EXAM 2 Flashcards
study of bacteria
bacteriology
study of fungi
mycology
study of parasites
parasitology
study of viruses
virology
prokaryote characterisitcs
- unicellular
- lack a membrane-bound nucleus
- lack membrane-bound organelles
- simpler genetic makeup
archaea
- cell wall lacks peptidoglycan
- dont cause human disease
size of bacteria
0.2 micrometers to 750 micrometers
micrometer
1x10^-6 meter
coccus
sphereical shaped
spirochete
spiral shaped
bacillus
rod shaped
strep
grows in a chain
staph
grows in grape-like clusters
diplo
grows in pairs
phospholipid head
polar-hydrophillic
phospholipid tail
nonpolar-hydrophobic
peptidoglycan
rigid, net-like lattice comprised of sugars (glycans/polysaccharides) and amino acids
how are peptidoglycans linked
2 repeating diasaccahrides crosslinked by short tetrapeptides
gram negative stain technique
allows classification of bacteria based on cell wall structure
gram negative bacteria
- stain pink
- THIN peptidoglycan layer in the cell wall
- contains periplasm between inner and outer membranes
- outer membrane present
- LPS present
- NO teichoic acid
gram positive bacteria
- stain dark purple
- THICK peptidoglycan layer in cell wall
- NO outer membrane
- MINO periplasm
- NO LPS
- contain teichoic acids
acid fast bacteria
cell walls contain waxy lipid called mycolic acid
- stain weakly as gram positive
flagellum
a thread-like appendage made up of multiple subunits of the protein flagellin *used for motility
chemotaxis
movement of an organism in response to chemical stimuli
phototaxis
movement in response to light stimuli
areotaxis
movement in response to presence or absence of oxygen
pilus
hair-like appendage, comprised of the protein pilin, that is found on the surface of many bacteria
*stick to surfaces
conjugative pili (sex pili)
used during conjugation to transfer DNA from one bacteria to another
conjugative pili steps
- pilus makes initial contact with recipient bacteria
- pilus draws in recipient bacteria
- DNA (mobilized plasmid) transferred from donor to recipient
- both bacteria now contain DNA in question
type IV pili - twitching motility
- movement along a solid surface
- crawling action
- only found at poles of cells
- important host colonization factor in certain pathogens
fimbriae
short structures used for attachment to surfaces
glycocalyx
viscous, gummy layer surrounding certain bacterial species
- typically polysaccharides, but can be polypeptides
- composition and thickness vary
slime layer
loose coating that does not exclude small particles
capsule
tight coating that does exclude small particles
functions of glycocalyx
- protection from environment
- protection from immune system
- attachment to surfaces
cytoplasm
gelatinous solution comprised of water, protein, carbohydrates, lipids, inorganic ions, and low-molecular weight compounds
*also contains nucleoid, plasmids, ribososmes, and inclusion bodies
what do prokaryotes lack
- cytoskeleton
- endoplasmic reticulum
- mitochondria
- microsomes
nucleoid
- single circular segment of double stranded deoxyribonucleic acid (DNA)
- encodes genetic information for cell function and structure
- smaller than most genomes
how many million base pairs is the human genome (haploid)
3,234 Mbp
plasmids
circular, extrachromosomal DNA found in many (but not all) bacteria
- replicate independently
5 classes of plasmids
- fertility F plasmids
- resistance R plasmids
- col plasmids
- degradative plasmids
- virulence plasmids
inclusion bodies
amorphous particles in cytoplasm used as reverse nutrients stored during periods of nutrient abundance
endospores
- metabolically inactive structures that preserve the cells genetic information, allowing the cell to survive during times of extreme stress
- highly resistant to environmental stress
- can germinate back into vegetative cell
sporulation
bacteria storing genetic information in a pod during times of environmental stress
what kind of bacteria produce most endospores
gram negative bacteria
how do bacteria grow
binary fission
what elements are required in large amounts for bacteria to grow
N2, H2, CO2, Carbon, PO4, Iron, Sulfur, Potassium, Calcium, Magnesium and energy
what elements are required in trace amounts for bacteria to grow
Mn, Zn, Cobalt, Molybdenum, Nickel, Copper, Selenium
prototroph
a microorganism that can derive all nutritional requirements for growth from the micronutrients and macronutrients supplied
fastidious
microorganisms that have complex and special nutrient requirements
- might require special vitamins or amino acids to grow
obligate aerobe
absolute requirement for O2
facultative aerobe/anaerobe
grow either aerobically or anaerobically
obligate anaerobe
ideal growth in absence of O2
4 phases of bacterial growth
- lag phase
- exponential (logarithmic) phase
- stationary phase
- death
lag phase
initial or beginning of growth
exponential phase
great increase in numbers
stationary phase
no increase in number of bacteria
heterotrophic bacteria
- essentially all pathogenic bacteria
- obtain energy from organic compounds
photosynthetic bacteria
- synthesize their own glucose
- less apt to be pathogenic
autotrophic bacteria
- no sunlight
- no organic compounds
- use inorganic compounds
- less apt to be pathogenic
what are the ways bacteria can generate energy
- aerobic respiration
- anaerobic respiration
- fermentation
- photosynthesis
bacteria producing energy through aerobic respiration
- major energy producing mechanism for aerobes
- consists of 3 major pathways: glycolysis, krebs cycle, and electron transport chain
how much ATP does 1 molecule of glucose yield
38 molecules
what is the primary substrate in the glycolytic pathway
glucose
what is the primary end product of the glycolytic pathway
pyruvate
what happens in the investment phase of glycolysis
2 ATPs are spent
what happens in the payoff phase of glycolysis
4 ATPs and 2 NADHs are gained
summary of glycolytic pathway
- 1 glucose –> 2 pyruvates
- net gain of 2 ATPs
- NADH generated (converted to ~3 more ATP)
initial step of krebs cycle
2 NADH are produced for energy
krebs cycle overview
- net gain of 2 ATPs
- 6 more NADH produced
- 2 FADH2 produced
what is electron transport + oxidative phosphorylation
- a series of electron transfers within the cytoplasmic membrane
- generate ADP and ATP from NADH and FADH2
- accomplished with cytochromes and enzymes
bacteria producing energy through anaerobic respiration
- utilizes the same three pathways as aerobic respiration
- but O2 is not the terminal electron acceptor (NO3, SO4, CO3, and Fe3+ are instead)
- produce energy by reducing substrate
- LESS ATP is generated **
bacteria producing energy through fermentation
- generates energy primarily using the glycolytic pathway
- simple organic end-products formed from anaerobic dissimilation or metabolism of glucose
- LESS ATP generated**
bacteria producing energy through photosynthesis
- converts light to ATP
- not a feature of pathogenic bacteria
final electron acceptor in aerobic respiration
oxygen
what determines phenotype
genotype
genome
entire collection of genetic material in a cell or virus
gene
heritable unit of genetic material that define a particular trait
genotype
genetic makeup
phenotype
physiological or physical traits
chromosomes
- genome organized into packaged strands of DNA
- number does not influence organism complexity
prokaryotic chromosomes
- 1-3 chromosomes
- circular
eukaryotic chromosomes
- numerous linear chromosomes
- histones to package
- mitochondria and chloroplasts
plasmids
circular and extracheomosomal
nucleic acids
- built from nucleotides
- phosphate
- sugar (deoxy or ribose)
- nitrogen base (purine or pyrmidine)
- in RNA: ribonucleotides
structure of DNA
antiparallel
central dogma
DNA–>RNA–>proteins
DNA replication
- process by which a cell copies its genome before division
- Bidirectional
- typically very fast and accurate
- few mutations
- proofreading mechanisms
- enzymes
- unwind DNA, copy DNA, rewind parent and new DNA
leading strand
- continuous replication by DNA polymerase III (5’ to 3’)
- DNA polymerase I replaces RNA primer with DNA
- ligase
lagging strand
- discontinuous replication by DNA polymerase III
- okazaki fragments
- DNA polymerase I and ligase remove and replace primers
eukaryotic DNA replication
- takes longer, involves more protein factors
- multiple replication initiation sites
- slower: amount of DNA and packaging
how are genes expressed
proteins
transcription
DNA–> RNA
translation
RNA–> proteins
steps of transcription
- initiation
- elongation
- termination
RNA polymerase
- binds to promoter
- complementary ribonucleotides (U-A)
- continues until it has its terminator sequence
where does protein synthesis take plase
- prokaryotes: cytoplasm
- eukaryotes: nucleus
transcription initiation
RNA polymerase binds to the promoter and DNA unwinds, revealing the template strand
transcription elongation
RNA polymerase travels down the DNA. The RNA strand is built from 5’–>3’ as complementary ribonucleotides are paired with the template strand
transcription termination
a terminator sequence at the end of the translated gene signals the RNA polymerase to fall off ther DNA and release the new RNA
mRNA
carries genetic messages in triplet codes and is translated to build a protein
tRNA
cloverleaf structure shaped molecule serves as an adaptor molecule to usher amino acids into the ribosome during translation
rRNA
takes on complex stem and loop structures and combines with proteins to build structures
splicing mRNA
- mRNA contains non-protein coding regions (introns)
- introns are removed by splicosome creating a coherent protein-encoding mRNA strand
- processed mRNA with joined exons is ready to be exported to the cytoplasm to be translated
translation steps
- initiation
- elongation
- termination
location of translation
cytoplasm in both prokaryotes and eukaryotes
what carries out translation
ribosomes
- rRNA and proteins
- APE sites
- large and small subunits
translation initiation
- ribosome attaches to mRNA and scans until it reaches a start codon (AUG)
- initiator tRNA carrying amino acid methionine then enters the ribosomes P site
- the start codon on the mRNA base pairs with the anticodon on the initiator tRNA
genetic code redundancy
- protects versus mutations
- wobble 3rd position
translation elongation
- ribosome constructs the protein
- incoming tRNA;s codon pairs with codon in ribosomes A site
- peptide bond forms between amino acids, transferring the growing protein chain to tRNA in A site
- ribosomes translocates down mRNA; tRNA in the A site shifts to the P site
- the tRNA in the P site shifts to the E site, exiting the ribosome
translation termination
- ribosome encounters stop codon
- termination factor enters the ribosome
- ribosome releases the protein and detaches from the mRNA
translation in eukaryotic cells
most mRNA encodes a single protein
translation in prokaryotic cells
- mRNA is commonly polycistronic
- polysome formation
post translational modification
- addition of organic and/or inorganic factors
- trimming of AA sequence
- often required for proper protein function
- way to regulate how often mRNA is made into protein
regulating protein synthesis
~20% of a cells genes are expressed at any given time
- need mechanisms to turn certain proteins on or off according to cells needs
constitutive genes
housekeeping genes; always on
facultative genes
not always on
pre transcriptional regulation
controlled by operons
operons
collection of genes controlled by shared regulatory elements
- promoter
- genes
- repressor
- operator
inducible operon
OFF by default; can be turned on
repressible operon
ON by default; can be turned off
lac operon when glucose is present but lactose is NOT
- no transcription
- repressor is bound
lac operon when glucose is NOT present but lactose IS present
- high transcription
- allolactose inactivates repressor; not allowing it to bind
arg operon when arginine is low
- insufficient amount of arginine cannot activate the repressor
- repressor cannot bind to operator because it is not associated with arginine
- transcription occurs
arg operon when arginine is high
- abundant arginine activates repressor
- activated repressor binds to operator
- transcription is blocked
lac operon
inducible operon
arg operon
repressible operon
mutation
a change in genetic material of a cell or virus
substitution mutation
an incorrect nucleotide is added
insertion mutation
addition of one or more nucleotides
deletion mutation
removal of one or more nucleotides
silent mutation
no change in the amino acid sequence
**degeneracy
missense mutation
single change in amino acid sequence
nonsense mutation
single change in the amino acid sequence that results in a stop codon
reversion mutation
restores to the wild type gene sequence
frameshift mutation
mutations that result in a shift of the reading fame, changing the way the mRNA transcript is read
spontaneous mutation
naturally occurring due to errors in DNA replication; creates evolutionary diversity
mutagens
agents that increase rate of mutations
carsiongens
mutagens that promotes development of cancers
chemical mutagens
- organic or inorganic agents
- arsenic, asbestos, compounds in tobacco
physical mutagens
UV light, X rays, radioactive gamma rays
biological mutagens
- RECOMBINATION
- viruses, transposons
excision repair
- damaged DNA clipped and removed
- DNA polymerase I lays down new nucleotides
- ligase seals
vertical gene transfer
cells passing genetic information from parent cell to offspring
horizontal gene transfer
passing genetic information between cells independent of cell division
examples of horizontal gene transfer
- conjugation
- transformation
- transduction
- transposons
conjugation
- bacteria use a cytoplasmic bridge called a pili to copy and transfer a special plasmid known as the F plasmid (fertility factor)
high frequency recombination
a bacteria with the F factor integrated into its chromosomal DNA
transformation
bacteria take up extracellular DNA
Griffiths experiment
conversion of a non-pathogenic pneumococcal bacteria to a virulent strain
transduction
viruses transfer bacterial DNA between different bacterial hosts
generalized transduction
- bacteriophage infects a bacterial cell
- phage replicates in the host. Most phages contain only phage DNA, but occasionally a phage will package a piece of the hosts DNA
- the transducing phage injects DNA from prior host
specialized transduction
- bacteriophage injects a bacterial cell
- the bacteriophage’s DNA recombines into the host chromosome
- at some point the bacteriophage DNA excises from the host chromosomes and may take neighboring host genes with it
- all of the manufactured phage particles will contain phage DNA and the host genes that were excised with the phage DNA
- the bacteriophage injects its DNA into a new host
- the bacteriophage integrates into the chromosomal DNA of the new host, which endows the new host with genes from the phages prior host as well as phage DNA
antimicrobials
- drugs against microbes
- therapeutic compounds that kill microbes or inhibit their growth to prevent pathogenic action
- categorized based on the type of pathogen they target
alexander fleming
- unable to grow staphylococcus aureus near mold at the zone of inhibition
- called the moled penicillin: first antibiotic
basic criteria for drugs used as chemo-therapeutic agents in the treatment of infectious disease
- effective against microbes
- sufficiently nontoxic to the host
- able to be purified in high amounts
broad spectrum antimicrobial agent
drug is effective agains a broad range of microbes
narrow spectrum antimicrobial agent
antimicrobial targets a limited range of microbes
- effective aginst one group or subgroup
- present less disruption to normal microbiota
limited spectrum antimicrobial agent
drug is effective against a single organism/disease
empiric therapy
a medical treatment with a broad spectrum drug initiation while waiting for culture/ID results
criteria of antimicrobial drugs
- nontoxic to the host and without undesirable side effects
- nonallergenic to the host
- not eliminates normal microbiota
- able to reach the infected part of the body
- inexpensive and easy to produce
- chemically stable
- resistance is unlikely to develop
naturally occurring antimicrobials
substances produced by microorganisms that inhibit other living microorganisms
synthetic antimicrobials
manufactured by chemical processes
semisynthetic antimicrobials
chemical modification of naturally occurring antibiotics
modifying antimicrobial drugs
- antimicrobial compounds can be modified by chemical means
- drugs in later generations have expanded capabilities over their predecessors
next generation drugs
result from each successive round of chemical modification
selective toxicity
goal is to inhibit or kill the pathogen with little or no toxic effect on the patient
how is selective toxicity achieved
exploiting vulnerable targets
hepatotoxic
toxic to liver
nephrotoxic
toxic to kidneys
oral administration
- preferred antimicrobial route
- convenient and cost effective
parenteral administration
- any route not involving the GI tract
- usually an injection or infusion
- faster onset of drug
half life of drug
time it takes for half of a dose to be eliminated or deactivated by the body; determines frequency of adminstration
bacteriostatic drugs
- prevent/inhibit bacteria from growing
- target bacterial protein synthesis and metabolic pathways
- patients own immune system eventually kills off latent bacteria
batericidal
- kills bacteria
- targets bacterial cell walls, cell membranes, or nucleic acids
- does NOT rely on patients immune system to eliminate bacteria
- kill normal microbiota
antiviral drugs
- do not destroy their target pathogen but inhibit viral development
- viruses use the host cell to replicate to antiviral drugs are difficult to make
- aim to target and disable essential virus-specific proteins
- effective when viruses are actively replicating
1st category of antiviral drug targets
target viral replication cycle
2nd category of antiviral drug targets
stimulate the hosts anti-viral immune responses
what is the most effective way to reduce significant viral infection
vaccination
anti-fungal drug targets
- target fungal-specific compounds not in host cells
- interfere with cell wall synthesis –> lysis
- interfere with cell membrane stability and structure causing death
- interfere with nucleic acid synthesis
anti-parasitic drug
- target intracellular components
- difficult to develop
- limited by their toxicity
assessing susceptibility to antibiotics (AST)
determine the organism causing the specific infection and which antimicrobials will inhibit the growth of the infecting microbe; will identify and report drug resistance in pathogens
aga diffusion tests
- determine a basic antimicrobial susceptibility profile
- relatively inexpensive and can be used to determine pathogen susceptibility
kirby-bauer disk diffusion test
- agar diffusion test
- determines susceptibility only
epsilometer test (E-test)
- agar diffusion test
- determines susceptibility and minimum inhibitory concentration assays
minimum inhibitory concentration (MIC) assays
determine the lowest concentration of an antimicrobial agent that inhibits growth
minimum bactericidal concentration (MBC) assays
determine the lowest concentration of an antimicrobial agent required to kill the organism
antimicrobial resistance (AMR)
occurs when a microbe is not affected by a drug therapy that is intended to inhibit or eliminate the pathogen
intrinsic antimicrobial resistance
- natural resistance to microbial drugs based on inherent microbial structure/function
- makes certain pathogens/infections harder to treat/eliminate
acquired resistance
- acquired by genetic mutation or acquisition of resistance genes
- resistance occurs when drug concentration levels within the cell are kept below the MIC
types of acquired resistance
- alter drug’s target
- inactivate drug
- reduce drug concentrations inside the cell
superbugs
strains of bacteria, viruses, parasites and fungi that are resistant to the antimicrobials commonly used to treat the infections they cause
superinfections
result when superbugs emerge from the initial infection resistant to the treatment and become the primary cause of a second infection
emergence of drug resistance
- antibiotic resistance is fueled by natural selection
- noncomplicance with prescribed dosing parameters
- antimicrobial misuse
antimicrobial stewardship
coordinated program that promotes the appropriate use of antimicrobials to promote patient outcomes, reduce and combat microbial resistance and decrease the spread of infections caused by multidrug resistant organisms
staphylococcus characteristics
- gram positive
- cocci
- form irregular clusters
- non-spore formers
- non-motile
- typically lack a capsule
where is staphylococcus found?
- everywhere in nature
- part of normal human microbiota
- typically an opportunistic pathogen
how are staphylococcus infections transmitted
- direct transmission (skin, hands, sputum, pus)
- enter through respiratory route, hair follicles, or breaks in the skin
how are staphylococcus different from other gram positive cocci
- they are facultative anaerobes
- grow in the presence of bile salts
- produce catalyase; breaks H2O2 into H2O and O2
how to tell difference between different staphylococcus species
- coagulase test: production of coagulase
- genomic/DNA based ID
- culture media: mannitol salt agar, blood agar
coagulase test with S.aureus
coagulase +
coagulase negative staphylococcous
S.epidermidis and S. saprophyticus
how to tell the difference between the coagulase negative staphylococcous
susceptibility to antibiotic novobiocin
S. aureus
- major pathogen of staphylococcus genus
- coagulase positive
- most common causes of bacteremia and infective endocarditis
- spreads through direct contact
- significant cause of chronic BIOFILM infections
cell wall associated virulence factors
- peptidoglycan
- teichoic acid
- capsule (microcapsule)
- clumping factor
- protein A
protein A
- binds to host antibodies (IgG) at the Fc region
- blocks opsonization
extracellular enzymes virulence factors
- coagulase
- staphylokinase
- hyaluronidase
- lipase
- thermonuclease
- catalase
- proteases
- beta-lactamase
coagulase
- plasma clotting protein
- converts fibrinogen to fibrin
- detected by tube free coagulase test
staphylokinase
- activates plasminogen to form plasmin (digests fibrin)
- cleaves IgG and particular complement proteins
hyluronidase
- spreading factor
- digests hyaluronic acid
beta-lactamase
resistance to beta-lactam class of antibiotics
toxin virulence factors
- hemolysin
- leukocidin
- enterotoxin
- toxic shock syndrome toxin
- exfoliative toxin
hemolysin
- lyse host red blood cells
- alpha hemolysin: causes beta hemolysis on blood agar plates
leukocidin
lyse white blood cells
super antigens
- binds to TCR outside of normal region
- nonspecific activation of T cells
- activates 20-30% of T cells
- excessive activation of T cells
- massive cytokine release–> inflammatory response in entire body
toxic shock syndrome
- toxigenic infection
- inflammation in entire body; full body cytokine response
- in menstruating or postpartum women
- treatment: replacement of fluids, ICU, antibiotics
enterotoxin
- superantigen
- food poisioning
- ingestion of preformed toxin
- heat stable
- increased intestinal peristalsis
toxic shock syndrom toxin-1
stimulates production of interleukin by macrophages
exfoliative (epidermolytic) toxin
- protease that causes peeling of superficial skin layers
- dissolves intracellular bridges
infections caused by S.aureus
- superficial infections
- toxigenic infections
- systemic infections
superficial infections
- cutaneous infections-pyodermic
- pus formation
- sebaceous glands, hair follicles, wounds
- self resolve or topical antibiotics to treat
staphyloccoal scalded skin syndrom (SSSS)
- toxigenic infection
- neonatal disease
- exposure to exfoliative toxin A and B (separates epidermal layer from dermis)
- starts as an erythema around mouth and neck
- treatments: antibiotics, rehydration of skin
gastrointestinal disease
- toxigenic infection
- food poisoning - gastroenteritis
- **enterotoxin: disrupts gastrointestinal lining
- route of infection: food handlers, lesions on skin, unrefrigerated foods
systemic infections
- septicemia (sepsis)
- pyaemia (pyemia)
- osteomyelitis
- pneumonia
- endocarditis
- meningitis
septicemia (sepsis)
- bacteremia: bacteria in the blood
- infection of multiple sites within the body
- bacteria spread from initial site of infection
pyaemia
- type of sepsis caused by staphylococcus
- widespread, distinctive abscesses
nosocomial infections
- infections acquired from a hospital
- S.aureus is leading cause of HAI
- there is an increase in antibiotic resistance resistant strains of S. aureus
MRSA (methicillin-resistance staphylococcus aureus)
acquisition of resistance genes via horizontal gene transfer
methicillin
- narrow spectrum beta-lactam antibiotic
- binds to penicillin-binding proteins causes cell death
streptococci
- gram positive cocci
- grow in pairs or chains
- catalase negative (no bubbles)
- fastidious: require complex media for growth
- faculative aerobes
- large heterogenous group of bacteria
most common strptococcal pathogens
- streptococcus pneumoniae
- streptococcus pyogenes
- streptococcus agalactiae
lancefield group
a serologic system based on the reaction of specific antisera with surface carbohydrate antigens
hemolytic pattern
RBC lysis on blood agar plates
phenotypic trains
biochemical reactions and antibiotic senstivities
molecular studies
designating species and sub-species genetically
alpha hemolytic
colonies surrounded by green
beta hemolytic
clear transparent
gamma hemolytic
no notable sones around the colonies
S. pneumoniae
- alpha hemolytic
- encapsulated, found in pairs
- commonly colonizes the human nasopharynx
- significant global cause of illness and death
pneumococcal transmission
transmitted from person to person via infected respiratory secretions/droplets
pneumococcal colonization
- inhabit the healthy human nasopharynx
- strains are typically carried asymptomatically for weeks to months
- nasopharyngeal colonization does not usually result in disease
- NP colonization is a necessary step for the development of pneumococcal disease
pneumolysin
a secreted cytotoxin that lyses cells and damages tissues
**pneumococcal virulence factor
polysaccharide (pneumococcal) capsule
a protective, antigenic, carbohydrate layer anchored to the external surface of the cell
**pneumococcal virulence factor
- most important determinant of virulence
- protects agains phagocytosis, antibiotics, and environmental stressors
- basis of pneumococcal vaccines
invasive pneumococcal disease (IDP)
infection of a normally sterile body fluid or organ
otitis media
- non-invasive pneumococcal disease
- middle ear disease
sinusitis
- non-invasive pneumococcal disease
- inflammation of the facial sinus cavity
pneumonia
- non-invasive pneumococcal disease
- serious lung infection that inflames the alveoli
bacteremia
- invasive pneumococcal disease
- bacteria in the blood stream
meningitis
- invasive pneumococcal disease
- inflammation of the meninges, the membranes that cover the brain and the spinal cord
S. pyogenes
- group A strep GAS
- beta hemolytic
- bacitracin sensitive
- colonization is infrequent
- pathogenic
- infections begin in throat or skin
s. pyogenes transmission and pathogenesis
- person to person contact
- mild to life threatening
- large # of virulence factors
M protein s. pyogenes virulence factor
- major protein coating the cell surface
- contributes to phagocytosis evasion
hyaluronic acid capsule s. pyogenes virulence factor
- protects against phagocytosis
- not produced by all strains
- weak immunogen
streptolysins s. pyrogenes virulence factor
damage cell membranes, cause beta hemolysis phenotype
streptococcal pyrogenic exotoxins s. pyrogenes virulence factor
linked to rash, TSS, and severe invasive infections
s. pyrogenes GAS pharyngitis
- sterp throat
- scarlet fever
s. pyrogenes GAS skin and soft tissue infections
- superficial skin and progressively deeper tissue infections occur following breach in protective skin layer
- impetigo
-erysipelas and cellulitis - necrotizing faciitis
s. pyrogenes GAS infection complication: non-supportive sequelae
- rheumatic fever
- glomerulonephritis
- PANDAS
S. agalactiae
- group B strep: GBS
- beta hemolytic
- part of normal human GI and GU tract microbiota
- major cause of potentially fatal sepsis, pneumonia, and meningitis in newborns
S. agalactiae virulence factors
capsule and beta hemolysin
S. agalactiae GBS treatment
prompt diagnosis and intiation of antimircobial therapy
