Prokaryotes

Bacteria contain no other cytoplasmic organelles other than ribosomes

Genetic information on circular chromosomes AND smaller circular plasmids (extrachromosomal)

Peptidoglycan (rigid mesh made from linear polysaccharide chains)

Polysaccharide is made from polymer of NAM [N-acetylglucosamine] & NAG [N-acetylmuramic acid]; repeating units)

Tetra-/penta-peptide (containing D & L amino acids) attached to NAM to help cross-link polysaccharide chains

Gram Positive: 20-80 nm (external to cell membrane)

Gram Negative: 5-10 nm (bt/w inner & outer membranes)

Because eukaryotes don't have cell walls!

thick peptidoglycan (PG) layer w/ teichoic (TA) & lipoteichoic acids (LTA)

TA- water soluble/anionic polymer; req for virulence & viability

LTA- TA + fatty acid in cytoplasm mem

act as surface antigens (help distinguish bact serotypes)

promote attachment to specific receptors on mammalian cell surf

shed into host => innate response (weaker than endotoxin)

unnecessary for bacterial growth

poorly antigenic

important for virulence

promotes adherence

antiphagocytic

protection from toxins (eg. detergents or antibiotics) 

what types of bacterium produce endospores?

what are endospores?

when are they produced?

some gram positives

endospores: non-replicating entity; thick coat; DNA; other essential substances; toughest life form (survive under extreme conditions: heat, cold, desiccation, radiation)

unfavorable conditions: some bacterium sporulate (form endospores)

favorable conditions: spores re-germinate into vegetative form of the bacteria

ropelike propellers 

composition: helically coiled proteins (flagellin)

make bacterium motile towards food AND away from poisons

virulence factor: assist in attachment to human cells

H-antigen

monotrichous

lophotrichous

amphitrichous

peritrichous

1. outer membrane

2. periplasmic space

what are fimbriae? 

what bacteria posses this?

function?

F-antigens

hairlike microfibrils ("common pili")

straighter/thinner/shorter than flagella

start in plasma membrane & protrude through cell wall

gram negative bacteria have fimbriae

act as adhesins (major virulence factor)

gram negative bacteria

permeability barrier (keeps large molecules out- lysozymes/antimicrobials)

protection from external conditions (eg. digestive system of host)

asymmetric barrier (inner leaflet-normal; outer leaflet-mostly LPS)

gram negative bacteria

gram negative bacteria have many of these proteins

some proteins are porins (form pores, allow diffusion of small hydrophilic molecules)

responsible for: many organelle functions

contains: transport proteins (nutrient uptake/substance release)

inner lining: actin-like filaments (deter shape)

assists: septum formation for cell division

content: mycolic acid, cord factor, wax D, & sulfolipids

function: virulence & antiphagocytosis

location: surrounding PG layer (linked w/ arabinogalactan)

alpha chain: (22-26 C) usually constant for a single species

beta chain: (50-65 C) varies in length, substituents, unsaturated positions

1. ziehl-neelsen stain

2. kinyoun and modified kinyoun stain (cold acid-fast stains)

3. fluorochrome stain

acid fast stain

requires: heating slide to help basic fuchsin to enter bacterial cell

cold acid fast stains

no heating, instead: incr conc of fuchsin & phenol

modified version: use weak acid decolorizer

*used for weak acid-fast sp (ie. Nocardia)

weak acid-fast stain

no fuchsin, instead: 2 fluorescent dyes (auramine & rhodamine)

1. lag phase: slow growth following culture innoculation

2. log/exponential phase: maximal growth rate *antibacterial most effective

3. stationary phase: growth ceases (reached maximum amt of nutrients/space)

4. death phase: cell numbers decline 

S. aureus

S. epidermidis

Corynebacterium species

Staphylococcus

Moraxella

Corynebacterium

Neisseria

Hemophilus

mycoplasma species

Bacteroides fragilis

E. coli

P. mirabilis

Enterobacter

Klebsiella

Lactobacillus

Enterococcus

Pseudomonas species

Streptococcus

Fusobacterium

Actinomyces species

Staphylococcus epidermidis

Propionibacterium acnes

Lactobacillus

Enterococcus

Gardnerella

Neisseria species

E. coli

Enterococcus

Bacteroides

Mycobacterium species

1. acquisition/colonization

2. immune evasion/infection

3. replication/proliferation

4. dissemination, disease, & excretion (find new host)

1. inhalation

2. ingestion

3. travel

4. sexually transmitted

5. accidental/surgical

6. zoonosis

7. needle-stick

damage caused by bacteria 

AND

host response to infection

1. strain and innoculum size

2. response to host conditions

3. length of bacterial presence

4. host factors