case report reporter: i2 陳鴻文. a 45-year-old man who had been feeling unwell for several months...
TRANSCRIPT
Case reportCase report
Reporter: I2 Reporter: I2 陳鴻文陳鴻文
• A 45-year-old man who had been A 45-year-old man who had been feeling unwell for several months feeling unwell for several months visited his internist complaining of visited his internist complaining of headache, dizziness, nausea, vomiting, headache, dizziness, nausea, vomiting, extreme tiredness, and feverextreme tiredness, and fever. The . The patient had been taking prednisone for patient had been taking prednisone for a relapse of chronic ulcerative colitis. a relapse of chronic ulcerative colitis.
• On examination, the physician noted thaOn examination, the physician noted that the patient had t the patient had nuchal rigidity and appnuchal rigidity and appeared confusedeared confused. He performed a lumbar . He performed a lumbar puncture. CSF was sent to the laboratorpuncture. CSF was sent to the laboratory for bacterial and viral cultures. The Gray for bacterial and viral cultures. The Gram stain showed m stain showed many neutrophils but nmany neutrophils but no bacteriao bacteria. .
• To rule out amebic encephalitis, the phyTo rule out amebic encephalitis, the physician asked that a wet mount be preparsician asked that a wet mount be prepared from the patient’s CSF. Microscopic ed from the patient’s CSF. Microscopic examination of this preparation revealeexamination of this preparation revealed d motile amebic trophozoitesmotile amebic trophozoites. Cultures . Cultures were negative for bacteria and viruses. were negative for bacteria and viruses.
• A biopsy specimen containing the A biopsy specimen containing the parasite causing this patient’s parasite causing this patient’s infection is shown in Fig. 29.1.infection is shown in Fig. 29.1.
QUESTIONSQUESTIONS
• 1. Which ameba would you expect to 1. Which ameba would you expect to be causing this patient’s infection? be causing this patient’s infection? What is the name of this infection? What is the name of this infection?
AnswerAnswer
• Acanthamoeba spp.Acanthamoeba spp.• granulomatous amebic encephalitis (GAE)granulomatous amebic encephalitis (GAE) Once infected, a person may suffer with headaOnce infected, a person may suffer with heada
ches, stiff neck, nausea and vomiting, tirednesches, stiff neck, nausea and vomiting, tiredness, confusion, lack of attention to people and sus, confusion, lack of attention to people and surroundings, loss of balance and bodily control, rroundings, loss of balance and bodily control, seizures, and hallucinations. Signs and symptoseizures, and hallucinations. Signs and symptoms progresses over ms progresses over several weeksseveral weeks and death u and death usually occurs.sually occurs.
QUESTIONSQUESTIONS
• 2. Which ameba may cause a more 2. Which ameba may cause a more serious and acute CNS infection and serious and acute CNS infection and may be confused with this parasite? may be confused with this parasite?
AnswerAnswer
• Naegleria fowleriNaegleria fowleri Infection with Infection with Naegleria Naegleria causes the disease causes the disease primary aprimary a
mebic meningoencephalitis (PAM)mebic meningoencephalitis (PAM), a brain infla, a brain inflammation, which leads to the destruction of brain tissummation, which leads to the destruction of brain tissue. e.
Initial signs and symptoms of PAM include headache, fInitial signs and symptoms of PAM include headache, fever, nausea, vomiting, and stiff neck. As the ameba cever, nausea, vomiting, and stiff neck. As the ameba causes more extensive destruction of brain tissue this lauses more extensive destruction of brain tissue this leads to confusion, lack of attention to people and surreads to confusion, lack of attention to people and surroundings, loss of balance and bodily control, seizures, oundings, loss of balance and bodily control, seizures, hallucinations. The disease progresses rapidly and infhallucinations. The disease progresses rapidly and infection usually results in death within ection usually results in death within 3 to 7 days3 to 7 days. .
QUESTIONSQUESTIONS
• 3. How can you distinguish between the3. How can you distinguish between these amebae? se amebae?
QUESTIONSQUESTIONS
• 4. How do the infections caused by 4. How do the infections caused by these two parasites differ? these two parasites differ?
AnswerAnswer
• PAM occurs in persons who are generally healtPAM occurs in persons who are generally healthy prior to infection. Central nervous system ihy prior to infection. Central nervous system involvement arises from organisms that penetrnvolvement arises from organisms that penetrate the nasal passages and enter the brain thrate the nasal passages and enter the brain through the cribriform plate. The organisms can ough the cribriform plate. The organisms can multiply in the tissues of the central nervous smultiply in the tissues of the central nervous system and may be isolated from spinal fluid. In ystem and may be isolated from spinal fluid. In untreated cases death occurs within 1 week of untreated cases death occurs within 1 week of the onset of symptoms. the onset of symptoms.
AnswerAnswer
• GAE occurs in persons who are immunodeficient in soGAE occurs in persons who are immunodeficient in some way; the organisms cause a granulomatous encepme way; the organisms cause a granulomatous encephalitis that leads to death in several weeks to a year afhalitis that leads to death in several weeks to a year after the appearance of symptoms. The primary infectioter the appearance of symptoms. The primary infection site is thought to be the lungs, and the organisms in n site is thought to be the lungs, and the organisms in the brain are generally associated with blood vessels, the brain are generally associated with blood vessels, suggesting vascular dissemination. Prior to 1985 amosuggesting vascular dissemination. Prior to 1985 amoebae had been reported isolated from diseased eyes oebae had been reported isolated from diseased eyes only rarely; cases were associated with trauma to the enly rarely; cases were associated with trauma to the eye. In 1985-1986, 24 eye cases were reported to CDC aye. In 1985-1986, 24 eye cases were reported to CDC and most of these occurred in wearers of contact lensend most of these occurred in wearers of contact lenses. It has been demonstrated that many of these infectis. It has been demonstrated that many of these infections resulted from the use of home-made saline solutions resulted from the use of home-made saline solutions with the contact lenses.ons with the contact lenses.
QUESTIONSQUESTIONS
• 5. 5. How is the laboratory diagnosis of How is the laboratory diagnosis of this infection made? this infection made?
AnswerAnswer
• In Naegleria infections, the diagnosis caIn Naegleria infections, the diagnosis can be made by microscopic examination n be made by microscopic examination of of cerebrospinal fluid (CSF)cerebrospinal fluid (CSF). A wet moun. A wet mount may detect t may detect motile trophozoitesmotile trophozoites, and a , and a Giemsa-stained smear will show trophozGiemsa-stained smear will show trophozoites with typical morphology.oites with typical morphology.
AnswerAnswer
• In Acanthamoeba infections, the diagnoIn Acanthamoeba infections, the diagnosis can be made from microscopic examisis can be made from microscopic examination of stained smears of nation of stained smears of biopsy specibiopsy specimens (brain tissue, skin, cornea) or of comens (brain tissue, skin, cornea) or of corneal scrapingsrneal scrapings, which may detect , which may detect trophtrophozoites and cystsozoites and cysts. Cultivation of the caus. Cultivation of the causal organism, and its identification by diral organism, and its identification by direct immunofluorescent antibody, may alect immunofluorescent antibody, may also prove useful.so prove useful.
QUESTIONSQUESTIONS
• 6. Does the ameba causing CNS 6. Does the ameba causing CNS infection in this patient cause other infection in this patient cause other types of infections? types of infections?
AnswerAnswer
• AcanthamoebaAcanthamoeba can enter the can enter the skinskin throuthrough agh a cut, wound, or through the nostrilscut, wound, or through the nostrils. . Once inside the body, amebas can travel Once inside the body, amebas can travel to the to the lungslungs and through the bloodstrea and through the bloodstream to other parts of the body, especially tm to other parts of the body, especially the he central nervous system (brain and spicentral nervous system (brain and spinal cord)nal cord)..
AnswerAnswer
• Through improper storage, handling, anThrough improper storage, handling, and disinfection of contact lenses, Acanthad disinfection of contact lenses, Acanthamoeba can enter the moeba can enter the eyeeye and cause kera and cause keratitis resulting superficial corneal abrasiotitis resulting superficial corneal abrasions.ns.
QUESTIONSQUESTIONS
• 7. Which other free-living ameba, 7. Which other free-living ameba, recently placed in the same genus as recently placed in the same genus as this parasite, causes a CNS infection this parasite, causes a CNS infection in humans? in humans?
AnswerAnswer
• Acanthamoeba culbertsoni Acanthamoeba culbertsoni • Acanthamoeba polyphaga Acanthamoeba polyphaga eyes infectioneyes infection• Acanthamoeba castellaniiAcanthamoeba castellanii • Acanthamoeba palestinensis Acanthamoeba palestinensis CNS infectionCNS infection• Acanthamoeba astronyxis Acanthamoeba astronyxis CNS infectionCNS infection• Acanthamoeba hatchetti Acanthamoeba hatchetti eyes infectioneyes infection• Acanthamoeba rhysodesAcanthamoeba rhysodes
QUESTIONSQUESTIONS
• 8. Why is there no satisfactory 8. Why is there no satisfactory treatment available to treat this treatment available to treat this infection? infection?
AnswerAnswer
• Treatment with Treatment with sulfamethazinesulfamethazine may be effecti may be effective in controling ve in controling Acanthamoeba spp.Acanthamoeba spp.
• The following agents have been used to succeThe following agents have been used to successfully eliminate the amoebic infection in the essfully eliminate the amoebic infection in the eye: ye: ketoconazole, microconazole, and propamketoconazole, microconazole, and propamidine isothionateidine isothionate; however, ; however, penetrating keratopenetrating keratoplastyplasty has been necessary to restore useful visi has been necessary to restore useful vision.on.
Thanks for your attentionThanks for your attention