1. Case No. 26 LIM, YOONTAEK Clark

2. Case EF, a fresh college graduate, is applying for a job at a pharmaceutical company. EF, a fresh college graduate, is applying for a job at a pharmaceutical company. Routine laboratory examinations were requested. Routine laboratory examinations were requested. Fecalysis revealed: (+) E. histolitica Fecalysis revealed: (+) E. histolitica Asymptomatic Asymptomatic

3. Entamoeba histolytica Protozoan parasite, cause of diarrhea, dysentery, liver abscess and other syndromes Protozoan parasite, cause of diarrhea, dysentery, liver abscess and other syndromes Occurs primarily in developing countries, but immigrants, travelers, diagnosed with infection in U.S. Occurs primarily in developing countries, but immigrants, travelers, diagnosed with infection in U.S. Must be distinguished clinically from Entamoeba dispar, a morphologically identical parasite that is non-invasive and does not cause disease Must be distinguished clinically from Entamoeba dispar, a morphologically identical parasite that is non-invasive and does not cause disease Onset of colitis usually gradual with symptoms > 1 wk, distinguishing it from bacterial dysentery Onset of colitis usually gradual with symptoms > 1 wk, distinguishing it from bacterial dysentery Infective stage : mature tetranucleated cyst Infective stage : mature tetranucleated cyst

4. Transmission Polluted water supply Polluted water supply Unclean handling by injected individuals Unclean handling by injected individuals Droppings of flies and other insects Droppings of flies and other insects Use of human excrement an vegetable gardens Use of human excrement an vegetable gardens Gross carelessness in personal hygiene Gross carelessness in personal hygiene In homosexual acquired through sexual, anal intercourse In homosexual acquired through sexual, anal intercourse

5. SITES OF INFECTION Colon: dysentery, ameboma (tumor-like lesion of colonic lumen; can be confused radiographically with cecal cancer), toxic megacolon Colon: dysentery, ameboma (tumor-like lesion of colonic lumen; can be confused radiographically with cecal cancer), toxic megacolon Liver: abscess, can rupture causing peritonitis Liver: abscess, can rupture causing peritonitis Lung: empyema (right sided- direct extension from liver) Lung: empyema (right sided- direct extension from liver) Heart: pericarditis (direct extension from liver) Heart: pericarditis (direct extension from liver) Brain: abscess (hematogenous spread, rare) Brain: abscess (hematogenous spread, rare) Skin: usually perineal, genital Skin: usually perineal, genital GU: recto-vaginal fistula GU: recto-vaginal fistula

7. Diagnosis of amebic colitis  Observation of red cell-containing motile trophozoites on fresh stool smear (insensitive); always heme + stool  Colonoscopy: biopsy or scraping at margin of colonic mucosal ulcer: parasite may be seen; H&E shows necrosis, classic flask-shaped ulcer  Stool antigen test that distinguishes Eh from E. dispar is available, more sensitive than microscopy of stool  Serology 99% sens. for amebic liver abscess; 88% sens. for colitis, but Abs may be present yrs. later so that serology may not be useful in immigrants from Eh-endemic regions  Ultrasound of liver: cannot distinguish amebic from pyogenic abscess, but can guide aspiration if necessary  Liver abscess aspiration--yields anchovy paste-like material, lack of WBCs (due to lysis by parasite) clue to diagnosis, parasites usually not seen

8. Laboratory Diagnosis Microscopy Microscopy Microscopy Microscopic identification of cysts and trophozoites in the stool is the common method Microscopic identification of cysts and trophozoites in the stool is the common method Fresh stool: wet mounts and permanently stained preparations (e.g., trichrome). Fresh stool: wet mounts and permanently stained preparations (e.g., trichrome). Concentrates from fresh stool: wet mounts, with or without iodine stain, and permanently stained preparations (e.g., trichrome). Concentrates from fresh stool: wet mounts, with or without iodine stain, and permanently stained preparations (e.g., trichrome). E. histolytica trophozoites can also be identified in aspirates or biopsy samples obtained during colonoscopy or surgery E. histolytica trophozoites can also be identified in aspirates or biopsy samples obtained during colonoscopy or surgery

9. Trophozoites of Entamoeba histolytica Trichrome stain Trophozoites of Entamoeba histolytica with ingested erythrocytes (trichrome stain) Line drawing

10. Invasive form Invasive form Active, progressive, indirectional Active, progressive, indirectional Found in liquid stool Found in liquid stool Eccenteric karyosome, “bulls eyes” Eccenteric karyosome, “bulls eyes” 1 nucleus 1 nucleus Presence of ingested RBC Presence of ingested RBC Killed by exposure to air or stomack acid - > cannot cause infection Killed by exposure to air or stomack acid - > cannot cause infection

11. Cysts of Entamoeba histolytica Line drawing Wet mounts stained with iodine Stained with trichrome

12. Infective stage Infective stage Found in formed stool Found in formed stool 4 nuclei 4 nuclei Cigar-shape chromatoidal body Cigar-shape chromatoidal body With glycogen mass With glycogen mass

13. Diagnosis Immunodiagnosis Immunodiagnosis Immunodiagnosis Antibody Detection; Enzyme immunoassay (EIA) kits for Entomoeba histolytica Antibody Detection; Enzyme immunoassay (EIA) kits for Entomoeba histolytica 95% of patients with extraintestinal amebiasis 95% of patients with extraintestinal amebiasis 70% of patients with active intestinal infection 70% of patients with active intestinal infection 10% of asymptomatic persons who are passing cysts 10% of asymptomatic persons who are passing cysts Detectable E. histolytica-specific antibodies may persist for years after successful treatment, so the presence of antibodies does not necessarily indicate acute or current infection Detectable E. histolytica-specific antibodies may persist for years after successful treatment, so the presence of antibodies does not necessarily indicate acute or current infection Antigen Detection Antigen Detection Useful as an adjunct to microscopic diagnosis in detecting parasites and to distinguish between pathogenic and nonpathogenic infections Useful as an adjunct to microscopic diagnosis in detecting parasites and to distinguish between pathogenic and nonpathogenic infections

14. Diagnosis Molecular methods Molecular methods PCR is the method of choice for discriminating between the pathogenic species (E. histolytica) from the nonpathogenic species (E. dispar) PCR is the method of choice for discriminating between the pathogenic species (E. histolytica) from the nonpathogenic species (E. dispar)

15. Treatment of amoebiasis by Rang Acute invasive intestinal amoebiasis resulting in acute severe amoebic dysentery : metronidazole (or tindazole) followed by diloxanide Acute invasive intestinal amoebiasis resulting in acute severe amoebic dysentery : metronidazole (or tindazole) followed by diloxanide Chronic intestinal amoebiasis : diloxanide Chronic intestinal amoebiasis : diloxanide Hepatic amoebiasis : metronidazole followed by diloxanide Hepatic amoebiasis : metronidazole followed by diloxanide Carrier state : diloxanide Carrier state : diloxanide

16. Treatment of amoebiasis by katzung Clinical setting DOC (adult dosage) Alternative drugs (adult) Asymptomatic intestinal infection Luminal agent : Diloxanide furoate, 500mg tid 10days Iodoquinol, 650mg tid for 21days Paromomycin, 10mg/kg tid for 7days Mild to moderate intestinal infection Metronidazole, 750mg tid or 500mg IV every 6hours 10days + Luminal agent + Tetracyclin, 250mg tid 10days or Erythromycin, 500mg qid 10days Severe intestinal infection Same as mild to moderate infection Luminal agent + Tetracyclin, 250mg tid 10days or Dehydroemetine or emetine, 1mg/kg SC or IM 3~5days Hepatic abscess, ameboma and other detraintestinal disease Same as mild to moderate infection Dehydroemetine or emetine, 1mg/kg SC or IM 8~10days followed by (in abscess only) chloroquine, 500mg bid 2days then 500mg qd 21days + Luminal agent * Diloxanide furoate : not available in U.S.

17. Treatment for asymptomatic patient Luminal agents alone should be used (not absorbed) Luminal agents alone should be used (not absorbed) Iodoquinol: 650 mg tid x 20 days Iodoquinol: 650 mg tid x 20 days Paromomycin: 25-35 mg/kg/d in 3 divided doses x 7 days Paromomycin: 25-35 mg/kg/d in 3 divided doses x 7 days

18. Metronidazole (nitroimidazole) DOC for treatment of extraluminal amoebiasis DOC for treatment of extraluminal amoebiasis Kills trophozoites but has no effect on the cysts Kills trophozoites but has no effect on the cysts Most effective drug available for invasive amoebiasis involving the intestine or the liver, but less against in the lumen of the gut Most effective drug available for invasive amoebiasis involving the intestine or the liver, but less against in the lumen of the gut MOA : damage to the DNA of the trophozoite by toxic oxygen products generated from the drug MOA : damage to the DNA of the trophozoite by toxic oxygen products generated from the drug Pharmacokinetics Pharmacokinetics Given orally Given orally Rapidly and completely absorbed. Rapidly and completely absorbed. Peak conc : 1~3 hours Peak conc : 1~3 hours T1/2 : 7 hours T1/2 : 7 hours Excreted in urine Excreted in urine Also used in Giardiasis (DOC), Trichomoniasis (DOC) Also used in Giardiasis (DOC), Trichomoniasis (DOC)

19. Metronidazole (nitroimidazole) S/E S/E Frequent: GI intolerance, metallic taste, headache, dark urine (harmless) Frequent: GI intolerance, metallic taste, headache, dark urine (harmless) Occasional: peripheral neuropathy (with prolonged use, usually reversible), phlebitis at injection sites, disulfiram-like reaction with alcohol, insomnia, stomatitis. Occasional: peripheral neuropathy (with prolonged use, usually reversible), phlebitis at injection sites, disulfiram-like reaction with alcohol, insomnia, stomatitis. Drug interaction Drug interaction Disulfiram and ethanol : avoid co-administration Disulfiram and ethanol : avoid co-administration Barbiturates may decrease metronidazole levels Barbiturates may decrease metronidazole levels

20. Iodoquinol Lumninal agent Lumninal agent 90% not absorbed 90% not absorbed Unknown mechanism Unknown mechanism Effective for trophozoite in lumen but not in bowel wall or tissue Effective for trophozoite in lumen but not in bowel wall or tissue S/E S/E GIT GIT Increase protein bound iodine Increase protein bound iodine Dermatitis, urticaria Dermatitis, urticaria Neurotoxin Neurotoxin Nephrotoxin Nephrotoxin

21. Diloxanide furoate Luminal agent Luminal agent Inactive against tissue trophozoite Inactive against tissue trophozoite Unknown mechanism Unknown mechanism Direct amoebicidal action, affecting the amoebae before encystment Direct amoebicidal action, affecting the amoebae before encystment DOC for asymptomatic infection DOC for asymptomatic infection No serious side effects No serious side effects Contraindicated in pregnancy Contraindicated in pregnancy S/E S/E Itchy rash (urticaria) Itchy rash (urticaria) Itching (pruritus) Itching (pruritus) Excess gas in the stomach and intestines (flatulence) Excess gas in the stomach and intestines (flatulence) Vomiting Vomiting

22. Paromomycin sulfate An aminoglycoside An aminoglycoside Luminal only Luminal only S/E S/E GIT GIT Renal toxicity Renal toxicity Caution with GIT ulceration since drug can be absorbed with more toxicity Caution with GIT ulceration since drug can be absorbed with more toxicity

23. Emetine & Dehydroemetine For tissue trophozoite For tissue trophozoite Oral unreliable Oral unreliable IM or SC is preferred; never IV – toxic IM or SC is preferred; never IV – toxic Only for 3~5 days not more than 10days Only for 3~5 days not more than 10days Dehydroemetine is preferred (less tosic) Dehydroemetine is preferred (less tosic) For severe amoebiasis where metronidazole cannot be used For severe amoebiasis where metronidazole cannot be used Combine with luminal agent Combine with luminal agent S/E S/E Pain at injection site : sterile abscess Pain at injection site : sterile abscess Arrythmia, CHF, hypotension Arrythmia, CHF, hypotension Contraindication Contraindication Cardiac disease Cardiac disease Renal disease ( cannot be excreted & may accumulated ) Renal disease ( cannot be excreted & may accumulated ) Young children & pregnancy Young children & pregnancy

24. Thank you!