Chapter 6 Flashcards
Prokaryotes
Unicellular, bacteria are these
Difference in prokaryotic cells from eukaryotic
Lack formed nucleus and cytoplasmic organelles
Most have a cell envelope that contains a cell wall
What is the cell wall of bacteria make of? What does the material do?
Peptidoglycans, substance not found in eukaryotes
Provides support to the cell in pressure changes
Pili function
Hair like projections that alllw bacterial to stick to surfaces and transfer genetic material between cells
Glycocalyx function
Serve to protect bacteria from phagocytosis
Binary fision
Bacterial reproduction
DNA is copied and sorted into 2 progeny cells
Plasmids
Extra normal DNA circlets where additional bacterial genes to go during binary fision
Contain genes that are capable of being transmitted to other bacterial cells
What affects the rate of bacterial cell division?
Species, nutrients, temp, pH
Endospores
Produced by several genera of bacteria
Highly durable, live for fucking forever
When conditions are permissive, they germinate and grow into vegetative bacterial cells
How are bacteria classified? (3)
Staining
- gram stain
- reflects chemistry and structure of cell wall
Cell shape
Special features
- pathogenicity
- antibiotic resistance, etc
Bacteria shape category: cocci
Circles
Ex, coccus, diplococci, streptococci, staphylococci
Bacteria shape category: bacilli
Rods
Ex. Bacillus, diplobacilli, streptobacilli, palisades
Bacteria shape category: budding and appendaged bacteria
Weird shaped mfs
Have hyphas or stalks
Bacteria shape category: random shaped ones
Likely not super important, dont worry till the end
Enlarged rod - zipper one
Vibrio - kidney shape
Helical form - RBC lookin
Corkscrew - like a popcorn twist
Spirochete - what one strand of DNA looks like
Filamentous - squiggly worm lookin
What does the virulence of bacteria depend on
Their ability to resist attack from the host defences
Tissue injury caused by bacteria in the host depends on:
Number of bacteria
Virulence
Site of infestation
Resistance of the tissue
Bacterial toxins classes
Proteins (secreted) and lipopolysaccharides (endotoxins)
Most important point about bacterial toxins
Both types of toxins are produced by a range of bacteria and diffuse into blood and otehr fluids
This allows them to act as sites distal from the site of bacterial infection
Toxin and action: clostridium tentanii
Tetanospasmin toxin
Inhibited inhibitory neurons in CNS, result in paralysis
Toxin and action: vibrio cholerae
Cholera toxin
Activation of adenylyl cyclase
- promotes intestinal secretion of fluid
- leads to diarrhea
Toxin and action: bordatella perussis
Pertussis toxin
Inhibits adenylyl cyclase
- reduced phagocytosis
- leads to whooping cough
Toxin and action: corynbacteria diptheriae
Diphtheria toxin
Inhibits protein synthesis
- cell death
- leads to tracheal pannus
Toxin and action: Escherichia coli
E. coli heat labeled protein
- similar to cholera toxin
- diarrhea
Toxin and action: Shigella dysenteriase and family
Shiga protein
- inhibits protein synthesis
- leads to diarrhea
Toxin and action: Clostridium botulinum
Botulinum toxin
- inhibits Ach at neuromuscular junctions
- leads to flaccid paralysis
Also food poisoning
Toxin and action: Bacillus anthracis
Anthrax toxin
- cytokines secretion
Toxin and action: staphylococcus aureus
Exfoliatin B
- leads to separation of skin layers
Staphylococcus aureus (shape, symptoms)
Cluster of grapes shaped
Very resilient to antibiotics
Causes
- boils
- impetigo
- wound infections
- pneumonia (50% mortality)
- osteomyelitis
- endocarditis
Mainly occurs in immunocompromised people
Staphylococcus aureus virulence factors
Coagulase
- coagulates blood and plasma
Hemolysis
- lyses RBCs, skeletal muscle, myocardiocytes, renal tissue
Staphylococcus epidermidis (shape, facts)
Cluster of balls
Part of natural human flora
- opportunistic pathogen
Most common nosocomial infection
Streptococci shape
Bead like chains
Streptococci group A causes…
Cause tonsillitis etc
Strep throat (hemolytic S. pyogenes)
- can lead to rheumatic fever and glomerularnephritis
Streptococci group B action
Colonize the gut and gentian tract
- can cause septicemia and meningitis in neonates if passed
Leading cause of pneumonia
Streptococcus pneumoniae
What antibiotic are most strep species sensitive to
Penicillin
Gram positive cocci
Staphylococcus aureus
Staph epidermidis
Streptococci both groups
Strep pneumoniae
Neuisseria gonorrhoeae (symptoms, facts)
STI
Manifests as acute urethritis
Infection can spread from wherever it started (gentials, mouth, etc) and become disseminated and affect many systems
Neisseria meningitidis is a major cause of
Epidemic meningitis
Gram negative cocci
Neisseria gonorroeae
Neisseria meningitidis
Corynebacteria diphtheria
Causes diphtheria
Transmitted respiratory
Gram positive rod
Leads to a formation of pseudomembrane in the pharynx made of dead tissue, fibrin, blood cells, and live bacteria
- causes obstruction
Nasty photo in the textbook of the mouth
Reservoir is asymptomatic humans
High mortality rate if untreated (35%)
Corynebacteria diphtheria causes…
Psuedomembrane buildup in mouth
Myocarditis, neurological effects
Bacillus anthracis
Cause of anthrax
Found in soil, produces endospores
Transmitted usually through animals
Has potent toxin
Three forms of anthrax and what they affect
Cutaneous
- skin, low mortality
Gastrointestinal
- more lethal
Pulmonary
- caused by spore inhalation
- high toxin production leads to cadiovascular shock, 80% mortality
Clostridia
Group of bacteria found in soil
Release exotoxins, some very potent
Spore forming
Clostridium perfringens
Causes gas gangrene
Associated with septic abortion, crush injuries, compound fractures, gun wounds
Clostridium botulinum
A Cause of food poisoning
Can cause death by resp failure
Toxin paralyzed skeletal muscle
- can be used therapeutically to relax muscles
Clostridia types (3)
Clostridium perfringens (gas gangrene)
Clostridium botulinum (food poisoning but worse)
Clostridium tetani (tetanus)
Clostridium tetani
Cause of tetanus aka lockjaw
- organism found in soil and GI tract
- enters though skin openings
Clostridium tetani toxin and what it does
Tetanospasmin
Targets terminal synapses of NMJ, inhibiting release of glycine and GABA
- leads to spastic paralysis
- eventually leads to respiratory muscle paralysis and has a mortality to 40-60%
Pseudomonas aeriginosa
Gram negative rod
Common nosocomial infection
Identifiable by pus or sputum colour due to green/blue bacteria colour
Escherichia coli
E. Coli
Common component of gut microflora
There is a strain that produces toxins which we know E. coli from
Escherichia coli toxin
Shiga toxin
Causes hemorrhagic diarrhea
- in immunocompromised people can lead to hemolytic uremic syndrome which causes kidney failure
Common to get E. coli by eating contaminated food, stuff
Salmonella enterica
Causes typhoid fever
- serious diarrhea
Spread through fecal matter in water or food
Organism attacks liver
Brucella
Gram negative rod
Cause brucellosis
- common in farm workers (direct animal contact, or respiratory)
- causes acute undaluating fever, anorexia, fatigue etc
Can lead to endocarditis
Bordetella pertussis
Causes whooping cough (very contagious)
Produced pertussis toxin
Yersinia pestis
Bubonic plague bacteria
Has reservoirs in mice and rats
- passed by fleas
Bacteria colonizers in lymph nodes
- mainly cervical, axilla, groin
- swollen nodes form pustules that erupt
Bubonic form can progress to septicemic or pneumonic form
Very high mortality
Acid-fast bacteria (and the two pathogens of interest here)
Called this due to staining properties
- have waxy coating made of mycolic acid
- allows bacteria to avoid phagocytosis
- spread slowly
- challenging to culture
Two human pathogens that are acid fast
- TB and leprosy
- both from the mycobasteriaceae family
What causes TB?
Mycobacteria tuberculosis
Mycobacterium tuberculosis complex (5)
M. Tuberculosis
M. Bovis
M. Africanum
M. Canetti
M. Microti
Cases of TB (latent, carriers?)
1/10 are active and infectious
1/3 of those have complications
About 1/4 are infected but most are latent
Most common opportunistic infection in HIV patients
What happens during TB?
Colonization in lungs
Phagocytosis unsuccessful due to TB being an acid-fast (waxy coated) bacteria
Causes distinct form of inflammation with granulomas and caseous necrosis (primary TB)
Types of TB
Primary
- granulomas and caseous necrosis
Secondary
- severe lung complications like pulmonary fibrosis or hemorrhage
Extra pulmonary
- when it spreads to other tissues from lungs (1 in 5)
Disseminated TB
1 in 10 of those (extra pulmonary TB) cause widespread infection with granulomas in other tissues
TB test in at risk populations
Mantoux test
- skin test to cellular immunity (type 4 HS)
More definitive diagnosis is radiography
Treatment of TB
3 month course of antibiotics
- isoniaxid + either rifampicin or rifapentine
Gram negative rods (6)
Pseudomonas aeriginosa
Escherichia coli
Salmonella enterica
Brucella
Bordatella pertussis
Yersinia pestis
Mycobacterium leprae and leprosy
Causative agent of leprosy (aka Hansens disease)
- relative of TB
Leads to chronic inflammation (like TB), but the damage occurs in peripheral tissues like skin and mucosa of eyes and URT
Transmitted by respiratory aerosol
- transmission only successful if there is repeated contact and genetic susceptibility to infection
- 3-5 incubation period before S/S (lesions, loss of sensation and motor strength)
Classifications of clinical leprosy (2)
Paucibacillary
- five or less poorly pigmented numb skin patches
Multibacillary
- more than 5
Confirmation is done by acid fast staining or DNA detection in bacteria via samples
Curable using 6 month antibiotics
(Rifampicin, Dawson, clofazimine)
Spirochetes (3)
Gram positive rods with helical shape
Leptospira, borrelia, treponema
Leptospiro
Carried by animals and shed in urinary tract
Can manifest in fever, myalgia, pulmonary hemorrhage, meningitis, acute kidney injury
Treated with doxycycline
Borrelia burgdorferi causes…
Lyme diseae
Borrelia burgdorferi
Transmitted through ticks mites and fleas
Manifestations
- fatigue
- fever
- migrates
- rash where bite is
- 15% experience nerve system damage
Treated with antibiotic like azithromycin, doxycycline, or amoxicillin
Treponema pallidum
Syphilis - STI
- can be transmitted vertically
- untreated mortality of 50%
Once inside, quickly spreads to other tissues and reaches lymph nodes in hours
- primary, secondary, latent, tertiary stages
Treponema pallidum - primary
Primary syphilis
- red Papule on infection site
Treponema pallidum - secondary
Secondary syphilis
- symptoms arise are spirochetes distributed to lymph nodes
- skin rash, fever, swollen nodes
Treponema pallidum - latent and tertiary
Latent
- after primary and secondary
- can become latent
Tertiary (1/3)
- organ damage resulting in retinitis, CNS complications, bone pain
Diagnosis of syphilis and treatment
Serological and DNA testing
- mainly in the latent stage
Treatment by penicillin
- global challenge right now is penicillin resistant syphilis
Viroids
Short pieces of RNA, no protein coat
(Hep D9
Prions
Misfolded porteins iwth no nucleic acid
- cause holes in the brain
Exotoxins
Toxins produced and excreted by bacteria
Endo toxins
Toxins present in the cell wall of bacteria
Gram positive infections (4)
Anthrax
Clostridia
Cornyebacteria
Mycobacteria
