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135 Cards in this Set

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Average bacterial diameter
Small (0.3-2 micrometers)
Bacterial cellular membranes lack these
Sterols, with the exception of Mycoplasma, are not a component.
Mycoplasma cell membranes contain what, making them different from all other bacterial cell membranes?
Cholesterol
The bacterial cell wall is composed of what?
Peptidoglycan
How bacteria replicate
binary fission (assexual)
Bacteria contain mono- and poly-cistronic mRNA. The presence of what allows for this?
Shine-Dalgarno sites allow for what property of bacteria?
Normal flora of blood, stomach and internal organs
These have NO common organisms and are generally sterile
Important normal flora of cutaneous surfaces, including urethra and outer ear
Common: Staph epidermidis
Less common: Staph aureus, Corynebacteria (diphtheroids), streptococci, yeasts (Candida spp.)
Important normal flora of the nose
Common: Staph aureus
Less common: S. epidermidis, diphtheroids, assorted streptococci
Important normal flora of the oropharynx
Common: Viridians streptococci, including Strep mutans
Less common: assorted Streptococci, nonpathogenic Neisseria, nontypeable H. flu (unencapsulated)
Important normal flora of the gingival crevices
Common: Anerobes (Prevotella, Fusobacterium, Streptococcus, Actinomyces)
Important normal flora of the colon (in breastfed babies)
Common: Bifidobacterium
Less common: Lactobacillus, streptococci
Important normal flora of the colon (in adults)
Common: Bacteriodes (predominant,) Escherichia, Bifidobacterium
Less common: Eubacterium, Fusobacterium, Lactobacillus, gram-negative anaerobic rods, Strep faecalis and other streptococci
Important normal flora of the vagina
Common: Lactobacillus, group B strep in 15-20% of women
Less common: assorted streptococci, gram-negative rods, diphtheroids, yeasts
Encapsulated bacteria
Strep pneumo, Klebsiella pneumo, Haemophilus influenza, Pseudomonas aeruginosa, Neisseria meningitidis, Cryptococcus neoformans
These bacteria can adhere to inert materials through the creation of biofilms
Staph epidermidis, Strep mutans
Responsible for dental plaque
Strep mutans
Factors that assist with bacterial adherence
Pili/fimbriae (in gram negative cells)
Teichoic acids (in gram positive cells)
Adhesins (colonizing factor, pertussis toxin, hemagglutinins)
IgA proteases (cleaved Fc portion may coat bacteria and bind them to cellular Fc receptors)
Antiphagocytic surface component of Strep pyogenes
M protein
Antiphagocytic surface component of Neisseria gonorrhoeae
pili (antiphagocytic in which organism?)
Antiphagocytic surface component of Staph aureus
A protein
These bacteria contain IgA proteases which destroy mucosal IgA
Haemophilus, Neisseria, S. pneumoniae
Siderophores
these chelate ("steal") and import iron into bacteria, effectively obtaining needed nutrients
M. tuberculosis evades intracellular killing by this mechanism
this bacteria prevents phagosome-lysosome fusion
Listeria evades intracellular killing by this mechanism
this bacteria escapes the phagosome before phagosome-lysosome fusion
Invasins
surface proteins that allow an organism to bind to and invade normally non-phagocytic human cells, thus escaping the immune system (such as in Yersinia pseudotuberculosis)
Another name for endotoxin
LPS
Where endotoxin is found
Gram-negative outer membrane
Toxic portion of LPS
Lipid A, generally not released until cell death
Exception: N. meningitidis overproduces outer membrane fragments
Mechanism of LPS
activates macrophages, leading to release of TNF-a, IL-1, and IL-6. This leads to tissue damage. Damage to the endothelium from bradykinin-induced vasodilation leads to shock, and DIC is mediated through the activation of Hageman factor.
Can LPS be converted to a toxoid?
No, so LPS remains non-immunogenic and cannot be used for vaccines
Protein toxins secreted from bacterial cells (both gram positive and gram negative)
Exotoxins
Can exotoxin be converted to a toxoid?
Yes, these are modifiable by heat or chemicals to a nontoxic but immunogenic form useful for vaccination.
The A and B components of exotoxins have these functions
B component Binds specific receptors to assist the internalization of A
A component is the Active component (often an enzyme)
Toxin, Mode of Action, and Disease Role of Corynebacterium diphtheriae
Diphtheria toxin
ADP ribosyl transferase inactivates EF-2
Primarily targets heart, nerves and epithelium
Inhibits eukaryotic cell protein synthesis
Toxin, Mode of Action and Disease Role of Pseudomonas aeruginosa
Exotoxin A
ADP ribosyl transferase inactivates EF-2
Primary target is the liver
Inhibits eukaryotic protein synthesis
Toxin, Mode of Action and Disease Role of Shigella
Shiga toxin
Interferes with 60s ribosomal subunit
Inhibits protein synthesis in eukaryotic cells
Enterotoxic, cytotoxic and neurotoxic
Toxin, Mode of Action and Disease Role of EHEC
Verotoxin (shiga-like toxin)
Interferes with 60s ribosomal subunit
Inhibits protein synthesis in eukaryotic cells
Toxin, Mode of Action and Disease Role of Clostridium tetani
Tetanus toxin
Blocks release of inhibitory transmitters glycine and GABA
Inhibits neurotransmission in inhibitory synapses
Toxin, Mode of Action and Disease Role of Clostridium botulinum
Botulinum toxin
Blocks release of ACh
Inhibits cholinergic synapses
Toxins of Staph aureus
Toxins: TSST-1 & Alpha toxin
Mode of Action and Disease Role of TSST-1
An endotoxin enhancer, this toxin is pyrogenic and decreases liver clearance of LPS and superantigen.
Causes fever, increases susceptibility to LPS, rash, shock and capillary leakage
Mode of Action and Disease Role of Alpha toxin
In Staph aureus, this toxin intercalates and forms pores in the cell membrane of eukaryotic cells
In C. perfringens, this toxin is a lecithinase that damages cell membranes and causes myonecrosis
One toxin in two different bacteria, causes two different effects
Toxin, Mode of Action and Disease Role of Strep pyogenes
Exotoxin A, aka pyrogenic toxin
Similar to TSST-1
Endotoxin enhancer
Fever, increased suceptibility to LPS, rash, shock, capillary leakage, cardiotoxicity
Toxin, Mode of Action and Disease Role of ETEC
Heat labile Toxin (LT)
Stimulates adenylate cyclase by ADP ribosylation of GTP binding protein
Promotes secretion of fluid and electrolytes from intestinal epithelium
A cAMP inducer toxin
Toxin, Mode of Action and Disease Role of Vibrio cholerae
Cholera toxin
similar to E coli LT-- stimulates an adenylate cyclase by ADP ribosylation
Profuse, watery diarrhea
Toxin, Mode of Action and Disease Role of Bacillus anthracis
Anthrax toxin (3 proteins, 2 toxins)
EF = edema factor -> adenylate cyclase
LF = lethal factor
PA = protective antigen (B component for both)
Decreases phagocytosis, causes edema, kills cells
Toxin, Mode of Action and Disease Role of Bordetella pertussis
Pertussis toxin
ADP ribosylates Gi, the negative regulator of adenylate cyclase -> increased cAMP
Histamine sensitizing
Lymphocytosis promotion
Islet activation
Toxin, Mode of Action and Disease Role of Clostridium perferingens
Alpha toxin
Lecithinase activity causes myonecrosis
Bacterial capsule
present in many gram positive and gram negative bacteria, composed of polysaccharide gel (except B. anthracis), protects against phagocytosis until opsonized, immunogenic (except S. pyogenes and N. meningitidis.)
Capsule component of B. anthracis
polypeptide of poly D-glutamate
Nonimmunogenic cell capsules
S. pyogenes (hyaluronic acid)
N. meningitidis (sialic acid)
Chemical composition and fuctions of bacterial outer cell membrane
Gram-negative only
Lipid A & polysaccharide (LPS)
LPS = endotoxin
Lipid A = toxic moiety
PS = immunogenic portion
Contains protein porins for passive transport and proteins for attachment and virulence
Bacterial cell wall composition and function
Made of peptidoglycan, net of NAG-NAM
Functions to provide support, cell shape and protection from osmotic damage.
Synthesis inhibited by penicillins and cephalosporins.
Confers gram reaction
Gram positives have this in their cell wall, which gram negative bacteria do not. What is its function?
Techoic acids
Immunogenic, induce TNF-a, IL-1
Acid-fast bacteria have this in their cell wall, which other bacteria do not. What is its function?
Mycolic acids
Confers resistance to drying and chemicals
Periplasmic space-- location, bacteria and function
Gram negative bacteria only
Located between inner and outer cell membranes
Contains enzymes to break down large molecules, aids regulation of osmolarity
Cytoplasmic membrane-- location and function
Gram positive and gram negative
Phospholipid bilayer with embedded proteins
Selective permeability and active transport
Carrier enzymes for oxidative metabolism, phosphorylation, phospholipid synthesis, DNA replication, peptidoglycan crosslinking, penicillin binding proteins
Pili or fimbria-- type of bacteria, composition and function
Primarily gram negative
Made of glycoprotein (pilin)
Adherence to cell surfaces, attachment to other bacteria during conjugation
Flagellum -- type of bacteria, composition and function
Gram (+) and (-)
Made of protein (flagellin)
Used for motility
Axial filaments-- type of bacteria, composition and function
Spirochetes and gram negative bacteria
Made of protein
Used for motility
internal flagellum
Acid fast bacteria turn this color with methylene blue stain
Red color after methylene blue staining indicates these bacteria
Acid fast bacteria
Mycobacterium
Legionella
Nocardia (partially)
Bonus: protozoan parasites with acid-fast oocysts
Cryptosporidium and Isospora
Corynebacterium diphtheriae have granules of this
volutin granules are useful for identifying this species
Endospores-- bacteria, composition and function
Gram positive only
Made of keratin coat, calcium dipicolinate
Confers resistance to heal, chemicals and dehydration (not reproductive)
Bacteria that make endospores
Bacillis and Clostridium
Special media for anaerobes
thioglycolate
Special media for Corynebacterium
Loffler's coagulated serum medium (selective)
Tellurite agar (differential)
1 selective and 1 differential
Special media for enteric bacteria
Eosin methylene blue (differential)
MacConkeys (differential)
Special media for enteric pathogens
Hektoen enteric agar (differential)
Xylose-lysine-deoxycholate agar
Special media for Vibrio cholera
TCBS (thiosulfate citrate bile salts sucrose agar) (selective)
This organism likes an alkaline growth medium
Special media for Legionella
Charcoal yeast extract agar (selective)
Special media for Mycobacterium
Lowenstein-Jensen medium (selective)
Special media for Neisseria from normally sterile sites, Haemophilus
Chocolate agar
Special media for Neisseria from sites with normal flora
Thayer-Martin selective medium (selective)
This is a chocolate agar with vancomycin, nystatin and colistin to inhibit normal flora
Growth requirements of mycoplasma
cholesterol, purines and pyrimidines
Bacteria requiring cysteine for growth
Francisella, Brucella, Legionella, Pasteurella
The 4 sisters Ella at the Cysteine chapel
Growth requirements of Haemophilus
X (protoporphyrin) and V (NAD) are required by what bacteria for growth?
These bacteria are obligate aerobes
Mycobacterium
Pseudomonas
(Bacillus)
Superoxide dismutase
O2 + 2H ------->H2O2
enzyme contained by most obligate anaerobes
Microaerophilic (requires low but not full oxygen tension) bacteria
Campylobacter
Helicobacter
Obligate anaerobes
Actinomyces
Bacteriodes
Clostridium
ABCs of anaerobes
DTaP vs DTP
Diphtheria-- diphtheria toxoid
Tetanus-- tetanus toxoid
Pertussis -- killed pertussis cells vs acellular pertusis toxoid, filamentous hemagglutinin and pertacin.
Neisseria vaccine is active against these capsular polysaccharides, but not against which one that causes 50% of US cases?
Active against Y, W-135, C and A
Not active against B (capsule is sialic acid, non-immunogenic)
Bacillus anthracis vaccine
supernatant of partially purified proteins used as vaccine for military or occupational usage
Salmonella typhi vaccine (ty21)
attenuated bacterial vaccine for travelers to endemic typhoid areas
HIB vaccine (H. influenza type B)
protects against 95% of US cases
capsular polysaccharide conjugated to protein, making a T cell dependent vaccine which infants respond to
BCG vaccine
attenuated strain of mycobacterium bovis
does not prevent pulmonary TB, but does prevent dissemination
not used in US
Yersinia pestis vaccine
Killed cellular F-1 antigen vaccine
Used in military in endemic areas and with laboratory workers
Gram negative aerobic cocci
Neisseria & Moraxella
have what shape, respiration and gram stain?
Gram negative aerobic rods
Pseudomonas, Legionella, Brucella, Bordetella, Francisella
have what shape, respiration and gram stain?
Gram negative helical microaerophilic bacteria
Campylobacter & Helicobacter
have what shape, respiration and gram stain?
Gram postive cocci
Staphylococcus & Streptococcus
have what shape and gram stain?
Gram positive aerobic or facultative rods
Bacillus, Listeria, Corynebacterium, Nocardia, Mycobacterium
have what shape, respiration and gram stain?
Gram positive anaerobic rods
Clostridium, Actinomyces, Eubacterium, Propionibacterium, Lactobacillus
have what shape, respiration and gram stain?
Spore forming bacteria
Bacillus & Clostridium
... are capable of what?
Non-gram staining bacteria
Mycoplasma & Ureaplasma
... are not capable of what?
Gram negative facultative anaerobic rods
Esherichia, Shigella, Salmonella, Citrobacter, Klebsiella, Enterobacer, Serratia, Proteus, Yersinia, Vibrio, Pasteurella, Haemophilus
have what shape, respiration and gram stain?
Gram negative anaerobic straight or helical rods
Bacteroides, prevotella, Fusobacterium, spirochetes, Rickettsia, Chlamydia
have what shape, respiration and gram stain?
Spirochetes
Treponema, Borrelia, Leptospira
... are all what?
Features of all Staphylococcus species
Gram positive, cocci arranged in clusters, catalase positive
Staphylococcus aureus
Description, Virulence factors and Associated Diseases
Coagulase positive, Beta-hemolytic
Contains protein A, TSST-1, enterotoxins, exfoliatins, cytolysins
Causes: osteomyelitis, infective endocarditis in IVDU, abscesses, TSS, gastroenteritis and suppurative lesions
Staphylococcus epidermidis
Description, Virulence factors and Associated Diseases
coagulase negative, no hemolysis, susceptible to novobiocin
Part of normal skin flora, can form a biofilm
Causes: catheter and device infections, endocarditis in IVDU
Staphylococcus saphrophyticus
Description, Virulence factors and Associated Diseases
coagulase negative, non-hemolytic, resistant to novobiocin
Causes: UTIs in newly sexually active women
What color on blood agar is associated with beta hemolysis?
"Clear" color on blood agar is indicative of this type of hemolysis
What color on blood agar is associated with alpha hemolysis?
Green color on blood agar is indicative of this type of hemolysis
What color on blood agar is associated with gamma hemolysis?
Red color on blood agar is indicative of this type of hemolysis
Common features of all Streptococcus
gram positive cocci in chains or pairs, catalase negative
This streptococcus is serotyped by capsular antibodies
Strep pneumo
... is serotyped by what?
This streptococcus is serotyped by the M protein
Strep pyogenes
... is serotyped by what?
Lancefields' groups A-O refer to what?
Streptococci are serotyped by what, using known antigens to cell wall carbohydrates?
S. pyogenes
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: A
Hemolysis: beta
Bacitracin-sensitive, PYR test positive
S. agalactiae
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: B
Hemolysis: beta
Bacitracin resistant, hippurate utilized, cAMP test positive
Enterococcus faecalis
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: D
Hemolysis: alpha, beta or none
Growth in 6.5% NaCl, PYR test positive
S. bovis
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: D
Hemolysis: alpha or none
No growth in 6.5% NaCl
S. pneumonia
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: not groupable
Hemolysis: alpha
bile-soluble, inhibited by optochin
S. viridans
Lancefield group, hemolysis, and important lab characteristics
Lancefield Group: not groubable
Hemolysis: beta
not bile-soluble, not inhibited by optochin
Diseases caused by S. pyogenes
pharyngitis, scarlet fever, pyoderma, impetigo
... can all be caused by what?
Rheumatic fever occurs after this, and manifests through this mechanism
post-streptococcal pharyngitis with group A strep
antibodies to heart tissue (mean 19 days)
fever, joint inflammation, carditis
post-streptococcal glomerulonephritis occurs after this infection, and manifests in this manner.
post-strep pharyngitis, immune complexes bind to glomeruli, leading to pulmonary edema, hypertension and dark urine.
Group B Strep = Strep agalactiae
commonly causes what?
Neonatal septicemia and meningitis
Treatment for group B strep
ampicillin with cefotaxime or gentamicin
used to treat which Strep infection?
Predisposing conditions for strep pneumoniae pneumonia
antecedent influeza or measles infection, COPD, congestive heart failure, alcoholism, asplenia
... predispose to what infection?
Pathogenic factors in Strep pneumo
IgA protease aids colonization
Teichoic acids aid attachment and are highly inflammatory in CNS
Polysaccharide capsule, major virulence factor, inhibits phagocytosis
pneumolysin O is a hemolysin
postive Quelling reaction
this test demonstrates capsular swelling with type-specific antiserum in Strep pneumo
Quelling = Swelling
positive latex particle agglutination test
this test for capsular antigen in spinal fluid is diagnostic for S. pneumo meningitis
Actions of pneumolysin O
This hemolysin/cytolysin in S. pneumo causes:
damage to respiratory epithelium
inhibition of classical complement fixation
inhibition of leukocyte respiratory burst
Most common cause of adult meningitis
S. pneumo-- most common cause of what in adults?
Most common cause of otitis media and sinusitis in children
S. pneumo-- most common cause of what in children?
Reason for S. pneumo resistance to penicillin
chromosomal-- altered penicillin binding proteins
treatment of S. viridans infective endocarditis
penicillin G with aminoglycoside useful for treatment of this Strep infection
Pathogenesis of enterococcus endocarditis
medical procedures in GI or GU tract --> bloodstream --> previously damaged heart valves --> endocarditis
Disease associated with group D Gram-positive cocci in chains, PYR test +, with variable hemolysis
urinary and biliary tract infections
Enterococcus faecalis
vancomycin resistance in enterococcus faecalis
resistant strains of this have D-alanyl D-lactate as terminal of the UDP-N-acetylmuramyl pentapeptide, which functions in cell wall synthesis but is not inhibited by the drug in question