Module 13 (Enterobacteriaceae)

What is the Gram reaction and shape of Enterobacteriaceae?

Gram-negative, short rods

Do Enterobacteriaceae form spores?

No, they are non-sporeforming

Which genera of Enterobacteriaceae are non-motile?

Shigella and Klebsiella

What type of respiration do Enterobacteriaceae use?

Aerobic but can be facultatively anaerobic

What type of flagella do motile Enterobacteriaceae possess?

Peritrichous flagella, except shigella and klebsiella(non-motile)

What antigen is responsible for the capsular polysaccharide?

K (capsular) antigen

Which genus within Enterobacteriaceae has a thick, oval capsule?

Klebsiella

What antigen is associated with flagellar proteins?

H (flagellar) antigen

What is the K antigen composed of?

Capsular polysaccharide

What is the O (somatic) antigen composed of?

O-specific polysaccharide chain of lipopolysaccharide

What is the Vi antigen, and which genus possesses it?

Virulence antigen, found in Salmonella

What is a distinguishing biochemical feature of Enterobacteriaceae?

All ferment glucose with acid production

How do Enterobacteriaceae reduce nitrate?

They reduce nitrate (NO3) to nitrite (NO2)

Are Enterobacteriaceae oxidase-positive or oxidase-negative?

Oxidase-negative

What enzyme test is positive in Enterobacteriaceae?

Catalase test

What are the four lactose-fermenting genera within Enterobacteriaceae?

Citrobacter, Escherichia, Enterobacter, Klebsiella

What are the four non-lactose fermenting genera within Enterobacteriaceae?

Shigella, Yersinia, Proteus, Salmonella

What is the primary mode of transmission of Escherichia coli?

Fecal-oral route

What is the role of Escherichia coli in the intestine?

Normal flora that helps produce Vitamin K

E.coli Commonly found in the ____________ of ________________

lower intestines and warm blooded animals

E.coli was discovered by? In?

Theodore Escherich in 1885

It is a Strain of E.coli that has lethal toxins

O157:H7

What is the best-known fimbrial antigen in Escherichia coli?

K88 (F4)

What are the four main antigens of Escherichia coli, and what is the function of the F antigen?

O, K, H, and F antigens; the F antigen has an adhesive function.

What are the two types of enterotoxins produced by enterotoxigenic E. coli?

Heat-labile (LT) and heat-stable (ST) enterotoxins

What is the function of the heat-labile enterotoxin (LT) A subunit of E. coli?

Activates adenylate cyclase, increasing cyclic AMP and causing diarrhea

What does the STa enterotoxin of E. coli activate?

Guanylate cyclase, leading to diarrhea

What disease is caused by E. coli O157:H7?

Hemorrhagic colitis and hemolytic-uremic syndrome (HUS)

What are the six pathogenic types of Escherichia coli?

ETEC, EPEC, EIEC, AEEC, EHEC, EAEC

What is the main virulence mechanism of Enteropathogenic E. coli (EPEC)?

Intimin adhesins causing attachment and effacement of intestinal cells

What is the main virulence mechanism of Enteropathogenic E. coli (ETEC)?

Uses fimbrial adhesins to bind to enterocytes in the small intestines

What is the main virulence mechanism of Enteropathogenic E. coli (AEEC)?

Produce shiga-like toxins and destroy microvilli layers

What is the main virulence mechanism of Enteropathogenic E. coli (EHEC)?

Possesses Shiga toxin, which elicits intense inflammatory response

What is the main virulence mechanism of Enteropathogenic E. coli (EIEC)?

Invades enterocytes and deeper mucosal layers

Which pathogenic E. coli strain is highly invasive and causes shigellosis-like syndrome?

Enteroinvasive E. coli (EIEC)

Which pathogenic E. coli strain is Invades intestinal epithelial cells and replicates intracellularly

AIEC (Adherent-Invasive E. coli)

Most infamous strain of EHEC (Enterohemorrhagic E. coli)

O157:H7

Which pathogenic E. coli strain non-invasive, produces hemolysins and ST enterotoxins

EAEC (Enteroaggregative E. coli)

What does Enteroaggregative E. coli (EAEC) cause?

Watery diarrhea without fever

What species of Enterobacteriaceae is the most widely studied as a model organism?

Escherichia coli

What disease does Escherichia coli cause in piglets 1 to 4 days old?

Neonatal enteritis

What is the major symptom of neonatal enteritis in piglets?

Profuse, pale yellow, watery diarrhea

Change of diet leads to massive colonization of anterior small intestine of Hemolytic E.coli

Weanling enteritis

What type of E. coli is responsible for edema disease in pigs?

Enterotoxigenic E. coli (ETEC)

What is the other term for Edema disease in swine?

Bowel edema

What disease is caused by E. coli in cattle during the first week of life?

White scours

What is the major causative agent of mastitis in cattle?

Escherichia coli

What disease does E. coli cause in lambs?

Colibacillosis (enteric diarrhea)

What reproductive disorder can E. coli cause in mares?

Abortion

What are two major urinary tract infections caused by E. coli in dogs?

Bacteremia and pyometra

What disease does E. coli cause in poultry?

Avian colibacillosis and coligranuloma

What is another name for coligranuloma in poultry?

Hjarre’s disease

What is another name for Omphalitis in chicks?

mushy chick disease

What disease is caused by E. coli in rabbits?

Cecitis and diarrhea

What passive immunity component protects against E. coli infections in piglets?

Fimbrial K88 antigen

What test is commonly used to detect E. coli antigens?

Fluorescent Antibody Test (FAT)

What diagnostic method is used for confirming E. coli in infections?

Culture and isolation

Which genera in Enterobacteriaceae are considered opportunistic pathogens?

Citrobacter, Enterobacter, Serratia, Morganella, Edwardsiella

What medium is commonly used for differentiating lactose and non-lactose fermenters?

MacConkey agar

What is the major virulence factor of Salmonella?

Vi (virulence) antigen