Unit 6: Bacterial Infection Flashcards
0what are some maternal factors that can impact the developing foetal microbiome?
- mother’s gut microbiota
- vaginal infection
- peridontitis
what are some postnatal factors that can impact the developing foetal microbiome?
- antibiotics
- breast feeding
- host genetics
- environment
how is a healthy GIT microbiome defined?
a population of 10^14 bacteria of at least 1000 species and belonging to 4 major phyla, the majority (90%) of which are anaerobes
what are some features of a dysbiosis (bad) microbiome?
- increase in firmicutes:bacteriodete ratio
- decrease in bacteriodes fragalis = pro-inflam
- more proteobacteria, less bifidobacteriodes
what are the main uses of probiotics?
- used to maintain good/ healthy microbiota
- therapeutic restoration of the microbiome
what are some correlations of continuous antibiotic use in early life?
- development of childhood asthma + milk allergies
- IBD (mouse model)
- obesity (mouse model)
- permanent alterations in microbiome
what is the transmission sources of canine leptospirosis?
- contact with infected urine - both direct and indirect
how would subclinical form of canine leptospirosis be clinically presented?
- inapparent, disease maintained in host
- very common form
- chronic shedding in urine
how would peracute form of canine leptospirosis be clinically presented?
- acute clinical disease
- death of incidental host
- shock and internal bleeding
how would acute form of leptospirosis be clinically presented?
- haemorrhage, fever, anorexia, shock, jaundice, kidney/liver failure
- reluctance to move
- death
how would chronic form of leptospirosis be clinically presented?
- multisystemic organ failure, chronic hepatitis
- chronic renal damage
what diagnostics can be used for diagnosing leptospirosis?
- direct leptospire detection = darkfield microscopy + culture
- molecular detection + genotyping = PCR + WGS/MLST
- serology = MAT + other immunoassays
what is the difficulty of using culture to detect lepto infection?
- requires specialised media
- very rapid growth of parasite
- takes around 13 weeks to confirm infection
- many serovar, serogroups and genomospecies
what are the pros and cons of using PCR for lepto detection?
- sensitive in leptospiraemic phase = early detection in acute phase
- can be used for blood and urine samples
- variable urine shedding = false neg
- costly reagents
- no identification of serovars
what is MLST?
multi locus sequence typing
what is the LIPS assay? what are good targets?
- luciferase immunoprecipitation assay - outer membrane proteins = LigA/LigB
antibody binds = virulence factor that is expressed when colonising
describe the process of the LIPS assay
- amplify + clone OMP gene
- subclone into expression vector (at either N or C terminal) = fusion protein
- express recombinant fusion protein - culture + lyse
- immunoprecipitate = add serum + protein A sephrarose (captures IgG + immune complexes)
- wash, add substrate + measure luminescence
what are the current treatment options for tuberculosis?
- long regimen drug treatment (MDR, XDR TB)
- BCG vaccine (not effective to adult TB)
what is different about the structure of the cell wall of mycobacteria?
- looks similar to g-ve (lipid-peptidoglycan-lipid) with some big differences
- long chain branched mycholic acids with glycolipids tops
- linked with lipopolysaccharides
- addition of porins
how do mycobateria release virulence factors?
- ESX-1 secretion system = secretion if pore-forming toxin = EsxA = escape from phagosomal compartment
what effects can EsxA/B have on the immune system?
- antagonist to TLR2
- inhibits MHCI presentation
- innate immune system still triggered
what are some ways in which mycobacteria can inhibit phagolysosome fusion?
- protein and lipid secretion
- surface proteins prevent phagolysosome maturation = PI3P (maturation marker)
- PKnG = fusion inhibition
what is being measured during a pathogen diagnostic test?
- growing/ cultivation of the pathogen
- nucleic acid
- surface antigens
what is being measured during an immune response diagnostic test?
- antibodies
- T cell response
what are the pros and cons of using sputum smear microscopy for AFB as a diagnostic for TB?
- light microscopy = inexpensive
- identifies most infectious patients
- no identification of drug resistance
- doesn’t distinguish MTB from non-TB mycobacteria
what are the pros and cons of using urine LAM as a diagnostic for TB?
- inexpensive and results within 30 mins
- can be used at bedside
- only used for HIV positive patients
what are the pros and cons of using TB-LAMP as a diagnostic for TB?
- simple and easy visual display
- results in an hour
- sensitivity increased as CD4 cell count decreases
- doesn’t identify drug resistance
