Gram positive, Cat pos organisms
- GPC
- Catalase positive
- aerobes and facultative anaerobes
- only Staph aureus is clinically significant
- humans are the natural reservoir
S. Aureus
GPC , Cat pos
- have many virulent factors: Catalase, Coagulase, DNAse, hyaluronisase…
- usually skin and soft tissue infections
- can cause bactermemia, sepsis, ostomylitis
Coag Negative staph
- coag and DNAse negative
- Epidermitis Saprohyticus, Lugdunensis
- form biofilms
- saprophyticus is resistant to novobiocin
Catalase test
use hydrogen peroxide to determine if the organism has catalase
Coagulase
is used to differentiate S. Aureus from other coag negative staph.
- Staph produces free and bound coagulase
- mix with rabbit plasma to observe clumping
-
Mannitol Salt agar
is selective and differential media
- used for the isolation and presumptive ID of S. Aureus
- SA is able to ferement mannitol turns media to yellow
- has lots of salt
Novobiocin
make a .5 mcfarland standard
- streak a lawn and place a novo. disc one the media
- Saprophyticus is resistant
A Disc
Bactracin
- streak for lawn
- add disc
- S. Pyogenes susceptible
CAMP
Streak S. Aureus down the center then close in the opposite directions streak other things
- if postive the hemolysis will be arrow shaped
- Group B strep
Optochin disc
P disc
- used to determine S. Pnuemonia
- > than 14mm for susceptible
Klebsiella
Lactose Ferm on MAC
encapsulated so mucoid colonies
- Pneumo - neg, Oxytoca- Pos
Proteus
swarmer
- non lac ferm
- mirabilas- neg, virgalis - pos
- phenolalanine deaminase pos
MAC plate
- uses bile salts and crystal violet in the medium to encourage growth of GNR
MRVP
1st part: add methyl red to indicate acid end products fermentation glucose
- VP: detects neutral end products of glucose fermentation
Oxsidase
swab colony
- add oxidase reagent blue is positive
- pseudomonas: positive
- E. Coli negative
indole
the ability of the oranism to produce indole
- add Kovacs reagent to tube and a red color is positive
- Rapid indole: swab colony, indole positive
Nitrate reduction
nitrate to nitrite
- add solutions a and B
- if red positive
- if negative add zince to see if it will reduce nitrite to nitrate if red on second time its negative
Tube is a nitrate broth with a durham tube
Citrate
to see if the organism uses urea as its carb source and ammonium as its nitrogen source
- streak a citrate agar (do not stab)
- positive (K. pneumonia) green to blue
- negative: E. Coli
Urea
ability to produce urease
- streak urea slant
- magenta color change positive(K. pneumonia, P. Mirabilis)
- negative E. coli
Decarboxylase tests
the ability to decarboxylate AA to amine form,
- base has only glucose,then a lysine and ornathine broth =
- if they are purple they are positive, if yellow negative
TSI
differentiates GNR based on Carb fermentation
- glucose feremnted in slant and butt
- Lactose and Sucrose can be fermented in the Slant
- K/K( red/red)= no carb fermenetaion
- A/A(yellow/yellow)= glucose and sucrose/lactose ferm
- K/A (red/yellow)= only glucose ferm
- black butt= glucose fermented/h2s
LIA
ability to decarboxylate or deaminate lysine and produce H2S
- used to screen suspicious shigella/ Salmonella
- in the butt glucose fermentation and lysine decarbox.
- in slant demainates
- K/K(purple/purple)= lysine is decarbylated
- K/A(purple/yellow= (lysine not decarbox)
- R/A(red/yellow)= lysine deaminated
MIO
determines GNR motility,indole, and ornathine production
- ornathine = purple throughout tube
- motility- growth away from the slab line
- indole= add kovacs reagent red is positive
