E. Coli Flashcards
(64 cards)
1
Q
What is Enterobacteriacae
A
- Gram Negative
- Facultatively anaerobic
- Rod shaped
- Ferment glucose to acid and gas
- May or may not ferment lactose
- Habitat: GIT, soil, and water
- 30 genera and >90 species
2
Q
Which Enterobacteriacae ferment Lactose?
A
- Escherichia
- Klebsiella
- MacConkey Agar turn pink
3
Q
Which Enterobacteriacae do NOT ferment lactose
A
- Salmonella
- Proteus
- Morganella
- Serratia
- Yersinia
- MacConkey Agar stays yellow
4
Q
What are the most important Genera of Enterobacteriacae?
A
- Most Common:
- Escherichia: E. coli
- Samonella: S. enterica
- Klebsiella: K. pneumonia
- Less Common:
- Klebsiella aerogenes
- Proteus mirabilis; P. vulgaris
- Morganella morganii
- Serratia marcescens
-
Yersinia:
- Y. pestis
- Y. pseudotuberculosis
- Y. enterocolitica
5
Q
What are the Coliform Bacteria
A
- Escherichia coli
- Klebsiella pneumonia
- Klebsiella aerogenes
6
Q
Where is E. coli found?
A
- Normal inhabitant of the lower intestinal tract
- Predominant facultative organism
- Soil and water
7
Q
What are the Antigenic Characteristics of E. coli?
A
- Somatic (O) (cell wall)
- 187 groups
- lipopolysaccharides
- Endotoxin production - septicemic infection
- Capsule (K)
- Polysaccharide
- Adhesion, protection against phagocytosis
- Flagella (H)
- Protein
- Motility
- Fimbrial/Pilus (F)
- Protein
- Adhesion
8
Q
How are the pathotypes/virotypes of E. coli classified?
A
- Intestinal Pathogenic E. coli (IPEC)
- AKA: Diarheagenic E. coli (DEC)
- Extraintestinal Pathogenic E. coli (ExPEC)
9
Q
What are the categories of IPEC?
A
- Patterns of attachment on host cells
- singly or in aggregates
- Effects on host cells
- none or destruction
- Production of toxins
- Invasiveness
10
Q
Enteropathogenic (EPEC)
A
- Attachment is pili mediated
- Loss of microvilli (effacement)
- Invasion and structural changes
- Produce hemolysin
- Cause diarrhea in hums and animals (pigs)
11
Q
What hemolysins are produced by E. coli?
A
- 3 types:
-
Alpha hemolysin (Hly, encoded by hly)
- produced mainly by ETEC and ExPEC
-
Enterohemolysin (Ehx, encoded by ehx)
- Produced by STEC
-
Cytolysin A (ClyA, encoded by clyA)
- Produced by many strains
-
Alpha hemolysin (Hly, encoded by hly)
- Purpose: obtain Iron from lysed RBCs
12
Q
What is Shiga toxin-producing E. coli?
A
- STEC, VTEC, or AEEC
- Attachment is mediated by a protein intimin (not pili)
- Loss of microvilli (effacement)
- Invasion and structural changes
- Produces Shiga toxin (Stx)
- ~150 serogroups >400 serotypes
- associated with outbreaks or sporadic diarrheal diseases in humans
- Most common is E. coli O157:H7
13
Q
What is Shiga Toxin (Stx)?
A
- 2 subunits: A and B (A-B toxin)
- 2 types:
- Stx1 (100% homology)
- Subtypes: Stx1a, Stx1c, and Stxd
- Stx2 (50% homology)
- subtypes: Stx2a, Stx2b, Stx2c, Stx2d, Stx2e, Stx2f, Stx2g
- Stx1 (100% homology)
- Stx2e involved in edema disease in swine
- Stx2 is more cytotoxic
- Target Cells: Enterocytes and Endothelial cells.
14
Q
What diseases do STEC infections cause?
A
- Humans: (O157:H7)
- Hemorrhagic enteritis
- Hemolytic and Uremic syndrome (HUS)
- Food borne
- Pigs:
- Edema disease
- Chickens:
- swollen head syndrome
15
Q
What are the serotypes of STEC?
A
- ~150 serogroups and >400 serotypes
- 7 serogroups are more often involved than others
- Most common: O157:H7
- Other major: O26, O45, O103, O111, O121, O145
16
Q
What is Enteroinvasive E. coli (EIEC)
A
- Multiply inside the cell
- “Salmonella - like”
- Invasion and cellular destruction
- Cause bacteremia or septicemia
- Mostly seen in poultry (APEC)
17
Q
What is Enterotoxgenic E. coli? (ETEC)
A
- ‘Cholera-like’
- Attach (pili mediated) but do NOT invade
- Produce enterotoxins
- Heat labile (LT, 60C or 15 min)
- Heat stable (ST, 100C for 30 min)
- LT is Cholera toxin-like
18
Q
What are the LT toxins?
A
- Enterotoxin
- A-B toxin
- 2 types: LT-I and LT-II
19
Q
What are the ST toxins?
A
- Enerotoxin
- Small 2kDa proteins
- STa (methanol soluble): fluid accumulation in the intestine
- STb (methanol insoluble)
20
Q
What is Enteroaggregative E. coli? (EAggEC)
A
- New group
- Form aggregates (stacked brick adherence)
- Do not invade
- Produce ST-like (heat stable), called “EAST” and hemolysin-like toxins
21
Q
What is Cytotoxin Necrotizing Factor Producing E. coli? (CNF-PEC)
A
- Attach but do not invade the cells
- Produce a toxin (CNF) that causes necrosis
- Cause:
- diarrhea in calves, pigs and humans
- Mastitis in cows
- UTI in dogs
22
Q
What diseases doe Extraintestinal Pathogenic E. coli (ExPEC) cause?
A
- Septicemia
- Mastitis in dairy cows
- Uterus (Metritis)
- Urinary tract (UPEC)
- Air sacculitis in chickens and turkeys (APEC)
23
Q
What are the important Virotypes of E. coli in animals?
A
- ETEC: Intestinal infections (enterotoxins)
- EPEC: Intestinal and extraintestinal infections
- STEC: Edema disease in Pigs (Shiga Toxins)
24
Q
Who is affected by Intestinal Colibacillosis?
A
- Piglets
- Calves
- Lambs
- Goat kids
25
Where does Extraintestinal Colibacillosis occur?
* Septicemic or localized infections in:
* mammary gland
* Urinary tract
* Uterus
26
What are the modes of infection for *E. coli* and what do they result in?
* Ingestion: Enteritis
* Inhalation: Mostly in poultry - Respiratory infection
* Direct infection: Entry into an organ
* Teat canal: Mastitis
* Urethra: UTI
* Vagina: Metritis
27
What are the 3 forms of Colibacillosis in Swine?
* Neonatal enteritis
* Post weaning diarrhea (weanling enteritis)
* Edema disease
28
What is Neonatal enteritis?
* Occurs in the first 3-4 days of life
* Profuse diarrhea (pale yellow and watery)
* Mortality almost 90%
* Death due to dehydration
29
What is Post Weaning Diarrhea?
* Caused by: EPEC, ETEC, and STEC strains
* Toxins: Enterotoxins (ST, LT, EAST), hemolysin, Stx2e
* Usually seen within the first week of weaning
* Affected pigs develop diarrhea, depression, anorexia, and fever
* Low mortality
30
What is Edema disease?
* Caused by STEC
* Stx(Stx2e) is major virulence factor
* 7-10 days after weaning
* Edema of the submucosa of the stomach and colon and SQ tissues (eye lids)
31
What are the predisposing factors of Edema disease
* Age 7-10 days after weaning
* Change of feed
* Rapid growth
* Diarrhea
32
What are the clinical signs of Edema disease?
* Edema: eyelids, facial area, stomach, colon, mesenteric lymph nodes, gall bladder, larynx, etc.
* Peculiar squeal
* Neurological: Convulsions, Ataxia
* Recumbency with paddling of legs
33
What is the mortality rate of Edema disease?
* 65%
* Death in 1-3 days
34
How can Edema disease be prevented?
* Separation of sick pigs
* Vaccine (recombinant toxoid)
* Antibiotic in the Feed (CTC, Enrofloxacin)
35
What is White Scour?
* Colibacillosis in calves
* During the 1st week of life
* Severe diarrhea, feces full of gas bubbles
* Virulence factor: Enterotoxin (STa)
* Death in 3-5 days from dehydration
36
What is the Septicemic form of Colibacillosis in Cattle?
* Occurs in calves deprived o colostrum
* Virulence factor: Endotoxin
* Endotoxic shock and death
37
What is Coliform mastitis?
* Mastitis from *E. coli*
* 30-50% of cases
* Frequently seen in high-producing dairy cows
* Mostly mild cases
* Clinical signs: Swelling of the udder, discolored milk, blood clots, loss of milk production
38
What is the Pathogenesis of Choliform mastitis?
* Entry through the teat
* Adherence to mammary cells
* Virulence factors: Pili, Endotoxin, CNF
* Absorption of endotoxin leads to fever, depression, and occasionally death
39
How is Choliform Mastitis treated/prevented?
* Antibiotics: Amoxicillin, Cephalosporins
* Vaccine: Endotoxin-based (J5 strain)
40
What diseases does Colibacillosis cause in other large animals?
* Neonatal enteritis
* lambs and kids
* occasionally septicemic
* Enteritis in foals
* Mastitis and metritis in mares
41
What does Colibcillosis cause in Dogs and Cats?
* Diarrhea is NOT common
* Commonly isolated from genital and urinary tract infections
* Cystitis and pyometra in bitches
* Prostatitis in males
42
What are the Virulence factors of UTIs in Dogs?
* Pili: adherance
* Hemolysin
* Cytotoxin Necrotizing factor (CNF)
* Protease enzyme
43
What does colibacillosis cause in Poultry?
* Enteric infection is rare
* Respiratory infections (air-sacculitis)
* Cellulitis: Swollen head syndrome
* Coli-Granuloma (Hjarre's Disease): chronic rom with granulomatous lesions in the walls of the intestinal tract, liver, and lungs.
* Localized or systemic (Colispeticemia)
* Avian strains (APEC) do NOT cause diseases in other animals
44
What is Air-sacculitis?
* Causes:
* inhalation of fecal dust
* inhalation of ammonia predisposes to colonization
* Secondary to viral and mycoplasma infections
* Pneumonia: pleuropneumonia, pericarditis, etc.
* Significant economic loss
44
What is Cellulitis?
* Infection of the subcutis
* seen in lower abdomen and thigh region
* Swollen Head syndrome:
* Cellulitis affecting periorbital region
* Caused by STEC strains
* Significant economic losses
45
What is the Public Health significance of *E. coli?*
* Similar serotypes, but animals are not a source of human infection
* Enterotoxins are similar but pili antigens are different
* STEC (O157:H7) are zoonotic pathogens
46
How do you Diagnose an *E. coli* infection?
* Presumptive Diagnosis:
* Age
* Clinical signs
* Isolation from fecal sample
* Key: interpretation
* methods:
* determination of surface antigens and toxins
* Serology to detect O, K, F antigens
* Slide agglutination, ELISA, FAb
* Molecular: PCR for virulence genes
* Histopathology: Adherent *E. coli* cells
* Light and electron microscopy; Fab tech)
47
How do you Treat?
* Antibiotics:
* Aminoglycosides (neomycin)
* Tetracyclines
* Fluid Therapy:
* Rehydration and electrolyte balance
48
What are Control Measures for Neonatal Enteritis?????
* Sanitation and management
* Newborn animals should get colostrum
49
Are there vaccinations for *E. coli?*
* Pilus-based vaccines for neonatal enteritis:
* F4 (K88), F5 (K99), F6 (987P)
* Pregnant sows and cows are vaccinated for passive transfer
* Autogenous bacterins
* Recombinant Stx toxoid for edema disease
* J5 vaccine for mastitis (LPS vaccine)
50
Are there vaccinations for *E. coli?*
* Pilus-based vaccines for neonatal enteritis:
* F4 (K88), F5 (K99), F6 (987P)
* Pregnant sows and cows are vaccinated for passive transfer
* Autogenous bacterins
* Recombinant Stx toxoid for edema disease
* J5 vaccine for mastitis (LPS vaccine)
51
What illnesses does STEC cause in humans?
* Diarrhea:
* mild to severe
* +/- blood
* Hemolytic uremic syndrome (HUS)
* Mostly in children
* Thrombocytopenic purpura (TPP)
* mostly in adults
52
What are the most common Non-O157 STEC groups?
* O26 (22%)
* O111 (16%)
* O103 (12%)
* O121 (8%)
* O45 (7%)
* O145 (5%)
* These 6 account for 71% of non-O157 STEC infections
53
How do O157 and non-157 STEC infections compare?
54
What is the incidence of STEC illnesses in the US?
* Food born illness is about 66% of STEC illnesses
* O157 accounts for:
* 36% of illnesses
* 89% of hospitalizations
* 100% of deaths
55
What about STEC in foods?
* *E. coli* O157:H7 declared an adulterant in '94
* in '11 six non-O157 STEC (O26, O45, O1-3, O111, O121, and O145) were also declared as adulterants
* Testing ground beef by Food Safety Inspection Service (FSIS) began in June 2012
56
Why are STEC infections of Public Health importance?
* Human pathogen, NOT animal pathogens
* Cattle are major reservoirs
* Most are food borne:
* Beef and dairy
* Fruits and veges
57
*E.coli* O157:H7
* First recognized in 1982
* important food borne pathogen
* Causes:
* hemorrhagic colitis
* Hemolytic Uremic Syndrome (HUS) - acute renal failure, hemolytic anemia and thrombocytopenia
* Present in the GI tract, particularly in the hindgut of cattle
* Shed in feces
* highly variable shedding
58
Pathogenesis of *E.coli* O157:H7
* Colonizes intestinal cells
* Produces Stx (Verotoxin)
* Damages endothelial cells, which causes thrombocyte aggregation and capillary damage in the kidney or other organs
* No enterotoxin
* NOT invasive
58
Pathogenesis of *E.coli* O157:H7
* Colonizes intestinal cells
* Produces Stx (Verotoxin)
* Damages endothelial cells, which causes thrombocyte aggregation and capillary damage in the kidney or other organs
* No enterotoxin
* NOT invasive
59
What is the prevalence of *E. coli* O157:H7 in cattle?
* Herd level: 80-100%
* Prevalence in dairy and beef cattle: 10-28%
* Shedding is seasonal
* higher in summer and early fall
* Shedding is \<102 per gram of feces
* Super shedders \>103
60
How do carcasses get contaminated?
* During Hide removal
* physical transfer
* Aerosol
* Evisceration
* gut contents
61
What are some sources of *E. coli* O157:H7?
* Undercooked ground beef
* Unpasteurized milk
* Unpasteurized fruit juices
* Drinking water and recreational water
* Contaminated leafy vegetables
62
How is the spread of *E.coli* O157:H7 prevented?
* Preharvest:
* management
* Probiotics
* Bacteriophages
* Vaccine
* Post Harvest:
* Hide and carcass wash
* Implementation of Hazard Analysis and Critical Control Points (HACCP) in slaughtering and Meat Processing procedures
* Adequate cooking (160F for 15 sec)
* Pasteurization of milk and fruit juices
