Intro To Bacteria Flashcards
Prokaryote
No cytoplasmic organelle other than ribosomes, genetic info stored in circular chromosome, can have plasmids (plasmids)
Gram positive
Thick (20-80nm) cell wall external to cell membrane (purple is positive)
Gram negative
Thin cell wall, between inner/out membrane
Aerobic bacteria
Grows in the presence of oxygen
Facultative
Can grow in the presence or absence of oxygen
Anaerobic bacteria
Grows in the absence of oxygen
Fastidious bacteria
Special growth requirements
Non-fastidious bacteria
Simple growth requirements
Capnophilic bacteria
Requires CO2
Halophilic baccteria
Salt loving
Gram positive cell wall characteristics
Thick peptidoglycan wall with teichoic (TA) and lipoteichoic acids (LTA). Are important for viability, virulence, and serotyping. Promote attachment to mammalian cells, low endotoxin activity
Protein synthesis inhibitor MOA
Better in toxigenic diseases than cell wall inhibitors.
Encapsulated bacteria
Looks polysaccharide layer (or protein layer). Unnecessary for growth but important for virulence. Promotes adherence, anti-phagocytic, poor antigen
Endospores
Produced under unfavorable conditions. Non-replicating entity with thick coat. Contain DNA/essential substances. Toughest life form, can germinate back to vegetative cells
Flagella
Are H-antigens. Motility towards food and away from poisons. Assist in bacteria attachment to human cells (virulence factor)
Types of flagella
Mono- Lopho- Amphi- Peri- (-trichous)
Fimbriae
Fimbriae are F-antigens. Hair-like projections (thinner/shorter than flagella). Originate in plasma membrane and protrude thru cell wall. Can act as adhesins and are major virulence factors
Outer membrane of gram negative bacteria
Permeable barrier for large molecules. Protects from adverse conditions. Asymmetric bilayer (normal inner, outer is primarily LPS)
Bacterial Lipopolysaccharide (LPS)
Gram negative bacteria. Integral part of outer membrane, released after cell death! When host senses LPS, turns on defense at its disposal
Acid-fast/Partially acid-fast bacteria
PG layer is surrounded by wax-like lipid coat. Lipid coat contains mycolic acid, cord factor, wax D, sulfolipids. Lipid coat responsible for virulence and antiphagocytic.
What determines acid fastness?
C-chain length of mycolic acids
Lag phase
Bacteria has very little growth
Exponential phase
Populations double every 20 minutes
Stationary phase
Growth phase
Death phase
Bacteria die faster than they multiply
What part of the intestine has the most bacterial cells?
Small intestine
Low number of bacteria sites
Bladder, uterus, parts of GI/Respiratory tracts
Normally sterile sites (no bacteria)
Blood, lymph, CSF, synovial fluid, sub-epidermal tissue
Step(s) of infection: epidemiology
Acquisition/colonization
Step(s) of infections: virulence
Immune evasion/infection —> replication/proliferation—>Dissemination and disease
Step(s) of infection: identification
Treatment
Transmission of bacterial pathogens
Bacterial shedding, talking (f, p, t, s sounds spread more), stability of pathogens in environment, living conditions, age group and immune-status
Factors that affect outcome of bacterial infections
Strain and inoculum. Length of presence, host factors.
Virulence factors
Used for survival and disease
Toxins from bacteria
When are in the blood, can harm the body
