Role of Microbiology Lab Flashcards
What are the two important functions of microbiology labs?
Clinical- diagnosis of infection in an individual patient for everyday management of infections
Epidemiological- support for infection prevention and control in searching for source and route of transmission of HAI.
What are the 6 minimal requirements for microbiology services?
1- set up inside the facility (if not possible, negotiate a contract for diagnostic microbiology with the nearest lab)
2- available every day including Sundays and holidays (ideally on a 24 hour basis)
3- able to examine blood, CSF, urine, stool, wound exudate or swab, respiratory secretions, and perform basic seriological tests (HIV, HBV and HCV)
4- identify common bacteria and fungi to species level
5- perform susceptibility testing using disc-diffusion methodology
6- perform basic phenotyping (serotyping and biotyping).
What species can you serotype for?
Salmonellae, Shigellae, P. aeruginosa, N. meningitidis.
What species can you biotype for?
S. typhi.
What is the zone of inhibition?
The Zone of inhibition is a circular area around the spot of the antibiotic in which the bacteria colonies do not grow. … The zone of inhibition can be used to measure the susceptibility of the bacteria to wards the antibiotic.
What are the 3 classical bacteriological methods?
Direct smear
Culture
Antigen detection.
What are the 4 roles of diagnosing infection?
Classical bacteriological methods
Sensitivity testing
Antibody detection
Molecular methods.
What is a positive and negative of antibody testing?
Not very useful in the early stages of infection
It is good at deciding what type of organism is present.
What is the simplified scheme for bacterial identification?
Specimen…Direct examination…Culture…Pure culture and identification to species…Species name established…Typing or fingerprinting for taxonomic or epidemiological purposes.
What are the 4 different types of cocci?
Single coccus
Pair of cocci
Cluster of cocci
Chains of cocci.
What are the different types of rods?
Single rod
Chain of rods
Curved rod
Spiral.
What is the shape of strep mutans?
Chains of cocci.
Do gram negative or gram positive bacteria have a thick peptidoglycan cell wall?
Gram positive.
What are the six stages of the gram stain?
1- prepare a heat fixed film of bacteria on a glass slide
2- stain with crystal violet for one minute and rinse with water
3- treat with Gram’s iodine for one minute and rinse with water
4- briefly decolourise with acetone or ethanol (a few seconds depending on thickness of film)
5- counter stain with basic fuchsin or safranin (pink dye) for one minute and rinse with water
6- blot dry and view under oil immersion.
What does gram staining tell us?
Cell wall composition.