VMCB 122 > Enterobacteriaceae > Flashcards

Enterobacteriaceae Flashcards

(112 cards)

Study These Flashcards
1
Q

What is the morphology and staining of Enterobacteriaceae

A

Gram negative

Peritrichous flagella

Straight rods (bacilli)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Are you able to distinguish Enteriobacteriaceae by morphology alone?

A

Not at all. Their features can easily be mixed up with other motile bacillary genus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Considering that Enterobacteriaceae is gram negative what is the expected cell wall composition?

A

Inner and outer membranes
Thin peptidoglycan layer sandwhiched between
Periplasm
Lipopolysaccharides protruding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What structures are found in the outer membrane of Enterobacteriaceae?

A

Phospholipids
Lipid A as endotoxins
LPS
Lipoproteins (Braun’s)
Enterobacterial common antigen (ECA) as a an acidi polysaccharide
OmpA for OM stability
Porins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are capsular polysaccharides?

A

Acidic polysaccharides that contain:
M (mucous) antigen = protect from desiccation
K (kapsel) antigen = serotyping and prevent phagocytosis, to resist serum, and for adherence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two kinds of adhesins?

A

Fimbrial (pili) and Afimbrial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are fimbrial adhesins?

A

Hair-like projections that bind to host cell receptors and the F-pili is for conjugation between bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are afimbrial adhesins?

A

Amorphous capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the first afimbrial adhesin in E. coli?

A

Afimbrial adhesins (AFA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of Lipid A as an endotoxin?

A

It can cause sever toxic reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does Lipid A cause toxic reactions?

A

By binding to CD14 to trigger expression of proinflammatory cytokines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the action of proinflammatory cytokines?

A

It can cause coagulation which present as endotoxemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are Siderophores and why are they important?

A

Because they compete for iron binding in the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does siderophore compete with the host own iron-bound proteins?

A

When bacteria releases siderophores in the system, it can bind with free Fe3+ and Fe2+ creating a siderophore-Fe complex which uniquely binds to bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is Enterobacteriaceae differentiated?

A

Lactose fermentation in MacConkey
Selective/indicator media reactions
Colonial morphology (each members have specific morphology)
TSI and IMViC tests
Serotyping
Molecular techniques

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some lactose fermenting Enterobacteriaceae?

A

E. coli and Enterobacter aerogenes
Citrobacter
Klebsiella

E E C K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How can you tell that they are lactose fermenting Enterobacteriaceae?

A

MacConkey agar would have a distinct red color and the formation of pink colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is an indicator that an Enterobacteriaceae cannot ferment lactose on MacConkey’s?

A

It remains colorless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are some examples of non-lactose fermenting Enterobacteriaceae?

A

Salmonella typhinurium
Proteus vulgaris
Yersinia
Serratia
Shigella

SPYSS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does E. coli interact with Brilliant Green Phenol Red Lactose Sucrose (BPLS) agar?

A

Formation of yellow colonies and pigmentation of agar due to production of acid from fermentation of lactose and/or sucrose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the reaction of E. coli and Salmonella sp. on XLD agar?

A

E. coli would form yellow colonies
Salmonella sp. would form black colonies (H2S production)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the reaction of E. coli on Eosin Methylene Blue agar?

A

It would present a metallic green sheen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the meaning if there is no green sheen on EMB agar but growth is observed nonetheless?

A

That it is a lactose fermenter but it is not E. coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the appearance of Klebsiella on BAP?

A

Large and pink mucoid colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the appearance of proteus on BAP?
Swarming colonies in concentric circles due to rapid spread
26
Who are the major pathogens under the Enterobacteriaceae family?
E. coli Salmonella serotypes Yersinia species
27
What are the opportunistic pathogens under the family Enterobacteriaceae
Proteus species Klebsiella pneumoniae Enterobacter aerogenes Less important enterobacter that carry resistant genes
28
What are the two strains of pathogenic E. coli?
Diarrheagenic - found in the gut Extra-intestinal - found in other organs
29
What are the 5 species under the Genus Escherichia?
E. coli E. albertii E. fergusonii E. hermannii E. vulneris
30
When are Diarrheagenic E. coli relevant?
in neonatal piglets, calves and labs Important in post-weaning diarrheal infections
31
Where do extraintestinal E. coli cause infections?
Urinary tract, umbilicus, blood, lungs, wound infections
32
What are some infections caused by Extraintestinal E. coli?
Septicemia, air sacculitis pneumonia, omphalitis
33
How is omphalitis characterized as?
When the umbilical cord balloons with gas
34
What are the five major categories of E. coli based on their Pathogenicity?
Enterotoxigenic (ETEC) Enteropathogenic (EPEC) Enteroinvasive (EIEC) Enterohemorrhagic (EHEC) Cytotoxin necrotizing factor - producing E. coli
35
Where do these categories of pathogenic E. coli arise?
From commensal E. coli that have received virulence factors from Transposons, Pathogenicity islands, Phages, and Plasmids from pathogenic E. coli Or from commensal E. coli that have undergone mutations
36
How would you describe E. coli in terms of their physical characteristics? (Shape, arrangement, gram test)
Straight, gram negative rods
37
What are the cell wall components of E. coli?
LPS, OMPs, LP, porins, and a thin PG layer
38
What are the antigens present on the cell wall of E. coli?
O antigen K antigen (capsule) H antigen (flagella)
39
Which Adhesin is common in Enterotoxogenic E. coli?
F4 and F18 adhesins
40
What are the cell products of medical interest of E. coli?
Capsule Cell wall Heat labile enterotoxin Heat stable enterotoxin Shiga toxin Hemolysins Type 3 Secretion System
41
What is the difference between Heat labile (LT) and Heat stable (STa, STb) enterotoxins?
LTs cause secretory diarrhea STas and STbs cause osmotic accumulation of water into the gut
42
43
What is the Shiga toxin?
A secreted toxin that is similar to Shigella dysenteriae serotype I (which is a hemolytic uremic syndrome)
44
What are hemolysins?
Cellular products that cause the lysis of erythrocytes and impair neutrophils Cause the a/B/y hemolysis
45
What is a Type 3 Secretion System or T3SS?
it allows for the assembly of proteins to form a hollow tube to inject (injectisome) bacterial contents past translocons directly into the host cell
46
How are E. coli diagnosed in the laboratory?
Bacterial isolation Virulence genes (fimbrial and enterotoxin) by PCR Multiplex PCR format Histopathology Fluorescent-labelled antibody technique
47
How do you treat, control and prevent E. coli infection?
Good management practices Vaccination Correcting fluid and electrolyte imbalance Administration of NaHCO3 in acidotic animals Glucose to enhance absorption of absorbed Na Using anti-microbial agents such as Gentamicin, TMPS, ceftiofur
48
Which Klebsiella species are medically important in ruminants?
K. pneumoniae and K. oxytoca
49
50
What do K. pneumoniae and K. oxytoca cause in ruminants?
Bovine mastitis and genitourinary tract infections
51
What are other important Enterobacter species?
E. cloacae and E. aerogenes
52
What do E. cloacae and E. aerogenes cause in hosts?
Bovine mastitis, contaminated wounds, urogenital tract infection
53
What does Citrobacter cause in hosts?
Contaminated wounds, urogenital tract infection
54
The Salmonella genus is composed of three species
S. bongori - humans S. enterica S. subterranea
55
Which Salmonella species has over 2500 serotypes?
S. enterica
56
How does Salmonella invade hosts?
Feco-oral route
57
Why is Salmonella so problematic?
Because its serotypes are listed as species
58
How are Salmonella serotypes named?
[S. enterica] serovar Typimurium then [S.] Typimurium [denotes italics]
59
What are some clinically significant Salmonella serotypes in ruminants?
*S.* Dublin *S.* Typhimurium *S.* Newport
60
What diseases does Salmonella cause in ruminants?
Enterocolitis, enteritis pneumonia
61
What are some clinically significant Salmonella serotypes in Swine?
*S.* Typhyimurium *S.* Choleraesuis
62
What diseases Salmonella cause in swine?
Acute, fulminating septicemia Chronic intestinal disease
63
What are some clinically significant serotypes of Salmonella in horses?
*S.* Typhimurium *S.* Anatum
64
What does Salmonella cause in dogs and cats?
Septicemia
65
What do motile strains of Salmonella such as *S.* Typhimurium cause in poultry?
Paratyphoid in 2 week old chicks
66
What does *S.* Pullorum cause in poultry
Septicemia in 2-3 week old chicks
67
What does *S.* Gallinarum cause in poultry?
Acute septicemia Fowl typhoid
68
What do S. enterica ssp. arizonae and diarizonae cause in reptiles and fowls?
Avian Arizonosis
69
What capsule type does Salmonella have?
A capsule with a polysaccharide antigen called Vi (virulence)
70
Which serotypes produce Vi?
ser. Typhi and Paratyphi
71
What is the Kauffman-White scheme?
It is a classification that groups Salmonella into serotypes based on the surface antigens that are present
72
What are the cellular products of medical interest of Salmonella?
Adhesins LPS Flagella T3SS Enterotoxins Siderophores Stress proteins
73
Which Salmonella are non-motile?
*S.* Pullorum and *S.* Gallinarum
74
Why is the T3SS a product of medical interest?
Since there are 22 reported Salmonella Pathogenicity islands and they can promote the invasion of intestinal epithelium
75
How does the T3SS work?
The effector molecules rearrange the actin cytoskeleton in an act called Membrane ruffle formation This destabilizes tight junction This allows bacteria to move between cells This then causes an inflammatory response
76
What is the function of Enterotoxins of Salmonella (Stn)?
Not good for virulence Maintains membrane integrity
77
What happens if Salmonella siderophores are mutated?
Reduce their virulence
78
What is the function of Stress proteins in Salmonella?
It allows bacteria to survive in low pH
79
What is the pathology of Salmonella?
Infections in the intestinal tract Fibrinosuppurative, necrotizing, hemorrhagic inflammation Causes erosive, ulcerative, diphtheritic membrane formation in the intestines Can cause necrotizing inflammation in the liver The septicemic form can cause a fibrinoid change in blood vessels, vasculitis, thromboembolism, hemorrhages and infarction
80
81
How is Salmonella diagnosed in the laboratory?
From fecal, blood, bone, spleen samples Cultivating Salmonella from tissues on blood agar Rapid test kits
82
What selective media selects for Salmonella?
MacConkey XLD Hektoen enteric medium Brilliant green
83
What media enriches the growth of Salmonella?
Selenite F Tetrathionate
84
85
What can be used to definitively identify Salmonella?
Presence of somatic and flagellar antigens Bacteriophage typing Multiplex PCR
86
How is Salmonella treated, controlled, and prevented?
By introducing competing flora such as probiotics Nursing care Using antibiotics that can penetrate deep into the cell such as Ampicillin, enrofloxacin, TMPS, florfenicol
87
How many species are under Yersinia?
17 species
88
What is Yersiniosis?
Zoonotic infections in rodents, pigs, and birds
89
Which Yersinia species affects humans and non-human primates?
Y. pestis Y. pseudotuberculosis Y. enterocolitica
90
What diseases do Y. pestis cause in rodent and other domestic animals?
Septicemia and adenopathy
91
What do Y. enterocolitica and Y. pseudotuberculosis cause in domestic animals?
Mesenteric lymphadenitis Terminal ileitis Acute gastroenteritis Septicemia
92
What significant disease has Y. pestis brought upon humanity?
The Black Plague
93
Why is Y. pestis deadly?
The three pathogenic species have a similar specificity to bind to lymph tissues They can resist the 1st line of defense (non-specific immunity) Can resist phagocytosis Can form extracellular colonies
94
How is the plague spread?
Transmitted by fleas (Xenopsylla cheopis)
95
How does Y. pestis replicate in its vector host?
By replicating in the midgut until it block the proventriculus at which point they must infest a new host
96
Which Yersinia species affects fish?
Yersinia ruckeri
97
What does Y. ruckeri cause in fish?
Red mouth and septicemic disease in salmon and trout
98
What are some descriptive features of Y. pestis?
Gram negative Coccobacilli Slow growers Psychrotrophs (cold tolerant)
99
Are Yersinia species hemolytic?
They are not
100
What selective media is used to differentiate Yersinia and Aeromonas?
Cefsulodin-Irgasan-Novobiocin Agar (CIN Agar)
101
Where should we collect Yersinia samples from?
Sampling of affected sites such as lymph nodes, edematous tissues (fluid filled), nasopharynx, transtracheal aspirates, CSF and blood
102
How is Yersinia diagnosed in the lab?
DNA techniques Serological tests such as Hemagglutination, Hemagglutination-inhibition, and enzyme-linked immunosorbent assay
103
How is Yersinia controlled?
Eliminating fleas and rodents Antimicrobial therapy (aminoglycosides, chloramphenicol, fluoroquinolones)
104
What does Shigella cause in human and nonhuman primates?
It can cause bacillary dysentery (shigellosis)
105
What are the Shigella species that cause colonal infection?
S. dysenteriae S. flexneri S. boydii S. sonnei
106
What is the notable toxin produced by the Shigella genus?
Shiga toxin (Stx)
107
What other bacteria carries the Shiga toxin?
Shiga-toxin producing E. coli
108
Do all Shigella serotypes produce Shiga toxin?
No only the S. dysenteriae serotype I carries the genes capable of producing Stx
109
What does the Shigella toxin cause?
**Dysentery** Severe vascular lesions in the colonic mucosa Hemorrhagic colitis Hemolytic uremic syndrome
110
How is Shigella diagnosed in the lab?
Using a gram-negative broth (GN broth) Using an enrichment broth such as Selenite and tetrathionite broth Isolating them with specific media
111
Which media is used to isolate Shigella?
Hektoen enteric medium XLD SS agar (which is somewhat inhibitory)
112
What appearance would Shigella have when grown on Hektoen enteric agar?
Green, raised, and moist colonies
VMCB 122
flashcards
Decks in class (20)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions