E.coli O104;H4 Emerging infection

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E. coli
0104H4emerging pathogen new
concerns

• Dr.T.V.Rao.MD

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Shiga toxin-producing
Escherichia coli (STEC)current outbreak

• Shiga toxin-producing Escherichia coli (STEC) can
  cause severe enteric infections and the
  potentially life threatening hemolytic uremic
  syndrome (HUS).  Prompt diagnosis of these
  infections is important to implement early
  clinical management that minimizes the likelihood
  of developing HUS, to reduce the risk of
  transmitting the infection to others, and to
  detect outbreak
• Commonly consumed vegetables are source of spread.

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New report on E.coli 0104 h4 outbreak

• Large outbreak of Shiga toxin-producing
  Escherichia coli O104H4 (STEC O104H4)
  infections ongoing in Germany. The responsible
  strain shares virulence characteristics with
  enter aggregative E. coli (EAEC). As of June 2,
  2011, case counts confirmed by Germanys Robert
  Koch Institute include 520 patients with
  hemolytic uremic syndrome (HUS) a type of
  kidney failure that is associated with E. coli or
  STEC infections and deaths.

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European Centre for Disease Prevention and
Control (ECDC)
Reports

• Disease Prevention and Control (ECDC) said the
  "causative agent" was a strain of bacteria that
  are called Shiga toxin-producing Escherichia
  coli, or STEC.

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Vegetables as source of
E.coli infections

• While suspicion has fallen on raw tomatoes,
  cucumbers and lettuce as the source of the germ,
  researchers have been unable to pinpoint the food
  responsible. The outbreak is considered the
  third-largest involving E. coli in recent world
  history, and it is already the deadliest. Twelve
  people died in a 1996 Japanese outbreak that
  reportedly sickened more than 9,000, and seven
  died in a Canadian outbreak in 2000.

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Cycle of events in spread of stec Ruminants and
contamination cycle
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Cycle of events in spread of stecSTEC Ruminants
and contamination cycle
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Shiga Toxins

• E-coli isnt usually disease- causing, a major
  commensal in humans.
• Shiga toxin is one of the most potent toxins
  known to man, so much so that the Centers for
  Disease Control and Prevention lists it as a
  potential bioterrorist agent
• Most kinds of E. coli bacteria do not cause
  disease in humans, indeed, some are beneficial,
  and some cause infections other than
  gastrointestinal infections, such urinary tract
  infections.

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What are Shiga toxin-producing E. coli?

• Some kinds of E. coli cause disease by making a
  toxin called Shiga toxin. The bacteria that make
  these toxins are called Shiga toxin-producing
  E. coli, or STEC for short. You might hear them
  called Vero cytotoxic E. coli (VTEC) or
  Enterohemorrhagic E. coli (EHEC) these all refer
  generally to the same group of bacteria. The most
  commonly identified STEC in North America is E.
  coli O157H7 (often shortened to E. coli O157 or
  even just O157). When you hear news reports
  about outbreaks of E. coli infections, they are
  usually talking about E. coli O157.

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E.coli 0104 h4 resembles
E. coli serotype O157H7

• E. coli serotype O157H7 is a rare variety of E.
  coli that produces toxins which are capable of
  inflicting damage to the lining of the intestine.
  These toxins are closely related or identical to
  the toxin produced by Shigella dysenteriae and
  are referred to as Shiga toxins. In very rare
  instances, the infection can progress to
  hemolytic uremic syndrome ("HUS") and kidney
  failure. E. coli O157H7 can survive at low
  temperatures as well as under acidic conditions,
  and the infectious dose is relatively small.

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E.coli 0104h4 picked up new genes

• t's observed that E. coli O104H4 has picked up
  some new genes, almost certainly through
  horizontal gene transfer, in which stretches of
  DNA are picked up from other E. coli strains, or
  possibly different species entirely. Once
  incorporated into the genome, the new genes can
  provide the bacteria with entirely novel
  properties. In the case of E. coli O104H4, tests
  have shown that it now carries a gene for
  shigatoxin, which is commonly found in other
  disease-causing strains of this species.

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Structure of STEC

• The toxins produced by STEC were named based on
  their similarity in structure and function to
  Shiga toxins produced by Shigella dystenteriae
  type . Shiga toxin 1 (Stx1) is neutralized by
  antibodies against Shiga toxin, whereas Shiga
  toxin 2 (Stx2) is not neutralized by antibodies
  against Shiga toxin but is neutralized by
  homologous antibodies

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The new strain of E.coli 0104 h4
a hybrid strain

• Strain appeared "to be a hybrid of two different
  E. coli types.
• The hybrid strain also contains the Shiga-like
  toxin from Enterohaemorrhagic E.coli, This toxin
  binds to and damages kidney cells and can lead to
  potentially fatal HUS.

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genome OF A KILLER German and Chinese scientists
cracked the genetic code behind the strain of
Escherichia coli
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Stec are referred as verocytotoxins

• STEC are also referred to as verocytotoxigenic E.
  coli STEC that cause human illness are also
  referred to as Enterohemorrhagic E. coli.

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How the patients present

• Symptoms of STEC infection include severe stomach
  cramps, diarrhea (which is often bloody), and
  vomiting. If there is fever, it usually is not
  very high. Most people get better within 57
  days, but some patients go on to develop
  HUSusually about a week after the diarrhea
  starts. Symptoms of HUS include decreased
  frequency of urination, feeling very tired, and
  losing pink color to skin and membranes due to
  anemia.

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hemolytic uremic syndrome (HUS)

• Around 510 of those who are diagnosed with STEC
  infection develop a potentially life-threatening
  complication known as hemolytic uremic syndrome
  (HUS). Clues that a person is developing HUS
  include decreased frequency of urination, feeling
  very tired, and Persons with HUS should be
  hospitalized because their kidneys may stop
  working and they may develop other serious
  problems. Most persons with HUS recover within a
  few weeks, but some suffer permanent damage or
  die.

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Need for early diagnosis reduces renal damage

• Early diagnosis of STEC infection is important
  for determining the proper treatment promptly.
  Initiation of parenteral volume expansion early
  in the course of O157 STEC infection might
  decrease renal damage and improve patient outcome

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Prompt laboratory diagnosis

• Prompt laboratory diagnosis of STEC infection
  facilitates rapid subtyping of STEC isolates by
  public health laboratories and submission of PFGE
  patterns to PulseNet, the national molecular
  subtyping network for foodborne disease
  surveillance . Rapid laboratory diagnosis and
  subtyping of STEC isolates leads to prompt
  detection of outbreaks, timely public health
  actions, and detection of emerging STEC strains.

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Samples are taken from a cucumber for a molecular
biological study

• As a major outbreak of a highly toxic strain of
  E. coli bacteria continues to sicken residents of
  Europe, medical experts are racing to find the
  source

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Early processing of results yields better
results.

• Specimens should be sent to the laboratory as
  soon as possible for O157 or 0104 STEC culture
  and Shiga toxin testing. Ideally, specimens
  should be processed as soon as they are received
  by the laboratory. Specimens that are not
  processed immediately should be refrigerated
  until tested if possible, they should not be
  held for gt24 hours unpreserved or for gt48 hours
  in transport medium.

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STEC infections diagnosed with..

• STEC infections are usually diagnosed through
  laboratory testing of stool specimens (feces).
  Identifying the specific strain of STEC is
  essential for public health purposes, such as
  finding outbreak. Slabs that test for the
  presence of Shiga toxins in stool can detect
  non-O157 STEC infections.  However, for the O
  group (Serogroup) and other characteristics of
  non-O157 STEC to be identified. Shiga
  toxin-positive specimens must be sent to a
  Reference laboraoreis in doubtful cases of 0104
  serotypes

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0157and 0104 can be isolated on selective medium

• To isolate O157 STEC, a stool specimen should be
  plated onto a selective and differential medium
  such as sorbitol-MacConkey agar (SMAC) , cefixime
  tellurite-sorbitol MacConkey agar (CT-SMAC), or
  CHROMagar O157.

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Culture for STEC

• O157 and 0104 STEC can usually be easily
  distinguished from most E. coli that are members
  of the normal intestinal flora by their inability
  to ferment sorbitol within 24 hours on
  sorbitol-containing agar isolation media

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CHROMagar for E.coli O157

• Rapid and reliable detection of the
  enterohaemorrhagic E.coli O157. Easily
  distinguishable colonies due to the purple
  colouring they have aquired. Most other bacterial
  species are inhibited, giving blue or colourles
  colonies. Despite specifity is improved in
  comparison to Sorbitol MacConkey Agar, when
  direct isolation method is used, the false
  positive must be screened out by additional tests
  and candidates must be further studied for
  confirmation.
• . E.coli O157 - purple
• other bacterial colonies - inhibited, blue or
  colourles

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Colonies appear as pink on CHROMagar

• After incubation for 1624 hours at 37C (99F),
  the plate should be examined for possible O157
  colonies, which are colorless on SMAC or CT-SMAC
  and are mauve or pink on CHROMagar O157

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Identification of 0157
latex agglutination test

• To identify O157 STEC, a portion of a
  well-isolated colony (i.e., a distinct, single
  colony) should be selected from the culture plate
  and tested in O157-specific antiserum or O157
  latex reagent as recommended by the manufacturer
  . Colonies that agglutinate with one of the
  O157-specific reagents and do not agglutinate
  with normal serum or control latex reagent are
  presumed to be O157 STEC. At least three colonies
  should be screened (CDC, unpublished data, 2009).
  If O157 STEC bacteria are identified in any one
  of the three colonies, no additional colonies
  need to be tested

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Identification with biochemical methods

• The colony in which O157 STEC are detected should
  be streaked onto SMAC or a nonselective agar
  medium such as tryptic soy agar (TSA), heart
  infusion agar (HIA), or blood agar and
  biochemically confirmed to be E. coli

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Pcr assays can detect genetic basis of stec

• PCR assays to detect the stx1 and stx2 genes are
  used by many public health laboratories for
  diagnosis and confirmation of STEC infection.
  Depending on the primers used, these assays can
  distinguish between stx1 and stx2 Assays also
  have been developed that determine the specific O
  group of an organism, detect virulence factors
  such as intimin and enterohemolysin and can
  differentiate among the subtypes of Shiga toxins

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Need for foolproof methods in diagnosis

• The new isolates of E.coli 0104 H4 are
  emerging pathogens with a potential to cause
  morbidity and mortality with community concern,
• The search is for the fool proof method for
  isolation and identification of the Bacteria

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Supportive treatment

• Non-specific supportive therapy, including
  hydration, is important. Antibiotics should not
  be used to treat this infection. There is no
  evidence that treatment with antibiotics is
  helpful, and taking antibiotics may increase the
  risk of HUS. Antidiarrheal agents like Imodium
  may also increase that risk.

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How can STEC infections be prevented?
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Handing washing the most essential step

• WASH HANDS thoroughly after using the bathroom
  or changing diapers and before preparing or
  eating food. WASH YOUR HANDS after contact with
  animals or their environments (at farms, petting
  zoos, fairs, even your own backyard).

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Proper cooking most essential step

• COOK meats thoroughly. Ground beef and meat that
  has been needle-tenderized should be cooked to a
  temperature of at least 160F/70C. Its best to
  use a thermometer, as color is not a very
  reliable indicator of doneness.

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avoid

• AVOID raw milk, unpasteurized dairy products, and
  unpasteurized juices (like fresh apple cider).
• AVOID swallowing water when swimming or playing
  in lakes, ponds, streams, swimming pools, and
  backyard kiddie pools.

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Need for prevention

• PREVENT cross contamination in food preparation
  areas by thoroughly washing hands, counters,
  cutting boards, and utensils after they touch raw
  meat.

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Role of antibiotics can they harm ?

• Antibiotics might increase the risk for HUS in
  patients infected with O157 STEC, and
  antidiarrheal medications might worsen the
  illness.
• True with 0104H4

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Delayed diagnosis leads to outbreaks

• Delayed diagnosis of STEC infections might lead
  to secondary transmission in homes, child-care
  settings, nursing homes, and food service
  establishments and might delay detection of
  multistate outbreaks related to widely
  distributed foods . Outbreaks caused by STEC with
  multiple Serogroups or PFGE patterns have been
  documented.

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WHO advises

• The World Health Organization is warning people
  not to take antibiotics if they get sick in the
  E. coli outbreak that began in Germany last
  month.
• Anti-diarrhea medication isn't recommended
  either, as it stops the bacteria from quickly
  leaving the body.

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Why drugs are dangerous

• Use of antibiotics other Antidiarrheal
  treatments "can actually make the situation
  worse." That's because killing toxin-producing
  bacteria, such as the ones responsible for this
  outbreak, can actually cause them to release more
  toxins. can actually make the situation worse."
  That's because killing toxin-producing bacteria,
  such as the ones responsible for this outbreak,
  can actually cause them to release more toxins.

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Vegetables too are infectious do believe it ???
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