Microbiology - Final - Part 1

davidwurbel7's version from 2015-08-14 01:35

Intestinal Micoparasites

Question Answer
Life cycle stage that is motile, reproducing, and metabolically activeTrophozoite
Life cycle stage that is resistant to harsh environmental conditions, metabolically inactive and usually infective to humanCyst
Areas of poor sanitation, contaminated water supplies. Asymptomatic carriers (shed cysts) – reservoir. Route of infection – ingestion of cystsEntamoeba histolytica
Passed out in stool. Infective. Spherical in shape with 1-4 nuclei, 10-20umEntamoeba histolytica Cyst
In freshly passed stool. Not infective. May contain ingested RBCs. 20-30umEntamoeba histolytica Trophozoites
Strains of E.histolytica that don’t cause disease & are non-invasive Inapparent Carriage
Abdominal pain, cramping, colitis with diarrhea. Passage of bloody stools (dysentery)Intestinal Amebiasis
Spread to liver - Amoebic Liver Abcess - lung, brain, heartExtraintestinal Amoebiasis
Lab test for ova and parasitesO & P Exam
Pain – upper right quadrant. Hepatomegaly. Systemic signs – fever, leukocytosis. Usually single abcess in right lobe of liverAmoebic Liver Abcess
Ultrasound, radiograpic imaging. Aspiration of abcess. Aspiration of abcess is “Anchovy paste”. Sterile on culture. Serologic testsAmoebic Liver Abcess Diagnosis
Treatment of Entamoeba historlytica infectionMetronidazole
Sylvatic (wilderness) distribution. Mountain streams & lakes. Reservoir – beavers and other animals. Urban distribution – daycare centers. Route of infection – ingestion of cysts in contaminated water. Cysts resistant to regular chlorine concentrations. Prevent by boil water / filterGiardia lamblia
Symptoms (mild → severe). Mild disease – foul-smelling diarrhea, flatulence, steatorrhea. No blood or pus in stool with malabsorption. Chronic disease with multiple relapsesGiardia lamblia
Stool specimens - If negative examine at least 3 samples. Duodenal aspirates. Entero-string test. O&P exam - for trophozoites and cysts. Antigen test which is more sensitive than O&PGiardia lamblia Diagnosis
Giardia lamblia treatmentMetronidazole
This test has replaced O&P in hospitals and labs and is more sensitiveGiardia Antigen Detection Test
Uro-genital flagellate. Only trophozoite, NO CYST. Infected males – Urethra & prostate gland. Infected women – Urethra & vagina. Transmission – sexual contactTrichomonas vaginalis
In women - common cause of vaginitisTrichomonas vaginalis
Symptoms may include yellowish, watery discharge with itching, burning & painful urinationTrichomonas vaginalis
Men - Primarily asymptomatic carriersTrichomonas vaginalis
Microscopic detection of trophozoites. Specimens – urethral & vaginal discharge. Saline wet mount (motile trophozoites). Stained smear (PAP)Trichomonas vaginalis - Diagnosis
Trichomonas vaginalis treamtment with this as well as co-treatment of sexual partner(s)Metronidazole
Intestinal pathogen. Distribution – Worldwide. Reservoir - swine. Transmission – Fecal-oral. Contamination of water supplies by swine feces. Person-to-person spread. Trophozoite and cyst formBalantidium coli
Resembles Intestinal amoebiasis. Symptoms - Abdominal pain, diarrhea with blood & pus. Ulceration of intestinal mucosa may occur. Extraintestinal invasion is rareBalantidium coli
Diagnosis – O&P exam of stool. Trophozoites & cysts – LARGEBalantidium coli
Treatment for Balantidium coliMetronidazole or Tetracycline
Size 20 - 30μm. Route of infection fecal-oral. Ingestion of contaminated food / water. Foul-smelling watery diarrhea with malabsorption (mimics giardiasis). Increasing awareness of Isospora infection in AIDS patients – watery diarrhea. Diagnosis by Acid-fast oocysts in stoolIsospora belli
Size 8 - 10μm. Route of infection contaminated water (animal reservoirs). Raspberries (Guatemala), basil, mesclun lettuce. Cysts are resistant to chlorination. Self-limited, watery diarrhea. Can be serious & chronic in AIDS patients. Diagnosis – detect acid-fast oocysts in stoolCyclospora cayetanensis
Size 4-6μm Transmission – water-borne. Contamination of municipal water supplies - Outbreaks of Cryptosporidiasis. Cryptosporidia resistant to chlorination. Contamination of recreational water facilities - water-parks, swimming pools. Person-to-person spread – daycare centers. Zoonotic spread (fecal-oral route)Cryptosporidium parvum
Asymptomatic carriage. Mild & self-limiting watery diarrhea. In AIDS patients - Profuse diarrhea, fluid loss. Chronic infection. Disseminated infections reported. Diagnosis Acid-fast oocysts in stool. Antigen test by EIACryptosporidium parvum
Cryptosporidium parvum is treated withNitazoxanide
Size 1 - 2 μm. Distributed worldwide, infect vertebrate & invertebrate animals. Transmission. Ingestion of spores shed in urine / feces. Immunocompromised individuals at increased risk of infection (AIDS patients)Microsporidia
Infections in Immunocompromised. Intestinal infection - Severe, persistent diarrhea. Infection of different organs. Disseminated infections. Diagnosis by Acid-fast spores in stool Microsporidia

Blood Microparasites

Question Answer
Water-borne. Swimming / diving in warm waters. Young, healthy adults. Primary amoebic meningoencephalitis. Acute onset – fever, stiff neck, vomiting. Rapid progression to coma and deathNaegleria
Diagnosis by wet mount of CSF – motile trophozoites seen. No bacteria (on gram stain). Culture negativeNaegleria
Naegleria treatmentAmphotericin B
Water-borne. Keratitis – infects the cornea. Contact-lens wearers. Severe pain, redness. Severe infections – loss of vision. Risk factors include swimming with contact lenses on. Poor contact lens hygiene.Acanthamoeba
Diagnosis by microscopic detection from corneal scrapingsAcathamoeba
Infect RBCs. Transmission – bite of female Anopheles mosquito. Sexual cycle - in mosquito. Asexual cycle - humansPlasmodium
Most prevalent Plasmodium worldwidePlasmodium vivax
Causes most deadly form of malariaPlasmodium falciparum
The two other species that can cause malariaPlasmodium ovale and Plasmodium malariae
When a mosquito bites a human, these enter the human and enter the bloodstreamSporozoites
Malaria is only transmitted by this animalFemale Anopheles
Plasmodium sporozoites infect this in the first stage of infectionLiver
In liver cells, the sporozoites undergo asexual reproduction and release these into the bloodstreamMerozoites
Once back in the blood stream, the merozoites infect this in the second stage of infectionRBCs
Some merozoites in the RBC, develop into these crescent shaped formsGametocytes
The sexual reproduction stage of Plasmodium occurs hereAnopheles
Some merozoites, enter a dormant stage in which they are calledHypnozoites
Hypnozoites can only occur with these species of PlasmodiumPlasmodium vivax and Plasmodium ovale
Plasmodium trophozoites form this in RBCsRing Forms
Plasmodium undergo asexual reproduction by the formation these in the RBCsSchizont
Incubation period is 7 – 30 days. Initial flu-like symptoms (fever, headache, muscle pain, nausea). Periodic cycles of fever, shaking chills and sweats every 48 or 72 hours (depending on the species). Fever, shaking chills, headache, bodyache, nausea, vomiting, profuse sweating and splenomegalyMalaria
Some infections complicated by serious organ failures or abnormalities in patient’s blood. Cerebral malaria. Severe anemia – due to hemolysis. Hemoglobinuria. Acute kidney failure. Respiratory distress. Hypoglycemia. Metabolic acidosisSevere Malaria
Cerebral malaria is usually caused byPlasmodium falciparum
Parasite adheres to the vascular endothelium→ clump together in blood vessels → obstruction and microvascular damage. Seizures, abnormal behaviour, comaCerebral Malaria
Detection of parasite in blood smears. Thin film - regular blood smear (specific). Thick film – sensitive. Giemsa-stained. Inside RBCs schizonts, “Ring forms”, and Gametocytes seen. Schuffner dotsDiagnosis Malaria
Plasmodia speciation is important for treatment because this can occurMixed Infections
Most prevalent species. Immature RBCs. Can form dormant hepatic phase (HYPNOZOITES)Plasmodium vivax
Immature RBCs. Dormant hepatic phase – hypnozoitesPlasmodium ovale
Infects only Mature RBCs. Quartan malaria (72 hr cycles)Plasmodium malariae
Infects any stage RBC. Heavy parasitemia. Multiple parasites can infect same RBC. Severe malaria - Hemolytic anemia. Cerebral malaria → coma & death. Kidney damage → “Blackwater feverPlasmodium falciparum
(Insert 2.22)
Question Answer
Infect RBCs. Zoonosis – infecting deer, cattle, rodents. Transmission – bite of Ixodes ticks. Distribution in US - Northeastern seaboard (Nantuket, Martha’s Vineyard, NY, MA) Those at increased risk include splenectomized people, functional asplenia, immunosuppression and advanced age (elderly)Babesia microti
Most infections - asymptomatic. Symptoms include malaise, fever, headache, chills, fatigue. RBCs–hemolytic anemia. Hepatomegaly, splenomegaly, renal failureBabesia microti
Blood smears. Multiple ring forms inside RBCs that forms a “Maltese” crossBabesia Diagnosis
Babesia treatmentClindamycin and Quinine
Intracellular parasite. Healthy people – carry parasite in tissues without any disease. Infection dangerous in pregnant women → fetuses and immunocompromised people, transplant recipients and AIDSToxoplasma gondii
Important reservoir - Cats. Cat feces has oocysts. Ingestion. Humans infections. Ingestion of raw meat and meat juices. Oocysts (changing cat litter)
Question Answer
Rapidly multiplying and invasive. Rupture cells and infect adjacent cells and spread through blood to all body tissues phase of ToxoplasmaTachyzoites
Development of immune response tachyzoites disappear and tissue cysts form and remain for the lifespan of the hostBradyzoites
Bradyzoites are confind by an immune response formingTissue Cyst
Usually found in CNS eyes, liver, lung, lymph nodes. Cause reactivation of disease if host becomes immunologically impairedTissue Cyst
Asymptomatic / mild flu-like symptoms. Transplacental transmission to fetusAcute Infection
Toxoplasma encephalitis and disseminated infectionsImmunocompromised / AIDS patients
Multiple ring-enhancing lesions seen on CT scanToxoplasma Encephalitis
Leading cause of focal CNS disease in AIDSToxoplasmosis
Serologic testing. Finding IgM and IgG against Toxoplasma. Demonstration of parasite in tissue. Polymerase chain reaction (PCR)Toxoplasma Diagnosis
Toxoplasma treatment for non-pregnant patientsPyrimethamine + Trimethoprim - Sulfamethoxazole
Toxoplasma treatment for pregnant women with acute infectionSpiramycin
Hemoflagellate. 3 species. Transmission – bite of SandfliesLeishmania
Leishmania donovani. Transmission - bite of Phlebotomus. Invasion of macrophages throughout RES. Clinical features. Initially Chills & sweating Hepatosplenomegaly. Associated black pigmentation of skin = KALA AZAR (black fever). Other features - lymphadenopathy, pancytopenia, fever and weight lossVisceral Leishmaniasis
Amastigotes in macrophagesLeishmaniasis
Caused by Leishmania tropica. Transmission – bite of Phlebotomus (sandfly). Characterized by a papule which ulcerates. Slow-healing ulcer* – 2 to10 months. Military personnel stationed in IraqCutaneous Leishmaniasis
Diagnosis – demonstrate amastigotes from ulcer biopsyCutaneous Leishmaniasis
Caused by L. braziliensis Vector – Lutzomyia (Sandfly). Destruction of mucous membranes of nasal septum and related tissue structures. South America (90% cases) Peru, Bolivia, BrazilMucocutaneous Leishmaniasis
Leishmaniasis treatmentPentavalent antimonials (stibogluconate) Amphotericin B / Pentamidine
Vector is the reduviid bug (kissing bug). Usually seen in South/Central America. Chagas diseaseTrypanosoma cruzi
Vector - tsetse fly. West/Central Africa. Sleeping sicknessTrypanosoma brucei
(Insert 2.64 - 70)
Question Answer
Bite of Tsetse fly ulcer. Early in disease organisms in blood and lymphatics posterior cervical lymphadenopathy (Winterbottom’s sign). Later in disease CNS involvment fever, headache diffuse encephalitis comatose. Death after a few years. Release of sleep mediators by organism causes profound somnolenceTrypanosoma brucei (African Trypanosomiasis)