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FA Bacteriology


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What are the a-hemolytic bacteria?
Streptococcus pnuemoniae (catalase positive and optochin sensitive)

Viridans Streptococci (catalase negative and optochin resistant)
What are the B-hemolytic bacteria?
Staphylococcus aureus (catalase and coagulase positive)

Strep pyogenes (catalase negative and bacitracin sensitive)

Strep agalactiae (catalase negative and bacitracin resistant)

Listeria monocytogenes (tumbling motility, meningitis in newborns, unpasteurized milk)
What is the role of Catalase and coagulase in gram positive cocci?
Catalase degrades H2O2, an antimicrobial component of PMNs. H2O2 is a substrate for myeloperoxidase.

Coagulase converts fibrinogen to a fibrin clot
Which gram + organisms make catalase?
Staphylococci make catalse, where Streptococci DO NOT.
Which gram + organisms make coagulase?
S. aureus makes coagulase

Staph epidermidis and Staph Saprophyticus DO NOT.
Describe the virulence of Staph aureus.
Protein A binds Fc-IgG, inhibiting complement fixation and phagocytosis

TSST is a superantigen that binds to MHC II and T Cell receptor, resulting in polyclonal T-Cell activation

Coagulase: converts fibrinogen to fibrin clot

Staph alpha toxin

Exfoliatins in SSS
What types of disease (2) does Staph aureus cause?
Inflammatory disease - skin infections, organ abcesses, pnuemonia

Toxin mediated disease - Toxic shock syndrome (TSST toxin), scalded skin syndrome(exfoliative toxin), rapid onset food poisoning (ingestion of pre-formed enterotoxin)

* S.aureus causes acute bacterial endocarditis
group A beta hemolytic strep that is bacitracin senstive?
Streptococcus pyogenes
T/F antibody to M protein enhances host defense against S. pyogenes.
What types of disease (3) are caused by S.pyogenes?
1. Pyogenic - pharyngitis, cellulitis, impetigo

2. Toxigenic - scarlet fever, toxic shock syndrome

3. Immunologic - rheumatic fever, acute glomerulonephritis
Describe Rhuematic fever caused by S.pyogenes?
Rheumatic fever = PECCS

Erythema marginatum
Subcutaneous nodules

may be caused by pharyngitis; Pharyngitis gives you rheumatic "phever"
How are Enterococci classified?
as Lancefeild Group D, based on the differences in the C carbohydrate on the bacterial cell wall
What disease do Enterococci cause?
UTI and subacute endocarditis

Enterococci are hardier than nonenterococcal group D

they grow in 6.5% NaCl and are Penicillin G resistant
Where do Viridans Strep grow in humans and what disease do they cause?
they are normal flora of the oropharynx (Viridans live in the mouth because they are not afraid of-the-chin (Optichin resistant)

cause dental caries (Strep mutans)and subacute bacterial endocarditis (S. anguis)
How is the Strep Viridans differentiated from s. pneumonie? How is it similar?
Strep Viridans is resistant to optochin, S. pneumoniae is sensitive

both are a-hemolytic
What are Obligate aerobes?
bacteria that use an O2 dependant mechanism to genrate ATP
What are some examples of obligate aerobes?
Psuedomonas aeruginos
Mycobacterium tuberculosis

Nagging Pest Must Breathe
Why does TB have a predilection for the apices of the lungs?
M. tuberculosis is an obligate aerobe, the lungs have the highest PO2
What types of disease to P.aeruginosa cause?
infections in burn patients
nosocomial pneumonia and pnuemonia in CF patients
What are obligate anaerobes?
bacteria that lack catalase and/ or superoxide and thus are susceptible to oxidative damage

they are generally foul smelling, difficult to culture, and produce gas in tissue

Anaerobes are normal flora of the gut
What are some examples of obligate anaerobes?
Are Aminoglycosides effective against obligate aerobes? Why or Why not?
AminOglycosides are NOT effective against obligate anaerobes because these antibiotics require O2 to enter the bacterial cell wall
Which bacteria are obligate intracellular bugs?
Rickettsia and Chlamydia
Cannot make their own ATP

"stay inside (cells) when its Really Cold"
Which bacteria are facultative intracellular bugs?

"Some Bugs May Live FacultativeLY"
What is the function of Peptidoglycan?
gives rigid support, protects against smotic pressure sugar backbone with crosslinked peptide side chains
What is the major surface antigen in the Cell Wall/ Cell Membrane of (gram positive)?
major surface antigen techoic acid induces TNF and IL-2
Describe the Outer Membrane of(gram negative) bacteria?
Site of endotoxin (LPS); major surface antigen Lipid A induces TNF and IL-1; polysacchride is the antigen
Plasma Membrane
site of oxidative and transport enzymes lipoprotien bilayer
protein synthesis RNA and protein in 50S and 30S subunits
space between the cytoplasmic membrane and outer membrane in gram negative bacteria contains many hydrolytic nzms, including B-lactamases
protects against phagocytosis

is Polysacchride (EXCEPT Bacillus anthracis, which contains D-glutamate)
Pilus/ Fimbriae
mediates adherance of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation glycoprotein
motility protein
provides resistance to dehydration, heat, and chemicals keratin-like coat; diicolinic acid
extra chromosomal DNA that contains a variety of genes for antibiotic resistance, enzymes, and toxins
mediates adherance to surfaces, especially foreign surfaces (eg indwelling catheters) polysacchride
For EXOTOXINS, give the following...?

1. Source
2. Chemistry
3. locations of genes
1. certain species of gram (+) and gram (-) bugs

2. polypeptide

3. plasmid or bacteriophage
For EXOTOXINS, give the following...?

1. Toxicity
2. Antigenicity
3. Source of Vaccines
1. high (fatal dose in order of 1 microgram)

2. induces high titer Abs

3. toxoids are used as vaccines
For EXOTOXINS, give the following...?

1. Heat stability
2. Typical diseases it causes
1. destroyed rapidly at 60 degrees C (EXCEPT staph enterotoxin)

2. Tetanus, botulism, diptheria
Are EXOTOXINS secreted from bacterial cells?
For ENDOTOXINS, give the following...?

1. Source
2. Chemistry
3. Location of Genes
1. cell wall of most gram (+) organisms

2. lipopolysacchride

3. bacterial chromosomes
For ENDOTOXINS, give the following...?

1. Toxicity
2. Clinical Effects
3. Mode of Action
1. low (fatal dose in order of hundreds of micrograms)

2. fever, shock

3. includes TNF and IL-1
For ENDOTOXINS, give the following...?

1. Antigenicity
2. Vaccines
3. Heat Stability
1. poorly antigenic

2. no toxoids formed and no vaccine available

3. stable at 100 degrees
What are typical diseases caused by ENDOTOXINS?
meningococcemia, sepsis by gram negative rods
Are ENDOTOXINS secreted from bacterial cells?
Which organisms are identified by each of the following stains...?

1. Ziehl-Neelsen
2. Giemsa's
3. PSA (periodic acid Schiff)
1. Acid Fast bacteria

2. Borrelia, Plasmodium, trypanasomas, Chlamydia

3. stains glycogen, mucopolysacchrides; used to diagnose Whipples disease
Which organisms are identified by each of the following stains...?

1. India Ink
2. Silver Stain
1. cryptococcus neoformans

2. Fungi, PCP
Describe the EXOTOXIN of each of the following organisms...?

1. Corynebacterium diptheriae 2. Bacillus Anthracis
1. inactivates EF-2 by ADP ribosylation (similar to exotoxin A of psuedomonas); causes pharyngitis and "pseudomembrane" in the throat

2. toxin complex; 1 toxin in the complex is a adenylate cyclase
Describe the EXOTOXIN of each of the following organisms...?

1. Clostridium tetani
2. C. botulinum
3. C. preferinges
1. blocks the release of inhibitory neurotransmitter glycine; causes "lockjaw"

2. blocks the release of ACh; causes anticholinergic symptoms, CNS paralysis; spores found in canned food, honey (causes floppy baby syndrome)

3. a-toxin is a lecithinase; causes gas gangrene; get doublezone of hemolysis on blood agar
Describe the EXOTOXIN of each of the following organisms...?

1. Staph aureus
2. Streptococcus pyogenes
1. toxin is a super antigen that binds to MHC II protein and T Cell receptor, inducing IL-1 and IL-2 synthesis in toxic shock syndrome; also causes food poisining

2. erythrogenic toxin (causes rash of scarlet fever) and streptolysin O (antigen for ASO antibody is found in rheumatic fever) Erythrogenic toxin is a superantigen; streptolysin O is a hemolysin
Describe the exotoxin of the following GRAM POSITIVE bugs...?

1. E.coli
2. Vibrio Cholerae
3. Bordetella pertussis
1. heat labile toxin stimulates adenylate cyclase by ADP ribosylation of G protein; causes watery diarrhea. Heat STABILE toxin stimulates guanylate cyclase
2. Stimulates adenylate cyclase by ADP ribosylation of G protein; increases pumping of CL- and H2O out into gut causing voluminous rice-water diarrhea
3. stimulates adenylate cyclase by ADP ribosylation; causes whooping cough; inhibits chemokine receptor, causing lymphocytosis
What is the most common cause of meningitis in...?

1. newborns (0-6 mos)
2. children (6 mo-6yrs)
3. ages 6-60
4. elderly >60 years
1. group B streptococci

2. streptococcus pneumoniae

3. N. meningitis

4. S. pnuemoniae
What is the purpose of IgA protease in bacteria AND which organisms have them?
allow bacteria to colonize mucosal surfaces

Streptococcus pnuemoniae
N. meningitidis
N. gonorrheae
Heamophilus influenza
Which bacteria make IgA protease? What is the function of IgA protease?
Strep pnuemo
N. meningitidis
N. gonorrhoeae
H. Influenzae
Which Bacteria/ Fungi characteristically have polysacchride capsules?
S. pnuemoniae
Klebsiella pnuemoniae
Haemophilus Influenzae
N. meningitidis
C. noefromans

Some Killers Have Pretty Nice Capsules
Which organism has a NON polysacchride capsule?
B. anthracis, poly D-glutamate capsule

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