Enterobacteriaceae- E coli Flashcards
Enterobacteriaceae overview
Reside in the GI tract of humans and animals Benefits: microbian antagonism -breakdown and absorption of the food -Waste processing -Vitamin K production 40 genera, 180 spp Gram - facultative anaerobic Rods or coccobacilli Oxidase negative Present in water, soil environment and GI tract of humans and animals- not environmental really Coliform bacteria Lactose += ecoli,
Genus Escherichia
E. coli- only clinically relevant one
Major pathogen in several animal species
Gram-negative coccobacilli
Lactose positive, oxidase negative, motile rods
E. Coli
Serotype: complete antigenic formula of an E coli
ex. O:26, K:60, F:41, H:11
O- O antigen (surface antigen- part of LPS)
H-Flagella
F-Fimbriae
K-Capsule
V diverse
E. Coli: pathogenicity
Strain dependent
Facultative pathogenic (eg. APEC)
Obligate pathogenic but then age dependent (few)
Differentiation between pathogenic and non-pathogenic strains not always evident but associated with:
-Certain serotypes (serotyping)
-Virulence genes (pathotyping-virotyping)
-Combinations of virulence genes
-Biotype (for RPEC only)
E. Coli: infections
Intestinal pathogenic strains Extra-intestinal pathogenic strains (ExPEC) -Respiratory -Septicemia -UTI -Pyometra -Mastitis
E. Coli: virulence factors
Depend on the pathotype Cell associated: -Endotoxin -Capsule -Fimbrial adhesions -Non-fimbrial adhesions
Extracellular
- Enterotoxins (work on intestine)
- Cytotoxins (toxicity for other cell types)
- Siderophores (septicemia)
E. Coli: Enteric Pathotypes
ETEC (enterotoxigenic) EHEC (Enterohemorrhagic) VTEC/STEC (Verotoxigenic/Shiga-like toxic) EPEC (Enteropathogenic) RPEC (Rabbit pathogenic)
E. Coli: Extra-intestinal pathotypes
APEC (Avian pathogenic) Necrotoxigenic (NTEC)- cattle Mastitis causing E coli- Cattle MMA in pigs UPEC- dogs
E. Coli: pigs
ETEC- Diarrhea VTEC-Oedema disease EPEC UTI MMA
E. Coli: Cattle
ETEC Septicemia: NTEC EPEC EHEC/VTEC Mastitis
ETEC in piglets- adhesion factors
Adhesion factor: F4 -Solely in pigs -Neonatal to post weaning F5 -Receptor only in very young animals: neonatal F6 -Neonatal F41 -Frequently together with F5 -Rare -Neonatal F18 -Oedema disease, from weaning on Non-fimbrial adhesions
ETEC in piglets- Enterotoxins (on plasmids)
- Heat labile toxin (LT)
- high molecular weight
- strong antigen: vaccination - Heat stable
- STa, STb
- EAST1 (enteroaggregative E coli heat stable toxin)
- Low molecular weight
- Little antigenic
ETEC in piglets- Virulence factors
Age dependent importance Neonatal ETEC -F4; F5; F6; F41 -STa; STb -Non hemolytic
Neonatal till 3 weeks
- F4
- LT; STa; STb; EAST1
- Hemolytic
Post weaning diarrhea
- F4; F18
- LT; STa; STb; EAST1
- Hemolytic
ETEC in piglets- Virulence and pathogenesis
In the intestine of healthy sows
Equilibrium between maternal immunity and infection pressure
Break in equilibrium=disease
-Increase infection pressure: low hygiene; presence of ETEC diseased piglets
-Lowering of maternal immunity
Sow: MMA (no milk); first delivery
Piglet: low birth weight; other infection
Too many piglets per sow
-Appearance of new type
ETEC in piglets: Piglet diarrhea
Distortion of equilibrium between immunity and microbial load: bacterial challenge too high and/or immunity too low (mainly maternal)
ETEC in piglets: Diagnosis
Symptoms and age:
- remain drinking
- v smelly feces
- dehydration
- Older piglets diarrhea (white, grey, not as watery)
- Bacteriology + Detection of virulence factors
- PCR
- Agglutination
ETEC in piglets: Treatment
Hydration (SC, IP) (PO, electrolyte solution plus glucoses and amino acids)
Antimicrobials (susceptibility profile)
ETEC in piglets: Prevention
Hygiene and management: prevention of spread, cleaning and disinfection
Vaccination sows:
-Inactivated vaccines: different strains (with different F factors)
-Purified adhesion factors and LT
-Two injections of which the last one 2-6 weeks before partus
-Live vaccine
Vaccination of piglets (only of use for F4)
-Live vaccine for (post) weaning diarrhea
Selection of receptor free piglets (F4)
VTEC- Oedema disease in piglets: Virulence and pathogenesis
- Adhesion small bowl: F18
- Specific receptor
- Adhesion from approx of 10 days on - Exotoxin
- VT2e or Stx2e: media necrosis (blood vessels) - Exotoxin: acute mortality
Oral intake of pathogenic E coli
Adherence and proliferation in intestine
Shiga toxin damages blood capillaries and increases fluid loss
Clinical Signs
VTEC- Oedema disease in piglets: Virulence and pathogenesis
Sow to piglet Weaning: stress -Change in intestinal flora -Maternal immunity Excretion -> infection pressure increase -> contamination other piglets Toxin production: media necrosis -Hyperacute: enterorhagia -Acute: permeability blood vessels oedema (CNS and dyspnea) -Slower: intravascular coagulation Endotoxin: shock and acute mortality
VTEC- Oedema disease in piglets: diagnosis
Symptoms: -<3 wks after weaning -Multiple piglets affected CS Bacteriology and confirmation virulence factors
VTEC- Oedema disease in piglets: Clinical signs
Acute mortality (some)
Diarrhea (rare)
Anorexia
Oedema: hoarse voice, CNS, dyspnoea, swollen eyelids
VTEC- Oedema disease in piglets: Treatment
Affected animals:
-fasting (elimination of toxin)
-Increase of intestinal peristaltic
-antimicrobial therapy (note: quite some resistance, susceptibility test)
Not yet affected animals
-antimicrobial therapy: incubation time of toxin 2-3 days (so you may still see symptoms after tx)
VTEC- Oedema disease in piglets: Prevention
Reduce stress at weaning (no castration, no vaccination, keep temp constant)
Feed composition: feed restriction; increase fiber content; starter feed before weaning
Adaptation of intestinal flora (reduction of E coli and toxin): probiotics; organic acids (have antibacterial effects); Zin oxide (in feed for first 14 days after weaning)
Antimicrobials
Vaccination in piglets at age of 2-4 days (live vxn contains recombinant VT2e)
Selection of receptor F18 negative animals
EPEC diarrhea in piglets: virulence and pathogenesis
Rarer, little known about its general role
Diarrhea at weaning
Virulence factors:
-BFP- bundle forming pilli, initial attachment
-Attaching and effacing- intimate attachment
-eae
-T3SS (needle) and injection of effector proteins
EPEC diarrhea in piglets: diagnosis
Bacterial isolation and detection of eae gene
EPEC diarrhea in piglets: treatment
Antimicrobials (oral)
EPEC diarrhea in piglets: Prevention
No vaccine
Little is known
E coli- UTI in pigs
Most important pathogen in UTI in pigs
Other bacteria can be involved too
Originated most probably from intestine
Virulence factors E coli infection in pigs?
Predisposing factors: hygiene, water intake, obstipation, age, individual (anatomical) differences
E coli- UTI in pigs: Diagnosis
Symptoms: Anorexia; Hematuria; Vaginal exudate; General malase
Bacteriology
E coli- UTI in pigs: treatment
Culling (fertility problems)
Antibiotics approx 3 wks
E coli disease in pigs: MMA or PPDS
MMA= Metritis-mastits-agalactiae = no milk PPDS= post partum Dysgalactiae Syndrome Etiology -hereditary -hormonal -feed -Infectious agents
E coli disease in pigs: Septicemia
Secondary to enteric infection
Rarely primary
E coli in bovines
ETEC: less than 3 d old EPED: older than 1 wk EHEC: zoonotic importance Septicemic (NTEC): neonates, lack of colostrum Mastitis
ETEC in bovines: Virulence and pathogenesis
Similar to pigs but: Animals less than 3 d old Adhesion: fimbriae -F5 (most common) -F41 (freq together with F5) -F17 (role not clear) (a,b freq assocaited with CNF2) (c with CS31A) -CS31A (related to F4) Freq relation to diarrhea in older animals Toxins: Sta and Stb
Equilibrium between immunity and infection pressure
Colostrum: too little too late too low in Ab
Infection: too early, too high (infection pressure)
ETEC in bovines: Diagnosis
ELISA
Culture and virulence gene detection: Agglutination/PCR
ETEC in bovines: Therapy
Separate sick animals Hydration Antibiotics: note- extremely high levels of acquired resistance -Diarrhea + fever: parenteral therapy -No fever: oral therapy NSAID (shock)
ETEC in bovines: Therapy on milking farms
Hygiene: separate calves from mothers Colostrum: of multi-parturiant animals Antibiotics p.o (4-5d) Vaccination of cows Antibodies p.o
EPEC in bovines
Not a common infection
Virulence: eae
-cfr pigs, different strains but same virulence and pathogenesis mechanism
EPEC in bovines: symptoms
Age: 1-8 wks
Mucoid diarrhea +/- blood
Mainly in large intestine
EPEC in bovines: therapy
Antibiotics
STEC/VTEC/EHEC in bovines
Only Zoonotic importance
Virulence genes: eae+stx1 and/or stx2
Specific serotypes
Responsible for serious infections with mortality (5-7%) and persistent lesions to kidneys
Also names Hemorrhagic Uremic Syndrome (HUS)
NTEC in bovines: virulence
ExPEC Facultative pathogenic (freq in intestinal tract) Virulence factors: serum resistance -iron uptake systems -endotoxin -capsule -adhesion factors (P, F17, AfaE-VIII, CS31A) -CNF1, CNF2 (cytotoxic necrotic factor)
NTEC in bovines: Pathogenesis
Uptake: per os OR umbilical cord
via lymphoid tissues of head and throat OR intestine
Septicemia
Hyperacute: acute mortality, shock
Acute: general symptoms, fast mortality
Slower with organ localization, poly arthritis, pneumonia, pleuritis, menigo-encephalitis
NTEC in bovines: Diagnosis
Clinical (age, symptoms, colostrum: low gamma globulins in serum)
Isolation + PCR for virulence genes
NTEC in bovines: Therapy
NSAID (shock)
Antibiotics (susceptibility testing)
Gamma globulins: plasma from older animals
NTEC in bovines: Prevention
Make sure that the calves get good quality colostrum
E coli Mastitis in bovines
No virulence factors known Environmental origin DD gram +/ gram - infection: -Gram -: with fever -Frequently lost udder quarter Prevention: hygiene Treatment: systemic antibiotics
E coli disease in cats and dogs: enteric
Isolation from feces: significance???
Dogs: freq + other pathogens
-ETEC, EPEC, VTEC, EIEC: both in clinically healthy as well as diarrheic
Cat???
E coli disease in cats and dogs: Cystitis- dog
UTI
Fimbriae: type one, F12, F13, associated with human UTI
Specific serotypes (O2, O4, O6, O83)
50% a-hemolytic
E coli disease in cats and dogs: Cystitis- cat
Seldom (high osmolarity of urine is antibacterial)
E coli disease in cats and dogs: cystitis- treatment
Check for underlying causes (bladder stone, tumor)
In general, broad spectrum antibiotics
E coli disease in cats and dogs: pyometra
Dog- same strains as cystitis
Treatment frequently surgery and antibiotics
E coli disease in poultry and other birds: APEC
Most important bacterial disease in broilers and layers
Facultative pathogen- normal e coli flora contains approx 10% pathogenic serotypes
Extra-intestinal disease: septicemia-colibacillosis
E coli disease in poultry and other birds: APEC- virulence
Specific serotypes- most frequent: O1, O2, O78
Virulence factors- not understood what is important
-fimbriae/pilli
-iron capturing systems
-serum resistance
E coli disease in poultry and other birds: APEC- pathogenesis
Different clinical appearances represent a different pathogenesis
Clinical appearances:
-Neonatal colibacillosis (septicemia)
-Respiratory colibacillosis and septicemia
-egg yolk peritonitis (layers)
-Scabby hip/necrotic dermatitis (broilers)
Coli granuloma (old backyard chickens)
Otitis media (part of swollen head syndrome)
Chronic respiratory colibacillosis + arthritis
APEC: neonatal colibacillosis, pathogenesis
Contamination of eggshell
Neonatal contamination
Manipulation of chicks
Upon cooling after lay: shrinking of content
Yolk rest infection (omphalitis)
Sepsis -> death
Polyserositis, Airsac, Pericard -> growth retardation
APEC: respiratory colibacillosis, Pathogenesis
Excretion via feces
Increase of inection pressure- dust has Ecoli
Inhalation of pathogenic e coli
Damage respiratory epithelium: dust, viral infection, vxn, NH3
APEC: egg yolk peritonitis, pathogenesis
Endogenic infection
Start of lay
Chronic form in older animals
APEC: scabby hip/ necrotic dermatitis
E coli O78, O2 Frequently also other bacteria Exogenous Difficult to diagnose- feathers Found at slaughter Prevention- lower density of animals
APEC: diagnosis
Pathological lesions Isolated of ecoli from different internal organs (liver, spleen, lung) Serotyping (O1, O2, O78) Yolk rest infection Acute sepsis Coligranuloma Airsacculitis
APEC: treatment
Very difficult
Antibiotics: susceptibility tests necessary
APEC: prevention
Hygiene
Stress
Temp/ventillation
Vaccine- for breeding stock immunization, broilers and layers
Ecoli diarrhea in rabbits: RPEC
EPEC (eae positive) Diagnosis: CS -Isolation and subtyping (necessary): bio-/serogroup (1+/O109) is mainly pathogenic to suckling rabbits; others are pathogenic to weaned rabbits -PCR on eae Tx: antibiotics care! toxicity
