Microbial cultivation

Question 1

koch’s Postulates theory

Answer 1

Pathogen must be in all cases, Grown in pure culture, cells grown must cause disease in healthy, Pathogen then reisolated

Question 2

Microbial diversity

Answer 2

Diff species utilize+ tolerate diff nutrients

Question 3

Medical Micro does

Answer 3

Isolation, Identification + control of human pathogens

Question 4

Cultures

Answer 4

Self amplifies - Grow until colony visible

Question 5

Sub lethal injury

Answer 5

consequence of exposure to chemical/ physical Process that clamages but doesn’t kill Microorganism
May need resuscitation

Question 6

conditions for culture

Answer 6

gaseous requirements
optimum temp
nutrients needed for growth
competitors discouraged

Question 7

Bacteriology does

Answer 7

Isolates pathogens via culture (24-48 hrs) , phenotypic testing

Question 8

Mycology (Fungi) uses

Answer 8

Culture then m microscopy to identify species

Question 9

Selective agents

Answer 9

suppress growth of contaminants e.g antibiotics, crystal violet, bile salts

Question 10

Differential agents

Answer 10

Allows growth of 2 or more organisms = diff colours E. g PH indicators, coloured substates

Question 11

Faecal sample cons

Answer 11

High background flora (competitors)

Question 12

wound sample cons

Answer 12

contaminated with Skin flora use blood or McConkey agar

Question 13

Culture Pros + cons

Answer 13

cheap, effective but slow

Question 14

Bacteria + fungi methods

Answer 14

Culture, microscopy, PCR

Question 15

viruses methods

Answer 15

Serology (Abs) , PCR

Question 16

Parasite methods

Answer 16

Microscopy, FISH, PCR

Question 17

Microscopic methods Pros

Answer 17

Quick results needed e.g meningitis

Question 18

Urine analysis

Answer 18

Microscopy or Flow Cytometry

Question 19

Blood Cultures for

Answer 19

Septicemia

Question 20

Parasitology method

Answer 20

Microscopic detection of structures

Question 21

Virology method

Answer 21

Serology to detect Abs, Molecular tests e.g PCR
Igm = current infection
I GG = previous infection/ vaccination

Question 22

Positive culture

Answer 22

Further ID to confirm e.g Gram stain or MALDI

Question 23

Presumptive ID

Answer 23

Selective+ differential agars then further tests

Question 24

Molecular ID method example

Answer 24

16 S r RNA gene sequencing

Question 25

what ID techniques do?

Answer 25

give genus + species

Question 26

Typing methods

Answer 26

further discrimination based on phenotype/ genotype that differ between Single Species

Question 27

clone

Answer 27

Bacterial strains indistinguishable by genotype

Question 28

clonal complex

Answer 28

Natural diversity between mother + daughter cells

Question 29

Why type bacterial species (x4)

Answer 29

identify cases v outbreaks, chain of transmission, strain evolution, new pathogens

Question 30

phenotypic typing methods example

Answer 30

phage typing, serotyping, biotyping (enzymes)

Question 31

phage typing

Answer 31

infected cells lyse=plaques

Question 32

Serotyping

Answer 32

Abs raised to o Ag : Agglutination= Positive

Question 33

Genotyping

Answer 33

DNA polymorphisms using PCR+ electrophoresis

Question 34

Ribotyping

Answer 34

1) Isolate DNA+ fragment with enzymes
2) Gel electrophoresis +transfer to membrane
3) Membrane with labelled probes hybridized to target r RNA
4) visualization: phonographic/ X-ray film
5) Banding pattern compared to database