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Enterobacteriacea Flashcards

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1
Q

Enterobacteriaceae has the largest collection of Gram … bacilli

its has 30…. and > 120 ,,,

Classified by

  • bio
  • an…
  • ….
A 
Largest collection of medically important Gram negative bacilli.
30 genera and >120 species.
Classified by:
Biochemical properties
Antigenic structure
Molecular typing methods.
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2
Q

structure and growth requirements

size?

Non,,,, or ,,,, with peritrichous
……

Asporo….

Grow …. on non selective ….

Either aerobically or …..

A 
Moderately sized Gram negative bacilli. 
(up to 1um x 6um).
Nonmotile or motile with peritrichous flagellae. 
Asporogenic.
Grow rapidly on non selective media
Either aerobically or anaerobically.
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3
Q

structure and growth requirements

Heat stable …. is the major cell wall …. - consists of 3 components :

  • 0 poly….,soma…
  • A core polysaccharide common to all enterobacteriaaceae
  • Lipid A

Serological identification is based on 3 major groups of antigens

  • …., ….. capsular …..
  • …… A

Serological identficication is based on 3 major groups of antigens

  • capsular …
  • H …..
A

Heat stable LPS is the major cell wall antigen – consists of three components
0 polysaccharide, somatic antigen.
A core polysaccharide common to all enterobacteriaceae.
Lipid A
Serological identification is based on 3 major groups of antigens
O, K capsular antigen
H flagellar antigen.

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4
Q

Structure and Growth requirements

  • Simple ….. ……..
  • Ferment glucose. reduce ,,,
  • catalase ….
  • cytochrome oxidase …..
  • Can be differentiated by growth on ….. ……
  • detection of presence or absence or enzymes coded on the chromosome
  • biochemical tests
A

Simple nutritional requirements
Ferment glucose, reduce nitrate
Catalase positive
Cytochrome oxidase negative
Can be differentiated by growth on selective media
Detection of presence or absence or enzymes coded on the chromosome.
Biochemical tests.

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5
Q

virulence factors

Some common to all genera, some only in specific genera.

Endotoxin:

  • Common to all …… and …… Gram ….. bacteria
  • Lipid A released at cell lysis

Capsule:
- Protected from …

Antigenic Phase variation
- Capsular …. and …. ……. under genetic control

A

Some common to all genera, some only in specific genera.
Endotoxin
Common to all aerobic and anaerobic Gram negative bacteria.
Lipid A released at cell lysis.
Capsule.
Protected from phagocytosis.
Antigenic phase variation.
Capsular K and H flagellar antigens under genetic control.

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6
Q

Virulence factors

Sequestration of Growth Factors
- . . . .acquisition via siderophores enterobactin and …. or …..

Resistance to serum killing
- Prevention of complement ….. to the …… ……

Antimicrobial resistance
- Encoded on transferable ……. and …. within species and …….

A

equestration of Growth factors
Iron acquisition via siderophores enterobactin and aerobactin or haemolysins.
Resistance to serum killing.
Prevention of complement binding to the cell surface.
Antimicrobial resistance.
Encoded on transferable plasmids and exchanged within species and genera.

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7
Q

Classification of Enterobacteriaceae

Escherichieae - includes E.coli and shigella

  • E.coli …. and …. positive and ferments lactose
  • Shigella non …, indole ….. and non lactose …….

Salmonellae
- H2s +ve Indole negative, ,motile. Lysine……

Klebsielleae includes Klebsiella, Enterobacter, Hafnia and Serratia
- VP …..

  • Proteaea Includes proteus ……., Providencia
  • All urea positive.
  • Also all phenylalanine ….. ……
A

Escherichieae – includes E.coli and Shigella.
E.coli motile and indole positive and ferments lactose,
Shigella non motile, indole negative and non lactose fermenting.
Salmonellae
H2S+ve Indole negative, motile. Lysine positive.
Klebsielleae includes Klebsiella, Enterobacter, Hafnia and Serratia.
VP pos.
Proteaea. Includes Proteus, Morganella, Providencia.
All urea positive.
Also all phenylalanine deaminase positive.

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8
Q

Esherichieae

2 genera …. and shigella
- Genetically closelly related

E. coli most common species of Escherichia isolated clinically.

  • Causes wide range of disease
  • Broad range of virulence factors

Septicaemia - usually originates from …. or ……
- outcome dependant on source and state of patient

A

2 genera Escherichia and Shigella.
Genetically closely related.
E.coli most common species of Escherichia isolated clinically.
Causes wide range of disease.
Broad range of virulence factors.
Septicaemia – usually originates from UTI or gastrointestinal infection.
Outcome dependent on source and state of patient.

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9
Q

E.coli

Urinary tract infection

  • Bacteria originate in the colon.
  • Produce adhesins
    • P …
    • afim… …….
    • Haemolysin

Neonatal meningitis

  • 75% of strains associated with meningitis contain .. …… …….
  • Relatively uncommon
A

Urinary Tract infection.
Bacteria originate in the colon.
Produce adhesins – P pili, afimbrial adhesins and haemolysin HlyA.
Neonatal meningitis
75% of strains associated with meningitis contain K1 capsular antigen.
Relatively uncommon.

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10
Q

E.coli and Gastrointestinal infection

Gastroenteritis strains divided into …. groups

Gastroenteritis strains divided into 5 groups:

  • Entero….
  • …….. EAggEC
  • …. EPEC
  • ……EHEC
  • …… EIEC
A 
Gastroenteritis strains divided into 5 groups:
Enterotoxigenic ETEC,
Enteroaggregative EAggEC,
Enteropathogenic EPEC
Enterohaemorrhagic EHEC
Enteroinvasive EIEC
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11
Q

Entertoxigenic E,coli

Resembles cholera because the …… ……. to the mucosa of the small …… and symptoms …. caused by released to…

Vomiting and ….

  • Travellers diarrhoea
  • ….. days duration

2 types of toxin …… LT and …… ST

affect cyclic AMP

Several different … and … serotypes implicated

A

Resembles cholera because the bacteria adhere to the mucosa of the small intestine and symptoms caused by released toxins.
Vomiting and fever.
Travellers diarrhoea.
3-4 days duration.
2 types of toxin heat labile toxin LT and heat stable toxin ST.
Affect cyclic AMP.
Several different O and H serotypes implicated

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12
Q

Enteroaggregative E,coli

Newest virotype of E,coli

Cause persistent form of …. in children in ,,,,,,

Similar to …..

  • Bind to ….. ….. and release ST like toxin and ….. like toxin
  • …. in small clumps

strains involved and significant not fully understood. Possess …..

A

Newest virotype of E.coli.
Cause persistent form of diarrhoea in children in developing countries
Similar to ETEC,
Bind to small intestine and release ST like toxin and haemolysin like toxin.
Adhere in small clumps.
Strains involved and significance not fully understood. Possess GVVPQ fimbriae

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13
Q

Enteropathogenic E,coli (EPEC)

Attachment changes ultrastructure of …. cells

Attachin and effacing

  • damage … when bound
  • Rearrangement of host cell actin produces ….. like structure under ……

Invasive and cause inflammatory reponse
- More Invasive than …..or…..

Cause severe childhood …. in ….

A

Attachment changes ultrastructure of mucosal cells.
Attaching and effacing.
Damage microvilli when bound.
Rearrangement of host cell actin produces pedestal like structure under the bacteria.
Invasive and cause inflammatory response.
More invasive than ETEC or EAggEC.
Cause severe childhood diarrhoea in developing countries.

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14
Q

Enteroaemorrhagic E,coli (EHEC)
Recent recognised as cause of serious diseases in ,,,,,,,, countries

Fatalities because of Haemolytic uraemic syndrome, toxin mediated
- Shiga like toxin SLT causes intense inflammatory response.

One predominant …… and …….: 0157:h7

Very low infective dose

A

Recent recognised as cause of serious disease in developed countries.
Fatalities because of Haemolytic uraemic syndrome, toxin mediated.
Shiga like toxin SLT causes intense inflammatory response.
One predominant serogroup and serotype: 0157:H7.
Very low infective dose

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15
Q

Enteroinvasive E,coli (EIEC)

Invade and destroy ……… - dysentery like illness

  • Fever and …..
  • Blood and white cells in ……
  • …. toxin produced

symptoms indistinguishable from shigella dysentery

Large plasmid …. for …. and ….. genes

A

Invade and destroy colonic epithelium – dysentery like illness.
Fever and cramps,
Blood and white cells in stools.
No toxin produced.
Symptoms indistinguishable from Shigella dysentry.
Large plasmid (pINV) for invasion and chromosomal genes

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16
Q

Shigella

Four species

  • s Dysent….
  • S flex…..
  • S.boy…
  • s.son

Non-lactose fermenters and biochemically inert

  • no gas from …
  • S,sonnei decarboxylates …… (ONPG+)
  • S. dysenteriae is non …… …….
  • 45 antigen ……. serotypes
A

Four species.
S Dysenteriae,
S flexneri,
S.boydii
S.sonnei.
Non-lactose fermenters and biochemically inert.
No gas from carbohydrates.
S.sonnei decarboxylates ornithine (ONPG+)
S. dysenteriae is non mannitol fermenting.
45 antigen based serotypes.

17
Q

Shigella

Human pathogen causing …… (shigellosis) transferred by faecal - oral route
- Most infections in children

…. infective dose, less than 200 organisms

Invade and replicate in ….. …….

Attach to …. cells in …. patches

Shigella lyse the … ….. and replicate in host cell cytoplasm

A

Human pathogen causing bacterial dysentery (shigellosis) transferred by faecal-oral route.
Most infections in children.
Low infective dose, less than 200 organisms
Invade and replicate in colonic mucosa.
Attach to M cells in Peyers patches.
Shigella lyse the phagocytic vacuole and replicate in host cell cytoplasm.

18
Q

Shigella

Rearrangement of a….. filaments propels bacteria through the ….. to adjacent cells.

  • Bacteraemia uncommon because killed by ….. in blood

S.dysenteriae produces shiga toxin.

  • ….. toxin
  • Cleaves the rRNA in the ….. subunit of the host cell and disrupts …..
A

Rearrangement of actin filaments propels bacteria through the cytoplasm to adjacent cells.
Bacteraemia uncommon because killed by macrophages in blood.
S.dysenteriae produces shiga toxin.
A-B toxin.
Cleaves the rRNA in the 60s subunit of the host cell and disrupts protein synthesis

19
Q

Shigellosis

  • Abdominal cramps, diarrhoea, …… and ….. stools

…. days after ingestion

self ……. ……

Antibiotics reduce risk of

….. carriage represents persistent reservoir

A

Abdominal cramps, diarrhoea, fever and bloody stools.
1-3 days after ingestion.
Self limiting infection.
Antibiotics reduce risk of spread.
Asymptomatic carriage represents persistent reservoir.

20
Q

Salmonelleae

  • > 2000 …. described

found in ….. and …..

Animal reservoir except for s,typhi and s.paratyphi

spread by food and faecal oral route

young and … most at risk

A 
>2000 serotypes decribed.
Found in animals and humans. 
 Animal reservoir except for S.typhi and S.paratyphi.
Spread by food and faecal oral route.
Young and old most at risk.
21
Q

Salmonella infections

Invade and …… in cells lining the ….. of the terminal protion of the small …..
- infefective does 1 million organisms

Adherence to ….. leads to rearrangement of …-membrane ruffling

Englufment into ….. vesicles.

Replicate until cell lyses

A

Invade and replicate in cells lining the lumen of the terminal portion of the small intestine.
Infective dose 1million organisms.
Adherence to microvilli leads to rearrangement of actin- membrane ruffling.
Engulfment into endocytic vesicles.
Replicate until cell lyses.

22
Q

salmonella infections

Attachment and …. mediated by …. (INV) genes

Acid tolerance reponse gene (ATR) gene product gives ……

Catalase and ….. ……. protect from intracellular killing

Inflammatory repsonse condines infection to the ……, mediates prostagladins, stimulates cAMP and ….. ….. secretion

A

Attachment and penetration mediated by invasin (inv) genes.
Acid tolerance response gene (ATR) gene product gives acid tolerance.
Catalase and superoxide dismutase protect from intracellular killing.
Inflammatory response confines infection to the GI tract, mediates prostagladins, stimulates cAMP and active fluid secretion.

23
Q

Salmonella infections
Clinical syndromes
Enteritis -

6-48hrs after consuming contaminated food and water

Na..

vom…

Non bloody …

fev. ..
head. .
my. …

adominal ….

self limiting 2 days to 1 week

A 
Clinical Syndromes
Enteritis – 
6-48 hrs after consuming contaminated food and water.
Nausea, 
Vomiting, 
Non bloody diarrhoea, 
Fever 
Headaches, 
Myalgia 
Abdominal cramps.
Self limiting 2 days to 1 week.
24
Q

Salmonella infections

Can cause septicaemia in ….. patients because of ability to survive in ,,,,,

Distinguished by:
- Serotyping of … somatic antigens, (LPS), and H ………….

Kauffman and white scheme.

Enteric (Typhoid) fever caused by ……..

Paratypoid fever - milder - caused by ……

A

Can cause septicaemia in susceptible patients because of ability to survive in bloodstream.
Distinguished by:
Serotyping of O somatic antigens, (LPS), and H flagellar antigens (proteins).
Kauffman and White scheme.
Enteric (Typhoid) fever caused by S.typhi.
Paratyphoid fever – milder – caused by S.paratyphi.

25
Q

salmonella infections

Salmonella typhi produced very little …… and are less active biochemically
- Negative ……., ……

Typhoid fever can be fatal in up to …. of cases

Incubation period 1 week to 1 month

Bacteria persume to invade through …….

A

Salmonella typhi produce very little hydrogen sulphide and are less active biochemically
Negative ornithine, citrate.
Typhoid fever can be fatal in up to 10% of cases.
Incubation period 1 week to 1 month.
Bacteria presumed to invade through M cells.

26
Q

Typhoid fever

Bacteria multiply in the …. and ….. and released into blood stream

High fever, ….. and ……..

Bacteria move from …. to ……. and shed in bile in ……

causes severe ….. …….. and probably death

A

Bacteria multiply in the liver and spleen and released into blood stream.
High fever, flushed appearance and anorexia.
Bacteria move from liver to bloodstream and shed in bile into intestine.
Causes severe intestinal ulceration and probably death.

27
Q

Salmonella infections

If persists in the …….. ,
- Patient becomes chronic carrier

Classic example
- Typhoid mary, Mary mallon

Chronic carriage in …. of patients

A 
If persists in the gall bladder, 
Patient becomes chronic carrier.
Classic example 
Tyhoid Mary, Mary Mallon.
Chronic carriage in 1-5% of patients.
28
Q

Klebsielleae

K,pneumoniae and oxytoca
- appear as very….. ……. fermenting organisms

Cause wound, soft tissue, ………….

K,penumoniae causes pneumonia in susceptible individuals.
- peumonia involves ……. destruction of………. ……., cavity formation and blood stained sputum.

A

K.pneumoniae and oxytoca.
Appear as very mucoid lactose fermenting organisms.
Cause wound, soft tissue, urinary tract infections
K.pneumoniae causes pneumonia in susceptible individuals.
Pneumonia involves necrotic destruction of alveolar spaces, cavity formation and blood stained sputum.

29
Q

Proteae

Proteus, Morganalle and providencia
- All urease ……

Proteus 5 species,
Best known …..

Swarming ,,,,,

P.mirablilis causes wound and UTI infection
- Distinguished from vulgaris (indole+) by indole reaction

A

Proteus, Morganella and Providencia
All urease positive.
Proteus 5 species,
Best known mirabilis.
Swarming motility.
P.mirabilis causes wound and UTI infection.
Distinguish from vulgaris (indole+) by indole reaction.

Microbiology (13 decks)

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