- alpha: partial hemolysis, "greening" due to biliverdin
- beta: complete hemolysis, clearing
- gamma: non-hemolytic
types of serological typing
- Lipopolysaccharide side chain ("O" antigen)
- Capsular antigen ("K" antigen)
- flagellar antigen ("H" antigen)
- other cell surface proteins (like M protein of streptococci)
all cells stain purple, decolorizer (alcohol or acetone) removes LPS but not peptidoglycan, so safranin colors gram-, but gram+ remains crystal violet
acid fast stain
decolorizer (acid alcohol) takes away non-acid fast so acid-fast are red/carbolfuchsin, non are methylene blue
thick cell wall of gram + bacteria that traps pigment (gram - has thin layer). Sugar backbone with interlocking peptides. Lysozymes break sugar backbone to make wall fall apart
gram negative cell wall
- thin layer of peptidoglycan in periplasmic space, outer membrane is phospholipids paired with lipopolysaccharides.
- lysozymes can't cross this lipid bilayer while it's intact
acid fast cell envelope
- mycobacterium (gram+)
- lipids on outside, mycotic acid, peptidoglycan on the bottom. Waxy cell wall, heat drives stain in.
mollicutes and anaplasmataceae
bacteria with no cell wall. Take cholesterol from host to use. No peptidoglycan so stain gram-, but don't have LPS wall either.
- Flagellin protein, used for motility (chemotaxis).
- "H" antigen (antigenic)
- surface arrangement can vary (0, 1, 2, to all over surface)
- promote adherence
- bacteria to bacteria or bacteria to host cell
- "F" antigen
- polysaccharide or protein
- antigenic -- "K" antigen
- slime layer = loosely adherent capsule
- often antiphagocytic
- barrier to toxic hydrophobic (detergents)
- synthesis is very energy expensive, only make when necessary
- develop inside mother cell under nutrient-limited conditions. Dormant, no metabolic activity, highly resistant to environment.
- Germinate once reach appropriate environment. Dense core with LOTS of layers.
- require organic molecules, not just simple building blocks for synthesis of major cellular constituents.
- Can use to diagnose (plates without basic requirements, transmission through environment possible or just host-host)
- prefer low oxygen levels, can grow without O2
- campylobacter fetus
- ferments in the presence of O2
- strep equii
- respires with O2, ferments without
- E. coli, staph aureus
- killed by O2, ferments without it.
- Clostridium tetani, fusobacterium necrophorum
- requires O2, can't ferment
- mycobacterium bovis, bacillus anthracis
likes 45C -- likes it hot!
likes 4C, likes it cold (refrigerator okay)
- autonomously replicating extrachromosomal molecules
- not required for viability
- often encode virulence (TNFalpha inhibition, phagocytosis inhibition) or abx resistence
- insert via transposition (sometimes)
- lytic: lyse cell
- lysogeny: integration, cell replication making a "prophage". Integrase integrates into chromosomes, stay forever in generations. Could turn lytic. (botulism)
- carry many virulence genes
- present in pathogenic strains, messed up or absent in others.
- HUGE, different C+G than host
- associate with tRNA genes or insertion sequences
- often have cryptic mobility genes