Quizlet - Bacteria Flashcards
Bacterial Structures: Peptidoglycan
Gives rigid support, protects against osmotic pressure; Sugar backbone w/ cross-linked peptide side chains. (function; chemical composition)
Bacterial Structures: Cell wall / cell membrane (G+’s)
Major surface Ag; Peptidoglycan for support. Teichoic acid induces TNF and IL-1. (function; chemical composition)
Bacterial Structures: Outer membrane (G-)
Site of endotoxin (LPS), major surface Ag; Lipid A induces TNF and IL-1 Polysaccharide is the Ag (function; chemical composition)
Bacterial Structures: Plasma membrane
Site of oxidative and transport enzymes; Lipoprotein bilayer (function; chemical composition)
Bacterial Structures: Ribosome
Protein synthesis; 50S and 30S subunits (function; chemical composition)
Bacterial Structures: Periplasm
Space btw the cytoplasmic membrane and the outer membrane in G- bacteria; Contains may hydrolytic enzymes, including beta-lactamases (function; chemical composition)
Bacterial Structures: Capsule Function? Structure? (… and exception?)
Protects against phagocytosis; Polysaccharide (except in Bacillus anthracis , which contains D-glutamate) (function; chemical composition)
Bacterial Structures: Pilus/fimbria
Mediate adherence of bacteria to cell surface, sex pilus forms attachment btw 2 bacteria during conjugation; Glycoprotein (function; chemical composition)
Bacterial Structures: Flagellum
Motility; Protein (function; chemical composition)
Bacterial Structures: Spore
Provides resistance to dehydration, heat, and chemicals; Keratin-like coat, dipiclonic acid (function; chemical composition)
Bacterial Structures: Plasmid
Contains a variety of genes for ABX resistance, enzymes, toxins; DNA (function; chemical composition)
Bacterial Structures: Glycocalyx
Mediates adherence to surfaces, especially foreign surfaces (e.g. indwelling catheters); Polysaccharide (function; chemical composition)
Structures unique to gram (+) organisms
Teichoic acid Cell wall
Structures common to Gram +/- organisms
Flagellum, pilus, capsule, PDG, cytoplasmic membrane
Features unique to G(-) organisms
Endotoxin/LPS (outer membrane) Periplasmic space (location of many beta-lactamases)
Bacteria w/ unusual cell membranes/walls
Mycoplasma: contain sterols and have no cell wall Mycobacteria: Contain mycolic acid. High lipid content.
G(+) cocci
Staphylococcus Streptococcus
G(-) cocci
Neisseria
G(+) Rods
My cobacterium (acid-fast) List eria B acillus C lostridium C orynebacterium What happened when you were sending that email to Gram + Rod ? My List B ecame CC ‘d
My cobacterium (acid-fast) List eria B acillus C lostridium C orynebacterium What happened when you were sending that email to Gram + Rod ? My List B ecame CC ‘d
G(+) Rods
G(-) Rods
H ave Y ou E ver L istened to GNR (Guns n’ Roses = Gram (-) Rods)? I like B oy B ands. B esides, Fran kly, I P refer Garden s to jungles. Haemophilus Yersinia Enterics (separate card) Legionella (silver stain) Bordatella Brucella Bartonella Francisella Pasteurella Gardnerella (gram variable)
H ave Y ou E ver L istened to GNR (Guns n’ Roses = Gram (-) Rods)? I like B oy B ands. B esides, Fran kly, I P refer Garden s to jungles. Haemophilus Yersinia Enterics (separate card) Legionella (silver stain) Bordatella Brucella Bartonella Francisella Pasteurella Gardnerella (gram variable)
G(-) Rods
Branching Filamentous bacteria (G+)
Actinomyces Nocardia (weakly acid-fast)
Actinomyces Nocardia (weakly acid-fast)
Branching Filamentous bacteria (G+)
Pleomorphic (G-) bacteria
Rickettsiae Chlamydiae (Giemsa stain)
Rickettsiae Chlamydiae (Giemsa stain)
Pleomorphic (G-) bacteria
Spirochetes (G-)
Leptospira Borrelia (Giemsa stain) Treponema
Leptospira Borrelia (Giemsa stain) Treponema
Spirochetes (G-)
Neither G+ nor G- (b/c no cell wall)
Mycoplasma
Bugs that won’t Gram stain
These Rascals May Microscopically Lack Color Treponema (too thin to be visualized) Rickettsia (intracellular parasite) Mycobacteria (high-lipid-content cell wall requires acid-fast stain) Mycoplasma (no cell wall) Legionella pneumophilia (primarily intracellular) Chlamydia (intracellular parasite; lacks muramic acid cell wall)
Visualizing Treponemes
Darkfield microscopy and fluorescent Ab staining
Visualizing Mycobacteria
Acid-fast stain
Visualizing Legionella
Silver stain
Giemsa’s stain is used to visualize…?
use for: Borrelia Plasmodium Trypanosomes Chlamydia
PAS (periodic acid-Schiff) stain
stains glycogen, mucopolysaccharides; Used to diagnose Whipple’s dz (PASs the sugar)
Ziehl-Neelsen stain
Use to stain Acid-fast bacteria
India ink
used to visualize Cryptococcus neoformans
Silver stain
used to visualize: fungi, Legionella
Media/Special culture requirements for: H. influenzae
Chocolate agar w/ factors V (NAD) and X (hematin) (Media used for isolation)
Chocolate agar w/ factors V (NAD) and X (hematin)
H. influenzae
Media/Special culture requirements for: N. gonorrheae
Thayer-Martin media (Chocolate agar based, w/ various ABX) (Media used for isolation)
Thayer-Martin media (Chocolate agar based, w/ various ABX)
N. gonorrheae
Media/Special culture requirements for: B. pertussis
Bordet-Gengou (potato) agar (Media used for isolation)
Bordet-Gengou (potato) agar
B. pertussis
Media/Special culture requirements for: C. diphtheriae
Tellurite plate, Loffler’s media (Media used for isolation)
Tellurite plate, Loffler’s media
C. diphtheriae
Media/Special culture requirements for: M. tuberculosis
Lowenstein-Jensen agar (Media used for isolation)
Lowenstein-Jensen agar
M. tuberculosis
Media/Special culture requirements for: M. pneumoniae
Eaton’s agar (Media used for isolation)
Eaton’s agar
M. pneumoniae
Media/Special culture requirements for: E. coli
Eosin-methylene Blue (EMB) agar (blue-black colonies w/ metallic sheen) (Media used for isolation)
Eosin-methylene Blue (EMB) agar (blue-black colonies w/ metallic sheen)
E. coli
Media/Special culture requirements for: Lactose-fermenting enterics
Pink colonies on MacConkey’s agar (Media used for isolation)
Pink colonies on MacConkey’s agar
Lactose-fermenting enterics
Media/Special culture requirements for: Legionella
Charcoal yeast extract agar buffered w/ increased iron and cysteine (Media used for isolation)
Charcoal yeast extract agar buffered w/ increased iron and cysteine
Legionella
Media/Special culture requirements for: Fungi
Sabouraud’s agar (Media used for isolation)
Sabouraud’s agar
Fungi
G(-) Enterics (rod-shaped)
E. coli Shigella Salmonella Yersinia Klebsiella Proteus Enterobacter Serratia Vibrio Campylobacter Helicobacter Pseudomonas Bacteroides
Obligate aerobes
Use an O2-dependent system to generate ATP Examples: (Nagging Pests Must Breathe) Nocardia Pseudomonas Mycobacterium tuberculosis (w/ prediliction for apices of lungs, where PO2 is highest) Bacillus Also: to help remember Pseudomonas aeruginosa - AERuginosa is an AERobe
Pseudomonas aeruginosa O2 tolerance? Where does it show up?
P. AERuginosa is an AERobe seen in burn wounds, nosocomial pneumonia, and pneumonias in cystic fibrosis pts.
Obligate Anaerobes
Lack catalase and/or superoxide dismutase, and thus are susceptible to oxidative damage. Generally foul-smelling (short-chain FA’s), are difficult to culture, and produce gas in tissue (CO2 and H2). Normal flora in GI tract, pathogenic elsewhere. Examples: (anaerobes Can’t Breathe Air) Clostridium Bacteroides Actinomyces
Aminoglycosides and anaerobes
AminO2 glycosides are ineffective against anaerobes b/c these ABX require O2 to enter into the bacterial cell.
Obligate intracellular bugs
Rickettsia, Chlamydia (Stay inside [cells] when it’s R eally C old) *Can’t make their own ATP
Facultatively intracellular bugs
Some Nasty Bugs May Live FacultativeLY Salmonella Neisseria Brucella Mycobacterium Listeria Francisella Legionella Yersinia
Quellung Reaction
Postive quellung: If encapsulated bug is present, the capsule swells when specific anti-capsular antisera are added (Quellung = capsular swellung)
Capsule and vaccines
Capsule is Ag for vaccines (e.g. Pneumovax, H. influenzae B, meningococcal vaccines) Conjugation w/ protein increases immunogenicity and T-cell dependent response
Quellung (+) Bacteria
Encapsulated (Some Nasties Have Kapsules) Streptococcus pneumoniae Neisseria meningitidis Haemophilus influenzae (esp. type B) Klebsiella pneumoniae Polysaccharide capsule is an antiphagocytic virulence factor for above bacteria.
Urease (+) bugs
Particular Kinds Have Urease Proteus Klebsiella H. pylori Ureaplasma
Pigment-producing bacteria
S. aureus –> yellow pigment (Auerus is Latin for gold) Pseudomonas aeruginosa –> blue-green pigment (AERUGula is green) Serratia marcescens –> red pigment (Think of red maraschino cherries)
Virulence factors
Promote evasion of host immune response
Important virulence factors in S. aureus
protein A: Binds Fc region of Ig, disrupts opsonization and phagocytosis. IgA protease: Enzyme that cleaves IgA. Polysaccharide capsules also inhibit phagocytosis. [*also TSST-1, but I don’t think it’s technically a virulence factor]
protein A: Binds Fc region of Ig, disrupts opsonization and phagocytosis. IgA protease: Enzyme that cleaves IgA.
Polysaccharide capsules also inhibit phagocytosis. [*also TSST-1, but I don’t think it’s technically a virulence factor] Important virulence factors in S. aureus
IgA protease Who secretes it?
Secreted by S. pneumoniae, H. influenzae, and Neisseria to prevent phagocytosis
Secreted by S. pneumoniae, H. influenzae, and Neisseria to prevent phagocytosis
IgA protease Who secretes it?
Group A streptococcus virulence factors
M protein: Helps prevent phagocytosis
M protein: Helps prevent phagocytosis
Group A streptococcus virulence factors
Exotoxin vs. Endotoxin: Source
Certain species of some G(+) and G(-) organisms; Outer cell membrane of most G(-) bacteria and Listeria (Exo ; Endo)
Exotoxin vs. Endotoxin: Secreted from cell?
Yes; No (Exo ; Endo)
Exotoxin vs. Endotoxin: Chemistry
Polypeptide; Lipopolysaccharide (structural part of the bacteria. Released when lysed) (Exo ; Endo)
Exotoxin vs. Endotoxin: Location of genes
Plasmid or bacteriophage; bacterial chromosome (Exo ; Endo)
Exotoxin vs. Endotoxin: Toxicity
High (fatal dose on the order of 1 microgram); Low (fatal dose on the order of hundreds of micrograms) (Exo ; Endo)
Exotoxin vs. Endotoxin: Clinical effects
Various; Fever, shock (Exo ; Endo)
Exotoxin vs. Endotoxin: Mode of action
Various; Includes TNF and IL-1 (Exo ; Endo)
Exotoxin vs. Endotoxin: Antigenicity
Induces high-titer Abs called antitoxins ; Poorly antigenic (Exo ; Endo)
Exotoxin vs. Endotoxin: Vaccines
Toxoids useful as vaccines; No toxoids formed and no vaccine available (Exo ; Endo)
Exotoxin vs. Endotoxin: Heat stability
Destroyed rapidly at 60C (except staphylococcal enterotoxin); Stable at 100C for 1 hour (Exo ; Endo)
Exotoxin vs. Endotoxin: Typical diseases
Tetanus, botulism, diphtheria; Meningococcemia, sepsis by G(-) rods (Exo ; Endo)
Superantigens
Bind directly to MHCII and T-cell receptor simultaneously, activating large numbers of T-cells to stimulate release of IFN-gamma and IL-2
Toxins: TSST-1
Organism, toxin function: S. aureus SuperAg that causes toxic shock syndrome (fever, rash, shock).
S. aureus SuperAg that causes toxic shock syndrome (fever, rash, shock).
TSST-1
Toxins: Exfoliatin
Organism, toxin function: S. aureus Causes staphylococcal scalded skin syndrome
S. aureus Causes staphylococcal scalded skin syndrome
Exfoliatin
Toxins: Enterotoxins
Organism, toxin function: S. aureus (and others) Cause food poisoning
S. aureus (and others) Cause food poisoning
Enterotoxins
Toxins: Scarlet fever-erythrogenic toxin
Organism, toxin function: S. pyogenes SuperAg that causes toxic shock-like syndrome
S. pyogenes SuperAg that causes toxic shock-like syndrome
Scarlet fever-erythrogenic toxin
ADP ribosylating exotoxins
Interfere w/ host cell function. B (binding) component binds to a receptor on the surface of the host cell, enabling endocytosis. A (active) component then attaches an ADP-ribosyl to a host cell protein (ADP ribosylation), altering protein function.
Toxins: Diphtheria exotoxin
Organism, toxin function: Corynebacterium diphtheriae ADP-ribosylating A-B exotoxin that inactivates EF-2 (similar to Psudomonas exotoxin A) Causes pharyngitis and pseudomembrane in throat.
Corynebacterium diphtheriae ADP-ribosylating A-B exotoxin that inactivates EF-2 (similar to Psudomonas exotoxin A) Causes pharyngitis and pseudomembrane in throat.
Diphtheria exotoxin
Toxins: Cholera toxin
Organism, toxin function: Vibrio Cholerae ADP ribosylation of G-protein stimulates adenylyl cyclase Increased pumping of Cl- into gut and decreased Na+ absorption Water moves into gut lumen Causes voluminous rice-water diarrhea
Vibrio Cholerae ADP ribosylation of G-protein stimulates adenylyl cyclase Increased pumping of Cl- into gut and decreased Na+ absorption Water moves into gut lumen Causes voluminous rice-water diarrhea
Cholera toxin
Toxins: Heat-labile toxin, Heat-stabile toxin
Organism, toxin function: E. coli ADP-ribosylating A-B toxins Heat-labile: stimulates Adenylyl cyclase Heat-stabile: stimulates Guanylate cyclase Both: cause watery diarrhea Labile like the A ir, Stable like the G round
Toxins: Pertussis toxin (PT)
Organism, toxin function: Bordetella pertussis ADP-ribosylating A-B toxin that increases cAMP by inhibiting G-alpha1 Causes whooping cough Inhibits chemokine receptor –> causes lymphocytosis