Lecture 3 and 4 Flashcards
What is the bacterial iron binding protein?
Siderophore
What metal in humans is required by bacteria for electron transport?
Iron (Fe)
Describe generation curves of bacteria.
Peak is closer to higher temp range because enzymatic reactions occur faster with higher temp
What is the O2 metabolism of an aerotolerant microbe?
Don’t use O2 but not killed by it either
Define psychrophile, mesophile, thermophile, extreme thermophile.
Psychrophile - cold temps
Mesophile - like moderate temps; neither too hot/cold (15-45C)
Thermophile - like relatively high temps (40-70C)
Extreme thermophile - like high temps (70-100C)
What is the O2 metabolism of an microaerophile microbe?
Need O2, but O2 radicals are toxic
What happens in the lag phase?
Adapting to new nutrients
New enzyme synthesis - up-regulation
What is a persister cell?
dormant, non-dividing cell with slow metabolism
What happens in the exponential phase?
Growth and binary fision
What happens in the stationary phase?
Crowding, starvation or toxic conditions
New genes turned on to adapt to stress (usually toxins or virulence factor genes)
What happens in the decline phase?
Some cells lyse (maybe autolysis)
These cells cause a long, slow decline phase due to an asynchronous population…
Persister cells
What are autonomously replicating elements called?
Replicons
What is the difference between bacterial and viral chromosome?
Bacterial is usually circular, viral is circular or linear
A protein that binds upstream of promoter to allow transcription is called…
Activator
An environmental signal that turns ON genes no matter how is called…
Inducer
An environmental signal that turns OFF genes no matter how is called…
Repressor
What is the uptake of unpackaged/”naked” DNA?
Transformation
What are the 2 types of transformation?
Natural and induced
Cell must be competent to transform which is usually signaled by high cell numbers
Usually occurs when amino acids become limited
What are the importance of structural and regulatory associated proteins for bacterial chromosome?
Structural - anchors or bends DNA
Regulatory - turns genes on or off
Describe plasmids.
Circular, smaller than chromosomes, can exist in hundreds of copies, readily transferred by HGT
A protein that binds between promoter and gene to block transcription is called…
Repressor
What is natural plasmid transfer called?
Conjugation
Uptake of DNA by competence pheromones and use of quorum sensing is what kind of gene transfer?
Natural transformation
What is responsible for initiation of bacterial biofilms?
Quorum sensing
What is the main way bacteria can survive abx treatment?
Biofilm
How do F+ and F- cells interact?
F+ has genes for sex pili and F- has receptors for pili which allows them to attach
What is the importance of F-plasmids? (with respect to abx resistance)
F-plasmid gets integrated into the chromosome and can transfer adjacent chromosomal genes (possibly abx res. gene) by conjugation
What are R-plasmids?
Plasmids with multiple abx resistant genes
What is mefE?
Multiple drug efflux pump - can provide abx resistance by pumping abx out of cell
What is gene transfer by imprecise excision or packaging of phage called?
Transduction
What are the 2 types of transduction?
Generalized and specialized
How does generalized transduction work?
Random transfer of ANY gene that gets chopped up and put in a phage head
What phage cycle does generalized transduction use?
Lytic phage (one form of specialized)
What phage cycle does specialized transduction use?
Lysogenic phage (one form of specialized)
How does specialized transduction work?
Only genes near phage integration site can be transferred and the phage inserts into chromosome
Phage lysogens = Phage conversion… what is phage conversion?
phage carries gene for virulence factor from 1 bacteria to another
What is it called when transferred genes integrate into host chromosome to replace native genes?
Gene replacement
What is homologous recombination?
Recombination between same sequences
What is the result of an inverted repeat?
Inverted DNA sequence
What is the result of direct repeats?
Deletion of a DNA sequence b/t repeats
What are outer membrane vesicles?
Small vesicles that bud from outer membrane that contain genetic elements and signaling molecules (quoromones, toxins)
Can outer membrane vesicles fuse with other cells and transfer cargo?
Yes
Why are outer membrane vesicles important?
They can transmit pathogenic factors (toxins, abx resistant genes, virulence factors, quoromones)
What organisms most commonly use outer membrane vesicles?
G- pathogens
What are the benefits of E. coli, Oxalobacter, and gut microbiota?
E.coli - synthesized vit K
Oxalobacter - absorb excess oxalic acid
Gut - regulate TH17/Treg, interact c hormones for far reaching effect
What is the relationship called when bacteria harm us (parasitism) then become commensal?
Balanced pathogenicity
Inflammation is regulated by what T cell ratio?
TH17:Treg (gut bacteria balance this ratio)
T/F: Skin organisms are hard to colonize, different for different sites (even fingers)?
T (hard because of low pH and NaCl)
Important organisms in nasopharynx:
Normal:
1. diphtheroids - G+ club shape rods - Chinese
2. Staph epidermidis
3. Propionibacterium
Opportunists:
1. Strep pneumoniae - move into lungs = PNA
2. Neisseria meningitidis - gets released from attachments = meningitis
3. Hemophilus influenzae
Imp organisms in mouth:
- alpha-hemolytic Strep (S. mutans)
- Staph epidermidis (and aureus)
- Pasteurellaceae - bites
- Actinomyces israelii
- Neisseria (important opportunist)
- GramNeg in tonsil area
Important organisms in skin:
- Staph epidermidis (sometimes aureus) survive NaCl
- aerobic Corynebacterium (moist areas)
- Propionibacterium acnes - make butyric and propionic acids from lipids (sebaceous glands) - acne vulgaris
- G- org in moist areas
What org causes “lumpy jaw”?
Actinomyces israelii
What org serves as base layer on tooth surface for other bacteria to attach and grow?
Streptococcus mutans
How does gingivitis increase risk of infection?
Makes the tissue more friable
Imp organisms in stomach:
- Lactobacillus
2. H. pylori (~80% ulcers)
Imp organisms in duodenum (low pH):
- Lactobacillus
What 2 organisms cause vaginitis?
Gardnerella, Mycoplasma genitalium, lactobacillus
What are 2 very common organisms in the GI tract?
Streptococcus, Staphylococcus
Imp organisms in ileum-jejunum (higher pH)
- Enterobacteriaceae (facultative anaerobe)
2. Bacteroides (G- anaerobes)
Imp organisms in colon (must all be anaerobes)
- Bacteroides
- Fusobacterium
- Clostridium
- Facultative enterobacteriaceae
What are pre-op prophylactic abx?
neomycin/erythromycin + metronidazole (flagyl) - for anaerobes
What are the 3 gut enterotypes?
Bacteroides (high fat/low fiber - carbs)
Prevotella (low fat/high fiber - glycopeptides)
Ruminococcus (most common)
What are 4 enzymes that organisms use to get between cells?
- streptokinase-dissolves blood clots
- hyaluronidase-dissolves CT
- neuraminidase-Dissolves sialic acid glue
- collagenase-Destroys tissues
Hijacking of host cell actin and the formation of fillapodia networks is generically referred to as…?
Membrane ruffling (listeria-internalin)
Imp organisms in the vagina
- Lactobacillus
- Bacteroides
- Prevotella
- Finegoldia
- Gardnerella
- Mycoplasma genitalium
What happens if there is too little Lactobacillus?
more vaginal infections
Imp organisms in conjunctiva (most killed by lysozyme)
- Staph/Strep
- Hemophilus
- Neisseria
Where are sterile areas (no native flora)?
Lungs below trachea Internal organs (except GI tract) Fluids (blood, urine, lymph, semen) CNS Middle and Inner ear
What are 3 adhesion factors?
Pili/fimbriae, adhesins, capsules/glycocalyces
What is a type of adhesin?
G+ LTA
What is a tissue tropism?
specific adhesion to certain tissues
How to the halogens, Iodine and Chlorine, work?
Iodine - interferes with protein folding-can’t kill spores unless high concentration (betadine)
Chlorine - oxidizing agent (NaClO)-can’t kill spores unless high concentrations
What is particularly useful for staph and strep?
Phenolics, Biguanides (chlorhexidine)
Phenolics toxic but still use for staph
What mechanism do organisms taken up by non-professional phagocytic use to remodel the host’s cytoskeleton?
T3, T4, T6SS
What organisms are best treated by cationic detergents?
G+
What organisms use Ipas and Opas to promote engulfment by host cells?
Ipas - Shigella
Opas - Neisseria
What 2 proteins are involved on the pathogen and host to cause phagocytosis?
PAMP (on bacteria), PRR (on host)
What are 5 ways bacteria can avoid phagocytes?
- Prevent opsonization (by C3b complement)
- Antiphagocytic capsules (hide PAMP)
- M-protein and fimbriae
- LPS O-antigen variation or pili variation
- S. aureus protein A (attaches Ab backwards)
What chemicals do bacteria use to kill phagocytes?
Leukocidins, Hemolysins, Anthrax, Pertussis toxins
What are 5 ways for bacteria to deal with phagocytes?
- avoid them
- kill them
- prevent lysozomal fusion to phagocyte
- break out of phagolysozome
- resistance to lysozomal enzymes
Do you get a fever and inflammation with exotoxin or endotoxin?
endotoxin
What does antiseptic/disinfected mean?
Pathogens killed
What does pasteurized mean?
Most pathogens killed
What is the minimum inhibitory concentration (MIC)?
the minimum concentration which prevents bacteria from growing
What is the difference between the Kierby Bauer test and the E test?
Kirby Bauer - Qualitative
E test - Quantitative
What chemical class are high level sterilizers - kills spores?
Aldehydes
What level allows spores and some naked viruses to survive?
Intermediate
How do phenolics work?
denature proteins, dissolve membranes
What is particularly useful for staph and strep?
Phenolics, Biguanides
How do biguanides work?
damage cell membrane
What is a powerful biguanide used for surgical scrub?
chlorhexidine
Three examples of biofilms
Pseudomonas on skin
Stap epidermidis on catheters and implants
Strep mutans on teeth
Ratio of what to what is seen more in asthmatics?
Asthma: proteobacteria
Normal: bacteroides
Characteristics of exotoxin?
Usually AB type No fever Often via PAI Very toxic Can make toxoid
Characteristics of endotoxin?
Lipid A of LPS
GramNeg infections only
Fever via IL-1
Can’t make toxoid
How does alcohol work as disinfectant
Denatures proteins
Dissolves membranes
Dries out cells
(can’t kill all viruses or spores)
What is chlorhexidine limitation?
Spores
