Week 1 Review Flashcards
two general types of stains
gram and acid fast
throat swabs and fecal samples are never
gram stained because natural flora would stain with both
gram positive bacteria stain
purple with crystal violet+ which is embedded in the peptidoglycan layer(Cell wall)
Gram negative bacteria stain
red when saffarin is added after washing away CV+ with acetone or ethanol
Acid Fast Stain is sued for
acid fast bacteria that do not pick up the gram stain.
two genus of bacteria that are acid fast
mycobacteria (wekaly G+) and Nocardia (weakly G+
Ziehl Neelsen Stain
uses hot initial stain and cool counter stain, acid fast batriea appear red/pink and non acid fast appear blue or green(depending on methylene blue or malachite green was used.
Kinyoun Stain
does not require heating initial stain, same as ZN stain
Fluorochrome stain
uses rhodamine class fluorescent dyes
4 types of bacteria
obligate aerobes- can’t live without oxygen, and have catalase, peroxidase and superoxide dismutase
- -Faculative anaerobes, aerobes which have the capacity to ferment sugars in the absence of alcohol.
- -Microaerophiles- have no ETC but can tolerate low concentrations of oxygen since they have superoxide dismutase but no catalase.
- obligate anaerobes -soil dwelling bacteria that have no ETC and no enzymes that can degrade oxygen radicals and ROS
Typical bacterial size
.2-10micrometers except for mycoplasma spp.
4 major shapes of bacteria
cocci(spheres), Bacilli(rods), spiral(curved or twisted, square(not infectious, pleomorphic (lacks a distinct shape.
all coccoidal bacteria are
non motile except for the spirochetes(G- bacteria)
5 basic bacterial arrangements
single, dipolococci(pairs), streptococci(chains) staphylococci (clusters), tetrads.
Flagella is required for
motility in all bacteria except for spirochetes
flagella arrangement is either
polar, lateral/helical, in arrangment.
helical filament is composed of
flagellin(H antigen protine)
non motile bacteria which do not have flagella will be
H+
hook is a
short curved portion which anchors the helical filament to the basal body.
basal body
always contains a rod and 1 G+ or 2 G- sets of double rings which rotate in a Cw or a CCW direction.
S/M rings are
located in the inner membrane and are needed for rotation
L/P rings are located in
outer membrane (only in G- since G+ have only one lipid containing membrane and are used for stability.
Taxis
involuntary movement in response to a stimulus
Chemotaxis
voluntary movement in response to chemical stimulus (20 attractant and 10 repellent receptors in the cytoplasmic membrane)
unique to gram +ve
Thick petidoglycan layer that have Teichoic and Lipoteichoic acid. (these bind protons, adhesins and are virus receptor site.
Why do gram +ve stain purple
the stain penetrates teh petpidoglycan layer and attaches to the phospholipid layer of innermmebrane, when the wash is then enacted it shriks teh petidoglycan layer so that it traps the dye and it isn’t removed.
- have perplasmic space inonly some
- more permeable.
Unique to Gram -ve
thin peptidoglycan, has an outer membrane of braun proteins, has porins and lipopolysacc an endotoxin
- -have lipoproteins and peptidoglygan
- all have a periplasmic space and porin proteins,
- is less penetrable.
Lipopolysaccharide structure
O antigen is a a repeat of 40 units it has a core polysaccharide and toxic fatty acids and lipid A
LipoOligosaccharide
(bordella pertussis and neisseria meningitidis, C jejuni)
has a core and a Lipid A lacks O antigen. a terminal end.
Why do gram -ve stain rd
the peptidoglycan layer can’t shirnk enough to trap the crystal violet so it shrinks away.
effects of lysozyme
breaks Beta 1-4 bonds between NAM and NAG, so it destroys either a portion (spheroplas, Gram -ve due to porins) or the entire cell wall (grame +ve)
effect of penicillin
Prevents cell wall formation by binding to the PBP transpeptidases. this causes defective cell wall and no protection from osmotic shock
Mycoplasmataceae
lack cell wall their entire life and no petpidoglycan so they stain pink , resistant to cycloserine, lysozyme and penicillin
cotains sterols in their membrane and the cytoplasm is only ribosomes and DNA, very small genome.
–grows in diphasic colonies tha thav e afried egg like appearances
–require an agar with sterols and serum proteins.
– attachemnt to organelles is with a tapered tip plus P1 adhesin.
Rickettsiaeceae
genera rickettsia and prientia, are obligate intracellular pathogens and not cultivated on agar. they are also zoonotic through arthropods.
– rod/coccobacillary shapes, closely related to gram-ve have diaminopimelic acid. some have a capsule
Anaplasmataceae and Coxiella
medical importance- E. Chaffensis, E ewingii, A. phagocytophilum and C burnetti
are small oblicage intracellular pathogens that are also zoonotic.
Chlamydiaceae
Chlamydia, C ttrachomatis- only man to man
Chlamydophila- C psittci and C. Pneumoniae are zoonotic from bird to man,
–obligate intracellular pathogens that don’ generate ATP and descendants of Gram 0ve with 2 membranes but NO peptidoglycan. in 1 stage of life.
– has deveopmental forms elementary body and Regiculate body.
Developmental cycle of Chlamydiaceae
EB taken into host cell by phagocytosis, Next 8 hours EB reorganises –> RB Rb grows and divides by binary fission 24-48 hour RB reorganises –> EB and the host cell liberates EB
Characteristics of Fungi
Ekaryotic Saprobes.
two forms yeasts and moulds
Yeasts
unicelluar round oval and have asexual reproduction by budding using pseudohyphae
Moulds
multicellualr , hyphae with sexual or asexual reproduction(spores)
Hyphae have this and psuedohyphae don’t
permanence, differentiation, branching, arthrospores and chlamydiospores.
ALso have septate and aseptate.
Mycelium
an intertiwned mat of hyphae, some are vegetative (roots) and reproductive are the areal structures.
Dimorphic Fungi
Same organism exhibits mould and yeast form.
pathogeneicity is usually in yeas form at 37 *
Asperigillus sp, is always in mycelial phase, Torula is only a yeast. all appear gram positive.
Only fungus that has a capsule
Crypococcus neoformans.
Cell wall of Fungus
Thick and rigid, no peptidoglycan 75% polysacharide and 25% protein. Chitin with beta Glugan which is a target for treatment.
Cytoplasmic membrane of fungus contains
ergosterol
4 pathogenic subdivision
Zygomycotina, Ascomycotina, Basidomycotina, Deuteromycotina.
zygomycotina
no primary pathogens are opportunisitc, most primitive and are filamentous non septate. reproduce sexually and asexually through asexual spores.
ascomycotina
have sepatate asexual spores are conidia sexual spores are ascospores,
are yeats and mulds, dermatophytes some aspergillus sp.
Basidomycotina
septate produce sexual spores basiditospores, are mushrooms and puffballs.
aquisition of fungal infection means
systemic =inhalation subcutaneus= puncture wound, cutanesou =invade keratin and cutaneous tissue
Superficial, infections of skin and hair.
opportunistic, debilitated and traumatized patients immuno suppresed.
Gram positive Bacteria
cocci–Staphyloccocus, Streptococcus, Enterococcus.
Rods–Bacillus, Clostridium, Corynebacterium, Lactobacilli, Listeria, Propionibacterium
