Midterm 1 Flashcards
Robert Hooke and Antoni Van Leeuwenhoek (1600s)
developed single-lensed microscopes
Edward Jenner (1700s)
smallpox vaccine
Florence Nightingale (1800s)
hygiene is a great way to avoid infection
Pasteur and Koch (1800s)
microbes as causative agents of disease
Hans Christian Gram (1800s)
Gram’s stain
Paul Erlich (1900s)
606 salvarsan/arsphenamine for syphilis
Alexander Fleming (1900s)
penicillin
Gerhard Domagk (1900s)
sulfonamides
Avery, MacLeod, McCarty (1900s)
DNA as a transforming principle
Rich Roberts (1900s)
restriction enzymes
Herb Boyer, Stanley Cohen (1900s)
constructing recombinant DNA
Kary Mullis (1900s)
PCR
Taxonomy
classification into groups
Phylogeny
study of evolution and ancestry
Metabiome
cataloguing constituent members of microbial populations
Path of pathogen
colonize, multiply, transmit
Transient
colonize skin
Carrier state
has organism, but is unaffected
Microbiota on skin
Staphylococcus epidermidis, other staph, propionibacterium, diphtheroids
Conjunctiva
S. epidermidis and corynebacteria
Mouth
Streptococcus mutans, Neisseria, and Moraxella
Stomach and small intestine
sparsely inhabited
Colon
Bacteroides, Fusobacterium, Clostridium perfingens, E. Coli, enterobacteriaceae, enterococci, and yeasts
Nares
Staphylococcus aureus
Nasopharynx
Similar to mouth, Steptococcus pneumoniae, neisseria meningitidis, Haemophilus influenzae
Larynx and below, middle ear, and sinuses
Protected by mucociliary escalator
Urinary tract
mainly sterile
Vagina
Things from skin, colon, and perineum
Child bearing years: Lactobacillus, anaerobic GNRs, GPC, Gardenerella, Mycoplasma, Ureaplasma
Beneficial effects of bacteria
priming immune system, excludes other bacteria, and helps with nutrition
Identification of etiological agents (why they happen)
1) determine nature of disease
2) predict course and potential outcomes
3) tailor therapy
4) exclude non-infectious causes of symptoms
Conventional intervention
1) gross phenotype
2) biochemical characteristics
3) Antigenic structures
4) Toxin production
5) Nucleic acid sequences
6) Flow of information (DNA, RNA, enzymatic functions, structures)
Conventional Molecular Detection
1) probes for culture confirmation
2) PCR
3) Next Generation Sequencing
Primary pathogen
infects competent host
Opportunistic pathogen
infects compromised host
Virulence
quantitative measure of likelihood of causing disease
Infectivity
quantitative measure of a pathogen’s ability to infect another host
Colonization
1) adherence
2) motility
3) survival or fitness in an environment outside host
Multiply
1) nutrition
2) avoiding host immune surveillance
Host Defense Mechanisms
1) non-specific
2) Innate immunity/acute inflammation
3) Adaptive (Acquired/Specific) Immunity
Non-specific
First line of defense, always there and don’t require sensor/response mechanism
Innate Immunity
Early warning system, senses presence of invader, “alert” response
Adaptive Immunity
“Immune response”, targeted to invader, provides immunologic memory
GI Tract Normal secretions (non-specific)
Lysozyme (saliva)
Low pH
Bile salts
Mucus
GI Tract Normal microbiota (non-specific)
Compete for nutrients
Compete for host receptors
Produce bacteriocins
Stimulate production of antimicrobial peptides
Gut-associated lymphoid tissue (non-specific)
- Poised to deal with microbes that penetrate intestinal lining
- Secretory antibodies (slgA) are transported into gut lumen
- Specialized regions called Peyer’s patches sample the intestinal flora
- Phagocytic cells capture bacteria and bring them to the draining lymph node
Complement activation
- Induces inflammation
- Recruits leukocytes
- Opsonizes bacteria
- Kills bacteria by lysis
The Membrane Attack Complex (MAC) lyses:
- gram bacteria
- enveloped viruses
- host cells that display foreign proteins on their surface
Cells of the Innate Immune System
First to see pathogens -Epithelial cells -Endothelial cells Phagocytic Cells -Neutrophils -Dendritic cells -Macrophages
Triggers of Inflammation
Physical trauma, tissue damage
Bacterial products
-lipopolysaccharide (LPS), lipoproteins, peptidoglycans (PGN), lipoteichoic acid, DNA, others
Pattern Recognition Receptors
Central to innate immunity.
Toll-like receptors (TLRs): extracellular pathogens
Nod-like receptors (NLRs): intracellular pathogens
TLR 4
LPS
GRAM NEGATIVE
TLR 2
lipoproteins, peptidoglycans (PGN), lipoteichoic acid, glycolipids
GRAM POSITIVE
TLR 5
bacterial flagellin
TLR 9
bacterial DNA
TLR 3
Viral RNA
TLR 7,8
Independently activated by an antiviral compound
TLR 1
Binding partner with TLR 2; inhibits signaling by some bacterial products
Cationic Antimicrobial Peptides
Produced by epithelial, endothelial, and phagocytic cells to kill gram +/- bacteria, fungi, and some viruses.
Bind to the negatively charged microbial membranes and form pores that kill the cell
Pro-inflammatory cytokines
Dilation of capillaries
Extravasation of fluid
Diapedesis of leukocytes
Low conc.= activate cells in the local area
High conc.=induce fever and production of acute phase proteins
IL-8
recruits cells to site of infection
IL-6, TNF alpha, IL-1
activate cells (epithelial, endothelial, and phagocytes)
Phagocytic Defenses
- Opsonins (antibody) increase phagocytosis
- Microbes are taken up into phagosome
- Phagosomes fuse with lysosomes to form phagolysosomes
- Microbes are killed/degraded within the phagolysosome
Polymorphonucelear Leukocytes (PMNs)
Develop from bone marrow cells Short half-life Degrade phagocytosed bacteria and produce IL-8, IL-1, TNF First phagocytic cells mobilized Chemotaxis toward C5a
Macrophages and Dendritic Cells
Derived from blood monocytes
Act as antigen presenting cells (APC)
B cells
produces antibodies with a unique antigenic specificity
Antibodies
- Block attachment to host
- Neutralize toxins
- Promote opsonization
- Activate complement
IgM
primary antibody response
IgG
cross the placenta
IgE
triggers release of histamines
IgA
secretion
CD8
MHC class I Directly lyse infected cells
CD4
MHC class II
T helper cells
Produce cytokines
Cell wall antibiotics
B-lactams (penicillin and cephalosporins)
Glycopeptides (vancomycin)
Cell membrane antibiotics
polymyxins
DNA antibiotics
Fluroquinolones
Sulfonamides and trimethoprim
Metronidazole
Transcription antibiotics
Rifampin
Protein synthesis antibiotics
Aminoglycosides (gentamycin)
Macrolides
Tetracyclines
Lincosamides (clindamycin)
General mechanisms of resistance
Efflux
Restricted access to target
Inactivating enzymes
Target modification
Multi-resistant drug strains
Encode multiple genes
Encode a gene that can target multiple antibiotics
Selective pressure
B-lactams
Penicillins
Cephalosporins
Monobactams
Carbapenems
Vancomycin
Kills gram positive bacteria
Used to treat MRSA
Strains of Enterococcus
E. faecalis (susceptible)
E. faecium (more resistant)
Cephalosporin subclasses
1st Cefazolin (skin infection, surgical prophylaxis) 2nd (non important) 3rd Ceftriaxone (meningitis, endocarditis, etc) 4th Cefepime (life-threatening infection) 5th Ceftaroline (MRSA)
Rifampin
Targets transcription
Rapid selection for resistance
Aminogylcosides
Used against gram negative