Details Title: A&D 2010: Virulence factors Description: Virulence factors of pathogenic species Total Flash Cards: 116 Created: 01/18/2007 19:32:37		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Medical Flashcards
Cards in this set: Term Four general classes of virulence factors Definition * Adhesins * Extracellular enzymes * Antiphagocytic factors * Toxins Term What variable is used to quantify virulence? Definition LD50 (number of microbes needed to kill half of an infected population) Term Main difference between primary and secondary virulence factors? Definition * Primary factors directly cause disease (eg, exotoxins). * Secondary factors indirectly convey pathogenicity by facilitating growth, evasion of immune system, etc. Term Adhesins are usually what kind of macromolecule (lipis, protein, etc.)? Definition Usually proteins, but can be sugars too Term Function of adhesins Definition Determine specificity of infection Term Main extracellular enzymes that constitute virulence factors Definition * Hyaluronidase * Collagenase * Coagulase * Kinases Term Purpose of hyaluronidase and collagenase as virulence factors Definition Chew through hyaluronic acid and collagen in extracellular matrix to facilitate invasion and spread Term Purpose of coagulase and kinases as virulence factors Definition * Coagulase forms clots, making hiding place for bacteria * Kinases (eg, streptokinase) degrade clot to allow bacterial spread Term Major pathogens with coagulase and kinases Definition * Staphylococcus aureus * Streptococcus pyogenes Term Major pathogens with hyaluronidase and collagenase Definition Staphylococcus aureus Term What is the function of staphylokinase? Definition Chews through clots to help spread infection Term What extracellular enzymes are used to digest extracellular matrix? Definition * Hyaluronidase * Collagenase Term Deadly fungus with antiphagocytic capsule Definition Cryptococcus neoformans Term Composition of bacterial and fungal capsule Definition Non-immunogenic polysaccharides Term How do capsules help bacteria evade immune system? Definition Capsules are made of non-immunogenic polysaccharides; ie, they aren't recognized by the host's immune system, so macrophages and neutrophils don't detect them. Term What type of virulence factor is Streptococcus pyogenes' M protein? Definition Antiphagocytic Term Leukocidins have what function? Definition Destroy phagocytic white blood cells Term Is LPS an endo- or exotoxin? Definition Endotoxin Term Bacteria containing LPS are Gram-negative or Gram-positive? Definition Gram-negative (LPS is anchored to the outer cell membrane) Term Cytotoxins, neurotoxins, and enterotoxins are examples of endo- or exotoxins? Definition Exotoxins Term Where do exotoxins typically act on the host's cells? Definition * Cell surface (eg, by inserting a pore) * Intracellularly (eg, by interfering with metabolism) Term Inflammation and immune responses are typically in response to endo- or exotoxins? Definition Endotoxins Term Main difference between endo- and exotoxins Definition Exotoxins are secreted by the pathogen; endotoxins (ie, LPS) is part of the pathogen's structure Term Etiologic agent of typhoid fever Definition Salmonella typhi Term Etiologic agent of salmonellosis Definition Salmonella typhimurium Term Do pathogens usually have one or several virulence factors? Definition Several Term How is Staphylococcus aureus transmitted? Definition Airborne Term Is S. aureus Gram-positive or Gram-negative? Definition Gram-positive Term Species of Staphylococcus that is normal flora of nose Definition S. aureus Term S. aureus is responsible for common infections of what areas? Definition * Skin * Wounds Term Staphylococcus virulence factors Definition Enzymes * Coagulase * Staphylokinase * Lipase * Beta-lactamase Antiphagocytic factors * Polysaccharide slime layer * Protein A Toxins * Cytolytics (enterotoxin -> food poisoning) * Leukocidin (pus) * Exotoxins (variable) Term Extracellular enzyme virulence factors of Staphylococcus Definition * Coagulase * Staphylokinase * Lipase * Beta-lactamase Term Antiphagocytic virulence factors of Staphylococcus Definition * Polysaccharide slime layer * Protein A Term Toxins produced by Staphylococcus Definition * Cytolytics (enterotoxins causing food poisoning) * Leukocidin (kill phagocytic WBCs, producing pus) * Exotoxins (exfoliative toxin and TSS toxin) Term Are pathogenic Streptococci Gram-negative or Gram-positive? Definition Gram-positive Term Major pathogenic species in genus Streptococcus Definition * S. pyogenes * S. pneumonia * S. faecallis Term Other name for group A, beta-hemolytic Streptococcus Definition Streptococcus pyogenes Term Pathogenic species of Streptococcus that is alpha-hemolytic Definition S. pneumoniae, S. viridans Term Beta-hemolytic species of pathogenic Streptococcus Definition S. pyogenes Term Gamma-hemolytic pathogenic species of Streptococcus Definition S. faecalis Term Lansfield group A Streptococcus is also called what? Definition Streptococcus pyogenes Term Colony morphology of Streptococci Definition Chains of cocci Term Diseases/disorders associated with Streptococcus pneumoniae Definition * Bacteremia * Pneumonia (85% of cases) * Meningitis Term Species of Streptococcus commonly associated with endocarditis Definition S. viridans Term Are pathogenic Streptococci aerobic or anaerobic? Definition Anaerobic Term Two ways of classifying Streptococci species Definition * Immunogenic (Lansfield groups) * Hemolysis (alpha, beta, gamma) Term Streptococcus pyogenes virulence factors Definition * M protein (attachment, antiphagocytic, superantigen * Hyaluronic acid capsule (antiphagocytic) * Erythrogenic toxin (superantigen, scarlet fever rash) * Exotoxin B (necrotizing fasciitis) * Hemolysins/Streptolysins (blood-agar reaction) * Streptokinase (fibrinolytic) Term S. pyogenes virulence factor that causes necrotizing fasciitis Definition Exotoxin B Term S. pyogenes virulence factor that causes strep throat Definition Streptolysins S and O Term Antiphagocytic virulence factors of S. pyogenes Definition * M protein * Hyaluronic acid capsule Term Superantigen virulence factors of S. pyogenes Definition * M protein * Erythrogenic toxin Term S. pyogenes virulence factor responsible for blood-agar reaction Definition Streptolysin S Term S. pyogenes virulence factor that causes scarlet fever rash Definition Erythrogenic toxin Term S. pyogenes virulence factor that conveys tissue specificity and mediates attachment to host Definition M protein Term Antiphagocytic virulence factor of S. pyogenes that interferes with the C3b complement component Definition M protein Term Role of S. pyogenes erythrogenic toxin in disease Definition Scarlet fever rash Term Pathogenesis of rheumatic fever Definition S. pyogenes infection leads to Abs against M protein with cross-reactivity against myosin protein in heart, leading to heart valve damage Term Role of S. pyogenes in pathogenesis of acute glomerulonephritis Definition M protein antigen:antibody complexes lodge in glomeruli Term S. pyogenes disease associated with damaged mitral valve Definition Rheumatic fever Term Substructure of S. pyogenes that is structurally similar to compounds in host's joints Definition Hyaluronic acid (in S. pyogenes capsule) Term Major pathogenic Neisseria species Definition * N. meningitidis * N. gonorrhoeae Term Neisseria species are Gram-negative or Gram-positive? Definition Gram-negative Term Colony morphology of Neisseria Definition Gram-negative diplococci Term Neisseria virulence factors Definition * Polysaccharide capsule * Fimbriae (attachment to mucosal epithelium) * LPS * Protease (cleaves IgA antibodies) * Survival within macrophages Term Name for severe bacterial gastroenteritis Definition Dysentery Term How many E. coli O157:H7 cells does it take to cause disease? Definition Approximately 10 Term Bacteria associated with salmonellosis Definition * S. enteritidis * S. typhimurium Term Causative agent of travelers' diarrhea Definition E. coli Term Colony morphology and Gram staining characteristics of E. coli Definition Gram-negative bacillus Term Is E. coli part of the normal flora? Definition Yes, fecal flora Term E. coli virulence factors Definition * Adhesins * Fimbriae * LPS * Toxins Term Types of pathogenic E. coli Definition * EHEC (enterohemorrhagic; eg, O157:H7; produces shiga-like toxin) * ETEC (enterotoxigenic; two toxins; travelers' diarrhea) * EPEC (enteropathogenic; shiga-like toxin; diarrhea in infants/children) * EIEC (invasive colon disease; no toxins; invasiveness similar to Shigella) * UPEC (uropathogenic; P-pili; most UTIs) Term Most enteric infections are Gram-negative or Gram-positive? Definition Gram-negative Term Salmonella species that cause typhoid fever Definition * S. typhi * S. paratyphi Term Salmonella virulence factors Definition * Fimbriae (attachment) * Antigenic variation (change expression of H antigen) * Pathogenicity islands (SPI-1, SPI-2) Term Name for collection of genes that encode a virulence factor or set of such factors in Salmonella species Definition Pathogenicity island Term How do fimbriae convey virulence to Salmonella? Definition Allow for attachment to mucosal surface Term Bacteria associated with rapid mutation of H antigens Definition Salmonella Term Pathogenicity island that encodes proteins that prevent fusion of phagosome and lysosome Definition SPI-2 Term Function of SPI-1 pathogenicity island in Salmonella Definition Allow for type III endocytosis of bacteria into host cell Term Is Helicobacter pylori Gram-negative or Gram-positive? Definition Gram-negative Term H. pylori virulence factors Definition * Flagella * Adhesins * Urease * Toxins Term Function of urease on H. pylori Definition Catalyze conversion of urea and acid to bicarbonate and ammonium to allow H. pylori to inhabit acid environment of stomach Term Is urease a primary or secondary virulence factor? Definition Secondary, because it doesn't directly cause disease Term Pseudomonas aeruginosa colony morphology and Gram staining characteristics Definition Gram-negative bacillus Term Major nosocomial pathogen of burn patients Definition Pseudomonas aeruginosa Term Pseudomonas aeruginosa virulence factors Definition * Fimbriae * Adhesins * Capsule * Pyocyanin (impairs cilia, triggers superoxide formation) * Elastase * Bacteriocins Term Major Gram-negative bacillus associated with cystic fibrosis Definition Pseudomonas aeruginosa Term P. aeruginosa virulence factor that leads to superoxide formation and cilia dysfunction Definition Pyocyanin Term Function of capsule in P. aerugionisa Definition * Antiphagocytic * Adhesion Term What is P. aeruginosa resistant to? Definition Wide range of antibiotics and disinfectants Term Conditions in which Pseudomonas aeruginosa is a significant threat Definition * Burn victims * Cystic fibrosis Term Colony morphology, metabolism, and staining of Bacteroides fragilis ("B. frag") Definition Gram-negative anaerobic bacillus Term Predominant microbe of colon Definition Bacteroides fragilis Term Bacteroides fragilis virulence factors Definition * LPS * Capsule * Protease * Enterotoxin * Beta-lactamase Term Pathogen that can cause septicemia and peritoneal abscesses Definition Bacteroides fragilis Term Two main pathogens that produce endospores Definition * Clostridium * Bacillus Term Bacteria responsible for gangrene Definition Clostridium perfringens Term Causative agent of pseudomembranous colitis and severe diarrhea Definition Clostridium difficile Term Clostridium virulence factors Definition * Endospores * Exotoxins * Collagenase * Hyaluronidase * Protease Term Etiologic agent of botulism Definition Clostridium botulinum Term Causative agent of tetanus disease Definition Clostridium tetani Term Disease associated with Clostridium perfringens Definition Gangrene Term Disease associated with Clostridium difficile Definition Pseudomembranous colitis Term Botulinum toxin mechanism of action Definition Blocks release of acetylcholine from neuromuscular junction by inhibiting exocytosis machinery (VASP, SNAPs), causing flaccid paralysis Term Tetanus toxin mechanism of action Definition Inhibits release of inhibitory neurotransmitters through similar mechanism as botulinum toxin, causing ridig paralysis (lockjaw) and respiratory failure (spastic paralysis) with high mortality Term Bacteria that stains with acid-fast Definition Mycobacterium Term Mycobacterium staining characteristics Definition * Gram-positive * Acid-fast Term Bacteria capable of surviving within host macrophages Definition * Neisseria * Mycobacteria * Salmonella * Listeria Term Causative agent of leprosy (Hansen's disease) Definition Mycobacterium leprae Term Etiologic agent of tuberculosis Definition Mycobacterium tuberculosis Term Mycobacteria virulence factors Definition * Mycolic acid * Survives in alveolar macrophages * Cord factor Term Function of Mycobacterial cord factor Definition Cell wall protein keeps daughter cells attached after division; required for pathogenesis Term Virulence factor of Mycobacterium that allows it to remain viable in aerosol drops Definition Mycolic acid in cell wall Term Other name for leprosy Definition Hansen's disease Term Example of a Gram-positive acid-fast pathogen Definition Mycobacterium