Lec 1 Intro Flashcards
3 different major types of shapes used to distinguish bacteria?
- cocci [rounded]
- rods or bacilli [rod shape]
- spirochetes or spirilla [coarse shape]
3 different major staining characteristics used to distinguish bacteria?
- gram positive vs gram negative
- acid fast
- non-staining
Is mycoplasma staining or non-staining?
non-staining
Is myobacteria acid fast or non-staining?
it is acid fast
What is the shape of pneumococcus? Is it gram negative or positive?
- cocci in pairs
- gram positive
What are the three forms of cocci bacteria?
pairs, chains, clusters
What color does gram positive show up vs gram negative?
gram positive = blue/purple
gram negative = red/pink
What are two other names for pneumococcus?
Streptococcus pneumoniae
S. pneumoniae
What is the shape of group A strep? gram positive or negative?
gram positive cocci in chains
What is the scientific name for group A strep?
streptococcus pyogenes
What is the shape of staphylococcus spp? Gram positive or negative?
Gram positive cocci in clusters
What is the shape of neisseria spp? gram negative or positive?
gram negative cocci
What is the shape of campylobacter spp? gram negative or positive?
gram negative rods/bacilli
What is an example of a bacteria that cannot be visualized by gram stain?
spirochetes
What are 3 bacterial structures that are targets of antibiotic action?
- cell wall
- protein synthesis
- DNA synthesis
What is the structure of bacteria?
- prokaryotes with no organelles
What are characteristics of gram negative bacteria?
- two lipid bilayers surrounding thin layer of peptidoglycan
- outer lipid membrane contains porins and LPS
What are characteristics of gram positive bacteria?
- outer thick layer of peptidoglycan
- single inner lipid bilayer
- peptidoglycan layer contains surface proteins/carbs that can act as virulence factors [teichoic acid, lipoteichoic acid
What is the structure of the peptidoglycan layer?
- parallel strands of murein = alternating NAM [n-acetyl muramic acid] and NAG [n-acetyl-glucosamine]
- parallel strands are cross-linked by peptide chains
What is murein?
strand of alternating NAM and NAG that makes up the peptidoglycan layer
What are porin channels? Why are they important?
structure on outer lipid membrane of gram negative bacteria
- allow entry of nutrients and antibiotics
- modification of porin channel is a mech of antibiotic resistance
What are LPS [lipopolysaccharides]? Why are they important?
- LPS = lipopolysaccharide = endotoxins
- on outer lipid bilayer of gram negative bacteria
- important because as bacteria die, LPS are released and can trigger cytokine cascade that causes severe symptoms of infection distant to site of infection
What is normal flora vs transient flora?
normal = we have it all the time, low virulence, rarely causes disease transient = usually not normal flora but can easily colonize for period of time, slightly higher virulence, usually doesn't cause disease
What is one normal skin flora?
staphylococcus epidermis
What is one transient skin flora?
staphylococcus auereus
What are two normal upper respiratory tract flora?
- anaerobic cocci
- viridans streptococci
What are 3 normal bacteria in GI tract
- bacteroides [anaerobic rods]
- e coli [enterobacteriaceae]
- enterococci
What is one normal bacteria in GU tract?
lactobacillus
What are 3 transient upper respiratory tract bacteria?
- neisseria spp
- streptococcus pneumoniae
- haemophilus influenzae
What are the steps by which a bacteria becomes disease?
- bacteria enters
- bacteria adheres and colonizes and multiplies
- bacteria invades
- disease caused by either direct effect of organism on tissue or by the inflammatory immune response
What are the three factors that come together to cause disease
- bacterial factors = virulence factors
- host factors
- environmental factors
What are three environmental factors that lead to disease?
- overcrowding [easier to spread]
- climate [ex. in certain season]
- antibiotic use
What are 3 host factors that lead to disease?
- immunocompromised state
- extremes of age
- breach in barriers
What are some types of immunocompromised states that contribute to disease?
- primary congential immunodeficiencies
- AIDS
- transplantation
- cancer
- sickle cell disease
- alcohol use
- diabetes
- malnutrition
What are some examples of breaches in barriers that contribute to disease?
- skin and mucus membranes [break in skin]
- gastric pH [high gastric pH]
- flushing [urine, saliva] –> urinating/saliva you are forcing out organisms
- ciliary function
- mucus and secretory IgA
- normal flora
What are examples of virulence factors that contribute to disease?
- ability to block part of immune system response [phagocytosis, antibodies, complement]
- slime and biofilms
- toxins [endotoxin vs exotoxin]
- adhesion
- flagella
- ability to survive phagocytosis
- ability to survive in hostile environment
