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infection > 6.2 enterobacteriae > Flashcards

6.2 enterobacteriae Flashcards

1
Q

What are enterobacteriaecea as pathogens?

A

large, heterogeneous group of medically important pathogens

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2
Q

enterobacteriaceae :
1. gram staining
2. shapes ?

A
  1. gram negative
  2. rods or bacilli
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3
Q

< 20 species of enterobacteriaceae responsible for > 95% infection such as… (give examples of most common forms of infections)

A
  • UTIs
  • septicemia
  • intestinal infections
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4
Q

> 70% enterobacteriaecea responsible for what infections ?

A

urinary tract infections

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5
Q

where do infections with enterobacteriaceae originate from ?

A
  • animal resevoir
  • human carrier
  • endogenous spread of organisms
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6
Q

Enterobacteriaceae physiology ?
1. grow … ?
2. nutritional requirements are … ?
3. type of anaerobes ?

A
  1. slowly
  2. simple
  3. facultative
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7
Q

what do enterobacteriacea ferment and reduce ?

A
  1. ferment glucose
  2. reduce nitrate
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8
Q

enterobacteriaceae:
1. catalase positive / negative ?
2. unlike other gram-negative rods it’s oxidase status ?
3. pathogenic members don’t ferment …. ?
4. pathogenic members are resistant to …?

A
  1. positie
  2. negative
  3. lactose
  4. bile salts
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9
Q

Differences on solid medium colour between lactose fermenting colonies and non-lactose fermenting colonies ?

A
  • fermenting = pink
  • non-fermenting = colorless
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10
Q

List some enterobacteriaceae pathogenic to humans ? all end in spp

A
  • citrobacter
  • enterobacter
  • escherichia
  • klebsiella
  • morganella
  • salmonella
  • shigella
  • yersinia
  • hafina
  • plesiomonas
  • proteus
  • serratia
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11
Q

Name some common medically significant enterobacteriaceae

A
  • Citrobacter freundii, Citrobacter koseri
  • Enterobacter aerogenes, Enterobacter cloacae
  • Escherichia coli (opportunistic/pathogenic)
  • Klebsiella pneumoniae, Klebsiella oxytoca
  • Morganella morganii
  • Proteus mirabilis, Proteus vulgaris
  • Salmonella enterica (pathogenic)
  • Serratia marcescens
  • Shigella sonnei, Shigella flexneri (pathogenic)
  • Yersinia pestis, Yersinia enterocolitica, Yersinia pseudotuberculosis (pathogenic)
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12
Q
A
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13
Q

Examples of an primary pathogen of enterobacteriaceae

A

shigella
salmonela
uersina

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14
Q

Examples of an opportunistic pathogen of enterobacteriaceae

A
  • providencia
  • enterobacter
  • morganella
  • serratia
  • proteus
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15
Q

Example of an opportunistic / primary (mixed) pathogen of enterobacteriaceae

A

E. coli
K. pneumoniae

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16
Q

primary pathogens cause disease in ?

A

healthy host

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17
Q

opportunistic pathogen cause disease only in … ?

A

absence of normal host resistance (immunosuppressed host)

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18
Q

What are the virulence factors of enterobacteriaceae ?

A
  • Flagellar H antigen
  • Capsular K or Vi antigen
  • Liposaccharide (LPS)
  • O antigen
  • Core polysaccharide (present in all E.)
  • Lipid A (responsible for endotoxin activity)
  • Siderophores
  • Type III secretion system
  • Antimicrobial resistance
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19
Q

E. coli is a major componenet of the … ?

A

normal intestinal floar

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20
Q

what does E. coli cause by at least 6 mechanisms ?

A

diarrhoea

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21
Q

E. coli causes diarrhoea by at least 6 mechanisms, identified by the adjectives used to describe the respective strains…

what are these 6 mechanisms ?

A
  • STEC = shiga toxin producing strain
  • ETEC = enterotoxigenic strains
  • EIEC = enteropathogenic strains
  • EPEC = enteropathogenic strains
  • EAEC = enteroaggregative strains
  • DAEC = diffusely adherent E.coli
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22
Q

Most clinically relevant salmonella pathogens belong to what ?

A

Salmonella enterica spp

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23
Q

Salmonella enteric spp has how many subspecies and over 2500 ….. differentiated based on ….. antigens

A
  • 6 subspecies (I,II,IIIa,IIIb,IV,and VI)
  • serovars
  • H,K,O
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24
Q

What is the full taxonomic classification for Salmonella enterica serotype Typhi?

What is designated as ?

commonly referred to as …?

A

Genus: Salmonella, Species: enterica, Subspecies: enterica, Serovar: Typhi

It is designated as S. enterica serotype Typhi

commonly referred to as S. ser Typhi.

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25
Q

Salmonella enterica spp. causes …. ? what are 2 types ?

A

salmonellosis

  • gastroenteritis
  • enteric fever (typhoid fever)
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26
Q

salmonella typhi spp causes ?

A

typhoid fever

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27
Q

most common form of salmonellosis is ?

A

gastroenteritis

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28
Q

cause of salmonellosis ?

A

salmonella enteritidis

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29
Q

transmission of salmonellosis ?

A
  • contaminated food (poultry, dairy, eggs)
  • contaminated water
  • faecal-ocal route
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30
Q

symptoms (appear within 6-48 hours) of salmonellosis ?

A
  • nausea
  • vomiting
  • diarrhoea
  • fever
  • abdominal cramps
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31
Q

diagnosis of salmonellosis ?
what agar or media ?

A

stool sample analysis
(MacConkey agar or selective media)

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32
Q

Treatment of salmonellosis ?

A
  • rehydration
  • if in bloodstream = Cephalosporins
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33
Q

Pathogenesis of gastroenteritis causing salmonella (S. enterica)

A
  1. salmonella ingested in contaminated food / water
  2. bacteria attach to mucosa of small inestine and invade into the microfold (M-cells) of the peyer’s patches and endocytose into enterocytes
  3. bacterial invasion proteins are injected by type III secretion system
  4. production of salmonella enterotoxin which leads to local inflammation & diarrhoea
  5. pathogen kills host cells, triggering abdominal cramps & diarrhoea
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34
Q

Complication of salmonellosis (S. enterica) gastroenteritis ?

A

if bacteria enters the bloodstream, can lead to septicaemia

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35
Q

1 of the 4 key global causes of diarrhoeal disease is ?

A

salmonella

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36
Q

What illness is enteric (typhoid) fever ? caused by ?

A

acute, life-threatening illness

Salmonella Typhi

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37
Q

Transmission of enteric (typhoid) fever ?

A
  • ingestion of contaminated food / water
  • faecal-oral route
  • contact without carriers
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38
Q

symptoms of enteric (typhoid) fever ?

occur within 10 - 14 days and persis for 3-4 weeks

A
  • high fever
  • headache
  • constipation or diarrhoea
  • abdominal pain
  • malaise
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39
Q

Enteric (typhoid) fever has malaise within …1.. days following at least 1 week of ..2… ?

A
  1. 10 to 14 days
  2. constipation and abdominal cramping
40
Q

Enteric (typhoid) fever symptoms persist for duration ?

A

3-4 weeks

41
Q

diagnosis for enteric (typhoid) fever ?

A
  • stool sample analysis
  • blood
  • bone marrow
  • urine sample analysis
42
Q

treatment for enteric (typhoid) fever ?

A

antibiotics e.g.
* fluoroquinolones
* chloramphenicol
* cephalosporins

43
Q

Vaccination for enteric (typhoid) fever is recommended for people travelling to which countries ?

A
  • asia
  • africa
  • latin america
44
Q

Pathophysiology of S. Typhi infection (typhoid fever) ?

A
  1. ingestion of contaminated water / food
  2. Invasion of small intestine, enter bloodstream
  3. carried by WBC (phagocytosed NOT digested) to liver, spleen , bone marrow
  4. Bacteria multiply, re-enter bloodstream
  5. bacteria invade gallbladder, biliary system & lymphatic tissue of bowel
  6. bacteria pass into intestinal tract - can be identified for diagnosis in stool sample analysis (salmonella is shed in faeces) in lab
45
Q

Untreated typhoid fever is broken down into how many different stages ?

A

4

46
Q

In stage 1 of typhoid fever onset of symptoms is between …. days post-infection ?

A

5 - 14

47
Q

what is epistaxis ?

A

acute hemorrhage from the nostril, nasal cavity or nasopharynx

48
Q

what happens stage one of typhoid fever ?

A
  • stepwise fever
  • relative bradycardia
  • malaise (discomfort or uneasiness)
  • headache
  • cough
  • in 1/4 cases epistaxis can occur
49
Q

Stage 2 of typhoid fever ?

A
  • continuing high fever
  • bradycardia continue
  • extremely distended abdomen
  • abdominal pain
  • weight loss
  • dicrotic pulse wave
  • delirium is frequent, often calm and sometimes agitated
50
Q

stage 3 of typhoid fever is when …. what occurs ? list some :

A

complications
* intestinal hemorrhage
* intestinal perforation
* encephalitis (inflammation of the brain)
* fever persistence
* dehydration (increases delirium)
* increased delirium
* motionlessness (eyes half-opened)

51
Q

Stage 4 of typhoid fever ?

A

defervescence (very high fever) commences that continue into fourth week

52
Q

Death can occur from complications which arise from Typhoid fever.

Name these complications

A
  • overwhelming infection
  • pneumonia
  • intestinal bleeding (hemorrhage/perforation)
  • kidney failure
  • peritonitis (inflammation of peritoneum)
53
Q

Who are asymptomatic disease carriers of S. Typhi ?

A

healthy people who have survived typhoid fever, but in whom the bacteria are able to survive without causing further symptoms

54
Q

what’s the main source of chronic carriage of typhoid fever ?

A

infected gallbladders

55
Q

How are carriers of chronic carriage of typhoid fever treated ? and cured

A
  • long-term antibiotics
  • can be cured via = gallbladder removal surgery
56
Q

Shigella species are classified into four … ?

A

O - antigen-based serogroups

57
Q

What are the 4 O-antigen based serogroups that shigella species are classified into ?

A
  • A = S. dysenteriae
  • B = S. flexneri
  • C = S. boydii
  • D = S. sonnei
58
Q

Shigella spp. gram staining and shape ?

A

gram negative bacilli

59
Q

All 4 species of shigella spp. cause what ?

A

bacillary dysentry or shigellosis

60
Q
  1. Main mode and 2. can also be mode of transmission of Shigella ?
A
  1. direct person-person
  2. contaminated food/water
61
Q

symptoms of shigella ?

A
  • bloody diarrhea
  • intestinal pain
  • intestinal cramps
  • fever (sometimes)
62
Q

What members of enterobacteriaceae result in shigella ?

A

non-motile and non-capsulated

63
Q

Shigell only host is ?

A

human

64
Q

Incubation period for shigella ?

A

1-3 days

65
Q

Shigella spp. cause what illness ?

A

Shigellosis (baciliary dysentery)
* bacterial gastroenteritis
* caused by 4 shigella serogroups
* relatively few organisms can cause disease

66
Q

Describe pathogenesis of shigellosis infection

A
  1. shigella proliferate rapidly in small intestine, reach colon and attach to M-cells in Peyer’s patches
  2. following endocytosis, shigella replicates in cytosol
  3. rearrangement of actin filaments of host cells - so shigella can enter adjacent cells (spread)
  4. shigella produce shiga toxin (exotoxin) which kills host cells leading to symptoms (local inflammation, disease manifestation)
  5. shigella are quickly phagocytosed in the bloodstream
67
Q

Cause of shigellosis:
1. low/middle income countries =
2. high income countries =

A

1.Shigella flexneri
2.Shigella sonnei

68
Q

Transmission of Shigellosis?

A
  • faecal-oral route
  • ingestion of contaminated food/water/fomites
  • direct person-to-person contact
69
Q

symptoms of shigellosis occur within …. of infection ?

A

1-3 days

70
Q

symptoms of shigellosis ?

A
  • abdominal cramps
  • diarrhoea
  • fever
  • bloody stools
71
Q

diagnosis for shigellosis ?

A

stool sample analysis

72
Q

Treatment for shigellosis ?

A

Rehydration therapy
Antimicrobials

73
Q

List the examples of antimicrobials for shigellosis treatment

A

FACTS
* fluoroquinolones
* azithromycin
* ciprofloxacin
* trimethoprim
* sulfamethoxazole

74
Q

E. coli has some strains that are …. whilst others are ….

A
  • opportunistic pathogens
  • pathogenic
75
Q

Name 2 common virulence factors of E.coli

A
  • adhesins
  • exotoxins
76
Q

4 illnesses that E. coli causes ?

A
  • gastroenteritis
  • UTIs
  • meningitis
  • sepsis
77
Q

E.coli transmission ?

A
  • faecal-oral route
  • ingestion of contaminated food / water
  • consumption of undercooked beef or unpasteurised milk
78
Q

What is E.coli O157:H7 the most common cause of ?

A

Haemorrhagic colitis and haemolytic uermic syndrome

79
Q

What is most common cause of Haemorrhagic colitis and haemolytic uermic syndrome ?

A

E.coli O157:H7

80
Q

E. coli virulence factors

A
  • gram negative
  • fimbriae - cystitis and pyelonephritis
  • K capsule - pneumonia, neonatal meningitis
  • LPS endotoxin - septic shock
81
Q

What strain causes E.coli O157:H7 gastroenteritis ?

A

STEC or EHEC strains of E.coli

shiga toxin - producing or enterohaemorrhagic

82
Q

What are common sources of infection of E.coli O157:H7 gastroenteritis ?

A
  • undercooked beef
  • unpasteurised milk
83
Q

E.coli O157:H7 gastroenteritis incubation period?

A

1-8 days

84
Q

E.coli O157:H7 gastroenteritis treatment ?

A
  1. rehydration therapy
  2. antibiotics
  3. blood transfusion & haemolysis
85
Q

Yersinia infection leads to ?

A

enterocolitis (yersiniosis)

86
Q

cause of yersiniosis ?

A
  • Y. enterocolitica
  • Y. pestis
  • Y. pseudotuberculosis
87
Q

Transmission of yersiniosis ?

A
  • ingestion of contaminated foods (dairy, meat, poultry, fruits, vegetables, seafoods)
  • blood transfusions (higher mortality rate)
88
Q

symptoms of yersiniosis ?

A
  • watery of bloody diarrhoea
  • fever
  • abdominal pain (lasting up to 2 weeks)
89
Q

With yersinia symptoms present within …. days post-infection ?

A

4-6

90
Q

Yersinia disease can become … ?

A

chronic

91
Q

what can yersinia infection mimic ?

A

appendicitis

92
Q

How can yersinia infection mimic appendicitis ?

A

it affects terminal ileum and mesenteric lymph nodes are enlarged

93
Q

diagnosis of yersiniosis ?

A

stool sample analysis

94
Q

Treatment of yersiniosis

A

antimicrobial drugs can be used if required

95
Q

examples of antimicrobials that may be required for yersinia ?

A
  • Cephalosporins
  • Aminoglycosides
  • Chloramphenicol
  • Tetracyclines
  • Trimethoprim
  • Sulfamethoxazole

infection (29 decks)

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