E.coli 0104 H4 an Emerging Infection

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E.coli 0104 H4 an Emerging Infection

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E.coli 0104 H4 an Emerging Infection

  1. 1. E. COLI 0104:H4 EMERGING PATHOGEN – NEW CONCERNS Dr.T.V.Rao.MDDR.T.V.RAO MD 1
  2. 2. 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.DR.T.V.RAO MD 2
  3. 3. DR.T.V.RAO MD 3
  4. 4. NEW REPORT ON E.COLI 0104 H4 OUTBREAK• 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.DR.T.V.RAO MD 4
  5. 5. 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.DR.T.V.RAO MD 5
  6. 6. 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.DR.T.V.RAO MD 6
  7. 7. CYCLE OF EVENTS IN SPREAD OF STEC RUMINANTS AND CONTAMINATION CYCLEDR.T.V.RAO MD 7
  8. 8. CYCLE OF EVENTS IN SPREAD OF STECSTEC RUMINANTS AND CONTAMINATION CYCLEDR.T.V.RAO MD 8
  9. 9. SHIGA TOXINS• 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.DR.T.V.RAO MD 9
  10. 10. 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 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.DR.T.V.RAO MD 10
  11. 11. E.COLI 0104: H4 RESEMBLES E. COLI SEROTYPE O157:H7• 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.DR.T.V.RAO MD 11
  12. 12. E.COLI 0104;H4 PICKED UP NEW GENES• ts 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.DR.T.V.RAO MD 12
  13. 13. 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 antibodiesDR.T.V.RAO MD 13
  14. 14. 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.DR.T.V.RAO MD 14
  15. 15. GENOME OF A KILLER: GERMAN AND CHINESE SCIENTISTS CRACKED THE GENETIC CODE BEHIND THE STRAIN OF ESCHERICHIA COLIDR.T.V.RAO MD 15
  16. 16. 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.DR.T.V.RAO MD 16
  17. 17. 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 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.DR.T.V.RAO MD 17
  18. 18. HEMOLYTIC UREMIC SYNDROME (HUS)• 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.DR.T.V.RAO MD 18
  19. 19. DR.T.V.RAO MD 19
  20. 20. 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 outcomeDR.T.V.RAO MD 20
  21. 21. 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
  22. 22. 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 sourceDR.T.V.RAO MD 22
  23. 23. 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 >24 hours unpreserved or for >48 hours in transport medium.DR.T.V.RAO MD 23
  24. 24. 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 serotypesDR.T.V.RAO MD 24
  25. 25. 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), orDR.T.V.RAO MD CHROMagar O157. 25
  26. 26. 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 mediaDR.T.V.RAO MD 26
  27. 27. 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 colourlesDR.T.V.RAO MD 27
  28. 28. COLONIES APPEAR AS PINK ON CHROMAGAR• 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 O157DR.T.V.RAO MD 28
  29. 29. 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 testedDR.T.V.RAO MD 29
  30. 30. 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. coliDR.T.V.RAO MD 30
  31. 31. 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 toxinsDR.T.V.RAO MD 31
  32. 32. 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 BacteriaDR.T.V.RAO MD 32
  33. 33. 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.DR.T.V.RAO MD 33
  34. 34. HOW CAN STEC INFECTIONS BE PREVENTED?DR.T.V.RAO MD 34
  35. 35. 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).DR.T.V.RAO MD 35
  36. 36. 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 160°F/70˚C. It’s best to use a thermometer, as color is not a very reliable indicator of ―doneness.‖DR.T.V.RAO MD 36
  37. 37. 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.DR.T.V.RAO MD 37
  38. 38. NEED FOR PREVENTION • PREVENT cross contamination in food preparation areas by thoroughly washing hands, counters, cutting boards, and utensils after they touch raw meat.DR.T.V.RAO MD 38
  39. 39. 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 0104:H4DR.T.V.RAO MD 39
  40. 40. 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 haveDR.T.V.RAO MD been documented. 40
  41. 41. 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 isnt recommended either, as it stops the bacteria from quickly leaving the body.DR.T.V.RAO MD 41
  42. 42. WHY DRUGS ARE DANGEROUS• Use of antibiotics other Antidiarrheal treatments "can actually make the situation worse." Thats 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." Thats because killing toxin-producing bacteria, such as the ones responsible for this outbreak, can actually cause them to release more toxins.DR.T.V.RAO MD 42
  43. 43. VEGETABLES TOO ARE INFECTIOUS DO BELIEVE IT ???DR.T.V.RAO MD 43
  44. 44. FOLLOW ME FOR ARTICLES OF INTEREST ON INFECTIOUS DISEASES AND MICROBIOLOGY ..DR.T.V.RAO MD 44
  45. 45. • Created by Dr.T.V.Rao MD for ‘ e ‘ learning resources for Medical Professionals in the Development World • Email • doctortvrao@gmail.comDR.T.V.RAO MD 45

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