E.coli O104;H4 Emerging infection - PowerPoint PPT Presentation

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E.coli O104;H4 Emerging infection


E.coli O104;H4 Emerging infection – PowerPoint PPT presentation

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Title: E.coli O104;H4 Emerging infection

E. coli
0104H4 emerging pathogen new
  • Dr.T.V.Rao.MD

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.

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

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.

Cycle of events in spread of stec Ruminants and
contamination cycle
Cycle of events in spread of stec STEC Ruminants
and contamination cycle
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

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.

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.

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.

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

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.

genome OF A KILLER German and Chinese scientists
cracked the genetic code behind the strain of
Escherichia coli
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.

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

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

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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

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.

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

Early processing of results yields better
  • 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.

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

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.

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

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
  • . E.coli O157 - purple
  • other bacterial colonies - inhibited, blue or

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

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

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

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

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

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.

How can STEC infections be prevented?
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).

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.

  • 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.

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

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
  • True with 0104H4

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

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
  • Anti-diarrhea medication isn't recommended
    either, as it stops the bacteria from quickly
    leaving the body.

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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