e.coli 0104 h4 an emerging infection
DESCRIPTION
E.coli 0104 H4 an Emerging InfectionTRANSCRIPT
Dr.T.V.Rao.MD
E. COLI 0104:H4
EMERGING PATHOGEN – NEW CONCERNS
DR.T.V.RAO MD 1
• 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.
SHIGA TOXIN-PRODUCING ESCHERICHIA COLI (STEC)
CURRENT OUTBREAK
DR.T.V.RAO MD 2
DR.T.V.RAO MD 3
• Large outbreak of Shiga toxin-
producing Escherichia coli O104:H4
(STEC O104:H4) 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 Germany’s 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.
NEW REPORT ON E.COLI 0104 H4 OUTBREAK
DR.T.V.RAO MD 4
• Disease Prevention
and Control (ECDC)
said the "causative
agent" was a strain
of bacteria that are
called Shiga toxin-
producing
Escherichia coli, or
STEC.
EUROPEAN CENTRE FOR DISEASE PREVENTION
AND CONTROL (ECDC)
REPORTS
DR.T.V.RAO MD 5
• 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.
VEGETABLES AS SOURCE OF
E.COLI INFECTIONS
DR.T.V.RAO MD 6
CYCLE OF EVENTS IN SPREAD OF STEC
RUMINANTS AND CONTAMINATION CYCLE
DR.T.V.RAO MD 7
CYCLE OF EVENTS IN SPREAD OF STEC
STEC RUMINANTS AND CONTAMINATION CYCLE
DR.T.V.RAO MD 8
• E-coli isn’t 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.
SHIGA TOXINS
DR.T.V.RAO MD 9
• 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 O157:H7 (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.
WHAT ARE SHIGA TOXIN-PRODUCING E. COLI?
DR.T.V.RAO MD 10
• E. coli serotype O157:H7 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 O157:H7 can survive
at low temperatures as well as under
acidic conditions, and the infectious
dose is relatively small.
E.COLI 0104: H4 RESEMBLES E. COLI SEROTYPE O157:H7
DR.T.V.RAO MD 11
• t's observed that E. coli O104:H4
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
O104:H4, tests have shown that it
now carries a gene for shigatoxin,
which is commonly found in other
disease-causing strains of this
species.
E.COLI 0104;H4 PICKED UP NEW
GENES
DR.T.V.RAO MD 12
• 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
STRUCTURE OF STEC
DR.T.V.RAO MD 13
• 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.
THE NEW STRAIN OF E.COLI 0104 H4
A HYBRID STRAIN
DR.T.V.RAO MD 14
GENOME OF A KILLER: GERMAN AND CHINESE SCIENTISTS
CRACKED THE GENETIC CODE BEHIND THE STRAIN OF
ESCHERICHIA COLI
DR.T.V.RAO MD 15
• STEC are also
referred to as
verocytotoxigenic E.
coli; STEC that
cause human illness
are also referred to
as Enterohemorrhagic
E. coli.
STEC ARE REFERRED AS VEROCYTOTOXINS
DR.T.V.RAO MD 16
• 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 5–7
days, but some patients go on to
develop HUS—usually 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.
HOW THE PATIENTS PRESENT
DR.T.V.RAO MD 17
• Around 5–10% 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.
HEMOLYTIC UREMIC SYNDROME (HUS)
DR.T.V.RAO MD 18
DR.T.V.RAO MD 19
• 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
NEED FOR EARLY DIAGNOSIS –
REDUCES RENAL DAMAGE
DR.T.V.RAO MD 20
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.
DR.T.V.RAO MD 21
• 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
SAMPLES ARE TAKEN FROM A CUCUMBER
FOR A MOLECULAR BIOLOGICAL STUDY
DR.T.V.RAO MD 22
• 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 >24 hours
unpreserved or for >48 hours in
transport medium.
EARLY PROCESSING OF RESULTS – YIELDS
BETTER RESULTS.
DR.T.V.RAO MD 23
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
DR.T.V.RAO MD 24
• 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.
0157AND 0104 CAN BE ISOLATED ON
SELECTIVE MEDIUM
DR.T.V.RAO MD 25
• 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
CULTURE FOR STEC
DR.T.V.RAO MD 26
• 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
CHROMAGAR FOR E.COLI O157
DR.T.V.RAO MD 27
• After incubation for 16–
24 hours at 37°C
(99°F), 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
COLONIES APPEAR AS PINK ON
CHROMAGAR
DR.T.V.RAO MD 28
• 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 OF 0157 LATEX AGGLUTINATION TEST
DR.T.V.RAO MD 29
• 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
IDENTIFICATION WITH BIOCHEMICAL
METHODS
DR.T.V.RAO MD 30
• 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
PCR ASSAYS CAN DETECT GENETIC
BASIS OF STEC
DR.T.V.RAO MD 31
• 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
NEED FOR FOOLPROOF METHODS IN
DIAGNOSIS
DR.T.V.RAO MD 32
• 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.
SUPPORTIVE TREATMENT
DR.T.V.RAO MD 33
HOW CAN STEC INFECTIONS BE
PREVENTED?
DR.T.V.RAO MD 34
• 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).
HANDING WASHING THE MOST ESSENTIAL
STEP
DR.T.V.RAO MD 35
• COOK meats thoroughly.
Ground beef and meat that
has been needle-
tenderized should be
cooked to a temperature of
at least 160°F/70˚C. It’s
best to use a thermometer,
as color is not a very
reliable indicator of
―doneness.‖
PROPER COOKING MOST ESSENTIAL STEP
DR.T.V.RAO MD 36
• 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.
AVOID
DR.T.V.RAO MD 37
• PREVENT cross
contamination in food
preparation areas by
thoroughly washing
hands, counters, cutting
boards, and utensils
after they touch raw
meat.
NEED FOR PREVENTION
DR.T.V.RAO MD 38
• Antibiotics might increase the risk for HUS in patients infected with O157 STEC, and antidiarrheal medications might worsen the illness.
• True with 0104:H4
ROLE OF ANTIBIOTICS – CAN THEY HARM ?
DR.T.V.RAO MD 39
• 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.
DELAYED DIAGNOSIS LEADS TO
OUTBREAKS
DR.T.V.RAO MD 40
• 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.
WHO ADVISES
DR.T.V.RAO MD 41
• 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.
WHY DRUGS ARE DANGEROUS
DR.T.V.RAO MD 42
VEGETABLES TOO ARE INFECTIOUS
DO BELIEVE IT ???
DR.T.V.RAO MD 43
DR.T.V.RAO MD 44
FOLLOW ME FOR ARTICLES OF INTEREST ON
INFECTIOUS DISEASES AND MICROBIOLOGY ..
DR.T.V.RAO MD 45
• Created by Dr.T.V.Rao MD for
‘ e ‘ learning resources for Medical
Professionals in the Development World