BMS212 - Bacteriology > Enterobacteriacaea > Flashcards

Enterobacteriacaea Flashcards

(18 cards)

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1
Q

General features of Enterobacteriacaea

  • stain, shape
  • 3 antigens used in serotyping
A
  • Many genera: all gram negative bacilli
  • present in gut to soil and water “coliforms” (ferment lactose)
  • 3 antigens used in serotyping (is where antigen binds -> determined by colour production)
    • O antigen = somatic (part of cell wall ->LPS)
    • H antigen = flagellar
    • K antigen = capsular (or pili)
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2
Q

Genera within Enterobacteriacaea (10)

A
  • E. coli
  • Shigella
  • Salmonella
  • Klebsiella
  • Proteus
  • Yersinia
  • Citrobacter
  • Edwardsiella
  • Enterobacter
  • Serratia
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3
Q

Features, habitat & resistance of Enterobacteriacaea

A

Features: aerobic to faculatively aerobic
-oxidase neg
-Catalase pos
-glucose fermented to acid (& sometimes gas)
-majority motile
-grow well on artifical media
Habitat: alimentary tract of humans (part of normal flora) -> generally opportunistic pathogens
Resistance: no special features but more resistant than most vegetative bacteria to drying
-resistance to antibiotics readily acquired by plasmids and resistance now widespread

-family divided into tribes, which are divided into genera and species

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4
Q

Escherichia coli

  • where found
  • features
  • resistance
A
  • Found in gut (esp. large intestine, but some specialised strains can adhere to small intestine)
  • vast majority non pathogenic commensals (except if they get into wounds)
  • ferment lactose
  • indol positive
  • antimicrobial resistance major issue!
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5
Q

E.coli main disease syndromes

A
  • Gastroenteritis (various forms; esp. neonates)
  • Septicaemia (esp. neonates)
  • Environmental mastitis (mammory gland)
  • Urinary tract infections
  • Wound infections
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6
Q

Gastroenteritis

A
  • Caused by certain serotypes
  • various mechanisms
  • enterotoxigenic strains (ETEC)
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7
Q

Enterotoxigenic strains of E. coli (ETEC)

A
  • have adhesions that allow bacteria to adhere to enterocytes in small intestine (i.e. Pili called K88)
    • different in different animal species
  • -result in watery “secretory” diarrhoea
  • e.g. calves, lambs, foals, piglets, children under 5 most susceptible
  • responsible for traveller’s diarrhoea
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8
Q

Other strains of E. coli

A
  • enteropathogenic
  • enteroinvasive
  • enterohaemorrhargic
  • enteroadherant
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9
Q

Shigella

  • what infect
  • species & subtypes
  • what they induce
A
  • Infect humans & non-human primates
  • non-lactose fermenting, indole not produced, MR test positive, VP test neg, citrate not utilised
  • 4 species & subtypes
  • important enteric pathogen, associated w/ poor hygiene
  • produce cytotoxins and enterotoxins
  • induce colitis (inflammation of colon) and bloody diarrhoea
  • sometimes encode neurotoxins
  • severe gastroenteritis -> locally invasive type with necrotic ulcers
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10
Q

Salmonella

  • features
  • causes 3 things
  • habitat
A
  • Only one true species = S. enterica
  • motile
  • can invade cells
  • non lactose fermenting
  • important cause of eneritis, septicaemia, abortion
  • important zoonotic infections (mainly food borne)
  • now often multiple drug resistant
  • Habitat: GI tract of humans and animals
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11
Q

3 types of Salmonella (+ 2 examples)

A
  1. Host adapted: specific disease in a particular animal and has low virulence in other animals
    e. g. S. Typhi (Typhoid fever) and S. Paratyph (A & C)
  2. Partially Host adapted: Infection in host of origin & also a limited no. of other species
    e. g. S. Cholerase-suis (pig: necrotic enteritis & septicaema - occasionally infects humans) & S. Paratyphi B (human)
  3. Not Host-Adpated: The majority: cause diseases in many species (and zoonotic)
    e. g. S. Typhimurium (all species, some multiple drug resistant overseas) & S. Chester (all species)
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12
Q

Classification of Salmonella

A
  • Serovars determined on basis of multiple O (somatic) antigens and H (flagella) anigens (Kauffman-White scheme)
  • Additional strain typing traditionally done by “Phage typing” (viruses that infect bacteria) -> pattern of lysis after incubation defines the phage type of the isolate
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13
Q

Salmonella associated with humans

-S.Typhi & S. Typhimurium

  • how adapted are they
  • what they cause
  • transmission
  • drug resistance
A

S. Typhi

  • host adapted
  • causes typhoid or typhoid fever - is a severe septicaemic disease
  • mainly person to person transmission
    • long term carriers (i.e. Typhoid mary)
  • now often Chloramphenicol resistant

S. Typhimurium

  • Not host adapted
  • Common and important
  • enteritis (and sometimes with septicaemia)
  • food-borne zoonosis
  • multiple drug resistance
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14
Q

Klebsiella

  • features
  • what it can ferment
  • resistance
  • What it can cause
A

-Slimy capsule, non-motile
-Lactose fermenting, produce gas from glucose
-sporadic infections
-now often drug resistant (extended spectrum beta lactamase strains)
Causes;
-Respiratory infections
-Metritis
-Mastitis
-Enteritis
-Urinary tract infections

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15
Q

Proteus (e.g. P. mirabilis)

  • where found
  • what it can ferment
  • odour (what from)
  • features of infection (3)
A

-Found in soil & water
-non-lactose fermenting
-urease positive (hydrolyses urea to ammonia = fishy smell)
-swarming motility on agar
-resistant organism
Features of infection;
-Urinary tract infections
-Otitis externa (middle ear infection)
-Septicaemia in neonates
-Gastroenteritis in humans

*sporadic infection only

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16
Q

Yersinia

  • what it can ferment
  • special feature
  • 2 species and what they can cause
    - Y. pseudotuberculosis
    - Y. enterocolitica
Study These Flashcards
A
  • Non-lactose fermenting
  • cold enrichment (1-4degrees)
  • facultative anaerobes
  • intracellular organisms
  • zoonotic
  • Y. psudotuberculosis
    • may cause enteritis and septicaemia with small necrotic foci in many tissues of humans
  • Y. enterocolitica
    • human enteritis, cause of food poisoning (esp. from pork)
17
Q

Yersinia pestis - what is it

Study These Flashcards
A
  • Cause of the plague
  • clone of Y. pseudotuberculosis w/ gene loss and gain of 2 virulence plasmids
  • natural reservoirs in small mammals/rodents
  • if human bitten, develop bubonic plague (enlarged lymph nodes)
  • pneumonic forms can spread by the respiratory route; is highly transmissible
18
Q

Citrobacter, Edwardsiella, enterobacter and Serratia

  • what they are called as a group
  • Habitat
  • Pathogenicity

-special feature of serratia

Study These Flashcards
A
  • Comprise the paracolon group
  • lie between E. coli and Salmonella in biochemical characteristics
  • Habitat: GI tract, faecs, soil & water
  • Pathogenicity: occasional disease of GI tract
    • enterobacter is common cause of neonatal sepsis

-Serratia: pigment prodigiosin (red colour)

BMS212 - Bacteriology
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