E Coli And Influenza Flashcards
What type of bacteria is E. coli
Gram negative rod bacteria
Where is E. coli normal
Normal microbiota of the large bowels
Protects from salmonella
What infections does E. coli commonly cause
UTI
Intestinal infections
Sepsis or neonatal meningitis
Features of E. coli in the lab
Lactose-fermenting
Can use macConkey agar
Contains lactose
Antigens of E. coli
O H F K
Encode a specific structure of the bacteria
Structure of E. coli
Capsule K
LPS O
Fimbriae F
Flagella H
Production of toxins
Cell membrane
Most E. coli strains are
Harmless
6 strains of diarrhoeagenic E. coli
Enterotoxinigenic E. coli Enteropathogenic E. coli Shiga toxin-producing E. coli Enteroagressive E. coli Enteroinvaseive E. coli Diffusely adherent E. coli
What strains of E. coli are most common among children on the developing world
EPEC and EIEC
Enteropathogenic E. coli
Enteroinvasive E. coli
What causes travellers diarrhoea
Enterotoxigenic E. coli- through 2 toxins (heat labile and heat stable)
How does Enteropathogenic E. coli work
Creates a translocation tube to access and anchor into the enterocyte
How does Shiga toxin work
A and B subunits- inhibits protein synthesis within the cell and this causes cell death
E. coli strains that cause extra-intestinal disease are classified under
Extra-intestinal pathogenic E. coli (ExPEC)
Example of ExPEC
Uropathogenic E. coli
Adhesions- type 1 fimbrae
Toxins- LPS alpha haemolysis
Prevention of diarrhoea related E. coli infection
Avoid foods and drink that could be contaminated Raw fruits and veg Raw seafood or undercooked meat Unpasteurised dairy products Ice Food from street vendors
Treatment of diarrhoea related E. coli infection
Most will recover in a few days
Clear liquids
Oral rehydration solutions
Avoid antibiotics
Management of UTI related E. coli infection
Antibiotics
Trimethoprim or nitrofurantoin
What is flu/influenza
Acute viral infection of respiratory tract Highly infectious Orthomyxovirus Spherical and enveloped Negative strand RNA genome
Influenza important antigens
Haemagglutinin H (binds to cells of infected person)
Neuraminidase N (releases virus from host cell surface)
3 types of influenza
Influenza A: many animals, antigenic drift and shift, pandemics
Influenza B: only humans, antigenic drift, mainly older adults
Influenza C: humans and pigs, antigenic drift, produces mild disease
How is influenza transmitted
Respiratory route
Innate immune system barriers to entry of influenza
Respiratory epithelial cells are covered by a thick glycocalyx and tracheobronchial mucus that can trap virus particles
Ciliated respiratory epithelial cells mucocilliary escalator
Immunologic defence in lung including secretory IgA, natural killer cells and macrophages
How does influenza virus enter host cells
Attaches to Sialic acid residues on host cell glycoproteins or glycolipids
Receptor mediated endocytosis
Attachment and fusion functions associated with H protein
Viral release is facilitates by the neuraminidase protein, leaves sialic acid residue of glycoprotein on cell surface and allows release of viral particle
Symptoms of influenza
Fever, headache, sore throat, cough, aches and pains
Complications among for a large amount of fatalities
Incubation 1-5 days
Recovery within 7
Diagnosis of influenza
From symptoms and clinical assessment
Rapid antigen tests and PCR
Treatments of influenza
Anti virals and neuraminidase inhibitor
Vaccination
Formalin-inactivated vaccine against A and B for adults
Cold-adapted vaccine for children (virus particles in this vaccine reproduce in the nose and throat but not in the higher temperatures in the lugs)
Properties of flu
Constantly replicating
Life cycle of 6 hours
viral RNA polymerases have high error rate
Describe genetic drift
Point mutations lead to genetic variation in both surface antigens H and N
Minor antigenic changes
Describe antigenic shift
Major changes that occur suddenly when 2 or more different strains combine
New subtype and widespread epidemics
No previous immunity
Deaths in young people in Spanish flu
Cytokine storms
T cells attack and destroy the tissues in which the virus is replicating
