Bacteria - Gram negative Bacilli

Cards (77)

  • What are the 3 categories of gram-negative bacilli
    Glucose fermenters
    Non glucose fermenters
    Curved rods
  • What is the category of non fermenting gram negative bacilli
    Oxidase-positive
  • What are the 2 categories of glucose fermenting gram negative bacilli
    Oxidase positive
    Oxidase negative
  • What are basically all gram negative rods except for a few
    Glucose fermenting
    oxidase negative
    Enteric
  • What are the two main gram negative bacilli to know and what categories do they fit into
    E.coli (enterobacterales) - glucose fermentting, oxidase negative, enteric
    campylobacter - curved rods
  • Other than campylobacter what are examples of curved rods
    Helicobacter
    Lawsonia
    Vibrio
  • What is Enterobacterales a commensal of
    The GI tract
  • What is a secondary pathogen
    E.coli is bascially in all species as a secondary pathogen
    Another pathogen has to have caused a disease making the person more susceptible before an effect will be seen
  • Is salmonella a primary or secondary pathogen in reptiles
    Secondary as it is meant to be there as a commensal
    Unlike in people or most other animals where it is primary
  • What is a primary pathogen
    Causes the first infection can be foreign or opportunistic
  • Is enterobacterales oxidase postive or oxidase negative
    Negative
  • What does enterobacterales do to glucose
    ferment it to produce gas and acid
  • What does enterobacterales reduce NO3- to
    NO2-
  • Are enterobacterales aerobes or anaerobes
    Factultative anaerobes
  • Why when growing enterobacterales do you have to use selective macconkey agar
    Bile salts - because it selects against bacteria that doesn't like the gut therefore making it more likely to grow the bacteria you want and not gram positive
  • What are the two main species of enterobacterales
    E.coli
    Salmonella
  • What are the two categories of enterobacterales
    Lactose fermenting
    Non lactose fermenting
  • Is E.coli a lactose fermenter or a non lactose fermenter
    Lactose fermenter
  • Is salmonella a lactose fermenter or a non lactose fermenter
    Non-lactose fermeneter
  • How can you confirm E.coli Prescence in a lab
    Biochemical profiles - some enterobacterales may look similar
    MALDI-TOF - mass spec profiles produce a protein fingerprint for each species
  • How can E.coli be identified in house
    Uriselect
    Targets particular disease complexes
    The agar will change colour depending on the species growing based on common UTI infections
    You can instantly tell if a pathogen is present
    BAD - other bacteria doesn't grow without colour so you don't have full information
  • Where in the GI tract is E.coli a normal commensal of
    Large intestine and lower small intestine due to migration
  • How is E.coli disease usually acquired
    When it is present in a new site or has acquired a virulence gene
    large genetic diversity
  • What are the two subsections of E.coli and which is more common
    Extraintestinal - more common
    Enterotoxigenic
  • What type of infections does extra-intestinal E.coli cause and give examples
    Opportunistic infections such as UTI, wound infections and mastitis
  • What other soft tissue infections can extraintestinal E.coli infections cause
    UTI
    Pyometra
    Mastitis contaminated faecal material
    Septicaemia
  • What are the 3 pathogenicity variables of extraintestinal E.coli
    Endotoxin - as gram negative
    Fimbriae
    Iron-acquisition
  • How do fimbriae assist in E.coli UTI infections
    P-Fimbriae cause the adherence to the uroepithelium and so E.coli can resist flushing of urine
  • What bacteria type is ETEC
    Enterotoxigenic E.coli
  • What does enterotoxigenic E.coli cause is calves, lambs and piglets
    Neonatal diarrhoea - under a week
    Scours
  • What type of fimbriae is specific to calf gastrointestinal epithelium in Enterotoxigenic E.coli
    K88 fimbriae
  • Does enterotoxigenic E.coli have host specific fimbriae
    Yes
    Certain types adhere better to certain gut species
  • What are the two different types of toxin production that can be encoded for on the plasmid
    Heat labile (LT)
    Heat stable (Sta)
  • How does Enterotoxigenic E.coli work to cause disease 

    Adherence to intestinal epithelium using K88 fimbriae in pigs and cattle and K99 fimbriae in sheep and cattle
    Toxin production
    This causes hypersecretion of water / Cl-, reduce Na+ reabsorbtion
  • What other E.coli related diseases are there
    Enteropathogenic E.coli (EPEC)
    Oedema disease in pigs
    Enterohaemorrhagic E.coli (EHEC)
    Watery mouth
  • What bacteria is watery mouth caused by in lambs
    E.coli
  • How does E.coli cause watery mouth
    Colostrum deprivation
    Leads to an overgrowth of E.coli causing destabilisation
    Endotoxic shock - as has entered the blood stream - triggers a systemic inflammatory response
  • What does enterohaemorrhagic E.coli cause in humans
    Food poisoning
    (haemorrhagic colitis, haemolytic/uraemic syndrome)
  • How does E.coli cause oedema like disease in pigs
    Shiga like cytotoxin absorbed which targets endothelial cells of arteries
  • What cytotoxin is absorbed in oedema like disease of pigs caused by E.coli
    Shiga like cytotoxin - classic bacterial toxin