dr adhesins). Exotoxins (e.g., heat-stabile and heat-labile enterotoxins, Shiga toxins). Invasive capacity. Bacteremia (most commonly isolated gram-negative bacillus). Urinary tract infection (most common cause of bacterial UTIs; limited to bladder (cystitis) or can spread to kidneys (pyelonephritis) or prostate (prostatitis). At least six different pathogenic groups cause gastroenteritis (ETEC, EPEC, EIEC, EHEC, EAEC, DAEC); most cause diseases in developing countries, although EHEC is an important cause of hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in the United States. Neonatal meningitis (usually with strains carrying the K1 capsular antigen). Intra-abdominal infections (associated with intestinal perforation). Organisms grow rapidly on most culture media. Infections are controlled by use of appropriate infection-control practices to reduce the risk of nosocomial infections (e.g., restricting use of antibiotics, avoiding unnecessary use of urinary tract catheters). Maintenance of high hygienic standards to reduce the risk of exposure to gastroenteritis strains. Proper cooking of beef products to reduce risk of EHEC infections. Most common aerobic, gram-negative bacilli in the gastro-intestinal tract. Diseases ◦ Diagnosis ◦ Treatment, Prevention, and Control Bacilli ◦ Aerobes/ or facultative Vibrios curved bacilli, most prominent: Vibrio cholerae Vibrio parahaemolyticus Vibrio vulnificus Vibrio cholerae Infections ◦ ◦ Physiology and Structure Virulence ◦ ◦ ◦ ◦ ◦ Cholera toxin is primarily responsible for the watery diarrhea characteristic of this species. Adherence factors are important for establishing the initial colonization in the intestines, permitting the toxin to function. Organism found in estuarine and marine environments worldwide (including along the coast of the United States) associated with chitinous shellfish. Direct person-to-person spread is rare because the infectious dose is high. The infectious dose is high because most organisms are killed by stomach acids. Disease Cholera. Presentation can range from mild disease to severe life-threatening disease. Disease is characterized by profuse watery diarrhea. Death is caused by electrolyte abnormalities and massive fluid loss. Diagnosis ◦ Curved gram-negative bacilli. Facultative anaerobe. Fermenter. Strains subdivided by their O cell wall antigens. Two biotypes of V. cholerae O1 strains—E1 tor and classical (this is important for epidemiologic classification of isolates). Culture should be performed early in course of disease with fresh stool specimens. Treatment, Prevention, and Control Fluid and electrolyte replacement are crucial. Antibiotic therapy reduces the bacterial burden and exotoxin production, as well as duration of diarrhea. Doxycycline (adults), trimethoprim-sulfamethoxazole (children), or furazolidone (pregnant women) is administered. Improved hygiene is critical for control. The killed parenteral vaccine is of no value, but the newer oral vaccine has some protective value. Bacilli --------------- ◦ Aerobes/ or facultative Pasteurellaceae -- Actinobacillus ◦ small, facultatively anaerobic, gram-negative bacilli ◦ grows slowly ◦ Actinobacillus actinomycetemcomitans most important human pathogen Actinomyces. ◦ colonize the oropharynx of humans/animals ◦ responsible for periodontitis, endocarditis, bite wound infections, opportunistic infections. ◦ Spreads from the oropharynx through the blood stream + adheres to the damaged heart valve ◦ Treatment Serious infections with Actinobacillus species are treated with ampicillin, either alone or in combination with an aminoglycoside. Resistant Strains to ampicillin treated with cephalosporins or fluoroquinolones. Bacilli ◦ Anaerobes Bacteroides obligately anaerobic, short Gram-negative rods or coccobacilli. Bacteroides spp. restricted to species found in the gut (taxonomic change) most common agents of serious anaerobic infections B. fragilis is the main pathogen. Bacilli ◦ Anaerobes ------------------ ◦ Bacteroides fragilis Habitat and transmission Bacteroides species are the most predominant flora in the intestine serious anaerobic infections such as intra-abdominal sepsis, peritonitis, liver and brain abscesses, and wound infection.cs Strictly anaerobic, Gram-negative, non-motile, non-sporing bacilli, but may appear pleomorphic. polysaccharide capsule=important virulence factor. Culture and identification slow growth on blood agar -- grey to opaque, translucent colonies grow well in Robertson's cooked meat medium supplemented with yeast extract. Pathogenicity Mainly the result of its endotoxin and proteases No exotoxin Many Bacteroides infections are polymicrobial in nature. Treatment and prevention Sensitive to metronidazole and clindamycin. Penicillin resistance is due to β-lactamase production. Bacteroides spp. are normal gut commensals Bacilli ◦ Anaerobes ----------Fusobacterium ◦ Fusobacterium nucleatum Habitat and transmission Characteristics Gram-negative, strictly anaerobic, cigar-shaped bacilli with pointed ends Culture and identification F. nucleatum subsp. polymorphum (healthy gingival crevice), F. nucleatum subsp. nucleatum (periodontal pockets) F. nucleatum subsp. Vincenti Infections usually endogenous. blood agar -- dull, granular colonies with an irregular, rhizoid edge odoriferous hydrogen sulphide and methylmercaptan halitosis. Pathogenicity endotoxin Fusobacterium nucleatum is usually isolated from polymicrobial infections Combination with oral spirochaetes (Treponema vincentii and others) it causes the classic fusospirochaetal infections: ANUG Vincent's angina -- an ulcerative tonsillitis causing tissue necrosis often due to extension of acute ulcerative gingivitis. Cancrum oris or noma: a sequel of acute ulcerative gingivitis with resultant gross tissue loss of the facial region. Important bridging organisms between early + late colonizers during plaque formation. Antibiotic sensitivity and prevention Fusobacteria are uniformly sensitive to Penicillin Sensitive to metronidazole Bacilli ◦ Anaerobes Prevotella Prevotella spp. include saccharolytic oral and genitourinary species; some species are periodontopathic. Porphyromonas and Prevotella species are referred to as black-pigmented anaerobes - form a characteristic brown or black pigment on blood agar i.e. # of pigmented/nonpigmented species - moderately saccharolytic all produce acetic and succinic acid from glucose Prevotella spp. Habitat and transmission human oral cavity P.intermedia associated more with periodontal disease P. nigrescens is isolated more often from healthy gingival sites. Culture and identification Non-motile, Gram-negative rods; brown-black colonies on blood agar (when pigmented). Pathogenicity Prevotella intermedia is a true periodontopathogen. Oral non-pigmented species such as P. buccae, P. oralis and P. dentalis are isolated on occasion from healthy subgingival plaque Bacilli ◦ Anaerobes ◦ ------------ Porphyromonas gingivalis Habitat and transmission Found almost solely at subgingival sites -- advanced periodontal disease. Sometimes recovered from tongue/tonsils. Characteristics Non-motile, short, pleomorphic, Gram-negative rods. Culture and identification Grows anaerobically, with dark pigmentation w/media containing lysed blood Pathogenicity An aggressive periodontal pathogen in both humans and animals Fimbriae mediate adhesion capsule defends against phagocytosis Virulence Factors proteases that destroy immunoglobulins, complement and haemsequestering proteins, a haemolysin and a collagenase Capnocytophagia ◦ filamentous gram-negative bacilli capable of aerobic and anaerobic growth in the presence of carbon dioxide ◦ created for fusiform species isolated from periodontal pockets which grow under capnophilic conditions ◦ ability to glide over routine blood agar ◦ Spp. i.e.:Capnocytophaga ochracea (type species), C. sputigena, C. gingivalis, C. granulosa and C. haemolytica. ◦ Habitat The primary ecological niche is the subgingival area. ◦ Characteristics Long, thin fusiform organisms that demonstrate gliding motility seen on brightfield microscopy. ◦ Culture and identification Facultative anaerobes strains require CO2 for growth ◦ Pathogenicity Opportunist pathogens -- immunocompromised patients some strains produce an IgA1 protease. ◦ Gram + Rods Corynebacterium Rothia Diphtheroids ◦ Gram – Rods Eikenella corrodens Haemophilus Enterobacteriaceae Klebsiella Pseudomonas Escherichia ◦ Gram + Cocci Streptococcus Alpha-hemolytic Strep. Salivarius Strep. Mitior Strep. sanguis Strep. Mutans Strep. milleri Aerobes ◦ Gram + rods Actinomyces Lactobacillus Propionibacterium acnes Bifidobacterium Eubacterium Clostridia ◦ Gram – rods Bacteroides B. fragalis P. gingivalis P. endontalis P. intermedius P. melaninogenicus P. loescheii P. oralis Prophymonas Prevotella Anaerobes Gram + cocci ◦ Streptococcus Fusobacterium Beta-hemolytic F. nucleatum Strep. pyogenes Wolinella Capnocytophagia Enterococci ◦ Staphylococcus S. aureus S. epidermidis Spriochetes ◦ Treptonema Aerobes Gram + cocci ◦ Peptostreptococcus ◦ Streptococcus Gram – cocci ◦ Neisseria ◦ Branhamella Gram – rods Gram - cocci ◦ Veillonella Anaerobes Important to differentiate between Aerobes and Anaerobes since give status of disease progression i.e.: ◦ Periodontal Dz ◦ Type of infection: acute vs. chronic Cellulitis vs. abscess ◦ Antibiotic coverage ◦ Severity of infection: mixed vs. isolate predominate microbe Genus Streptococcus ◦ Gram+ cocci in chains - facultative anaerobes - variable haemolysis but α-haemolysis most common ◦ 1) mutans group Main species: Streptococcus mutans serotypes c, e, f; S. sobrinus serotypes d, g; S. cricetus serotype a; S. rattus serotype b; S. ferus; S. macacae; S. downei serotype h. Main intraoral sites and infections: tooth surface, dental caries. Genus Streptococcus 2) salivarius group ◦ Main species: Streptococcus salivarius; S. vestibularis. ◦ Main intraoral sites and infections: dorsum of tongue and saliva -S. vestibularis mainly reside in the vestibular mucosa (hence the name); not a major oral pathogen. Genus Streptococcus ◦ 3) anginosus group Main species: Streptococcus constellatus; S. intermedius; S. anginosus. Cultural characteristics: CO2-dependent; form small, non-adherent colonies on MSA. Main intraoral sites and infections: gingival crevice; dentoalveolar and endodontic infections Genus Streptococcus 4) mitis group ◦ Main species: Streptococcus mitis; S. sanguis; S. gordonii; S. oralis; S. crista. ◦ Cultural characteristics: small, rubbery (S. sanguis) or non-adherent (S. oralis and S. mitis) colonies on MSA. ◦ Main intraoral sites and infections: mainly dental plaque; tongue and cheek; possibly dental caries; infective endocarditis (except S. mitis). Anaerobic streptococci (genus Peptostreptococcus) Genus Stomatococcus ◦ Main species: Peptostreptococcus anaerobius; P. micros; P. magnus. ◦ strict anaerobes, slow-growing, usually non-haemolytic. ◦ Main intraoral sites and infections: teeth, especially carious dentin, periodontal and dentoalveolar abscesses in mixed culture. ◦ Main species: Stomatococcus (formerly Micrococcus) mucilagenosus. ◦ coagulase-negative, facultative anaerobes. ◦ Main intraoral sites and infections: tongue mainly, gingival crevice; not a major opportunist pathogen. Common isolates from dental plaque and include ◦ ◦ ◦ ◦ Genus Genus Genus Genus Actinomycetes Lactobacilli Eubacteria Propionibacteria. Genus Actinomyces ◦ ◦ ◦ ◦ ◦ Gram+ pleomorphic rods The most important human pathogen is A. israelii. ferments glucose strict or facultative anaerobes. Main intraoral sites and infections: Actinomyces odontolyticus, earliest stages of enamel demineralization + caries progression A. naeslundii implicated in root surface caries and gingivitis; A. israelii is an opportunist pathogen causing cervicofacial and ileocaecal actinomycosis Actinomyces gerencseriae and A. georgiae: minor components of healthy gingival flora. Genus Lactobacillus ◦ Gram+ bacilli ◦ Main species: Lactobacillus casei; L. fermantum, L. acidophilus; (others include L. salivarius, L. rhamnosus). ◦ Cultural characteristics: catalase-negative, microaerophilic ◦ Main intraoral sites and infections: Common oral inhabitants < 1% of the oral flora Dental plaque advancing front of dental caries lvls of salivary lactobacilli correlate with intake of dietary carbohydrates (cariogenic potential) Genus Eubacterium ◦ Gram-variable rods or filaments. ◦ Main species: Eubacterium brachy; E. timidum; E. nodatum; E. saphenum. ◦ obligatory anaerobes ◦ Main intraoral sites and infections: - dental plaque and calculus - implicated in caries and periodontal disease - comprise over 50% of the anaerobes of periodontal pockets - E. yurii is involved in ‘corn-cob’ formation in dental plaque Rothia dentocariosa ◦ a Gram-positive branching filament ◦ strict aerobe ◦ plaque + isolated from infective endocarditis. Bifidobacterium dentium ◦ ◦ ◦ ◦ Gram-positive strict anaerobe isolated from plaque role in disease is unclear. Genus Neisseria ◦ ◦ ◦ ◦ ◦ Gram- diplococci. Main species: Neisseria subflava; N. mucosa; N. sicca. asaccharolytic + non-polysaccharide producing facultative anaerobes. Main intraoral sites and infections: isolated in low numbers from tongue, saliva, oral mucosa and early plaque consume oxygen in early stages of plaque formation provide conditions conducive for the growth of anaerobes rarely associated with disease. Genus Veillonella Genus Veillonella Small, Gram-negative cocci. Main species: Veillonella parvula; V. dispar; V. atypica. strict anaerobes Lack glucokinase and fructokinase and hence unable to metabolize carbohydrates ◦ use lactate produced by other bacteria + raise the pH of plaque ◦ beneficial in relation to dental caries. ◦ Intraoral sites/infections: ◦ ◦ ◦ ◦ isolated from most surfaces - tongue, saliva and plaque. No association with disease. Genus Genus Genus Genus Haemophilus Actinobacillus Eikenella Capnocytophagia Genus Haemophilus ◦ Gram-negative coccobacilli. ◦ Main species: Haemophilus parainfluenzae; H. segnis; H. aphrophilus; H. haemolyticus; H. parahaemolyticus. ◦ facultative anaerobes ◦ requires haemin (X factor) and nicotinamide adenine dinucleotide (V factor) for growth. ◦ Main intraoral sites/infections: dental plaque, saliva and mucosae dentoalveolar infections acute sialadenitis infective endocarditis. Genus Actinobacillus ◦ Gram-negative coccobacilli ◦ microaerophilic or capnophilic (carbon dioxide-dependent). ◦ Main species: Actinobacillus actinomycetemcomitans ◦ fimbriae ◦ many virulence factors: leucotoxin, collagenase, protease that cleaves IgG. ◦ Main intraoral sites and infections: periodontal pockets -- aggressive forms of periodontal disease (e.g. localised and generalised aggressive periodontitis). Genus Eikenella ◦ ◦ ◦ ◦ ◦ ◦ Gram-negative coccobacilli. Main species: Eikenella corrodens. factor X-dependent Microaerophilic corroding colonies on blood agar. Main intraoral sites and infections: dental plaque dentoalveolar abscesses infective endocarditis some forms of chronic periodontitis. Genus Capnocytophagia ◦ Carbon dioxide-dependent, Gram-negative fusiform rods with ‘gliding’ motility. ◦ Main species: Capnocytophaga gingivalis; C. sputigena; C. ochracea; C. granulosa; C. haemolytica. ◦ capnophilic, medium-sized colonies with an irregular spreading edge. ◦ Main intraoral sites and infections: Plaque, mucosal surfaces, saliva infections in immunocompromised destructive periodontal Some produce IgA1 protease. Genus Porphyromonas Gram-negative rods, non-motile six serotypes based on capsular polysaccharides (K antigen) asaccharolytic. Main species: Porphyromonas gingivalis; P. endodontalis; P. catoniae. ◦ strict anaerobes, require vitamin K and haemin for growth. ◦ Main intraoral sites and infections: ◦ ◦ ◦ ◦ gingival crevice and subgingival plaque chronic periodontitis and dentoalveolar abscess P. gingivalis - highly virulent (prod of haemolysin, collagendegrading) fimbriae helps adhesion. Porphyromonas endodontalis - recovered from infected root canals. Genus Prevotella ◦ Gram-negative rods, non-motile ◦ moderately asaccharolytic ◦ Main species: - pigmented species include Prevotella intermedia; P. nigrescens; P. loeschii; P. corporis; P. melaninogenica; - Non-pigmented species include P. buccae; P. oralis; P. oris; P. oulora; P. veroralis; P. dentalis ◦ Strict anaerobes, req vitamin K and haemin for growth. ◦ Main intraoral sites and infections: periodontal pockets, dental plaque chronic periodontitis and dentoalveolar abscess. Genus Fusobacterium ◦ Slender, cigar-shaped ◦ Gram-negative rods with rounded ends ◦ Main species: Fusobacterium nucleatum; F. alocis; F. sulci; F. periodonticum. ◦ often asaccharolytic ◦ strict anaerobes ◦ usually non-haemolytic; Genus Fusobacterium ◦ ****F. nucleatum can produce ammonia + hydrogen sulphide from cysteine and methionine and is implicated as an odorigenic organism in halitosis. ◦ Main intraoral sites and infections: most common isolate is F. nucleatum normal gingival crevice, tonsils (F. alocis and F. sulci) or periodontal infections (F. periodonticum) acute ulcerative gingivitis, dentoalveolar abscess. Genus Leptotrichia ◦ ◦ ◦ ◦ Gram-negative filaments Main species: Leptotrichia buccalis. strict anaerobes Main intraoral sites and infections: dental plaque. No known disease association. Genus Wolinella ◦ ◦ ◦ ◦ ◦ Gram-negative curved bacilli motile by polar flagella. Main species: Wolinella succinogenes strict anaerobe. Main intraoral sites and infections: gingival crevice. Possible involvement in destructive periodontal disease. Genus Selenomonas ◦ Gram-negative curved cells with tufts of flagella. ◦ Main species: Selenomonas sputigena; S. noxia; S. flueggei; S. inflexi; S. diane. ◦ strict anaerobe. ◦ Main intraoral sites and infections: gingival crevice. No known disease association. Genus Treponema ◦ Motile Gram-negative helical cells, in three main sizes ◦ Main species: Treponema denticola; T. macrodentium; T. skoliodontium; T. socranskii; T. maltophilum; T. amylovarum; T. vincentii. ◦ all = strict anaerobes ◦ Main intraoral sites and infections: T. denticola - proteolytic than others proline aminopeptidase and and arginine-specific protease degrades collagen and gelatin. Found in the gingival crevice; associated w/ ANUG + destructive periodontal disease. Dental Caries ◦ Mutans streptococci ◦ Lactobacillus spp. involved more in the progression of the deep enamel lesion (rather than the initiation) pioneer organisms in the advancing ◦ Actinomyces spp. root surface caries Periodontal Microbes Dentoalveolar abscess Supporitive Osteomyelitis of the Jaws ◦ Anaerobes are the most common isolates – Bacteroides Prevotella Porphyromonas spp. Fusobacteria Anaerobic streptococci rarely enterobacteria present ◦ NOTE: Staphylococcus aureus MC osteomyelitis in long bones Oral Bacteroides Pen Fubsobacteria Anaerobic Cocci Alph-Strep 15-30 6 4 0 Erythromycin 0 85 18 0 Clinda 4 0 2 0 Metro 0 0 24 100 10 0 6 18 Cephalexin Brooks GF, Butel JS, Ornston LN, editors: Jawetz, Melnick and Aldenberg's medical microbiology, ed 19, Norwalk, Conn, 1991, Appleton & Lange Samaranayake, Lakshman P. Samaranayake. Essential Microbiology for Dentistry, 2nd Edition. Elsevier, 2001. 31.2 Sanjiv Harpavat Microcards Lippincott, Williams and Wilkins 2002 Peterson, LJ Microbiology of the Head and Neck. OMFS Surg Clin. 3:255, 1991 Ellis E, Hupp. Contemporary Oral and Maxillofacial Surgery 3rd ed.