4 classes of microbes
- Virus
- Bacteria
- Fungus
- Parasite
Morphology of bacteria
- Cocci
- Bacilli
- Spirals
- Pleiomorphic
Cocci
circle
Staph
cluster
Strep
string
Bacilli
rod
What is used to look at cell wall?
Gram stain
Gram +
- color
- peptidoglycan
- purple
- thick peptidoglycan, traps 1st dye
Gram -
- color
- peptidoglycan
- pink
- thin peptidoglycan layer
- has layer of lipopolysaccharide
Porins
how drug gets into bacteria
Function of flagella
motility
Function of pilli
for genetic transmission between bacteria; sexual transfer–importance in antibiotic resistance
Function of fimbriae
for adhesion
Why is morphology important?
If taking a sample it will be some of the first information that will clue you in to what organism it is
What is Pleiomorphic?
- found?
- what do we get?
- varied shapes
- extreme environments
- enzymes to run some of diagnostic testing
Cell wall
- used for protection
- target of beta-lactamases
Layers of cell protection
cell membrane, cell wall, capsule
Bacteria that will not stain
Syphilis, chlamydia
Importance of lipopolysaccharide layer in gram -
important in virulence of bacteria
E. coli
-has flagella, pilli, H antigen, O antigen, K antigen
Virulence factors of E. coli
- pilli
- flagella
- LPS
H antigen
- flagella
- used for testing in serology
O antigen
- antigenic variation
- seen in flu
- used for testing in serology
K antigen
-capsule
Importance of capsule
- antiphagocytic property
- can help with adherence
- can help form biofilm
- can dry out quickly
Bio-film
-ale to avoid complement/anti-body because it acts as barrier between the bacteria and the immune system
1st test when suspecting bacteria
gram stain
E. coli gram stain
-gram negative rods
How to test for aerobic/anaerobic
- catalase test
- culture
Plates used for E. coli
- Eosine methylene blue: will have metallic green sheen because it ferments lactose very quickly
- MacConkey agar: hazy bright pink
What does eosine methylene blue inhibit?
growth of gram + bugs
MacConkey agar
- Lactose negative- no color
- Lactose positive- pink
Catalase testing
- tests bacteria for catalase enzyme
- will add hydrogen peroxide to sample, looking to see if enzyme will cleave hydrogen peroxide into water and gas
Cytochrome C oxidase testing
- Cytochrome C oxidase is enzyme used in ETC of aerobic bacteria
- will be positive if the test turns blue
What kind of respiration does E. coli use?
- faculatative anaerobe
- can survive in aerobic environment, but prefers anaerobic respiration
Why would bacteria not want to be aerobic?
-Oxygen damages cell with radicals
Indole test
- looking for red ring
- breaks down tryptophan
Indole test and e. coli
positive
Acid fermentation test
-e. coli is mixed acid fermenter and produces gas
VP test
-looks for glucose fermenters
VP and E. coli
- negative; because only one substrate added
- however, E. coli can use glucose in aerobic environment
Methyl red test
- e. coli
- looks for mixed acid fermenters
- positive
Can body naturally degrade bacterial cell wall?
yes; with lysozymes
-cleaves between NAG/NAM complexes
NAG and NAM
- creates chain linked fance formation for cell wall
- always attached to different AA
- building blocks of chain made from NAG-NAM complex which binds to another complex with an AA bridge
lysostaphin
- natural body mechanism
- knocks out the cross bridges making the cell wall less stable
- used in gram +
How to get rid of lipopolysacharide
-dry it out
Things to consider when choosing anti-biotic
- Disease state of patient
- Prior adverse reaction
- Impaired elimination
- Patient age
- Pregnancy status
- Epidemiologic exposure
- Pharmacologic factors
Why is disease state of patient important?
-antibiotics are chemotherapeutic drugs because they are trying to kill/stop growth of living cell
Why is disease state of patient important?
- antibiotics are chemotherapeutic drugs because they are trying to kill/stop growth of living cell
- looking out for immuno-compromised individuals
Why is impaired elimination important?
-If you cannot get rid of of drug then it could cause toxicity
Why is age important?
- older: side effects of dizziness- can cause falls
- neonates: increased bili
Epidemiologic exposure
If patient lives in close contact with someone else and is infected with highly contagious organism then the people they live with need to be tested
Bacteriacidal
Kills the cell
Bacteriacidal
- Kills the cell
- targets the cell wall
Bacteriostatic
- Stops cell growth
- targets proteins
Post antibiotic effect
- in absence of anti-biotic there is still anti-biotic effect, lasts 1.5 hours to 6 hours
- can occur because as medication is excreted as long as concentration stays above MIC there is still antibacteria like effect
Minimal inhibitory concentration
Minimum amount of drug that will stop visible growth of bug
Minimal bacteriocidal concentration
Minimum concentration of drug that will kill the bug
How to choose proper drug
-empirically treat and then
Antimicrobials with activity against e coli
• Penicillin: Most commonly given • Cephalosporin: Most commonly given • Aminoglycosides: It’s a synergistic drug • Sulfonamides • Trimethoprim -fluoroquinolones
Physical barriers to infection
-mechanical, chemical, microbiological
Skin barriers
- m: epi cells are joined by tight junction, longitudinal flor of air/fluid
- c: fatty acids, antimicrobial peptides
- M: normal flora
Gut barriers
- m: epi cells are joined by tight junction, longitudinal flor of air/fluid
- c: low pH, antimicrobial enzymes, antimicrobial peptides
- M: normal flora
Lungs
- m: epi cells are joined by tight junction, movement of mucus by cilia
- c: pulmonary surfactant, antimicrobial peptides
- M: normal flora
Eye, nose, oral cavity
- m: epi cells are joined by tight junction,tears, nasal cilia
- c: antimicrobial enzymes in tears and saliva
- M: normal flora
How do antimicrobial peptides kill?
Disrupting pathogen membranes
Function of pentraxins
bind microbes and target them to phagocytes
Cells of innate immune system
-eosinophil, basophil, neutrophil, NK, T cell, mast cell, monocyte, macrophage, dendritic cell
Granulocytes
Eosinophil, basophil, neutrophil, NK cell
Phagocytic cells
-neutrophil, monocyte, dendritic cell, macrophage
Tissue resident cells
dendritic cell, macrophages, mast cell, plasma cell
lymphocytes
T cell, B cell
recognition mech of innate immunity
-rapid response, fixed, limited # of specificity, constant during response, multiple cell types
recognition mech of adaptive immunity
-slow response, variable, numerous highly selective specificities, improve during response, lymphocytes only
complement role in first line defense
Complement coats the surface of bacteria and extracellular virus particles and makes them more easily phagocytosed. Without such a coating, many bacteria resist phagocytosis, especially those that are enclosed in thick polysaccharide capsules.
Complement pathways
- alternative, lectin, classical
- all lead to activation of C3
Alternative pathway
- works at start of infection
- innate immunity
Lectin pathway
- innate immunity
- requires time
Classical pathway
- part of both innate and adaptive immunity
- requires the binding of either antibody or an innate immune-system protein called C-reactive protein to the pathogen’s surface.
Macrophage effector functions
- bacteria binding to macrophage
- bacterial component binding to macrophage
- induces engulfment and degradation
- induces the synthesis of inflammatory cytokines
Neutrophils moving to infection
-steps
- rolling adhesions, tight binding, diapedesis, migration
- Neutrophils have CXCL8 receptors and endothelial cells of vasculature near site of infection will express CXCL* so the neutrophils can bind to that site and then move though the vessel to get to the infection
TLR-4
- binds to?
- cells carrying receptor
- location
- binds to LPS of gam - bacteria
- macrophage, dendritic cell, mast cells, eosinophils
- plasma membrane
NF Kappa B
- used in
- function
- what occurs when non function
- TLR’s and NLR
- transcription factor that transcribes proinflammatory cytokines
- non function then you cannot combat against bacterial agents because you cannot produce defensins and cannot recruit WBC to help with fighting bacteria
NLR
-important for activation of the inflammasome and very important in transcribing definsins
NEMO disease
- A subunit of one of the IkB kinases in the NF-kB pathway is missing therefore
NF Kappa B cannot be released from inhibitory marker to induce transcription
-leads to abnormality in skin, hair, teeth and makes patient susceptible to bacterial infections
Neutrophils
-express many bacterial and fungal receptors making them super phagocytes
Dendritic cells and NK cells
- activate NK cells and help them to proliferate
- once NK cells are abundant and outnumber dendritic cells then they kill dendritic to regulate further activation of NK cells
- once NK cells are scarce and are outnumbered by the dendritic cells they drive the dendritic cells to mature into the form that initiates adaptive immunity
Netosis
unique form of cell death that is characterized by the release of decondensed chromatin and granular contents to the extracellular space.
Absence of — would prevent complement cascade from amplification?
cleavage of C3 by C3bBb
What molecule directly prevents formation of C3 convertase?
Factor I
Molecule that most directly stimulates migration of neutrophils from blood to tissues
C5a
Molecule that directly mediates destruction of complement-coated microbes
C3b
C3 deficiency
- When you don’t have C3, you don’t opsonize bacteria as well, so phagocytes are not phagocytizing as well. This leads to increased susceptibility of infection
- lack of opsonization and inability to utilizr the membrane attack pathway
Factor H/I deficiency
-causes uncontrolled activation of C3 via the alternative pathway resulting in depletion of C3 and causing C3 deficiency and susceptibility to bacterial infection
What is mechanism of joint pain in C3 deficiency?
stems from buildup of immune complexes in the joint
Factor D deficiency
Factor D cleaves factor B, so a deficiency in this factor would lead to factor B not being cleaved, and you can’t make C3 convertase. If you can’t make C3 convertase, you can’t cleave C3 which results in decreased opsonization because you can’t place C3b on pathogen’s surface. Pts with Factor D deficiency are at risk for serious infections.
Factor P deficiency
the factor 3 convertase from alternative pathway will not be stabilized so it will disintegrate very quickly and opsinozation will not work effectively
lymph capillary
- other name
- description
- role
- initial terminal capillaries
- discontinuous, anchored to the ECM, single layer of epithelial cells,
- role is the formation of the lymph.
collectine lymphatics
-contain smooth muscles so they are able to propel the lymph from one portion to the other.
lymph node
capsulated, it filters and it’s a reservoir for WBC.
lymphatic trunks
drain from the nodes to the ducts
lymphatic ducts
where the lymphatic is entering back into the venous system
What contributes to net flow rate in lymphatics
Formation and propulsion.
driving forces of lymphatic formation
Oncotic pressure and hydrostatic pressure. They help to move the fluid into the interstitial space and then from the interstitial space to the lymphatics.
driving forces of lymphatic propulsion
Systemic forces like blood pressure, respiration, exercise and massage. These systemic forces create a change in pressure which is important because fluid moves from high pressure to low pressure.
arteries and lymphatics
Lymphatic vessels are next to arteries which pulsate and that pulsating causes the lymphatic vessels and collecting vessels to continue to move.
Importance of GAGS in lymph formation
- highly negatively charged so they repel each other and because of that they are able to establish interstitial volume and neutrality which helps to create osmotic gradient leading to lymphatic formation so that the lymphatics can pick up the fluid.
- if disrupted there is less lymphatic formation in the interstitial terminal lymphatics.
anchoring filaments
- anchoring filaments pull open the terminal lymphatic capillaries and help to create a tissue pump or a second valve, increasing the luminal volume, causing the fluid to get in and forming the lymph and then sending them to the collecting lymphatics
- if damaged edema can be formed
sterling forces
needed to get the fluid from the capillaries into the interstitial space are hydrostatic and oncotic pressures
net filtration
- hydrostatic forces are greater than the oncotic forces
- hyrdostatic pressure is pushing pressure and will push the liquid from the capillaries to the interstitial space
net resorption
- oncotic forces are greater than hydrostatic forces
- oncotic pressure is pulling pressure and will pull the liquid from the interstitial space back to the capillary
venous insufficiency effect on lymph
- why?
- treatment
- Venous insufficiency means she’s cant move blood back to the heart so there is increased hydrostatic pressure in capillary on venous end, therefore less liquid from interstitum can be pulled back into the capillary and the fluid in interstitum is too much from lymph to completely drain which creates edema
- Also has fibrotic tissue which is leading to remolding of her ECM which could be affecting her Gags and anchoring filaments that affects lymphatic formation
- exercise and compression socks
thymus
-primary lymphoid tissue where the T-cells originate
activation of adaptive immune response
-dendritic cell will follow lymphatics from tissue to nearest lymph node, then present the antigen from the bacteria to the t-cells, t-cells will activate b cells which will turn into plasma calls and being making anti-bodies to bind antigen
what happens if antigen/pathogen is inserted directly in blood?
-it will travel to spleen first and be filtered out there since the spleen is abundant in lymphocytes (specifically T cells)
what cells are located in the peri-articular sheath of the spleen?
-t-cells
effect of Wuchereria bancrofti
-live in efferent lymphatics which causes a mechanical obstruction in those vessels, so there is a build up and no forward flow in the collecting lymphatics, the smooth muscles get stretched out further and stop working, the pressure builds up, the collecting lymphatics starts to distend. hydrostatic pressure in the lymphatics increases so fluid goes into the tissues instead of being moved through lymph vessels
what is primary cause of edema?
-genetic defect, specifically one in VEGF formation which will usually stimulates the formation of new capillaries (both arterial/venous and lymph) so a mutation will lead to absence of terminal lymphatics and absence of lymph formation, causing build up of fluid in interstitum