Flashcards in spring term practical MCQ Deck (57):
what is the proper term for throat and ear infections
upper respiratory infections
common bacteria to find in ENT samples
common bacteria in blood: aerobic
common anaerobic bacteria in blood samples
where should genital swabs be plated?
aerobic and anaerobic
pathogens in genital swabs
how should CSF be handled?
centrifuged for 10mins at full speed
resuspeneded sediment in 0.5ml of supernantant fluid
gram film this on blood and chocolate
common CSF pathogens
how should sputum samples be dealt with
plated on blood, choc, maconkeys and choc under 10% CO2
Optochocin disk on blood plate
optochochin on blood plate of sputum samples use
aids in differntiation between streptococcus pneominiae and other alpha-haemolotic streptococci
how should a faecal sample be dealt with?
emulsified in sterile saline and inncolulated into selenite broth, maconkeys agar or DCA or prestons agar
prestons agar results with faecal sample
small transparent colonies might be seen and should be gram stained and tested
this only occurs if no lactse fermenters found on macconkeys agar
pus and would exudates
granules indiactes this
whats the selective agent in macconkeys agar?
whats the differntiate agent in macconkeys agar?
lactose with bromo-cresol purple
why is sorbitol macconkeys used?
selective agent in desoxycholate citrate agar
sodium dexoycholate and citrate
why do salmonella on desoxycholate citrate agar have a central black dot?
production of Fes
detects presence of cytochome oxidase
purple colour indictes positive reaction
produced by aerobic bacteria to protect from toxic oxygen byproduct of peroxidase
ability of bacteria to ferment specific sugars eg gucose maltoe lactose
acid detected through color change
whats the two options of the result of the OF test
bacteria either degrate the sugrs using embden=meyerhof pathway to pyruvate
mixed acid fermenters producing acid
what is VITEK
better version of API strip
faster and accurate
how can LSP be used in sub-typing?
reagents can recognise O antigen side chain on LPS and the different ones of this recognise sub types within the genus of salmonella and E.coli
each sugar can be detected by specific antibody conferring the serotype specificity
what media does haemophilus onfluenzae require?
grows well on choclate
requires factors X (haemin) and V (NAD) to grow
red colonies on chomogenic UTI agar
cleaved by beta-galactoside
blue colonies on chromochenic UTI agar
cleaved by beta-glucosidase
purple colonies on chromogenic UTI agar
indicates other coliforms
what should stool samples be cultured for?
shigella and salmoella
media for campylobacter
media for Ecoli
media for shigella and salmonella
XLD or DCA after preenrichement in selenite broth
basic process of MALDI-TOF
bacteria loaded onto target plate
bacterial co-crystalises and becomes cloud of protons
ions travel through magnetic field
separate on mass and charge
detections of this and print out of mass spectra
uses latex beads coated with ab against serotype A carbohydrate
they aggultinate as the bind to surface of serotyped bacteria
bacterium with sensitivity to certain collections of phage types
lawn on bacteria on agar
add phage in refrence grid
plaques of lysis show sensitvity to the phage
why is subtyping important
track down source of infections
identifying a pathogenic subtype can be important also
what is In situ hybridisation used for?
uses a tissue section
can detect virus infections in cells
how does In situ hybridisation work?
DNA probe used of a few nucleotides, its labelled /tagged
sample heated and cooledallowing DNA to denature and probe hybridses
how is PCR used to subtyping?
rapidly amplifies known sequence of DNA and can detect the microbe when its hard to grow
very sesnsitie to low levels
another name of PCR
nucleic acid amplification
identifieds methicillin restiatnce in staph aureues
synthesis of capsular sialic acid in neiseria meningitis
restriction fragment length polymorphism
catalse test priniciple
catalase decomposes hydrogen peroxide with oxygen
use of catalase test
differentiation of staphylococcus from streptococcus and bacillus from clostridium
coagulase test principle
coagulase reacts with prothombin factor plasma creating a complex which reacts with fibrin producing fibrin forming a clot
citrate may be usedas sole source of carbon
pH value of medium raised
coagulase test used for
oxidase test principle
reaction detects cytochome oxidase activity
purple is pos
to determine if bacteri is oxidative or fermetative or both in using carbs
pink in closed tube: ferment
pink in closed tube: oxiative
pink in both: both pathways
distunguising between pathogenic and non-pathogenic staphylococci and between enterobcter and serratia
antisera reacting to cell surface (O) or flagella (H) antigens
observing pH increase when urease splits to urea,
pos: pink colour
what does the urease test differntiate?
identification of Proteus
number of baccteria in male urine normally bacteruria