Microbiology- Systematic Bacteriology Flashcards
4 main classifications of microorganisms
1 appearance/ structure
2 growth requirements
3 enzyme/ metabolic tests
4 molecular test
streptococcus structure
chain of 4-20 cocci
think stripe
staphylococcus structure
found in clumps
Example of organisms which do NOT stain well with gram stain
mycobacterium TB
- lipid rich/ waxy cell wall
Treponema pallidium
- causes syphyllis
aerobic
grow in oxygen
obligate aerobes
require oxygen
obligate anaerobes
killed by oxygen
facultative anaerobes
tolerate oxygen
capnophilic
prefer CO2 high environment
Selective media
presence of specific substances permits the growth of one organism over the other
Differential media
incorporation of chemicals produce visible changes in colonies that facilitate identification
Identification of streptococcus
haemolysis
colour of alpha haemolysis colonies
green
colour of beta haemolysis colonies
gold halo
colour of gamma haemolysis colonies
no haemolysis
What does metabolic profiling utilise?
carbon sources and amino acids
MALDI-TOF
matrix assisted laser desorption ionisation time of flight
not good for strep or staph
Virulence
capacity of a microbe to cause damage to the host
commensal
organism which s part of the normal flora
opportunistic pathogen
an organism that causes infection when opportunity/
change in natural immunity arises
Example of fungal infections
Candida
yeast
aspergilus
moulds
Examples of gram negative prokaryotic pathogens
neisseria
escherichia
Examples of gram positive prokaryotic pathogens
streptococcus
staphylococcus
enterococcus
clostridium
coliform
species of gram negative bacilli that look like E. Coli on gram film and blood agar
in which environment do coliforms best grow in?
aerobically
First line antibiotic used for treatment of infections caused by coliforms
gentamicin
cause of alpha haemolysis
enzymes denature Hb inside RBC-> green
partial haemolysis
cause of beta haemolysis
enzymes lyse RBC-> completely clears the surrounding the colony
complete haemolysis
most pathogenic streptococci are beta haemolytic
most significant pathogenic streptococci
Group A Streptococcus
cause of pneumonia
inhalation of streptococcus pneumonia, causing fibrous exudate to clog alveoli and bronchioles
streptococcus pneumoniae
Gm +ve alpha haemolytic cocci
commonest cause of pneumonia
most important group of non haemolytic streptococci
enterococci
Most common cause of UTI but part of normal bowel flora
clostridiodes
Gm +ve anaerobic bacilli
produce exotoxins which cause severe tissue damage
Why do patients with coliform (gram negative) sepsis become quickly unwell?
GM -ve cell wall releases endotoxin when bacteria dies
