Enterobacteriaceae 1 Flashcards
All members of the Enterobacteriaceae are:
Gram (-), Rods, ferment glucose to acid and gas
Over 90 species of Enterobacteriaceae have been discovered with _____ genera.
30
What is the habitat for Enterobacteriaceae?
Gastrointestinal tract, soil, and water
Are Enterobacteriaceae pathogenic or non-pathogenic?
can be either
Do Enterobacteriaceae grow readily on Blood Agar and MacConkey Agar?
Yes
The three major pathogens of the family Enterobacteriaceae are?
E. coli, Salmonella serotypes, Yersina spp.
The opportunistic pathogens of Enterobacteriaceae include:
Proteus species, Klebsilla pneumoniae, Enterobacter aerogenes
How do lactose fermenting enterobacteria present on MacConkey Agar? Give two examples of this class of bacteria
Pink colonies, Examples: E. coli and Klebsiella
What does it mean for a bacteria to be “coliform”?
It means they are Lactose-fermenting Enterobacteria
How do non-lactose fermenting enterobacteria present on MacConkey Agar? Give the two examples (discussed in class)
Colorless colonies, Examples: Salmonella and Yersinia
T/F Enterobacteria can either be Major pathogens, Opportunistic pathogens, or Non-pathogens
TRUE
E. coli is a facultative anaerobe, what does this mean?
Can grow with or without the presence of oxygen.
What is the normal habitat for E coli?
Lower small intestine and colon of warm blooded animals (intestinal commensal)
What is the most common aerobic species in feces?
E. coli
What does it mean for a pathogen to have O, K, and H antigens? Which Enterobateriaceae fits this description?
O - cell wall. K - capsule. H - flagella. E. coli
What are the predisposing factors for E. coli infection?
-age -immune status -nature of diet -heavy exposure to pathogenic strains
Colonization of the mammalian intestinal tract from the environs shortly after birth via fecal–oral route is a general characteristic of what pathogen?
E. coli
How can we classify E. coli?
Intestinal Pathogenic (IPAC). (has 4 subclasses) or Extraintestinal Pathogenic E. coli (ExPAC)
What class of E. coli causes the following? •Causes diarrhea in humans, principally in children. •Also, implicated to cause diarrhea in rabbits, pigs and dogs
IPAC: Enteropathogenic (EPEC)
What type of E. coli is described by the following? •Also referred to as ‘Cholera like’. •Causes hypersecretory diarrhea.
IPAC: Enterotoxigenic (ETEC)
Which type of IPAC is described by the following? •Cause bacteremia or septicemia. •Mostly seen in poultry.
Enteroinvasive (EIEC)
What type of IPAC is described by the following? •Recognized as a cause of serious food borne illness. •Produce Shiga toxin(s). •Serotype O157:H7
Enterohemorrhagic (EHEC ), Shiga toxigenic (STEC), or Verotoxigenic (VTEC), Also referred to as ‘Shigella like’.
E. coli serogroup O157:H7 may be associated with __________ in humans
Hemorrhagic enteritis and hemolytic uremic syndrome (Hamburgers!)
What type of E. coli cause septicemia, mastitis, and infections of the uterus, urinary tract, and air sacs (in chickens)?
Extraintestinal Pathogenic E. coli (ExPAC )
Urinary tract infections in dogs and cats are called
Urinary Pathogenic E. coli (UPEC)
E. coli infections in poultry (respiratory) are sometimes called
Avian Pathogenic E. coli (APEC)
What is the function of the cell wall (soma) (O) of E. coli in terms of its antigenic characteristic?
-endotoxin production -major importance in septicemic infections
The antigenic characteristic of E. coli’s capulse (K) is?
-adhesion -protection against phagocytosis
What are the three major routes of E. coli infection?
-ingestion -inhalation -direct infection
What is the route of transmission for enteric disease causing E.coli strains?
Oral route - once establishing in the small intestinal mucosa via pili they produce enterotoxins
How are neonates exposed to E. coli?
Neonatal animals are either exposed at birth in the vagina or very shortly after birth when they suckle. Also, feed and water contaminated with feces.
How does direct infection of E. coli occur?
Entrance of the organism into a location in the body in which it is not part of the flora.
What virulence factor of E. coli does the following: -cover and protect the bacterium from various unfavorable conditions including the host immune system
Capsule
How do enterotoxins work as a virulence factor for E. coli?
-Enterotoxins: cause fluid secretion (loss of water and electrolytes).
How do endotoxins work as a virulence factor for E. Coli?
-Endotoxin: fever, intravascular clotting.
What are the three predisposing causes to neonatal diarrhea?
- Not receiving colostrum - no colostrum immunity 2. New born animals do not possess protective gut flora 3. Poor hygiene/environment
What is the pathogenesis of E. coli?
Infection -> attachment via pili -> enterotoxin -> fluid, electrolyte loss
What are the pathogenic E. coli?
Enterotoxigenic E. coli ETEC). Enteropathogenic E. coli EPEC). Shiga toxin producing ( STEC)/(VTEC)/(EHEC)
In pigs, what clinical signs are typically seen on E. coli infection?
-Porcine neonatal diarrhea (less than 5 days old animals) (ETEC). -Porcine post weaning diarrhea, and edema disease (pigs of any age, common in weaning pigs) (STEC). -coliform mastitis in sows
In bovine, what clinical signs are common to see with E. coli infection?
-White scours/diarrhea in calves (ETEC). -metritis -Coliform mastitis in cows -arthritis in calf
In equine, what clinical signs are common to see with E. coli infection?
-Septicemia in young animals: foals -Metritis in mares
Watery mouth in lambs is a condition due to endotoxemia following septicemia caused by what Enterobacteriaceae?
E. coli
T/F E. coli is known to cause UTIs and Pyometras in dogs and cat
TRUE
E coli is known to cause_________ in cows and sows and is often acute with endotoxemia
Coliform mastitis
What determining test should be performed to confirm a diagnosis for E. coli and test the strains pathogenicity (identifying enterotoxigenic strains only)?
Slide agglutination test
What is the Method of choice for confirmation of clinical disease of E. coli?
PCR for virulence factors (Fecal culture +PCR
In the clinical setting, what is the most common infections we will see?
UTI of cat and dog. Would want to perform quantitative culture for diagnosis
Diagnostic tests used to diagnose E.Coli?
Clinical signs aid diagnosis: history is important regardless of infection. Direct microscopy: presumptive test. Culture feces, other specimens. Identification of colonies: biochemical characteristics or analytical profile index (API) strips. Agglutination test: especially for fecal cultures. PCR for virulence factors (Fecal culture +PCR.
What is one of the most important treatment options in treating E. coli with symptomatic diarrhea?
IMPORTANT to correct dehydration and electrolytes. Administration of oral antibiotics.
Why should Antimicrobial susceptibility tests be performed on E. coli?
To ensure an effective therapy since most Gram (-) bacteria are intrinsically resistant to antibiotics
What would we do to control E. coli cases?
Improve hygiene, management: sanitation, disinfection, reduce overcrowding. Vaccination! Ensure colostrom for neonates
Which one of the following is NOT a virulence factor of E. coli? A. Hemolysin B. Enterotoxins C. Pili/fimbriae D. Spore E. Endotoxin
D. spore
When diagnosing E. coli diarrhea in piglets… (select the most accurate answer) 1. Check the fecal smear for many Gram negative rods. 2. Look for mucoid colonies on blood agar. 3. Test pink colonies from MacConkey agar by agglutination test for pathogenic strains. 4. Test broth culture for motility. 5. Test culture for resistance to penicillin.
- Test pink colonies from MacConkey agar by agglutination test for pathogenic strains.
Disease caused by Salmonella is called
salmonellosis
Between E. coli and Salmonella which one does not ferment lactose?
Salmonella
What kind of flagella do Salmonella have?
peritrichous flagella.
Most Salmonella pathogenic serotypes are under which species; S. enterica or S. bongori?
S. enterica
The Salmonella of veterinary importance cause gastroenteritis in humans and animals and systemic infections in animals. What are these spp. of Salmonella?
S. Typhimurium, S. Dublin, S. Cholerasuis
T/F Salmonella cannot survive and multiply well outside the host
FALSE
True or False: Salmonella are obligate pathogen, NOT a normal flora.
TRUE
With Salmonella, Infections can be transient without invasion. If there is an invasion what happens?
Leads to ACUTE infection or become CARRIER.
What is the source of Salmonella?
Fecal contamination is the most common source of infection, Soil and water, Fertilizers, Feed ingredients, Fish, bone, meat meal, Milk & milk products, Eggs
What is the biggest predisposing factor of Salmonella infection?
Stress
The following are the virulence factors for which Enterobacteriaceae? •Enterotoxins •Cytotoxins •LPS •Flagella •Heat Shock Proteins
Salmonella
List the pathogenesis of Salmonella:
Colonize small intestine -> invade enterocytes -> inflammation of lamina propria (enterotoxin -> diarrhea) -> macrophages, neutrophils -> lymphatics -> blood -> endotoxin mediated fever, vascular damage -> complications (septicemia, pneumonia, meningitis, arthritis, abortion).
Which Enterobacteriaceae (of the three discussed in class) are a problem in intensively reared, food-producing animals?
Salmonella (Salmonellosis)
T/F Older animals are more susceptible to Salmonellosis than younger animals
FALSE
What are the three major clinical manifestations of Salmonellosis in animals?
- Enteritis (diarrhea - mucus, fibrin, blood) 2. Septicemia (fever, depression, death) 3. Abortion (Septicemia in pregnant animals may lead to abortion.)
Between the following Salmonella species, which is NOT host specific: - S. Typhimurium - S. Choleraesuis - S. Gallinarum - S. Dublin
-S. Typhimurium
In cattle, what disease conditions are associated with Salmonella?
enteritis, septicemia, abortion (S. Typhimurium, S. Dublin)
In swine, what disease conditions are associated with Salmonella?
Enteritis = S. Typhimurium, Septicemia = S. Choleraesuis
In horses, what disease conditions are associated with Salmonella?
mostly associates with stress, immunosuppressed, diarrhea, endotoxemia, death in foals. (S. Typhimurium)
In poultry, what disease conditions are associated with Salmonella?
enteritis/septicemia
What animals are reservoirs of Salmonella without showing clinical disease?
dogs and cats
What diagnostics are used to diagnose Salmonella?
Clinical signs aid diagnosis: history is important, Direct microscopy, Culture feces, other specimens, confirmation via agglutination test
When is antimicrobial treatment of Salmonella advised?
only in case of systemic disease
Quinolone antibiotics (such as danofloxacin), gentamicin and trimethoprim sulfa (TMS) are known to be useful drugs against ….
Salmonella
When there is systemic involvement , parenteral intensive treatment of acute cases using an antibiotic + I.V. administration of antiserum against endotoxin is recommended in what species?
horses and cattle
Are there good vaccines against Salmonella?
unfortunately no
