Pathology Lab Midterm

E. Coli: pink-->rose red
Enterobacter: mucoid, pink
Proteus: colorless [swarming]
Salmonella, Shigella: colorless
Pseudomonas: irregular, colorless-->pink

N. gonorrhoeae: glucose only
N. menigitidis: glucose + maltose
N. Sicca: glucose, maltose, sucrose

respiratory, urogenital specimens
Neisseria
chocolate agar base w/vancomycin to inhibit gram positives
Colistin to inhibit gram negatives and non-path Neisseria
Mystatin to inhibit fungy
Trimethoprim to inhibit Proteus

enterics
fermentation of glucose, lactose, or sucrose
production of gas and hydrogen sulfide
glucose only fermenters cause pH to change through out slant, acids at top oxidized rapidly + phenol red indicator remains neutral or alkaline. In butt, acids keep indicator yellow.
Ferrous ammonium sulfate and sodium thiosulfate in medium react w/H2S to form black ferrous sulfide.

conclusion: glucose + lactose fermented (E. coli)

conclusion: glucose only fermentation (Salmonella, Shigella)

conclusion: no fermentation (pseudomonas)

Conclusion: gas produced
E. coli, Salmonella

Hydrogen Sulfide produced
Salmonella

S. aureus
Lithium chloride, high glycine +K tellurite
Inhibits some gram +'s and gram -'s
S. aureus ferments mannitol (yellow color) and reduces tellurite to tellurium (black colonies)

differentiate Staphylococus from Streptococcus
heat-stable (68 degrees) catalase differentiates certain Mycobacteria
release oxygen from hydrogen peroxide

S. aureus from non-pathogenic Staphylococci
Activates plasma coagulation

enterics (c in IMViC)
Simmons citrate medium
Citrate as sole carbon source
Brom Thymol blue as the indicator: yellow-->green-->blue as pH changes from 6 to 7 to 7.6
nitrogen source is ammonium dihydrogen phosphate, broken down to ammonia by growing bacteria and becomes alkaline

enterics
broth w/glucose, lysine, and Brom cresol
initially purple-blue
glucose fermented --> pH acidic --> indicator turns yellow
LDC decarboxylates lysine --> cadaverine, renders medium alkaline and back to purple-blue
cover w/sterile mineral oil
yellow =negative

Proteus and Providencia from enterics
enzyme acts on phenylalanine to produce phenylpyruvate which complexes w/iron forming green precipitate.

pathogenic enterics
Salmonella, Shigella, Proteus lack beta-galactosidase and don't ferment lactose
identifies presumptive pathogens on MacConkey agar

Slant: acidic
Butt: Acidic
Gas: +
Hydrogen S: -

Slant: alkaline
Butt: alkaline
Gas: -
Hydrogen S: -

produced by Group B Streptococcus agalactiae
heat-stable protein produces synergistic hemolysis
named for Christie, Atkins, Munch-Peterson

hemin
Haemophilus speciation or from Bordetella
absolute requirement for H. influenzae + most non-para
tested on streaked plate blood agar

Nicotinamide adenine dinucleotide (NAD)
must be in media for growth of Haemophili (on blood agar)

presence of active flagella
in soft agar

differentiates S. pyogenes
Taxo A disc
topical antibiotic interferes w/third stage of peptidoglycan biosynthesis by binding to phyrophosphate

standard medium for antibiotic determinations

S. Saprophyticus from other Staphylococci

Streptococci
non-pathogenic Neisseria
Actinomycetes
Corynebacteria
Micrococci
Mycoplasma
Bacteriodes
Obligate anaerobes- gingival crevices

pathogenic
pale-colored colonies on selective and differential media (Eosin-Methylene Blue or MacConkey)
tested on TSI, phenylalanine deaminase (PDA), LDC, ODC to identify genus

V in IMViC
detects acetoin (intermediate)
Barrits Reagents A&B oxidize acetoin to diacetyl which reacts w/creatine to produce a red compound

on tryptone broth
tryptophanase break tryptophan --> indole
detects w/Kovacs reagent
rearing = indole produced

Indole
Methyl-Red
Voges-Proskauer
i
Citrate (bacteria pump out carbon dioxide byproducts to turn media basic)

MacConkey
Eosin-Methylene Blue
Hektoen Enteric or Brillant Green Agar
Inhibit growth of gram + and normal flora
Simmon Citrate: pH indicator
green color indicator

1.enterotoxigenic
2. enteropathogenic
3. enterohemorrhagic (most severe)

they have cytochrom C reductase in ETC, allows them to withstand oxidative burst

Gram negative, facultative anaerobes, asporogenous rods
peritrichously flagellated
reduce nitrate --> nitrite
ferment glucose and are oxidase negative
mostly saprophytic
cause nosocomial infections, pneumonia, meningitis, cystitis

gram +
aerobic, coccobacilli
neonatal meningitis
often arranged in palisades
narrow beta-hemolysis
growth at 4 degrees
colonize genital tract and infect fetus in utero

3 species: pertussis, parapertussis, bronchiseptica (rabbits)
resemble Haemophili
fastidious
strict aerobes
charcoal and starch needed in medium to absorb toxic fatty acids
methicillin inhibits normal flora

endemic meningitis
otitis media, bronchitis, pneumonia, cellulitis, septic arthritis, and epiglottitis
H. aegyptius --> conjuctivitis

gram negative bacilli
hemin and NAD requirements
most important pathogen = H. influenzae (endemic meningitis)

bacitracin sensitivity
CAMP test
bile-sensitivity, esculin hydrolysis
effect of temperature
latex agglutination

Gram positive
Catalase negative
Oxidase negative
Aerotolerant anaerobic homolactic ferementers
Defined by Lancefield Antigens (A-H, K-V)
S. pyogenes = A
S. agalactiae = B
S. equi = C
S. bovis = D
S. pneumoniae + viridans are major pathogens

Blood Agar
Glucose phenol red broth: glucose fermentation v. aerobic growth
Vogel-Johnson agar: mannitol fermentation + tellurite reaction
Mueller-Hinton: antibiotic sensitivity

found in soil and on the skin and mucous membranes
obligate anaerobes

Enterococci from Streptococci
Oxgall (bile) inhibits other Gram positives and ferric citrate detects production of esculetin from esculin, resulting in dark circles around colonies

Differentiation of hemolytic reactions
particularly the demonstration of beta-hemolysis from Group A Streptococci
usually sheep erythrocytes

Group D Strep
Skin and mucous membranes of the UR, GI, and GU tracts
normal flora
alpha hemolytic
hydrolyze esculin
resistant to bacitracin and high salt

enterics
lactose, bile salts, neutral red, crystal violet
Salmonella, Shigella = resistant to bile
neutral red detects lactose-negative colonies
pale pink/white v. red-lactose+ colonies