Bacteria - Gram negative Bacilli

• 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