Bacteriology Flashcards
are bacteria prokaryotes or eukaryotes
prokaryotes
prokaryotes
- lack membrane bound organelles
- smaller/less complex
- one circular chromosome
- +/- plasmids
plasmids
extra-chromosomal DNA
can carry antibiotic resistance or extra genes that make bacteria more virulent
how are bacteria most commonly classified
genus +/- species
bacteria morphology
shape of bacteria
- coccus: round/spherical
- bacillus: rod shaped
- coccobacillus: shortened rod shaped
- spirillum/spirochete: spiral
gram-positive
thick peptidoglycan layer
- stains dark purple
NO outer cell membrane
gram positive cocci
staphylococcus
streptococcus
enterococcus
gram positive rods
bacillus
listeria
erysipelothrix
corynebacterium
gram-negative
thin peptidoglycan layer
- stains red/pink on gram stain
HAS outer cell membrane
gram negative rods
E. coli
klebsiella
pseudomonas
includes enterobacterales and non-enterobacterales
enterobacterales vs non-enterobacterals
enterobacterales: facultative anaerobes that are present in GI tract
non-enterobacterales: facultative anaerobes or strict anaerobes
gram negative spirals
leptospira
borrelia
are gram negative cocci common in vet med
no - rare
mycoplasma
bacteria with no cell wall
aerobes
bacteria that can grow in the presence of oxygen
includes strict aerobes and facultative anaerobes
strict aerobes
only grow in the presence of oxygen
facultative anaerobes
bacteria that can grow with or without oxygen
microaerophilic aerobes
requires reduced oxygen
obligate anaerobes
bacteria that can only grow in the absence of oxygen
- clostridium, bactericides, fusobacterium
where are obligate anaerobes found
top of the epithelium of:
- oral cavity
- intestinal lumen
- mucus membranes of urogenital tract
common in abscesses due to being walled off from the body
what are bacterial toxins
endotoxins and exotoxins
exotoxin characteristics
- gram positive and negative
- released by live bacteria
- proteins or polypeptides
- NOT pyrogenic
- highly antigenic
- converted to toxoids that induce neutralizing antibodies
- potent toxins
- some variation between bacterial species and species affected
endotoxin characteristics
- gram negative
- released by dead bacteria
- lipopolysaccharides
- pyrogenic
- weakly antigenic
- not converted to toxoids, no neutralizing antibodies
- moderate toxins
- significant variation between bacterial species and species affected
lipopolysaccharide (LPS)
endotoxin found in gram negative bacterial outer membrane
causes inflammation
made of lipid A, core polysaccharide, O side chain
exotoxins
protein secreted from bacterial cells that cause host cell damage or disruption of function
often antigenic
- antitoxin = antibody to exotoxin
A-B exotoxins
disrupt cell function
disorganizers exotoxins
disrupt the host cell membrane (phospholipase, hemolysins, pore-forming)
superantigens
cause a massive stimulation of T cells
flagella
responsible for motility
pili and fimbriae
polypeptides used for adhesion to host cells and sexual conjugation of genetic material
capsule
polysaccharide or polypeptide surrounding bacterial cells
used by both gram positive and negative
inhibits complement fixation and phagocytosis
spores
dormant/inactive bacterial state in which the bacteria forms an extremely resistant bacterial wall
resistant to temperature, drying, chemical agents, host degradation
mostly gram POSITIVE
genetic transfer
acquisition of new genes allows for development of resistance and virulence
- conjugation
- transduction
- transformation
- transposition
conjugation
transfer of plasmids by sexual pili
transduction
genetic material transferred by bacteriophages
transformation
take up of naked DNA
transposition
transfer of mobile DNA
biofilms
multilayered bacterial community; bacteria are IMMOBILE/INACTIVE
become embedded in polysaccharide matrix
- matrix blocks entry of antimicrobials/immune system components
allows for adherence to surfaces
