Escherichia coli

Common name:

Colon bacillus

Habitat and transmission

• Normal flora in the large intestine; may colonize the vagina and urethra

• Acquired during birth and by fecal-oral route

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Commonly caused by E. coli, in approximately ___________________.

Urinary tract infection

90% of cases

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Results from endogenous spread of the bacteria from the large intestine as resident flora, and mechanically introduced into the urethra (e.g., careless personal hygiene, sexual intercourse, or catheterization)

Urinary tract infection

PATHOGENESIS AND CLINICAL MANIFESTATIONS

The colonization facilitates the ascent of bacteria from the urethra into the bladder causing ______________.

Urinary tract infection

cystitis

PATHOGENESIS AND CLINICAL MANIFESTATIONS

If the invading bacteria pass up the ureters to the kidney, ________________ results

Urinary tract infection

pyelonephritis

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Occurs primarily in women, a finding attributed to 3 features:

a. short urethra

b. proximity of the urethra to the anus

c. colonization of the vagina by members of the fecal flora

Urinary tract infection

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract infection

Occurs primarily in women, a finding attributed to 3 features:

a. short urethra

b. proximity of the urethra to the anus

c. colonization of the vagina by members of the fecal flora

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract infection

Signs and Symptoms:

a. Urinary frequency

b. Dysuria

c. Hematuria

d. Pyuria

e. Flank pain

None of these symptoms or signs is specific for E coli infection.

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract infection

Signs and Symptoms

The urge to pass urine more often than usual

Urinary frequency

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Signs and Symptoms

Painful urination

Dysuria

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Signs and Symptoms

The presence of blood in urine

Hematuria

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Signs and Symptoms

The presence of leukocytes, commonly referred to as pus, in the urine

Pyuria

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Signs and Symptoms

Pain in one side of the body between the upper belly area (abdomen) and the back; associated with upper tract infection, a sign of kidney involvement

Flank pain

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Primary virulence factor of E. coli to cause UTIs

P pili (P fimbriae)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Allow the bacteria to attach to the urinary epithelial mucosa and not be washed out with urine flow

P pili (P fimbriae)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Named for their ability to bind to and agglutinate human RBCs carrying the P blood group antigen

P pili (P fimbriae)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Resides in the cell wall and consists of the lipid A of the LPS

Endotoxin

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Responsible for much of the morbidity and mortality resulting from infections associated with these bacteria

Endotoxin

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Cytolysin that creates pores in eukaryotic cell membranes

Hemolysin

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Inhibits phagocytosis and chemotaxis of certain white blood cells

Hemolysin

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

A siderophore, .i.e., iron chelating agent, enabling E. coli to bind and transport iron for use by bacteria in iron-poor environments such as the urinary tract

Aerobactin

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

The determinant of the K antigen

Capsular polysaccharide

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Is antiphagocytic and inhibits the opsonizing and lytic activities of complement because of the identity of the capsular polysaccharides and the host carbohydrates

Capsular polysaccharide

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Urinary Tract Infection

Virulence Factors

Table PPT

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

A major cause of meningitis and septicemia and meningitis among newborns, along with Group B streptococci

Escherichia coli

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Acquired by newborns by vertical transmission from the birth canal just before or during delivery, when the mother’s vagina is heavily colonized or infection may also result if contamination of the amniotic fluid occurs

Neonatal Meningitis and Septicemia

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

A polymer of sialic acid possessed by approximately 80% of E. coli from meningitis cases

K1 antigen (capsular polysaccharide)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Antiphagocytic and provides some resistance against the usual sensitivity of E. coli to complement-mediated lysis

K1 antigen (capsular polysaccharide)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Cross-reacts with the group B capsular polysaccharide - of Neisseria meningitidis

K1 antigen (capsular polysaccharide)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Does not stimulate antibody production antibodies because of its similarity to host sialic acid polymers

K1 antigen (capsular polysaccharide)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Bind to vascular endothelium and epithelial lining of brain tissues

S fimbriae

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Allows the bacteria to chelate iron

Siderophore

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Neonatal Meningitis and Septicemia

Virulence Factors

Table PPT

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Diarrheal diseases associated with certain strains of E.coli

Gastroenteritis

PATHOGENESIS AND CLINICAL MANIFESTATIONS

________________ — the ultimate source of contamination; transmission by fecal-oral spread through contaminated water and food

Gastroenteritis

Human or animal feces

PATHOGENESIS AND CLINICAL MANIFESTATIONS

5 pathotypes of diarrheagenic E. coli, each causing diarrheal diseases with different distinct features in their epidemiology, clinical syndrome, and pathogenic mechanism:

Gastroenteritis

a. Enterotoxigenic E. coli (ETEC)

b. Enteropathogenic E. Coli (EPEC)

c. Enteroinvasive E. coli (EIEC)

d. Enterohemorrhagic E. coli (EHEC)

e. Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Two Clinical Syndromes

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Among children in tropical and subtropical climates, especially in developing countries, when they are being weaned off nursing and start to take food and drinks other than mother’s milk

Weanling diarrhea

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

When a person eats food, or drinks water contaminated with ETEC, esp. during travel to developing countries, to an area with poor public hygiene, inadequate sanitation, or reduced availability of sources of potable water

Traveler’s diarrhea (also referred to as Montezuma’s revenge, Delhi belly, or turista)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Causes watery, non-inflammatory diarrhea , resembling cholera, i.e, non-bloody and non-mucoid, accompanied by mild abdominal cramps; usually without vomiting or fever

Enterotoxigenic E. coli (ETEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Facilitate attachment to the intestinal epithelium by binding to specific carbohydrate receptors on the intestinal microvilli

Pili (fimbriae)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

(a) Heat-labile toxin (LT)

(b) Heat-stable toxin (ST)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

________________ is similar in structure and action to cholera toxin (choleragen) from Vibrio cholerae.

Heat-labile toxin (LT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

An A/B toxin composed of A subunit and 5 identical B subunits arranged in a ring.

Heat-labile toxin (LT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

Heat-labile Toxins

Enzymatically active portion

A moiety

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

Heat-labile Toxins

Activates cellular adenylate cyclase, causing an increase in the conversion of adenosine triphosphate to cyclic adenosine monophosphate (cAMP); accumulation of cAMP results to hypersecretion of both electrolytes and fluids into the intestinal lumen, resulting in watery diarrhea similar to cholera.

A moiety

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

Heat-Labile Toxins

Binding portion — binds strongly to the epithelial cells of the small intestine and facilitates the entry of A subunit into the cell

B moiety

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

Stimulates guanylate cyclase, causing increased production of cyclic guanosine monophosphate (cGMP)

Heat-stable toxin (ST)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Enterotoxins

Intracellular accumulation inhibits intestinal fluid uptake, resulting in hypersecretion

Heat-stable toxin (ST)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Virulence Factors

Heat-Labile Toxin

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterotoxigenic E. coli (ETEC)

Additional Notes (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Associated with ______________, usually less than 2 years of age; diarrheal outbreaks occurring in hospital nurseries and daycare centers, but cases in adults are rarely seen

Enteropathogenic E. Coli (EPEC)

infantile diarrhea

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Causes watery diarrhea with mucus, but without gross blood; also characterized by low-grade fever, malaise, and vomiting

Enteropathogenic E. Coli (EPEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Adheres to intestinal epithelial cells in localized microcolonies producing characteristic known as _____________________

attaching-and-effacing (A/E) histopathology

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Encoded by a plasmid, EPEC adherence factor EAF

Bundle-forming pili (BFP)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Fimbriae produced by EPEC strains which tend to aggregate and form bundles

Bundle-forming pili (BFP)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Mediate initial, non-intimate adherence of the bacteria with the surface of the enterocytes

Bundle-forming pili (BFP)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Encoded by chromosomal locus

Locus of enterocyte effacement (LEE)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Promotes intimate or tight adherence of the bacteria to the enterocytes

Locus of enterocyte effacement (LEE)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Virulence Factors

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteropathogenic E. Coli (EPEC)

Additional Notes

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Causes disease in people of all ages, however, it occurs most commonly in children in developing countries and in travelers to these countries

Enteroinvasive E. coli (EIEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Produces watery diarrhea with fever and abdominal pain

Enteroinvasive E. coli (EIEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Some patients present with dysentery, with very little stool, but much blood and mucus, closely resembling _____________

Enteroinvasive E. coli (EIEC)

shigellosis

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroinvasive E. coli (EIEC)

Virulence Factors

i. Invasion of intestinal epithelial cells

ii. Lysis of the phagosomal vacuole

iii. Movement through the cytoplasm, ultimately spreading to adjacent epithelial cells.

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroinvasive E. coli (EIEC)

Additional Notes

PPT

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Alternative nomenclature:

Shiga toxin-producing E. coli (STEC)

Verotoxin-producing E. coli(VTEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

The most common involved serotype

E. coli O157:H7

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Associated with epidemic and sporadic diarrhea, mostly in developed countries

Enterohemorrhagic E. coli (EHEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Has high prevalence of colonization in cattle or cows; transmission is by contamination of meat with cattle’s feces during slaughter, thus.

Enterohemorrhagic E. coli (EHEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

The source of most cases is considered to be ground beef, hamburgers in particular; unpasteurized dairy products and apple cider, bean sprouts, and spinach have been implicated in the spread of infection

Enterohemorrhagic E. coli (EHEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Prevalence

PPT

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Clinical Manifestations

Characterized by a watery diarrhea that progresses to bloody diarrhea, but the stool does not contain leukocytes; patients typically have little or no fever, and abdominal pain is common

Hemorrhagic colitis

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Clinical Manifestations

A thrombotic disease of the kidney microvasculature in which the endothelial cell is the primary site of damage

Hemolytic uremic syndrome (HUS)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Clinical Manifestations

Defined by a triad of features:

Hemolytic uremic syndrome (HUS)

‣ Microangiopathic hemolytic anemia — the appearance of fragmented red blood cells

‣ Thrombocytopenia — reduced platelet count

‣ Acute renal failure, evidenced by a low urine output

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Clinical Manifestations

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Virulence Factors

By binding tightly to cells and produce the same A/E phenomenon seen with EPEC strains

Attaching-and-effacing histopathology

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Virulence Factors

Called Shiga toxins (previously called the shiga-like toxins) which are identical to the Shiga toxin (Stx) produced by Shigella dysenteriae type I

Cytotoxins

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Virulence Factors

2 types — Stx1 and Stx2

Cytotoxins

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enterohemorrhagic E. coli (EHEC)

Virulence Factors

Table (PPT)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Newest strain

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Associated with diarrhea in persons of all ages in developing countries, but occurs predominantly in infants

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Is increasingly recognized as a cause of traveler's diarrhea, possibly second only to ETEC

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Characterized by watery, persistent diarrhea occurring more than 14 days in duration

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

With grade fever and little or no vomiting

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

White blood cells and red blood cells are absent.

Enteroaggregative E. coli (EAEC or EAggEC)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Flexible, bundle-for ming fimbrial structures

Aggregative adherence fimbriae (AAF)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Facilitate initial colonization

Aggregative adherence fimbriae (AAF)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Enhanced mucus production traps bacteria in biofilm producing the characteristic layering of the bacteria described as a pile of stacked-brick configuration

Mucus biofilm

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Promotes persistent colonization

Mucus biofilm

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Promotes nutrient malabsorption

Mucus biofilm

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

It is a cytotoxin

Enteroaggregative ST-like toxin (EAST1)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Results in damage to intestinal cells

Enteroaggregative ST-like toxin (EAST1)

PATHOGENESIS AND CLINICAL MANIFESTATIONS

Gastroenteritis

Enteroaggregative E. coli (EAEC or EAggEC)

Virulence Factors

Table (PPT)

PREVENTION AND CONTROL

• Control measures are not feasible as far as the normal endogenous microbiota is concerned.

• Sanitation and hygiene are important, however.

- Sanitation

• Sewage treatment and disposal

• Treatment of drinking water

- Hygiene

• Handwashing

• Proper food preparation