L11 Lab diagnosis

Question 1

what is lab diagnosis for

Answer 1

rapid accurate results
advise on diagnosis, treatment and infection management
infection control
surveillance
teaching

Question 2

how many diagnostic lab specimens are there a year

Answer 2

900,000

Question 3

what are sample examples that labs test

Answer 3

hospital
community - GP
environmental
public health

Question 4

what are the microbiological tests

Answer 4

microscopy
culture
serology
molecular techniques

Question 5

what are the pros of microscopy

Answer 5

cheap

rapid results

Question 6

examples of unstained microscopy samples

Answer 6

urine

Question 7

examples of stained microscopy samples

Answer 7

gram of CSF

ziehl neilsen sputa

Question 8

why is microscopy limited

Answer 8

if negative stain doesnt mean no infection

Question 9

what microscopy is used for faeces rotavirus

Answer 9

electron microscopy

Question 10

what replaced electron microscopy for rotavirus diagnostic

Answer 10

EIA tests

now PCR look for specific rotavirus sequence

Question 11

what sample is used for lung infection pneumonia

Answer 11

need from chest pneumococcal pneumonia

as sputum in lungs non sterile through respiratory tract

Question 12

what is used for quick identification system

Answer 12

MALDI TOF

Question 13

how is bacteria cultured

Answer 13

grows on solid or liquid media
agar added with nutrients
different oxygen and co2 levels

Question 14

what are the types of cultures

Answer 14

enrichment
selective
indicator

Question 15

what is chocolate agar

Answer 15

blood added that has been heated

Question 16

what is a positive CSF detection

Answer 16

growth as CSF is sterile

Question 17

what is enrichment

Answer 17

encourage growth of fastidious organisms

by adding host nutrients

Question 18

how are blood infections detected

Answer 18

infection in blood stream not many bacteria/ml
need to detect small numbers - wont grow on agar too little
grow in bottles with nutrients in an/aerobic conditions
if co2 made - growth

Question 19

what is an indicator culture

Answer 19

identify colonies of pathogens from mixtures

help identification of bacteria

Question 20

examples of indicator methods

Answer 20

macconkey

API

Question 21

what is selective culture

Answer 21

obtain pathogen from sample likely to contain other commensal bacteria e.g. stool sample

Question 22

what can grow on deoxycholate agar

Answer 22

salmonella

Question 23

cons of microscopy

Answer 23

operator dependent
sensitivity only positive if 100,000 organism/ml
rarely diagnostic

Question 24

cons of culture

Answer 24

time = can take weeks, worsen patient

non-viable organisms wont grow on agar

Question 25

what are the antibiotic sensitivity test methods

Answer 25

stokes/BSAC zones
breakpoint
MIC

Question 26

what gives evidence for virus growth

Answer 26

cytopathic effect
haemadsorption
antigen detection
electron microscopy

Question 27

what has replaced tissue culture for testing

Answer 27

PCR or serological testing

Question 28

why is tissue culture not used for detection

Answer 28

hard to keep virus alive

cant process lots of samples

Question 29

what is used for organisms hard/cant grow

Answer 29

serology

antigen-AB binding detect AB/antigen