Micro Term 3 Flashcards
Pox-viridae
Replicates in the cytoplasm
Complex, enveloped, dsDNA, icosahedral. Group I
Herpes-viridae
BV, CMB, VZV, HHV 6,8
dsDNA, Icosahedral capsid, enveloped
Group I
Rhabdo-viridae
Group V. -ssRNA, helical capsid, envelope, bullet-shaped. Must supply its own RNA pol (group V)
Rabies - raccoons, skunks ,bats are animal reservoirs
Transmission: bite of infected animal, sometimes aerosol by bats
Rabies receptor: ACh receptor on neurons
Orthomixo-viridae
-ssRNA, helical capsid, enveloped Segmented genome, replicates in nucleus ie influenza Group V Influenza: sialic acid R on epithelial cells (cell tropism det disease)
Retro-viridae
+ssRNA, icosahedral capsid, enveloped. RT, diploid. RT –>RNA/DNA hybrid. Gropu VI
Reo-viridae
dsRNA, icosahedral capsid, non-enveloped (but three layers of capsid).
ie Rotavirus is a reovirus
Group III
boceprevir
Blocks protease activ sit, antiviral, hep C
saquinavir
blocks proteas, HIV AIDS antiviral
Viroids
Virus without a capsid or envelope - only genome. small circular nucleic acid. So far only found as pathogens on plants. Replicatd by host RNA pol II. Hep D similar structure.
RNA does not code for protein, but has an enzymatic function -ribozym
ss close circle RNA
transfer via plasmodesmata from cell to cell
likely to interfere with siRNA
Satellite viruses
(defective) cannot replicat without a helper virus - 100x more defective than normal viruses du to mutation
pseudovirions
wrong DNA ie host cell instead of viral genome - can infect a new host but cannot replicate
corynybacteriumd iphtheriae
Produces diptheria toxin encoded by existent lysogenic prophage - bacterial regulator of gene transcription responsible for turning off/on production of toxin, depending on low extracellular iron concentrations. Diphtheria toxin production does not require activation of the bacteriophage, or exiting the lysogenic cycle.
Boceprevir
Hep C drug, antiviral, blocks protease activ site
Saquinavir
HIV/AIDS antiviral blocks protease
Torque Teno Virus
(-) ssDNA - TTV transfusion trasnmitted virus, 100% human prevalence some countries, lifelong viermia but not linked ot human disease. ssDN conv to dsDNA
Normally sterile sites
Blood, CSF, Pleural fluid (chest fluid), peritoneal and pericardial fluid, bone, joint fluid, Internal body sites (brain, heart, lymph, kidney, etc.)
Microbiata composition in disease
Psoriasis: Increased firmicutes to actinobacteria
Obesity: reduced bacteroidetes to firmicutes
Childhood-onset asthma: absence of gastric H pylori (esp cytotoxin associated gene A genotype)
Inflamm bowel disease (colitis) : larger populations of enterobacteriacea.
Tryptone soy broth, nutrient agar
General purpose, cpts include macronutrients, micronutrients, carbon source
Enrichment media
Blood agar, BCYE agar - general purpose cpts plus blood serum, antibiotics tc.
BYCE - legionella spp enhancement
Selection & Differentiation media
Cpts: salts, dyes (ie brilliant green), antibiotics, etc as needed for selection or differentiation
eg. MacConkeys - enteric lactate producing bacteria, e. coli
triple sugar iron agar - identify gram negative bacilli
Assay ie antibiotic sensitiviy medium
carefully defined formula ie mueller hinton agar.
- kirby bauer assay for antibiotic susceptibility profiles
Mechanism of gamma rays (ionising radiation) as sterilization
Disrupts DNA
Microwaves as sterilization
non-ionizing radiation, disrupts cell membranes
Hydrogen peroxide plasma as sterilization
Free radicals interact with cell membranes, enzymes, or nucleic acids
Ozone gas for sterilization
Oxidation ie cell membranes
Autoclaving
Denatures and coagulates proteins
Susceptibility profiles of microorganisms from most to least resistant
Prions, endospores, mycobacteria, small non-enveloped viruses, fungal spores, gram negative bacteria, vegetative fungi, large non-enveloped viruses, gram positive bacteria, enveloped viruses
Bactria that does not have a cell wall
Mycoplasma sp.
Pellicle
Tough outer membrane of a protoza, replacing cell wall
Chitin
Cell wall of fungi. B 1-4 linked homopolymer of N-acetylglucosamine
Teichoic Acid
Only found in Gram + bacteria. Acidic polysacchard, polymer of ribitol or glycerol and phosphate. LTA is just TA but attached to a lipid on the cell membrane.
They are cell wall gycopolymers - roles in infection, candidates for vaccine?
Mycoplasma sp.
ie. Mycoplasma pneumoniae
lack cell wall, and have cellular membrane that contains sterols
Mycobacterium TB
waxy outer coat (mycolic acids) with high % of lipids - don’t gram stain
Results in slow growth (MGT 20-24 hrs), longer incubation times, chronic infxns. Arabinogalactan
Stained by acid fast (Ziehl-Neelsen method)
AFB positive: pink/red
Non acid fast: blue
Bacillus anthracis
Causes anthrax. Spores inhaled, ingested or enter wounds.
Clostridium tetani
Causes tetanus - spores enter anaerobic wounds
Clostridium botulinum
Causes botulism - anaerobic food; toxin ingested
Clostridium difficile
Causes PMC (pseudomembranous colitis), present in gut; can germinate when microbiome disrupted.
Components of endospore
Core: DNA, energy gnerating, calcium dipicolinate and SASPs for stab and protec
Spore wall: peptido
Cortex: unusual peptido - water removal
Coat: Keratin like, responsible for resistance to chemicals
Exosporium: proteins, lipids, carbs
Bacterial structures; capsules
Strongly attached, difficult to remove, highly organized, important for virulence - antiphagocytic. . Heavily hydrated, not all bacteria. Hide surface antigens and thus hide bacteria from immune system. Protects from dehydration, facilitates surface attachments. Mostly sugars (polysaccharides) and water.
Bacterial structures; slime layer
Loosely attached, easily removed, relatively disorganized. Protect cell against dehydration, facilitates surface attachemnt
H. Influenzae
Capsule composition - polyribotol phosphate
Orthomyxo family. -ssRNA, enveloped, helical. Segmented genome, replicates in nucleus.
Streptococcus Pyogenes
Capsule composition: hyaluronic acid (tricks immune system, recognizes)
K antigen
Capsular antigen
Atrichous
no flagella
Lophotrichous
flagella bunch at one end
Amphitrichous
Bunched flagella on both ends of bacteria
Peritrichous
Flagella all around cell - ie like a spider
H antigen
Flagella antigen
Borrelia burgdorferi
Lyme disease. Spirochete, build in endoflagellum
Treponema pallidum
Syphilis. Spirochte. Bild in endoflagellum
Actinomycetales
Order, main species include aerobic mycobacterium TB, mycobacterium leprae (leprosy), mycobacterium marinum (wound infections). Nocardia ie nocardia asteroides complex (nocardiosis)
Anaerobic: actinomyces
Mycoplasma spp
atypical bacteria. smallest prokaryotes capable of independent growth. have sterols in membrane. no cell wall
clsas name: molliculites (soft skin)
5 families : mycoplasmatacea most significant
2 key specifies: mycoplasma pneumonia, mycoplasma genitalium. Ureaplasma
Chlamydia sp.
Cannot survive out of living host celll, canot be culture on lab media. Small enough to pass thru bacteriological filters. Use tissue culture stains ie Giemsa.
species: chlamydia trachomatis - trachoma, STI
chlamydophila pneumonia - pneumonia
chlamydophila psittaci - ornithosis/psittacosis
Complex life cycle: elementary bodies (infectious) and reticular bodies (replicative)
Rickettsia sp.
Cannot survive out of host cell, cannot b cultured in lab, small to pass thru bac filter, gram stain not used - tissue stains ie Giemsa.
Rickettsia rickettsi - rocky mountain spotted fever
Zygomycota (fungi)
eg. Rhizopus. Some spp cause disease in humans, important cause of food spoilage
Ascomycota (fungi)
eg. Candida albicans. are >90% of pathogenic fungi
Basidiomycota
Some produce toxins or hallucigenic compounds.
Candida albicans
In ascomycota phylum (division) of fungi
Is dimorphic - in humans is in yeast form
In culture: mycelial
In superficial cutaneous and mucous membrane infections is yeast and pseudohyphae
Algae
Unicellular - diatoms, dinoflagellates
mutlicellular - seaweeds
cellulose walls, photosynthtic (chlorophyll and chloroplast)
can be an INDIRECT cause of disease - algal blooms, neurotoxins, resp irritation. bioaccumulate in fish & subsequent ingestion
ie Paralytic shellfish poisoning (PSP)
Prepatent period
Period between infection with a parasite and the demonstration of that parasite in the body. esp determined by recovery of an infective form oocysts or eggs from blood or feces) (similar to incubation period of bacteria) - biologically different, parasite is undergoing developmental changes in host.
Four groups of protozoa based on movement
Sarcodina (amoeba), mastigophora (flagellates), ciliophora (ciliates), sporozoa (adult stage not motile)
Lymphatic Filariasis (nematode)
Vector borne, blood associated pathogen. Endemic in 83 countries, 120 million cases - 25 mill men with hydrocoele. 15 million people with lymphedema
Tropical africa, asia, americas, pacific - 66% clustered in SE asia, remaining in Africa. 2.8 million DALYs
Wucherria bancrofti, worms invade lymph nodes,
Schistosomiasis
Trematode ie fluke
Snails are host - cercariae penetrate skin of humans. ie transcutaneous from wading in infected freshwater. dermatitis, Humans are reservoirs (Liver and spleen enlargement, fibrosis, inflammation, portal HTN. Chronic infection can lead to squamous cell carcinoma of bladder nad pulm HTN. )
Echinococcus
Hydatid disease. Cestode (tapeworm)
diagnosis: imaging, serologic testing, exam of cyst fluid
cyst formation, rupture can cause anaphylaxis.
Ingestion of eggs in food contaminated with dog feces
sheep - intermediate host.
Generalized life cycle of the Nematodes
3 stages: egg, larva, adult
Pre-parasitic; for living or intermediate host
parasitic: definitive host, lara to adult
Paralytic Poliomyelitis
Fecal oral path, intial propagation in small intestines, viral reach to mesenteric lymph nodes. Initial viremia, secondary viremia to CNS - paralysis in 1% due to slow cycle time, allowance for IgG buildup.
Poliovirus (PERCH) is a picornavirus. ie +ssRNA, icosahedra, naked. Group IV.
Viruses causing perinatal infection transplacentally
CMV, Parvovirus B19, Rubella Virus
Viruses causing perinatal infection at time of birth
Hep B, Hep C, HSV 2, HIV, HPV
Viruses causing perinatal infection breast feeding
CMV, Human T cell lymphotropic virus
Focus-forming Units (FFU)
Quantify viruses that do not lyse the cell to make PFUs. Fluorescently labeled antibodies against viral cell surface proteins.
Our microbiata
Actinobacteria (skin nares), Bacteroidetes (mouth, gut), firmicutes (GU, mouth, gut etc), fusobacteria (mouth), protobacteria (mouth, skin)
Bacterial genome properties
dsDNA, single chromosome, circular or (sometimes linear), haploid no associated proteins, ribosomes: 70s composed of 50 and 30s, genome in the nucleoid
mycoplasma genitalium
chromosome size 0.58 . one of the smalllest bacteria that can still grow on agar - otherwise become obligate intracellular.
Mannitol Salt Agar
Selective: staph not inhibited by 7% NaCl. and Differential: S. aureus looks different than S. epidermis (acid production)
Bordetella Pertussis
Growth requirement: nicotinamide.
Bordet genou agar (potato extract)
Haemophilus sp
Growth requirement: X (hematin) and V factor (NAD+), chocolate agar contains X and V.
Legionella sp
Growth requirement: L-cysteine and iron
BYCE enhances growth
Disinfectants and antiseptics for bacteria
Everything except quat ammonium (disinfect). Antiseptic: everything, but parachlorometaxylenol is least effective
Disinfectants and antiseptics for mycobacterium
disinfectants: all except iodophores are less effective, and not quaternary ammonium compounds
Disinfectants and antiseptics for bacterial spores
Disinfect: Only formaldehyde and glutaralehyde are completely effective. H2O2 and chlorine are partially effective.
Antiseptic: none
Disinfectants and antiseptics for fungi
Disinfect everything except quat ammonium only partially.
Antiseptic: everything except triclosan less effective
Disinfectants for viruses
disinfect: Everything works except alcohol, phenolics, and quat are all only partially effective.
antiseptic: everything except parachorometaxylenol only partially effective
Algae cell wall composition
Cellulose, B(1,4) linked D glucose
Protozoa membrane
No cell wall - replaced by pellicle, a tough outer membrane
Fungi cell wall
Chitin ie B (1,4) linked homopolymer of N-acetylglucosamine (NAG)
Example of species with built in endoflagellum, for corkscrew attachment
Borrelia burgdorferi - lyme disease
treponema pallidum - syphilis.
Asexually produced fungal spores
Mitosis only : sporangiospores, conidiospores
Sexually produce fungal spores
Meiosis. Ascospores (sac), Basidiospores (club). How spores form is used for phylum classification
Tsetse Fly
Lif cycle: only asexual repro, so both in human and in fly.
Infective stage: blood meal
Diagnostic stage: Trypomastigotes in blood, after multiplication by binary fission
Clinical presentations of Amoebiasis (Entamoebae histolytica)
Noninvasive intestinal infection, amebic colitis, necrotising colitis, ameboma, liver abscess.
Diagnosis of certain blood-borne infections
Blood smeras
Thick: concentrate RBCs, lyse - high density of parasite numbrs
Thin: monolayer, better for structural detail. ie Differentiate between species of plasmodium. See band or ring forms etc.
Diagnostic use of Ultrasound for parasites
Dx Echinococcosis, Cysticercosis, Onchocerciasis, Lmymphatic Filariasis (microfilariae).
Info includes abscess/cyst/space occupying lesion
Number, size, location and condition.
Giardiasis
G. Lamblia. Group mastigophora (flagellats)
Fecal - oral route - day care, mountain sreams. Symptoms vary with host, asymptomatic –> acute –> chronic diarrheaa
2-3 billion cases world wide, 1-2 million/year in US. Most common.
Sporozoa
Group of protoza (adult stage non-motile) Phya: apicomplexa
Eg. Plasmodium (cause of malaria)
Plasmodium
A protoza, group sporozoa,
Cause of malaria
Exception: Protozoa that undergoes multiple fissions with sexual reproduction.
Definitive host is mosquito, not humans. ie sexual repro in mosquito.
Multi-stage lifecycle of most protozoa
Most have multi-stage life cycles with cyst and trophozoite forms eg. entamoebae histolytica
Trophozoite: motile, feeding stage, larger
Cyst: non-motile, resistant, smaller, multinucleated survival form.
Some (one or two) only have trophozoite stage.
Infective forms of intestinal protozoa transmitted by fecal-oral
Cyst, Trophozoite, oocyst
Infective forms of urogenital protozoa transmitted by sexual transmission
Trophozoite (t. vaginalis)
Infective forms of blood and tissue protozoa transmitted by insect vectors except for *
- cyst/trophozoite
pyrifiform body
*oocyst
promastigote, trypomastigote
Ascaris lumbricoides
Nematode (roundworm) metazoa
Reservoir: moist, warm shaded soil
Infection: ingested fertilized eggs (fecal/oral)
Diagnosis: eggs in faeces (microscope), worms in faeces mouth or nares.
Symptoms: Lungs (larvae) - asthma or pneumonia-like, cough SO wheeze. Intestine (adult worms) - diarrhea or bloody stools, Gen GI, severe: malnutrition, weight loss
Schistosomiasis
Trematode infection (fluke) metazoa
Reservoir: various animals ie dogs, cats, rodents, pigs, horse, goats.
Intermediate host: snails
Infection: transcutaenous ie wading in deep water. Infected cercariae swim, penetrate the skin of the human host
Diagnosis: eggs in faeces and urine
Echinococcus life cycle
Definitive host: SI of dogs, other canines. Becomes infected by ingesting the cyst-containing organs of infected intermediate host.
Diagnostic: Hyatid cyst in liver, lungs, etc.
Intermediate host: sheep, goats, swine, cattle, horses, camels, humans
Infective forms of nematodes (roundworms) metazoa
Egg, filariform larvae, 3rd stage larvae
Infective forms of trematodes (flukes) metazoa
Cercaria, Metacercaria
Infective forms of cestodes (tapeworms) metazoa
Proglottid, embryonated egg, cysticercus, cystericercoid
Trematode generalized life cycle
(1) miracidia - ciliated first stage larva, emerges from egg. Must penetrate intermediate host (ie snail) to continue life cycle. Followed by development of mother sporocyst.
(2) Sporocyst - larval form. Saclike srxr with germinal cells, bud off internally ,dvlp to other larval types
(3) cercariae - free swimming trematode. entry routes include skin penetration, encysting on vegetation or fish, penetrate and encyst arthropod hosts.
Cestode (tapeworm) generalized life cycle
Eggs from adults excreted, ingested by intermediate host, larvae develop, enter circulation and encyst, intermediate host consumed by definitive host, encysted form released in intestine; develops into adult.
Paratope
Antibody variable (H and L) domains which recognize and bind epitope, binds by non-covalent reversible forces
CDR
Complimentary detrmining regions on antibodies - 5-10 aas long, each variable domain has 3 CDRs.
CRD 3 is the most variable, closest to the C domain.
Rheumatic Fever
Some infections can trigger autoimmunity against self-antigens – complication caused by group A streptococcal infections due to cross-reacting antibodies. Antibodies against strep, clear bacteria. but cross react with self antigens and get swelling of joints, and dangerous potential damage to heart.
VDRL (Venereal Disease Research Lab) Syphilis Test
Uses cardiolipin extracted from ox heart as antigen. Fives flocculation - precipitation clump, with anti-syphilis antibodies. Identifies early syphilis infetions (treponema pallidum). Positive CSF reaction indicative of neurosyphilis. May give false positive results - ie in drug users, malaria, leprosy, measles, viral pneumonia, SLE, relapsing fever
IgG
IgG’s are monomers. 4 subclasses, differ in number of disulfide bonds and length of hinge region, aa sequence of constant heavy region
Most versatile Ig, can carry out all functions. Major Ig in serum (75%), major in extravascular spaces, capable of fixing complement (EXCEPT IgG4 does not)
IgG functions
Neutralization of microbes nad toxins. Opsonization of Ag for phago by macro and neutrophil. Activation of classical pathway of complement. Ab dependent cell cytotoxicity mediated by NK cells. Neonatal immunity - transfer across placenta and gut. Feedback inhibition of B cell activation.
Hepatitis B
Hepadnavirus family. dsDNA, enveloped, icosahedral
Group VII.
HIV receptors
CD4 with either CCR5 or CXCR4 on Th cells, macrophages.
Horizontal Gene Transfer
Via defective bacteriophage, partial host genome transferred to a new host
Cryptic Virus
Mutation in prophage leads to dysfunctional, embedded genome. Cannot leave
Chemoorganotroph
Use chemical energy, organic C as energy and C source. Ie pathogenic bacteria, fungi, and protozoa
Action of ethylene oxide gas as a sterilization technique
Alkylates amino acids, nucleic acids, etc
Lysozyme targt
Targets B1-4 glycosidic bond between NAM and NAG in PG of bacteria
Penicillin target
Interferes with PG crosslinking by transpeptidases
Positive stain
Ie basic dye with positive charge. Stains negatively charged molecules, ie cytoplasm of bacteria is negatively chartged
eg crystal violet, safranin, basic fushin, methylene blue
negative stain
Ie negative charge acidic dye, Is repelled from negatively charged molecules ie bacterial surface so dyes outside depositing aroudn the organism leaving the microbe clear but its border stained.
Fungal reproduction three mechanisms
- Production of spores (asexual - sporangio and conido) or sexual (ascospores, basidiospores)
- Budding
- Hyphal fragmentation
Asexual fungal spores (mitosis only)
sporangiospores, conidiospores
Sexual fungal spores (meiosis)
Ascospores, basidiospores
