Micro/Immuno – Flashcards
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| normal flora |
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| population of bacteria that normally reside in or on host (microbiome) |
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| indigenous flora |
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| almost always found in high numbers in a particular site low virulence potential |
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| supplemental flora |
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| nearly always present, but in low numbers can become indigenous if environment changes |
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| indigenous flora of oral cavity |
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| dominated by aerotolerant and strict anaerobic bacteria both gram positive and gram negative |
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| transient species |
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| may or may not be present at any given time |
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| ecological niches of oral cavity |
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| buccal epithelium dorsum of tongue supragingival tooth surfaces subgingival tooth surfaces |
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| flora of buccal epithelium |
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| mostly gram positive aerotolerant anaerobes (streptococci) |
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| flora of dorsum of tongue |
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| mostly streptococci (esp. Streptococcus salivarius) highly palpated surface produces anaerobic micro-environments (more strict anaerobes on tongue than buccal surfaces) |
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| flora of supragingival surfaces |
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| mostly aerotolerant anaerobes (usually not Streptococcus salivarius) |
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| flora of subgingival surfaces |
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| bathed in crevicular fluid, so essentially anaerobic |
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| oxygen tension within the oral cavity |
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| buccal/palatal mucosa and dorsum of tongue are essentially aerobic supragingival plaques an be either...aerobic initially and more anaerobic if allowed to grow for 3-5 days subgingival pocket is anaerobic |
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| mutualistic relationship |
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| both host and bacteria benefit |
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| commensalistic relationship |
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| bacteria neither harm nor help the host |
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| parasitic relationship |
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| bacteria benefits and host is harmed |
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| biofilm formation stage 1 |
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| pellicle formation forms immediately on a cleaned tooth surface |
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| pellicle |
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| mixture of salivary glycoproteins, phosphoproteins, and lipids that coats the surface of teeth and gums |
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| biofilm formation stage 2 |
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| initial adherence bacteria begin to adhere to the pellicle on the tooth surface via adhesins within 0-4 hours of cleaning teeth |
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| biofilm formation stage 3 |
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| aggregation 4-24 hours after cleaning, bacteria begin to adhere to one another via intercellular adhesins |
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| biofilm formation stage 4 |
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| after 24 hours there is a tremendous increase in species diversity within biofilm ("climax community") |
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| co-aggregation |
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| the adherence of one bacterial species to a different species |
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| biofilm formation stage 5 |
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| dispersal some bacterial species produce enzymes so that they can leave the biofilm to move to a new location |
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| therapeutic approaches to combat oral biofilms |
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| 1. physical removal (brushing and flossing) 2. direct administration of disinfectants/antimicrobials (flouride and ethanol) 3. colonization with a "safe" strain of S. mutans 4. vaccination |
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| bacteria associated with dental plaque |
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| Actinomyces and streptococci |
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| bacteria associated with periodontal disease |
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| Porphyromonas, Prevotella, Fusobacterium, Actinobacillus, Capnocytophaga, Wolinella |
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| salivary flow within oral cavity |
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| unstimulated - 0.32 mL/min stimulated - 1.7 mL/min |
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| aciduric/acidophilic |
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| acid-loving bacteria that are able to grow in low pH environments |
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| acidogenic |
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| bacteria that produce acid |
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| lactobacilli |
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| gram-positive bacilli anaerobic (aerotolerant) catalase negative fermentative metabolism acidogenic/aciduric |
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| lactobacilli and dental caries |
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| historically connected to caries when present in saliva, it is an indicator of carb intake (which is related to cariogenic activity) factor of progression, not initiation |
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| most clinically significant bacteria are... |
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| anaerobes |
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| polymicrobial infections |
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| when multiple species of bacteria act synergistically to cause disease |
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| cell structure of gram-negative bacteria |
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| 2 membranes! (outer and cytoplasmic) LPS layer (bound to outer membrane) very thin peptidoglycan layer perplasmic space btw the 2 membranes |
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| function of LPS layer |
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| makes the cell relatively impermeable contribes to the structural integrity of the cell |
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| structure of LPS layer |
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| composed of an O antigen, core region, and Lipid A |
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| O antigen |
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| outer layer, highly variable |
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| core region |
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| interface of LPS with membrane composed of rare sugars not found anywhere else in the biological world |
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| Lipid A |
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| embeds and anchors the LPS into the outer membrane undergoes hydrophobic reactions to keep it intact toxic part of the LPS |
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| physiological response to LPS |
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| fever (pyrogenic cytokines) neutropenia disseminated intravascular coagulation (DIC) - clotting/occlusion hypotension vascular collapse only causes problems when cell is lysed b/c LPS is embedded in membrane |
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| red microbial complex |
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| consists of Porphyromas gingivalis, Tannerella forsythia, and Treponema denticola (all of which produce powerful proteases & other destructive enzymes that contribute to periodontal disease) |
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| Bacteroides fragilis |
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| normal flora obligate anaerobe opportunistic (periodontal, abscesses, abdominal infections, endocarditis) atypical LPS - no endotoxin |
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| Prevotella intermedius |
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| normal flora anaerobe capsule - causes abscesses oral/pulmonary infections |
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| Fusobacterium |
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| normal flora anaerobe chronic ulcerative lesions Vincent's disease (pharynx) |
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| Eikenella corrodens |
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| normal flora facultative anaerobe fist fight injuries, abscesses, endocarditis, human bites, oral trauma pit formation on blood plates |
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| Pseudomonas aeruginosa |
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| obligate aerobe temperature tolerant can utilize most organic compounds opportunistic (hospitals, burn patients, CF) |
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| Legionella pneumophilia |
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| Legionnaires disease aerobic aerosol transmission man-made water environments associates with amoebae pneumonia |
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| Bordatella pertussis |
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| whooping cough aerosol transmission most prominent in neonates/infants B. parapertussis - milder form |
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| stages of whooping cough |
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| catarrhal paroxysmal convalescent |
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| catarrhal stage of whooping cough |
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| non-specific respiratory infection that progressively worsens most infectious stage transition from non-productive cough, to productive |
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| paraxysmal stage of whooping cough |
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| paroxyms (40-50 per day) - causes vomiting, hemorrhaging, hernia, pneumothorax |
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| convalescent stage of whooping cough |
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| prolonged, secondary infections pneumonia, seizures, encephalopathy |
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| virulence factors of whooping cough |
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| FHA - afimbrial adhesion (ciliated mucosal cells and PMNs) pili/fimbriae - correlates with max infectivity pertussis toxin - ADP ribosylation of GI protein leads to uncontrolled cAMP production DTaP vaccine - diphtheria, tetanus, pertussis |
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| characteristics of all staphylococci |
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| gram-positive cocci form clusters facultatively anaerobic catalase positive (bubbles form upon addition of H2O2) |
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| Staph aureus |
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| coagulase positive can ferment mannitol nasal carriage protein A, cytotoxins, superantigens, toxic shock, enterotoxins wound infections, abscesses, skin infections, osteomyelities, endocarditis, septecemia nosocomial infection, penicillin-resistant, methicillin-resistant |
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| Staph epidermidis |
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| coagulase negative, novobiocin sensitive normal skin flora blood culture contaminant opportunisitic pathogen hospital associated infections slime |
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| Staph saprophyticus |
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| coagulase negative, novobiocin resistant UTI's in young sexually active women |
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| Strep pyogenes |
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| group A strep: beta hemolytic, bacitracin sensitive pharyngitis, possible scarlet fever & strawberry tongue, skin infections, TSS sequelae of rheumatic fever, rheumatic heart disease (predisposes for endocarditis), glomerulonephritis M protein: multiple antigen types, important virulence factor |
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| Strep agalactiae |
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| Group B strep: cAMP+, hippurate hydrolysis, neonatal & postpartum infectinos |
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| Strep penumoniae |
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| alpha hemolytic, diplococcus, quelling reaction, optochin, bile pneumonia, sinusitis, otitis media, meningitis capsule with 90 stereotypes |
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| Enterococcus faecalis, faecium |
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| group D strep: salt, bile - esculin, GI tract, UTI, bacteremia, endocarditis, endodontic infections highly antibiotic |
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| Strep mutans/Strep sanguinis |
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| Viridans strep = oral strep: alpha hemolytic endocarditis mutans = caries = polymer formation from sucrose, acid production, and acid tolerance |
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| actinomycetes |
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| gram-positive bacteria most non-acid fast distinctive due to filamentous nature resemble fungi can be gram stained (irregular, beaded, branching) |
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| Actino israelli |
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| most common pathogen and only species to produce sulfur granules found at an increased incidence in plaque, calculus, and tonsillar crypts |
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| Actino viscosus |
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| colonize teeth induce periodontal lesions and gingivitis |
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| Actino naeslundii |
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| colonize tongue can be found in plaque |
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| Actino odontolvticus |
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| isolated from carious dentin |
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| Peptostreptococcus |
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| gram-positive cocci normal flora of mucocutaneous surfaces often found in necrotic pulp tissue usually associated with oral trauma or diseased gums A. magnus is most common |
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| Actino magnus |
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| most commonly found in respiratory tracts often recovered from subcutaneous and soft tissue abscesses associated with diabetes |
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| endospores |
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| synthesized in response to nutritional depletion resistant to desiccation, heat and chemicals |
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| Bacillus |
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| single or paired gram-positive bacilli non-motile aerobic sporeformer catalase positive polypeptide capsule embedded in virulence plasmid antiphagocytic 2 toxins made up of 3 proteins (PA, LF, EF) toxin causes increase in vascular permeability usually a disease of herbivores |
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| Bacillus anthracis |
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| caused by exotoxin inhalation anthrax (Woolsorter's disease) - spore germinates in lungs |
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| protective antigen (PA) |
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| binding and protective |
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| lethal factor (LF) |
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| activity protease that cleaves MAPKK |
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| edema factor (EF) |
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| activity andeylate cyclase |
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| lethal bacillus toxin |
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| LF+PA cell death and necrosis (by MAPKK) |
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| edema bacillus toxin |
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| EF+PA edema nad swelling electrolyte imbalance - adenylate cyclase leads to cAMP accumulation |
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| Clostridium |
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| sporulating rods anaerobic catalase negative |
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| C. tetani |
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| tennis racket appearance gram-positive, but sometimes stains gram-negative tetanospasmin - muscle spasms b/c toxin blocks release of inhibitory neurotransmitters treatment = vaccine, penicillin |
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| C. botulinum |
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| subterminal spore botulinum toxins - block neurotransmission at peripheral synapses by preventing release of acetylcholine (flaccid paralysis) food-bourne infant botulism - floppy baby syndrome treatment = antitoxin |
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| C. perfringens |
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| enterotoxin causes diarrhea myonecrosis (gas gangrene) - enzymes and toxins that degrade tissue - very rapid treatment = wound care, removal of devitalized tissues |
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| Corynebacterium |
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| non-sporulating gram-positive rods irregulary stains with dyes (metachromatic granules) obligate aerobe no capsule |
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| C. diphtheriae |
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| diphtheria toxin = ADP ribosyltransferase toxin arrests protein synthesis in mammalian cells by irreversible ADP ribosylation and inactivation of EF-2 (NAD+) maintained in population by asymptomatic carriage in oropharynx or on skin of immune people treatment = vaccine, antitoxin |
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| Neisseriae |
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| gram-negative diplococci non-motile aerobic/facultatively anaerobic |
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| N. meningitidis |
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| obligate human pathogen gram-negative oxidase positive virulence factors: polysaccharide capsule LOS - endotoxin pilus - adherence opacity proteins IgA protease receptors for iron uptake diagnosis = intracellular gram negative diplocacci within PNMs - presumptive positive treatment = antibiotic therapy |
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| N. gonorrhoeae |
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| gram-negative oxidase positive no polysaccharide capsule antigens = pili, opa, porin, LOS, IgA protease, receptors for iron uptake treatment = extended spectrum cephalosporins (only treatment choice due to resistance) |
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| Chlamydiae |
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| lack metabolic pathways to generate high-energy phosphate compounds - energy parasites exists in 2 forms - infectious elementary bodies (EB), and noninfectious reticulate bodies (RB) |
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| infectious elementary bodies (EB) of Chlamydiae |
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| dispersal form that is analogous to a spore very small - induces own endocytosis into host cell once inside phagosome, EBs converted to RBs for reproduction |
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| noninfectious reticulate bodies (RB) of Chlamydiae |
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| capable of binary fission detected as an inclusion in the cell RBs transform back into EBs host cells lyse and EBs are released |
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| C. trachomatis |
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| transmitted by close personal contact most common cause of sexually transmitted disease in the US co-infection with N. gonorrhoeae is common |
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| C. pneumoniae |
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| transmitted person-to-person by aerosols |
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| C. psittaci |
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| parrot flu infects birds and many mammals transmitted to humans by inhalation of bird feces |
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| trachoma biovar |
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| trachoma - infections in children transmitted eye-to-eye chlamydial STD - most common bacterial STD in US |
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| LVG biovar |
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| lymphogranuloma venereum - more prevalent in Africa, Asia, South America |
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| Mycoplasma |
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| smallest free living organism pleomorphic (coccoid, star, filamentous) lack peptidoglycan require complex media for growth (peptone, yeast, serum, cholesterol) |
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| pathogenic mycoplasma species |
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| M. pneumoniae - primary (atypical) pneumoniae Ureaplasma urealyticum - nongonococcal urethritis and PID |
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| bacteria associated with enamel caries |
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| smooth surface: S. mutans/S. salivarius pit & fissure: S. mutans |
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| bacteria associated with dentin caries |
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| anaerobes dominate (lactobacilli and actinomycetes) |
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| bacteria associated with root caries |
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| anaerobes (actinomycetes) |
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| acid theory |
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| the role of acid in caries (lactic acid from lactobacilli and acids from streptococci can dimineralize the enamel) |
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| Veillonella |
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| gram-negative anaerobic cocci abundant in supragingival plaque require lactate for growth (from other organisms) beneficial (protective) effect on dental caries |
