Exam 1 Flashcards
What are nutrients required by bacteria?
C, H, O, N, P, S
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
Why is a fever considered “good”?
It pushes bacteria over optimum temp to kill them off
Define psychrophile, mesophile, thermophile, extreme thermophile.
Psychrophile - cold tempsMesophile - like moderate temps; neither too hot/cold (15-45C)Thermophile - like relatively high temps (40-70C)Extreme thermophile - like high temps (70-100C)
Describe the symbiosis between facultative anaerobe and anaerobe.
Facutative anaerobe makes env more anaerobic for the anaerobe
What is the O2 metabolism of an aerotolerant microbe?
Can grow in both, but Don’t use O2
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 nutrientsNew enzyme synthesis - up-regulation
What happens in the exponential phase?
Growth and binary fision
What happens in the stationary phase?
Crowding, starvation or toxic conditionsNew genes turned on to adapt to stress (usually toxins or virulence factor genes)
What happens in the decline phase?
Some cells lyse (maybe autolysis)
What is a persister cell?
dorman, non-dividing cell with slow metabolism
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
What are the importance of structural and regulatory associated proteins for bacterial chromosome?
Structural - anchors or bends DNARegulatory - 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
A protien that binds upstream of promoter to allow transcription is called…
Activator
An environmental signal that turns ON genes is called…
Inducer
An environmental signal that turns OFF genes is called…
Repressor
What is an induce for Lac operon?
cAMP
What is the uptake of unpackaged/”naked” DNA?
Transformation
What are the 2 types of transformation?
Natural and induced
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
Uptake of DNA by high temp that opens membrane pores and uses CaCl2 to shield DNA charges and use of physical methods is what kind of gene transfer?
Induced transformation
What is natural plasmid transfer called?
Conjugation
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
What phage cycle does specialized transduction use?
Lysogenic phage
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 KOxalobacter - absorb excess oxalic acidGut - 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
For how long and where do temporary/”transient” flora reside?
hours to months in an area where normal flora already exists
What are opportunistic/pathobiont organisms?
Organisms not normally pathogenic that can cause disease under some conditions
In what ways do opportunistic organisms cause infection?
Immunocompromised people, accidental injury, inflammation
Inflammation is regulated by what T cell ratio?
TH17:Treg
How does accidental entry occur?
During surgery when transient flora go places they shouldn’t
T/F: Skin organisms are hard to colonize, different for different sites (even fingers)?
T
Important organisms in skin:
- Staph epidermidis (sometimes aureus) survive NaCl2. aerobic Corynebacterium (moist areas)3. Propionibacterium acnes - make butyric and propionic acids from lipids (sebaceous glands) - acne vulgaris4. G- org in moist areas
Do pH equalizing soaps worsen acne?
Yes
Important organisms in nasopharynx:
diphtheroids - G+ club shape rods - Chinese char.These 3 are opportunists:1. Strep pneumoniae - move into lungs = PNA2. Neisseria meningitidis - gets released from attachments = meningitis3. Hemophilus influenzae
Imp organisms in mouth:
- alpha-hemolytic Strep (S. mutans)2. Staph epidermidis (and aureus)3. Pasteurellaceae - bites4. Actinomyces israelii
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:
- Lactobacillus2. H. pylori (~80% ulcers)
Imp organisms in duodenum (low pH):
- 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)
- Bacteroides2. Fusobacterium3. Clostridium4. Facultative enterobacteriaceae
What are pre-op prophylactic abx?
neomycin/erythromycin + metronidazole (flagyl) - for anaerobes
What happens if gut flora directly attaches to epithelial cells? Is it normal?
Not normal. Causes pathology
What are the 3 gut enterotypes?
Bacteroides (high fat/low fiber - carbs)Prevotella (low fat/high fiber - glycopeptides)Ruminococcus (most common)
T/F: Gut flora are more diverse from person-person but have the same function
T
Describe acidity pattern of the vagina?
Birth - acidic pHUntil puberty - neutral pHAfter puberty - acidic pH
What 2 organisms cause vaginitis?
Gardnerella, Mycoplasma genitalium
Imp organisms in the vagina
- Lactobacillus2. Bacteroides3. Prevotella4. Finegoldia5. Gardnerella6. Mycoplasma genitalium
What happens if there is too little Lactobacillus?
more vaginal infections
Imp organisms in conjunctiva (most killed by lysozyme)
- Staph/Strep2. Hemophilus 3. Neisseria
Where are sterile areas (no native flora)?
Lungs below tracheaInternal organs (except GI tract)Fluids (blood, urine, lymph, semen)CNSMiddle and Inner ear
Are chronic or acute conditions usually more severe?
acute
What is a subclinical infection?
infection but no symptoms = carrier
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
What are 4 enzymes that organisms use to get between cells?
- streptokinase2. hyaluronidase3. neuraminidase4. collagenase
What is the function of streptokinase?
Dissolve blood clots
What is the function of hyaluronidase?
Hydrolyze connective tissue
What is the function of neuraminidase (vibrio and shigella)?
Degrades sialic acid “glue”
What is the function of collagenase (clostridium perfringes)?
Destroys tissue
Organisms may be taken up into cells by what 2 classes of cells?
Professional and non-professional phagocytes
Hijacking of host cell actin and the formation of fillapodia networks is generically referred to as…?
Membrane ruffling
What mechanism do organisms taken up by non-professional phagocytic use to remodel the host’s cytoskeleton?
T3, T4, T6SS
Listeria uses what protein to get into host cells?
Internalin
What organisms use Ipas and Opas to promote engulfment by host cells?
Ipas - ShigellaOpas - Neisseria
What cells are professional phagocytes?
M cells, Peyer’s patches, DC
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)2. Antiphagocytic capsules (hide PAMP)3. M-protein and fimbriae4. LPS O-antigen variation or pili variation5. 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 them2. kill them3. prevent lysozomal fusion to phagocyte4. break out of phagolysozome5. resistance to lysozomal enzymes
Do you get a fever and inflammation with exotoxin or endotoxin?
endotoxin
What does septic mean?
Contaminated
What does sterile mean?
EVERYTHING killed
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 tests uses disks and zones of inhibition?
Kirby Bauer test
What test uses breath of killed bacteria and measurement to determine dose?
E test
What is the difference between the Kierby Bauer test and the E test?
Kirby Bauer - QualitativeE 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
How to the halogens, Iodine and Chlorine, work?
Iodine - interferes with protein foldingChlorine - oxidizing agent (NaClO
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
How do cationic detergents work?
solubilize cell membrane
What organisms are best treated by cationic detergents?
G+
