Test 2- Enterobacteriaceae Flashcards
Enterobacteriaceae
- Reside in the GI tract of humans and animals
- Benefits Microbial antagonism
- Breakdown and absorption of the food
- Waste processing
- Vitamin K production
Is enterobacteriacea gram positive or negative?
Negative!
Thus it has Lipid A =Endotoxin
LPS
General Enterobacteriacae
- Gram-negative
- Facultative anaerobic because they live in the intestines
- Rods or coccobacilli
- Oxidase negative (except Plesiomonas, shigelloids)
Present in water, soil environment and the GI tract of humans and animals (not really environmental bacteria) Coliform bacteria
Lactose positive bacteria which includes: E. coli, Klebsiella, Enterobacter
Coliform enumeration is performed to evaluate faecal/sewage contamination- CHECK FOR SLAUGHTER PROCESS
(Enterococci are a better indicator of health risk in salt and fresh water. Enterococci are more species specific, and thus allows detection of source of contamination)
Species of Enterobactericase
- Escherichia
- Salmonella
- Yersinia
- Shigella
- Klebsiella
- • Proteus*
- • Enterobacter*
- • Citrobacter*
- • Serratia*
- more containtaments*
Opportunistic pathogens
• Klebsiella pneumonia • Klebsiella oxytoca • Enterobacter cloacae • Enterobacter aerogenes • Proteus mirabilis • Citrobacter freundii
The most common nosocomial infections/ health care ass. infections in ICU pts—- main importance in clinics
Escherichia coli
Lactose positive, oxidase negative, motile rods
ONLY CLINICALLY RELEVANT SPECIES
E. coli -General
- Very diverse species- labeled via morphology
- Shigella spp. are taxonomically also Escherichia
——————–Not present in animals
• Pathogenicity: strain dependent
————-Facultative pathogenic (eg. APEC)- can have but not be sick
———— Obligate pathogenic but then age dependent
- Differentiation between pathogenic and non-pathogenic strains not always evident
- Associated with
—————————–Certain serotypes (serotyping)
—————————–Virulence genes (pathotyping-virotyping)
—————————– Combinations of virulence genes- if a form of E.coli can’t adhere to the intestines
—————————– Biotype (for RPEC only)
E. coli -General • Infections
- Intestinal pathogenic strain
- Extra intestinal pathogenic strains (ExPEC)
—————- Respiratory
—————- Septicaemiae
—————- UTI
—————-Mastitis
E. coli -General • Virulence factors
- Virulence factors
- Cell associated
———– Endotoxin
———–Capsule
———– Fimbrial adhesins
———– Non-fimbrial adhesins
• Extracellular
———–Enterotoxins
———– Cytotoxins
———–Siderophores- captures iron
E. coli in pigs differentials
Typical Symptoms: diarrhea, edema, UTI, metristis/mastisits
• Bacterial diarrhea in fattening pigs, sows and boar
———- Brachyspira hyodysenteriae
———-Brachyspira pilosicoli
- Lawsonia intracellularis
- Salmonella (non host specific)
- Watery diarrhea
- neonatal/ 2-4wks/weaning
- Adhesion factors (small intestine)
- F4 (K88); F5 (K99); F6 (987P); F18; F41
- Enterotoxins (on plasmids)
- LT (heat labile)
- Sta, STb, EAST1 (heat stable)
E. coli disease in pigs: ETEC Adhesion factors (small intestine)
THIS ARE IMPORTANT FOR VACCINES!
• F4 (K88)- MOST IMPORTANT
——— F4: F4a,b; F4a,c; F4a,d (on plasmids)
———Specific receptor breeding of receptor free pigs; age depended presence- ONLY IN PIGS
———Mannose resistant
———Genes expressed at body Temperature, not at room Temperature
——— Solely in pigs
• F5 (K99) (on plasmids)
——— In pigs and bovines
——— Mannose resistant
———Expression Temperature dependent
——— Receptor only in very young animals: only involved in neonatal diarrhea
• F6 (987P); F18; F41
• F6 (987P) (mainly extrachromosomal)
———Neonatal
• F41 (chromosomal)
———Mannose resistant
———Pigs and bovines
———Frequently together with F5
———rare
• F18
——— See oedema disease
• Non-fimbrial adhesins
Eg. AIDA-I (adhesin involved in diffuse adherence)
E. coli disease in pigs: ETEC Enterotoxins (on plasmids) heat Labile
Enterotoxins (on plasmids)
Heat labile
- LT
- High molecular weight- STRONGER ANTIGENS
- Strong antigen
- Inactivated 30 minutes 60oC
- Activation of adenylate cyclase
- Na+ absorption
- CL- and HCO3+ secretion
Enterotoxins (on plasmids) • Heat stable
Heat stable
• STa
——— Activation of guanylate cyclase system
——— Na+ absorption DECREASES
———CL- and HCO3+ secretion- INCREASES
• STb
———Prostaglandin E2 secretion of water and electrolytes - INCREASED
——— Stimulationof5-hydrotryptaminesecretion
• EAST1 (enteroaggregative E. coli heat stable toxin)
——— Closely related to Sta
——— Also in EPEC,AEEC;VTEC- in other types of E. coli
- Low molecular weight
- Little antigenic
- Withstand 15 minutes 121oC
E. coli disease in pigs: ETEC
- Characteristics that are present most of the time: age dependent
- Neonatal ETEC
——— F5; F6; F41
——— STa; STb
———Non-hemolytic
• Neonatal till 4 weeks- RARE HEAT LABILE TOXINS
——— F4
———LT; STa; STb; EAST1
——— Hemolytic
• Weaning diarrhea
——— F4; F18
- ——– LT; STa; STb, EAST1
- ——– Hemolytic
E. coli disease in pigs: ETEC Epidemiology
• 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- leads to not enough clostriudm
- First delivery sows- lower immunity to begin with
Piglet:
——— Low birth weight
——— Other infection
———Too many piglets per sow- less clolostrium per piglet
• Appearance of new type
E. coli disease in pigs: ETEC Pathogenesis
- Ascending from lower bowel
- Oral uptake
- Small intestine
- colonization
Symptoms of E. coli in pigs
Remain drinking
Very smelly feces
Dehydration
Older animals diarrhea
- White grey
- Not as watery
E. coli disease in pigs: ETEC • Diagnosis
Detection of virulence factors
Agglutination tests- antigen and antibody clots together
PCR
E. coli disease in pigs: ETEC- Treatment and Prevention
Treatment
- Hydration (SC, IP) (PO, electrolyte solution plus glucoses and amino acids)
- Antimicrobials (susceptibility profile!- lots of resistance)
Prevention: keep infection pressure low and maternal immunity high
- Hygiene: prevention of spread
- Vaccination
——— Immunization sows
——— Inactivated vaccines: mixture of different serotypes ——— Purified adhesion factors and LT
———Two injections of which the last one 2-6 wks before partus
• Selection of receptor free piglets (F4)
E. coli disease in pigs: VTEC Oedema disease
• Oedema disease
———Post weaning
• Mixed ETEC/VTEC
———Oedema disease and diarrhea
The diarrhea is NOT caused by the VTEC– it’s generally from a mixed infection
E. coli disease in pigs: VTEC Virulence factors
• Adhesion small bowel: F18
——— Specific receptor (genetic resistance if absent)
• Exotoxin
——— VT2e or Stx2e: media necrosis
• Endotoxin: acute mortality