MICROB 2800: EXAM 1
72 Cards in this Set
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coccus
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spherical prokaryotic ball; bacterial shape
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bacillus
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rod shaped prokaryotic cell
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spirillum
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spiral-shaped prokaryotic cell
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vibrio
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comma-shaped prokaryotic cell
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pleomorphism
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when cells of a single species vary to some extent in shape and size
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irregular cluster infection
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Staphylococci and Micrococci
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chain-shaped cocci infectious disease
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streptococci
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Bacterial capsule
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located outside the cell wall
- usually sticky, viscous, gelatinous polysaccharide
- serves 3 functions: (1) attachment (2) prevent phagocytosis (3) differ among bacteria in thickness, organization, and chemical composition
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chemotactic
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cells move toward increased concentrations of that chemical (runs and tumbling)
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Fimbriae
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Hairlike, protein appendages found on prokaryotes. Used to help cells stick to surfaces and other cells.
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pili
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minor attachment and genetic transfer; protein that is used in conjugation
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peptidoglycan
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contains a protein-like sugar
Important b/c if we know if a cell has this, we can target and kill bact. cells and not human cells b/c only bact. have peptidoglycan.
only 2 sugars found in peptidoglycan (NAG and NAM)
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Gram-positive
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One lipid membrane surrounded by large, thick cell wall of PPG
-“Interwoven” in PPG sheets are teichoic acids = unique to the cell wall
• Stabilizes the cell wall and makes it stronger
- does not have outer membrane
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gram-negative
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Two lipid membranes (OM/IM) with periplasmic space (PPS) between
-No teichoic acids
-has outer membrane
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inclusions and granules
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storage structure during periods of nutrient abundance/depletion
inclusions are usually high energy
granules usually crystals of inorganic compounds
storage and survival under varying conditions
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bacterial genome
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dsDNA aggregated in a dense area of the cell (aka “Nucleoid”)
-Encodes everything: replication, structural, virulence properties, etc
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plasmids
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-Nonessential, sharable, “extra-genomic” pieces of circular dsDNA
• Often carry protective genes such as drug resistance genes or virulence factor genes
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ribosomes
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prokaryotic: 30 small subunit, 50 large subunit= 70S
- humans have 40 small subunit and 60 large subunit=80S
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Endospores
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-not offspring or reproductive forms. They are
dormant and metabolically inactive structures
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Spore will germinate (break from dormancy), allowing it to convert back into a growing bacterium.
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virus
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an infectious agent composed of nucleic acid, a protein shell (capsid) and an optional lipid envelope
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most common cause of acute infections that do not require hospitalization
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virus
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must have host cell
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virus
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tropism
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May infect, but only multiply if they invade a specific host cell type
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capsid
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-protein coat that covers and protects
the viral genomic material
-surface proteins can also allow for attachment to the host cell
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Two Major Shape Classifications of Capsids
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--Icosahedral -top circular
--Helical -- bototm rod shaped
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envelope
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optional) outermost coating of
protection for a virus, surrounds the capsid
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RDRP
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=essential to all RNA viruses regardless of (+) or (-)
-LOUSY at proofreading -- leads to high variation in populations (“mutations” known as ANTIGENIC DRIFT)
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RDDP
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used by retroviruses and known as reverse transcriptase
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normal flora
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normal bacteria found in a healthy person
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endogenous
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bacteria that is already within us
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exogenous
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bacteria that comes from outside sources
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strain
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similar, yet unique variants of one another; think dog breeds
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pathogenic
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ability to cause disease/harm
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Opportunistic pathogen
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a microorganism that normally does not cause disease but can under certain relatively unusual circumstances'
-can switch from good to bad especially when introduced to new locations
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What is a dedicated/Obligate pathogen?
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Not found in harmonious relationship w/ host
"Does not play nice w/ others"
actively trying to causes disease (exogenous)
-doesn't have to be successful, but it tries
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Virulence
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Degree or extent of pathogenicity
-severity of the disease depends on the arsenal of the pathogen and the host's susceptibility
-LD50, ID50
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virulence factors
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-molecules used to aid invasion and establish themselves in the host
-produce recognizable signs and symptoms
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2 types of virulence factors
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1. Physical cell structures (structural components)
2. Functional microbial proteins (“dedicated havoc molecules”) !
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biofilms
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Complex formations and associations of microbes
-miniature sites of microbes
-highly defended and very hard to treat
-normal growth of bacteria
-often involve many species of bacteria
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enzymatic factors
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-Similar to toxins but typically work on OUTSIDE of host cells.
-gain entry to deeper tissue layers
-proteins released from bacteria can chew through you (-ase)
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adhesion
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-external structures pili (genetic transfer,conjugation) and fimbrae (attachment)
-capsule (antiphagocytic)
-SPECIALIZED (M-protein or strep pyrogenes that has carefully evolved to attach to specific cells)
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2 major categories of toxins
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1. A-B subunits
2. pyrogenic
-toxins may travel to other body locations beyond the localized infection
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A-B Toxin
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B-unit- is for the binding site and facilitates the entry of the A unit
A-unit- active enzymatic activity
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MoA's for A-B toxins
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1. Protein synthesis inhibitors which targets ribosomes and shuts down protein synthesis
2.affect adenylate cyclases which leads to uncontrolled exports
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pyrogenic toxins
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non-specific host cell targets
-“Superantigens” - bacterial toxins that are potent activators of immune cells and often lead to the unneeded proliferation of T-cells which leads to toxic shock or inflammation
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TSST-1
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S.aureus Toxic Shock Syndrome Toxin (TSST-1) -- often associated with extended-use tampons
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SpeA/C
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Streptococcal pyrogenic exotoxins (SpeA/C) -- often associated with Strep TSS and “flesh eating disease” (erythrogenic)
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Lipopolysaccharide (LPS) pyrogenic toxin
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in gram-negative only (endotoxin)
-made of lipid A
LPS released from cell wall of Gram(-) upon lysis
• Overactivates immune cells
Generates a massive immune cytokine response
Fever, general inflammation, circulatory collapse, shock
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invasion
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Hiding & replicating inside host cells
-avoids immune detection
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circulation
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external structural for locomotion such as flagella
-traveling usually requires additional protective countermeasure like capsules
-must avoid immune killing/capturing
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quorum sensing
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cell-cell communication in bacteria
based on species specific signaling molecules that are secreted by cells and diffuse through the environment
response varies greatly (light emission, biofilms, etc.)
allows closely related bacterial cells to communicate and coordinate activity
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budding
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causes an envelope from the cell membrane to form around bacteria
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cytopathic effects
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virus-induced damage to the cell that alters its microscopic appearance
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4 types of CPE
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CPE 1= Lysis of cells - dead/necrotic/absent cells
CPE 2= Fusion of cells - “syncytia” or “giant cell” formation with abnormal function
CPE3= Inflammation - immune response to virus/abnormal cells
CPE4= Inclusion bodies - compacted masses of viruses or damaged cell organelles
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3 Parts to Anthrax Toxin
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1. PA- chaperone, acts as a “B” unit
2.EdemaF-“A” unit, upregulates cAMP & results in heavy edema
3. LethalF-“A” unit, stops cell signaling pathways resulting in cell death
Must combine PA + EF OR PA + LF to be effective
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Neisseria meningitidis
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-gram negative kidney-shaped diplococci; 7-25%
-VF: pili, capsule, LPS-causes the most serious form of meningitis and major immune response-shock
-bloodstream=Meningococcemia-LPS AND RASH
-Waterhouse-Friderichsen Syndrome: N.meng infection of adrenal glands
-capsule B is the most caus…
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Streptococcus pneumoniae
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gram+ lancet shaped diplococci
-common after ear infections, pneumonia---VF=capsule
-DOES NOT cause rash like n. meningitis
-1/3 of survivors will have neurological effects
-80 different capsules, but cap 3 is the WORST
-developing resistance to 3GCephs
-Prevnar and Pneumovax are pr…
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Haemophilus influenza
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-tiny Gram- pleomorphic rods
-leading cause after ear infections
-VF:capsule
-Part of N.Flora, OPPORTUNISTIC PATHOGEN
-type B was the major causative, but vaccine has virtually controlled it
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Listeria monocytogenes
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Gram+ varies in shape
-Food-bourne pathogen
-resistant to cold
-in healthy adults, the result is diarrhea
-in elderly or immunocompromised patients, fetuses, or neonates → affects the brain/
meninges and septicemia
VF: Invasin, lysteriolysin (LLO), actin nucleator (“comets”), moti…
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Neonatal Bacterial Meningitis
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-almost always transferred in utero or birth canal
*Gram(+) Streptococcus agalactiae (aka “Group B strep” in short chain)
in 90% of mother's N.flora; "childbed fever in mother is dx and she can then get meningitis too
*Gram(-) Escherichia coli from fecal flora contamination • Identifyi…
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Cryptococcus neoformans
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-fungal infection
-chronic with slow and gradual symptoms
-associated with birds or decayed plant matter; VF: large capsule
-dx:capsule stain on India stain
--More respiratory involvement than some meningitis cases
--May also have “gummy,” wet skin rash
-more respiratory involvement…
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Coccidioides immitis
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-fungus causing secondary meningitis
Usually begins with pulmonary infection prior to meningitis
• Found in soil, endemic in SW USA – “San Joaquin Valley Fever”
-Identifying characteristics are “Bag of coins” and “blocky spores” appearance microscopically
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viral meningitis
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-generally milder than bacterial
-90% caused by viruses migrating from other sites, often as RESPIRATORY
CC: ‘enteroviruses’ = human GI viruses
-aseptic
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Acute Encephalitis
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-almost always a viral infection; not contagious
-swelling of the brain tissue
-some people have milder symptoms including swollen LN, vomiting, and rash, but most have NO symptoms
-use antivirals and treat symptoms immediately
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Arborvirus Family
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vector-borne via insects
-non-intentional hosts are horses, birds, humans
*WESTN: only 1:150 will develop serious illness, but since it can infect nearly everyone; mutations
*ST. LOUIS ENCEPH: most common encephalitis that usually occurs in ADULTS
*LACROSSE/CALIFORNIA: non-fatal encep…
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Other Virus Families
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Herpesvirus: severe enceph. that is common in newborns & mothers HSV+----prognosis is poor--acyclovir
*JC Virus: “progressive multifocal leukoencephalopathy” (PML); most common in HIV/AIDS ppl; attacks brain cells and demyelinizes cerebrum
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Measles virus encephalitis
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PIE (post infection enceph) - part of immune response, not virus-related • Can follow MMR vaccine
-SSPE (subacute sclerosing panencephalitis) - years post-measles from persistent virus and direct infection... unclear why, but HIGH rate (~1:150)---latency
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Toxoplasma gondii
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-flagellated parasite
-reservoir in cats
-Mother asymptomatic or marked by mild symptoms such as headache, sore throat, lymph node enlargement, and low- grade fever
VF: eukaryotic and "fear factor"
-Identifying characteristics: appearance of parasite in tissue or cysts in muscle/brain…
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Rabies
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zoonotic and fatal encephalitis
cc: rhabdoviradae
vf: viral, enveloped
"furious rabies":Periods of agitation, disorientation, seizures, and twitching; Spasms in the neck and pharyngeal muscles lead to hydrophobia
"dumb rabies": Patient is paralyzed, disoriented and stuporous
-Immedia…
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Prion TSE's
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-transmissible spongiform encephalitis
-deposit of brain cells that lead to large holes in the brain (sponge)
*Mad Cow Disease: exogenous/consumed
*Creutzfeldt-Jakob disease (CJD) (mutated normal prion)
VF: convert normal proteins to bad proteins
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tetanus
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lockjaw
-Rigid paralysis disease -- clenching of the jaw, extreme arching of the back, flexion of the arms, and extension of the legs
cc: clostridium tetani- G+ spore-forming rods- gram stain is "lollipop"
vf: powerful neurotoxin called tetanospasmin
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Botulism
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-usually associated with eating bad preserved food
-symptoms:descending (flaccid) muscular paralysis and respiratory compromise
Food-borne– Ingestion of preformed toxin
• Infant botulism (‘floppy baby syndrome’)
– Entrance of botulinum toxin into the bloodstream – Honey as a major s…
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MICROB 2800: EXAM 1