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36 Cards in this Set
- Front
- Back
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Complications of Streptococcus pryogens |
•Scarlet fever-Red rash usually on skin of back, chest or trunk •Cellulitis-Necrotizing fasciitis flesh eating bacteria) •Rheumatic heart disease- Heart valve damage resulting in a “murmur” or valve leakage •Glomerulonephritis-Kidney damage leading to decreased kidney function or failure |
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Cellulitis |
Necrotizing fasciitis flesh eating bacteria); |
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Rheumatic heart disease |
Heart valve damage resulting in a “murmur” or valve leakage |
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Glomerulonephritis |
Kidney damage leading to decreased kidney function or failure |
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Virulence Factors Staphylococcus aureus |
•Toxin1–Associated with multi-system illness •ToxicShock Syndrome (TSS)•Occurs in males and females |
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Elek test |
Test for toxigenic strains of Corynebacterium diphtheria |
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S. salivarius,S. vestibularis
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-Gumdrop colonies on mitis salivarius agar (MSA)
-Produce fructose levans (linear polymer of fructose) -Non-hemolytic -Adhere to tongue, shed into saliva -Fimbriae- adherance structures |
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Diphtheria |
•Treatment-two fold 1-Antitoxin•Produced in horses•Patient may react to horse serum•Not effective once toxin inside host cells• 2-Antibiotics to stop the source of more Toxins |
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Staphylococcus epidermidis
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Epidemiology Habitat:
Urinary tract infections, catheter-related sepsis, joint infections Opportunistic Major “Normal Flora” on skin |
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Staphylococcus saprophyticus |
Epidemiology: UTI Adheres to epithelial cells in the UG tract Capable of causing disease in low numbers Leading cause of UTIs in young women |
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Virulence Factors of Group A Streptococcus pyrogens
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Somatic factors – associated with cell surface components
-M protein – anti-phagocytic, inhibits complement binding -Hyaluronic acid capsule – does not induce host response -Group A polysaccharide and PG fragments – inflammation |
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Staphylococcus aureus
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Infections
-Skin and wound infections (suppurative) – cuts, burns, surgery -Food poisoning from enterotoxin production -Exfoliative dermatitis from epidermolytic toxin -TSS -Secondary pneumonia -Endocarditis, osteomyelitis, septic arthritis |
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Lancefield Grouping Scheme |
Method which differentiates streptococci based on CW components extracted from various strains -Group antigens = C carbohydrate (cell wall) -Polysaccharides in CW -Different sugar = different serologic group -Type antigens = M proteins -Associated with virulence -Different M proteins = different types of infections |
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Rheumatic Fever
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-Associated with post-streptococcal infection
-Antibodies formed against microbe cross-react with cardiac antigens -Affects heart valve function -Dental patients with a history of rheumatic fever are predisposed to sub-acute bacterial endocarditis (SBE) |
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Diphtheria |
-Pseudomembrane formation -> obstruction -Systemic effects from toxin – cardiac failure, paralysis -Skin manifestations – chronic ulcers, pseudomembrane -May become bloodborne |
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Group B Streptococcus(Streptococcus agalactiae)
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Habitat and transmission
-Colonizes vaginal and rectal areas Infections -Invasive disease in newborns: Pneumonia, meningitis, sepsis -Adults: Young women - after childbirth, abortion, endometriosis, wound infection -Elderly – underlying disease, immunodeficiency |
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Clinical Infections of Neisseria gonorrhoeae |
Disseminated -Rare – bloodborne infections may cause septic arthritis, septicemia, pelvic inflammatory disease, and prostatitis Other -Anorectal -Oropharyngeal -Opthalmia neonatorum-conjunctivitis leading to blindness in the newborn |
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Hemophilus influenzae
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Clinical infections
-Most common cause of Meningitis in children 3 to 6 months old– serotype b Colonization, invasion, replication in mucous membranes -Bloodstream invasion (bacteremia) -Most frequent cause of Epiglottitis in children |
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Actinomycesis species
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We are not fungi!!
Prokaryotic Bacterial cell wall composition – no chitin Do not produce aerial hyphae Sensitive to bacterial antibiotics |
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Haemophilus sp.
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“Blood lovers”
-X factor (hemin) found in RBCs -V factor (NAD) -X factor in SBA, but V factor hydrolyzed -Chocolate agar – heating lyses RBCs, releases both factors -Satellitism – other bacteria provide V factor -Fastidious so antibiotics are added to media to prevent overgrowth by other organisms |
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Laboratory Diagnosis Haemophilus sp.
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Specimen processing and isolation
-Found in many clinical specimens -Die rapidly – need to be transported/processed ASAP -CHOC agar: 33-37C 5-10% CO2 Bacitracin reduces overgrowth of respiratory NF Vancomycin reduces overgrowth of genital NF “Rough” colonies in 18-24h; mucoid colonies 36-48h |
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Pathogenicity Actinomyces
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Actinomycosis
-8 Actinomyces species in the oral cavity -Plaque, calculus, tongue, tonsils, other soft tissue -Opportunistic infections frequently follow injury -Chronic, granulomatous, soft tissue infection (draining abscess formation) -Most infections monomicrobial; may be polymicrobial |
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Staphylococcus Virulence Factors
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Somatic antigens:
Capsules and slime layers -Protect pathogenic bacteria from phagocytosis by host -Help pathogenic bacteria adhere to host cellsProtein A -Competes with phagocytes for Fc region of IgG molecule Clumping -Coagulase - enzyme in CW that clumps plasma providing protection from host defenses |
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Clinical Infections Neisseria gonorrhoeae
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Men
-Short incubation period (2-7d) -95% symptomatic – urethritis (discharge, dysuria) -Prostatitis, epididymitis -50-75% women are astmptomatic |
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LumpyJaw Syndrome
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Symptoms include:Purulent material sent for examination demonstrates sulfur granules containing gram positive filamentous bacteria. The causative agent is most likely a member of the genus: Actinomyces
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Streptococcus mutans group
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S. mutans, S. sobrinus, S. cricetus, S. rattus
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Streptococcus mutans group
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-Ferment many sugars, including sucrose, mannitol and sorbitol
-Lots of acid production-> decrease in pH-> caries -Produce sticky, extracellular polysaccharides (dextrans, aka mutans) which hold plaque together -Has few fimbriae for attachment, relies on plaque |
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General Characteristics Streptococci
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Cocci arranged predominantly in chains
Gram positive Catalase negative Facultative or strict anaerobes |
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Staphylococcus Virulence Factors
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Enzymes:
Coagulase – promotes fibrin formation; protects from host Catalase – degrades H2O2 from host phagocytes Hyaluronidase – degrades hyaluronic acid in connective tissue Staphylokinase – degrades fibrin clot DNAse and RNAse – degrades nucleic acids |
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The Oral Streptococci
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General Characteristics:
-Gram positive cocci in chains -Usually alpha hemolytic, may be beta or gamma -4 main ‘species groups’ mutans group salivarius group anginosus group mitis group |
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Lactobacilli Characteristics
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Gram-positive coccobacillary forms
-Alpha or non-hemolytic - Facultative anaerobes These organisms ferment carbohydrates to form acids - Acidogenic And can survive well in acidic milieu -Aciduric |
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Corynebacterium diphtheriae
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Complex growth requirements – require 8 amino acids, not easily grown except on special media
Growth medium affects morphology and toxin production 3 distinct types of colonies observed: -Gravis strains – short rods, gray/black colonies on tellurite agar -Mitis strains – long, curved rods, shiny black colonies -Intermedius strains – long rods, creamy colonies |
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General Characteristics Neisseria
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Gram negative
DiplococciOxidase and catalase positive Humid environment Aerobic Increased CO2 (5%) Non-motile 32-36C 2 primary pathogens- Remainder are opportunistic |
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Neisseria gonorrhoeae
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Virulence factors:
Capsule Pili Cell wall proteins LPS IgA protease |
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Ecology of Actinomyces Species
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Surface properties and adherence
-Fimbriae help bacteria attach to host tissues Type I – teeth Type II – epithelial cells and other bacteria |
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Virulence Factors Staphylococcus
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Antibiotic resistance:
Penicillin -Plasmids carry gene for penicillinase -This enzyme is also called Beta-Lactamase -Plasmids are transferred by bacteriophage (transduction) Methicillin, oxacillin – synthetic penicillins Cephalosporins |
