GASTROINTESTINAL INFECTIONS I,II

Transcription

1 GASTROINTESTINAL INFECTIONS I,II

2 Gastroenteritis Definition? Inflammation of the digestive tract, particularly the stomach, and large and small intestines

3 Acute Infective Gastroenteritis A case of gastroenteritis is defined as an individual with 3 loose stools, or any vomiting, in 24 h, but excluding those (a) with cancer of the bowel, irritable bowel syndrome, Crohn's disease, ulcerative colitis, cystic fibriosis, coeliac disease, or another chronic illness with symptoms of diarrhoea or vomiting (b) who report their symptoms were due to drugs, alcohol, or pregnancy S.E. Majowicz et.al

4 Diarrhea Diarrhoea is defined as the passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual). (15 g/kg for children younger than 2 years and greater than 200 g for children 2 years or older) Frequent passing of formed stools is not diarrhoea, nor is the passing of loose, "pasty" stools by breastfed babies. WHO

5 Etiologies Bacterial Viral Parasitic Toxin mediated Drugs related Non-infectious

6 Viral gastroenteritis Sporadic gastroenteritis in infants (rotavirus) Epidemic gastroenteritis (sudden outbreaks in semiclosed communities caused by caliciviruses. Sporadic acute gastroenteritis of adults, (caliciviruses, rotaviruses, astroviruses, or adenoviruses)

7 Seasonality Noroviruses and astroviruses: winter, cooler temperature The highest incidence of rotavirus cases occurs during the months from November to April Adenovirus throughout he year

8 Pathophysiology Spread by fecal-oral contamination Airborne (norovirus) Pathomechanism: attachement to enterocytes, mononuclear inflamatory cell infiltation, carbohydrate malabsorption Enterotoxin secretion (rotavirus Ca dependent Cl secretion) Cytokine and chemokine secretion...

9 Clinical presentation Wide clinical spectrum based on individual host immune responses: Asymptomatic to fatal dehydration Typically: short viral prodrome, with mild fever and vomiting, followed by 1-4 days of non-bloody, watery diarrhea Very important to charachterize the symptoms from the history!!

10 Why? Viruses are the suspected cause of acute gastroenteritis when there is: Prominenet vomiting Incubation period is longer than 14 hours Family history of an entire illness that is over in less than 3 days. Pay special attention to history of cruise ships, sushi, seafood, daycare...

11 Examination of the patient Reveals: No or mild fever (with the exception of rotavirus) Signs of dehydration Mild abdominal tenderness Tachycaria, low blood pressure, altered mental status...all are signs of dehydration

12 Classify the diseases Sporadic infantile: Rotavirus (A,C), calicivirus, astroviruses, adenovirus Epidemic Caliciviruses, norovirus, norwalk virus Sporadic adult Caliciviruses, non group A rotavirus, astrovirus, and adenovirus.

13 Lab work If you are quite sure about the etiology, lab test is usually not indicated Routine tests Rotavirus: Rapid antigen testing of the stool Antirotavirus antibodies Calicivirus: PCR based techniques Reassurance!

14 Management Rehydration! Symptomatic tehrapy Probiotics Admit vs. Discharge?!

15 Bacterial Gastroenteritis Symptoms range from mild to servere Nausea, vomiting and diarrhea Abdominal pain, frequently a cramping abdominal pain that is relieved by defecation

16 Etiology Salmonella, Shigella, Campylobacter, Aeromonas are the leading causes of bacterial diarrhea worldwide E.coli Yersinia Clostridium

17 Seasonality Aeromonas and Shigella: higher incidence in summer and fall Campylobacter infection : In summer months Yersinia infection: In winter months and in colder climates

18 Pathomechanism Direct invasivion mucosal ulceration and abscess formation with a subsequent inflammatory cascade. Toxin mediated toxins control enteral and extraenteral cellular processes. E. coli heat-labile and heat-stable enterotoxins = activate enteral adenylate cyclase and guanylate cyclase E. coli enterohemorrhagic Verotoxin = seizures and hemolytic-uremic syndrome (HUS). Direct Adhesion Leading to local inflammation

19 Clinical spectrum Charachterize the frequency, consistency and appearance of stools Pay special attention to incubation periods Take careful history

20 Small bowel vs. large bowel Medscape

21 Incubation period Medscape

22 Etiology from history Dairy - Campylobacter, Salmonella, Listeria, and Staphylococcus species Eggs - Salmonella species Meats - C perfringens and Salmonella, Aeromonas, Campylobacter, andstaphylococcus species Ground beef - Enterohemorrhagic E coli Poultry - Campylobacter species Pork - C perfringens and Y enterocolitica Seafood - Aeromonas, Plesiomonas, Vibrio species, and astrovirus Oysters - Plesiomonas and Vibrio species and calicivirus Vegetables - Aeromonas species and C perfringens Alfalfa sprouts - Enterohemorrhagic E coli and Salmonella species Fried rice - Bacillus species Custards, mayonnaise - Staphylococcus species

23 Lab work As opposed to viral gastroenteritis, bacterial gastroenteritis warrants investigation Routine blood samples Stool cultures Most of the time the yield is low Fecal leukocytes presence excludes toxin related enteritis and viruses

24 Management Rehydration! Supportive Antimicrobial therapy in selected cases! Special attention to the Infants Elderly Immunocompromised Prolonged clinical symptomatic stage

25 Antimicrobial therapy Aeromonas 3.rd generation cephalosporin Clostridium diff. Metronidazole, Vancomycin V. Cholerae Tetracyclin Salmonella Ampicillin, 3.rd gen. Cephalosporin Carrier state! Shigella Ampicillin, Trimethoprim/sulfamethoxazole E.Colin Parenteral 3.rd gen. Cephalosporin HUS!!!

26 Clostridium difficile Gram positive, anaerobic, spore forming Colitis results from colonization of the colon by C. difficile, which also releases toxins leading to damage of the intestinal mucosa.

27 Etiology 20% of individuals who are hospitalized become colonized with C difficile Diagnosis should be suspected in a patient: Who has received antibiotics within the previous 3 months Has been recently hospitalized Occurrence of diarrhea 48 hours or more after hospitalization

28 The toxins Toxin A (enterotoxin) and Toxin B (cytotoxin) Toxins bind to specific receptors on the intestinal mucosal cells. They enter the cell by catalyzing a specific alteration of Rho GTPase proteins (actin polymerization, cytoskeletal architecture, and cell movement) Glucosylation of Rho GTPases inactivates the GTPase proteins collapse of the cytoskelton cell damage

29 Clinical picture Asymptomatic carrier state Mild self-limited diarrhea Pseudomembranous colitis Fulminant colitis Toxic megacolon Pathollogy.pitt.edu

30 Symptoms Watery bloody diarrhea Fever Abdominal cramps Anorexia, nausea

31 Lab workup Routine lab shows leukocytosis Increased inflammatory markers Impaired kidney function Electrolyte imbalances Hypoalbuminemia

32 Diagnosis Clinical picture Stool culture only on diarrheal samples (90-100%) Stool cytotoxin test (70-100%) EIA for detecting toxins A and B (79-80%)

33 NAP1 hypervirulent strain of C difficile is associated with the most serious sequelae of CDI, causing severe and fulminant colitis that is characterized by leukocytosis, renal failure, and toxic megacolon

34 Management Asymptomatic carriers: No treatment Mild, antibiotic-associated diarrhea without fever, abdominal pain, or leukocytosis: Cessation of antibiotic may be the only treatment necessary Mild to moderate diarrhea or colitis: Metronidazole (oral or intravenous) or vancomycin (oral) Severe or complicated disease: Vancomycin Combination therapy is also used

35 Fecal transplantation (>90% effective)

36 Metronidazole vs Vancomycin Oral is the preferred route Vancomycin is poorly absorbed in the intestinal tract Mild-moderate disease, no complications: Metronidazole is the prefered 1st choice as initial treatment Severe comlicated disease: Vancomycin

37 Relapse Relapse after treatment occurs in 20-37% of patients After a 1st relapse chances are 45% of a second relapse Risk factors include: Old age Debilitating illness Continues antibiotic use

38 Treatment of relapse Mild symptoms of recurrence in otherwise well patients no antibiotic therapy. Initial recurrence metronidazole Subsequent recurrences vancomycin prolonged tapered Rifaximin for allergic patients

39 Travelers diarrhea 30% to 70% of travelers depending on the destination and season of travel Most common pathogen is enterotoxigenic Escherichia coli (heat labile and heat stanle toxins) Campylobacter jejuni,shigella, Salmonella are also common High-risk areas: Asia, the Middle East, Africa, Mexico, and Central and South America.

40 Travelers diarrhea Watery diarrhoea (max.3-5 days), vomiting, abdominal cramps, 10-20%: dysentery May cause septicemia Prophylactic antibiotic? bismute-subsalicylate Retarding the expulsion of fluids into the digestive system by irritated tissues, by "coating" them. Stimulation of absorption of fluids and electrolytes by the intestinal wall Binding of toxins produced by E. coli Reduction in hypermotility

41 Parasitic gastroentritis Giardia is the most frequent cause of waterborne diarrhea swallowing water that has been contaminated by animal feces Giardiasis represents cross-infectivity between animal humans. Giardia intestinalis has been isolated from the stools of beavers, dogs, cats, and primates Charachterized by severe frequent Abdominal cramps

42 Pathomechanism Damage to the endothelial brush border, enterotoxins, immunologic reactions, and altered gut motility and fluid hypersecretion via increased adenylate cyclase activity. Adhesion causes increased epithelial permeability villous atrophy and shedding Leading finally to malabsorption and diarrhea

43 Clinical picture Same as bacterial gastroenteritis in addition to: Urticaria Malodorous, greasy stools

44 Giardiasis Diagnosis identification of Giardia intestinalis trophozoites or cysts in the stool Stool antigen enzyme-linked immunosorbent assays Treatment Metronidazole

45 Cryptosporidium Parasite living in the intestine of affected individuals or animals Mainyl affects children Depends om immunologic status of Patient increased intestinal permeability, chloride secretion, and malabsorption

46 Diagnosis acid-fast staining procedure is useful for the identification of oocysts Treatment: Nitazoxanide

47 Ascaris Ascaris lumbricoides, affects 1/3rd of the world population Presents with pulmonary and GI symptoms Clinical features: Malnutrition Anemia Growth retardation

48 Ascariasis

49 Round worm (Ascariasis) Infectionlandscape

50 Symptoms Early symptoms larval migration, 4-16 d after egg ingestion, respiratory symptoms result from the migration of larvae through the lungs. Fever, cough, dyspnea Late symptoms 6-8 wk after egg ingestion gastrointestinal symptom Apicareonline

51 Diagnosis Early phase Eosinophilia Sputum analysis may reveal larvae Increased IgE Late phase Stool examination to detect eggs Imgarcade

52 Treatment Early phase: Beta gonsist, steroids? Late phase Benzimidazoles Colonosyopy for removing worm masses

53 Amoebiasis Entamoeba histolytica Cyst trough the mouth trophozoit in the colon amoebic colitis cysts excreted via defecation Smptoms include: abdominal pain, loss of weight, diarrhoea, dysentery, fever: 40% Ameobic liver disease (after dissemination from colonic mucosa) Diagnosis: 3 fresh stool samples, culture, antigen detection, serology, endoscopy Treatment with metronidazol Treatment of carriers!

54 Annalsgastro.gr

55 Infection by nematodes Ascariasis, trichriasis, hook worm, filariasis Blood picture shows eosinophilia!!! Treatment by Albendazole or Mebendazole

56 Food poisoning Staphylococcus aureus (heat resistant toxin) meat, puddings, pastries and sandwiches (2-6 h) Bacillus cereus (enterotoxin) (Ip: 1-6 h) Clostridium botulinum botulism neurotoxin, nausea, dryness of the mouth, constipation, ocular symtomps, dysphagia, dysarthria, symmetric paralysis of the legs, paralysis of the respiratory organs, incontinency of the urine and stool

57 Prevention General hygienic principals (wash the hands!) Food hygiene Isolation of the patients Epidemic measures Specific prevention: vaccination rotavirus at months prevent 74% to 87% of all rotavirus illness episodes.

58 Thanks you for your attention