lab pt1 Flashcards
ns: is the media selective/differential? why is it helpful?
bap (differential; lysing of red blood cells)
msa (selective and differential; helps isolate S. aur)
what microorganism do nasal swabs screen for
staphylococcus aureus
ns: what media is set up and why
blood agar plate and mannitol salt agar plate
ns: S. aur on media
growth: beta hemolytic
gram stain: gram positive cocci
catalase: positive
slide coagulase: positive
ns: if S. aur what is the next thing to find? MRSA or MSSA isolate?
Screen for MRSA (methicillin resistant staphylococcus aureus)
ns: how do you determine if its MRSA or MSSA
you determine if it is MRSA with a cefoxitin disc
ns: how and when do you set up/read test
transfer 18-24 hr old culture in saline solution and plate on MH plate (streak 3 way) place cefoxtinin disc in middle
read after 18-24 hrs
ns: how is test resulted
The test will either be methicillin resistant or sensitive
ns: expected result for MRSA and MSSA
MSSA: sensitive (greater than 20mm zone)
MRSA: resistant (less than 19mm zone)
ns: clinical implication of patient with this test result
t: symptoms presented by patient? what is important when collecting specimen
t: pathogen you are looking for in sample
streptococcus pyogenes
t: how do you incubate these plates (AIR or CO2), what temp?
incubated at 35 degress celcius in CO2 incubator
t: what growth media are you looking for
colony: small beta hemolytic colonies
gram stain: gram positive cocci
catalase: negative
t: what test is performed to determine whether you isolated the pathogen
bacitracin susceptibility test
t: how do you set up test and what are expected results
inoculate BAP plate and plate bacitracin disc between the first and second quadrants; if there is a zone of inhibition than it is sensitive and positive for group A streptococci
t: what is patients diagnosis
positive for streptococcus species
s: what diagnosis is patient being evaluated for
s: under what conditions did you incubate plate
35 degrees celsius in CO2 incubator
s: what is growing on media
colony: alpha hemolytic
gram stain: gram positive cocci
catalase: negative
s: what is the next test performed and how do you set it up
optochin sensitivity test
plate isolated colones on BAP; streak first quadrant three ways and continue to streak normally then place optochin disk on the primary streak
s: how is the test resulted and what is the expected result
the test is resulted as either sensitive (greater than 14mm) or negative (less than 13 mm)
the expected result is sensitive streptococcus pneumoniae isolated
u: what are the three common pathogens
e coli (most common)
pseudomonas aeruginosa
klebsiella pneumoniae
u: what will the gram stains of all three organisms be
gram negative rods
u: what will all three look like on plates
e coli (b-hemo; lactose fermenter)
k. pne (non-hemo; mucoid lactose fermenter)
p.aer (b-hemo; nonfermenter
u: why is urine plated to a BA and MAC )
BAP: records colony size, shape, and hemolysis
MAC: records whether its a lactose fermenter
u: how was the urine plated (qualitative vs quantitative streak)
quantitative streak
u: is BA/MAC selective/differential
BAP: differential
MAC: both selective/differential
u: what spot biochems do you want to set up on your isolate
- oxidase
- spot indole
u: what will positive/negative reactions look like
oxidase: positive (violet/purple)
spot: indole: positive (blue-green)
u: what is the suspected organism you have
escherichia col
rapid tests function
designed to perform bedside, check its not expired/stored properly, they have internal controls
beta hemolytic
complete clearing (halo/zone around isolate)
alpha hemolytic
partial lysis (greenish brown(
non hemolytic
no lysis
lactose fermenter on MAC
pink/purple
non lactose fermenter on MAC
no color change on agar
mannitol fermenter on MSA
yellow
non mannitol fermenter on MSA
non color change
what does positive catalase test look like
gas bubbles
what does positive oxidase test look like
turns purple
what does positive indole test look like
turns blue green
