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Microbiology Part 2. Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis.

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Presentation on theme: "Microbiology Part 2. Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis."— Presentation transcript:

1 Microbiology Part 2

2 Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis

3 These are all dimorphic fungi Mold in the soil, yeast in tissues – Cold = mold, Heat = Yeast All cause pneumonia, can disseminate Tx: ketoconazole or fluconazole for local infection; Ampho B for systemic

4 Mycology – Systemic mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis

5 Histoplasmosis Transmitted by inhalation of asexual spores Mississippi and Ohio River Valley Causes pneumonia In bird or bat droppings “Histo Hides” (in macrophages)

6 3-5 um


8 Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis

9 Blastomycosis East of Mississippi River and Central America Cases Inflammatory lung disease, which can disseminate to skin and bone – Granulomatous nodules “Blasto Buds Broadly” (broad-base budding yeast)

10 5-15um


12 Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis

13 Coccidioidomycosis Transmitted by inhalation of asexual spores Southwestern United States, California – San Joaquin Valley Causes pneumonia and meningitis; can disseminate to bone and skin Cases increase after earthquake “Coccidio Crowds” – spherule filled with endospores

14 20-60 um


16 Mycology – Systemic Mycoses Histoplasmosis Blastomycosis Coccidioidomycosis Paracoccidioidomycosis

17 Latin America Budding yeast with “captain’s wheel” appearance – Larger than RBC

18 40-50 um


20 Cutaneous mycoses - Dermatophytes Tinea versicolor – Caused by Malassezia furfur – Causes hypopigmented patches by degradation of lipids producing acids which damage melanocytes – Occurs in hot, humid weather – Tx: topical miconazole, selenium sulfide (Selsun) – KOH prep show “spaghetti and meatballs”


22 Cutaneous mycoses - Dermatophytes Tinea pedis, cruris, corporis, capitis – Caused by Microporum, Trichophyton, and Epidermophyton – Pruritic lesions with central clearing resembling a ring – See mold hyphae on KOH prep – Pets are reservoir – Tx: topical azoles

23 Opportunistic Fungal Infections Candida albicans – Systemic or superficial – Yeast with pseudohyphae at 20°, and germ tubes at 37° – Oral and esophageal thrush in immune compromised – Vulvovaginitis – Diaper rash – Endocarditis (in IVDA) – Disseminated candidiasis – Chronic mucocutaneous candidiasis – Tx: Nystatin for superficial infection, Ampho B for serious systemic infections

24 Jagged edges with satellite lesions Psuedohyphae and budding yeast at 20° Germ tubes at 37°

25 Aspergillus fumigatus – Mold with septate hyphae that branch at 45° – Allergic bronchopulmonary aspergillosis – Lung cavity aspergilloma (“fungus ball”) – Invasive aspergillosis in immune compromised and pts with CGD Opportunistic Fungal Infections


27 Cryptococcus neoformans – Heavily encapsulated yeast – In soil, pigeon droppings – Culture on Sabouraud’s agar; stain with India Ink – Latex agglutination test to detect polysaccharide Ag – Cryptococcal meningitis; “soap bubble” lesion in brain Opportunistic Fungal Infections


29 Mucor and Rhizopus sp. – Mold with irregular nonseptate hyphae branching at wide angles – Mostly in ketoacidotic diabetic and leukemic patients – Proliferate in walls of blood vessels and cause infarction – Rhinocerebral, frontal lobe abscess – rapid spreading Opportunistic Fungal Infections


31 Pneumocystis jiroveci – Yeast; inhaled – Pneumonia in immune suppressed – Diffuse and bilateral CXR appearance – Dx: lung biopsy or lavage; silver stain – Tx: TMP-SMX, pentamidine, dapsone – Prophylaxis CD4 <200 Sporothrix schenckii – Dimorphic fungus – cigar shaped budding yeast; lives on vegetation – Sporotricosis – “Rose gardener’s disease” – Local pustule or ulcer; follows lymphatic drainage – Tx: itraconazole, or potassium iodide Opportunistic Fungal Infections


33 Antifungals

34 Ampho B – MOA: Binds ergosterol, forms membrane pores allowing leakage of electrolytes – Use: Systemic mycoses; intrathecally for fungal meningitis (does not cross BBB) – Toxicity: Fever/chills, nephrotoxicity, arrhythmia Nystatin – MOA: Binds ergosterol disrupting membrane, too toxic for systemic use – Use: “Swish and swallow” for oral thrush, topical for diaper rash and vulvovaginitis Azoles – MOA: inhibits fungal sterol synthesis – Use: systemic mycoses – Toxicity: gynecomastia, inhibits P450

35 Flucytosine – MOA: inhibits DNA synthesis – Use: systemic mycoses with Ampho B – Toxicity: Bone marrow suppression Caspofungin – MOA: Inhibits cell wall synthesis (inhibits synth of β- glucan) – Use: Invasive aspergillosis Terbinafine – MOA: Inhibits fungal enzyme squalene epoxidase – Use: dermatophytoses Griseofulvin – MOA: interferes with microtubule function, disrupts mitosis; deposits in keratin containing tissue – Use: Oral for superficial infections; inhibits growth of dermatophytes – Toxicity: Teratogen, carcinogenic, increases P450 activity

36 Parasites

37 Single celled organisms Giardia lamblia – Dz: bloating, flatulence, foul-smelling fatty diarrhea, seen in campers – Transmission: cysts in water – Dx: Trophozoites or cysts in stool – Tx: Metronidazole Entamoeba histolytica – Dz: Amebiasis – bloody diarrhea, liver abscess, RUQ pain – Transmission: cysts in water – Dx: Serology, trophozoites or cysts in stool – Tx: Metronidazole and iodoquinol


39 Cryptosporidium – Disease: severe diarrhea in AIDS pts, mild disease in non-immunocompromised – Transmission: cysts in water – Dx: Cysts on acid-fast stain – Prevention by filtering city water Toxoplasma gondii – Disease: brain abscess (ring-enhancing lesions); congenital toxo  chorioretinints, hydrocephalus, intracranial calcifications – Transmission: cysts in meat or cat feces; crosses placenta – Dx: Serology, biopsy – Tx: Sulfadiazine + pyrimethamine


41 Naegleria fowleri – Disease: rapidly fatal meningoencepalitis – Transmission: swimming in fresh water lakes, enter via cribriform plate – Dx: Amoebas in spinal fluid – Tx: none Trypanosoma – T. gambiense, T. rhodesiense – Disease: African sleeping sickness = enlarged LN, recurring fever, somnolence, coma – Transmission: Tsetse fly – Dx: Blood smear – Tx: Suramin for blood borne disease; melarsoprol for CNS penetration

42 Trypanosoma cruzi – Disease: Chagas disease = dilated cardiomyopathy, megacolon, megaesophagus; South America – Transmission: Reduviid bug – Dx: Blood smear – Tx: Nifurtimox Leishmania donovani – Disease: Visceral leishmaniasis (kala azar) = spiking fevers, hepatosplenomegaly, pancytopenia – Transmission: sandfly – Dx: macrophages with amastigotes – Tx: Sodium stibogluconate


44 Plasmodium – malaria, cycle fever, HA, anemia, splenomegaly – P. vivax/ovale Cycles QOD, dormant form in liver treated with primaquine – P. falciparum Severe, cycles QD, RBCs with parasite occlude capillaries in brain, kidneys, lungs – P. malariae – Transmission: Anopheles mosquito – Dx: Blood smear – Tx: chloroquine, if resistance use mefloquine; primaquine for dormant form in P. vivax/ovale

45 Babesia – Disease: Babesiosis = fever and hemolytic anemia; in NE USA – Transmission: Ixodes tick (same as Borrelia of Lyme Dz; may coinfect) – Dx: Blood smear; RBC with “Maltese Cross” – Tx: Quinine, clindamycin Trichomonas vaginalis – Disease: vaginitis = foul-smelling greenish discharge, itching and burning – Transmission: sexual – Dx: Trophozoites on wet mount – Tx: Metronidazole


47 Helminths - Nematodes Enterobius vermicularis (pinworm) – Food contaminated with eggs; intestinal infection; anal pruritis; scotch tape method Ascaris lumbricoides – Eggs visible in feces; intestinal infection; Loffler’s eosinophilic pneumonitis Trichinella spiralis – Undercooked meat, usually pork; inflammation of muscle, periorbital edema Strongyloides stercoralis – Larvae in soil penetrate skin; intestinal infection; causes vomiting, diarrhea and anemia




51 Acylostoma duodenale, Necator amercanus – Hookworms; penetrate skin of feet; intestinal infection can cause anemia (Fe deficiency) Dracunculus medinensis – In drinking water; skin inflammation and ulceration Onchocerca volvulus – Blackflies; hyperpigmented skin and river blindness; Allergic reaction to microfilaria Loa loa – Deer fly, horse fly, mango fly; swelling in skin; can see worm crawling in conjunctiva Wuchereria bacrofti – Mosquito; blockage of lymphatic vessel; 9mo – 1yr after bite to get elephantiasis Toxocara canis – Food contaminated with eggs; granulomas and visceral larva migrans; blindness if in retina


53 Helminths - Cestodes Taenia solium – Pork tape worm; ingested larvae encysted in undercooked pork; ingestion of eggs causes cysticercosis, and neurocysticercosis Diphyllobothrium latum – Fish tape worm; ingestion of larvae in freshwater fish; B12 deficiency anemia Echinococcus granulosus – Eggs in dog feces, Hydatid cyst (anaphylactic response to echinoccocal Ag in cyst)

54 Helminths - Trematodes Schistosoma – Snails are host; cercariae penetrate skin; cause granulomas, fibrosis, inflammation of spleen and liver. S. hematobium SCC of bladder Clonorchis sinensis – Undercooked fish; inflammation of biliary tract  pigmented gallstones; cholangiocarcinoma Paragonimus westermani – Undercooked crab meat; inflammation and 2° bacterial infection of lung  hemoptysis

55 Viruses

56 Vaccines Live attenuated – Smallpox, VZV, yellow fever, Sabin’s polio, MMR Killed – Rabies, Influenza, Salk polio, HAV Recombinant – HBV, HPV

57 DNA Viruses Herpesviruses – HSV-1: herpes labialis; keratoconjunctivitis; gingivostomatitis; temporal lobe encephalitis – HSV-2: herpes genitalis; neonatal herpes – VZV: Chickenpox, shingles – EBV: Mono (positive monospot), Burkitt’s – CMV: infection in immunosuppressed especially transplant recipient; congenital infections; mono (negative Monospot); Owl’s eye inclusions – HHV-6: roseola (exanthem subitum); high fevers for several days that can cause febrile seizure, followed by diffuse macular rash – HHV-7: clinically insignificant – HHV-8: Kaposi’s sarcoma


59 Dx of HSV Tzanck test – smear of opened vescicle to detect multinucleated giant cells – For HSV-1, HSV-2, VZV

60 Hepadnavirus: – HBV; acute or chronic hepatitis; vaccine; has reverse transcriptase but not retrovirus Adenovirus – Febrile pharyngitis, pneumonia, conjunctivitis Parvovirus – B19: aplastic crisis in sickle cell, “slapped cheek” (erythema infectiosum, 5 th disease); RBC destruction leads to hydrops fetalis Papillomavirus – HPV, warts, CIN, cervical cancer Polyomavirus – JC: progressive multifocal leukoencephalopathy in HIV Poxvirus – Largest DNA virus – Smallpox, vaccinia (milkmaid’s blisters), Molluscum contagiousum


62 RNA Viruses Picornaviruses – Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV – Rhinovirus: common cold – Coxsackie: myocarditis, hand foot and mouth disease, aseptic meningitis Reovirus – Segmented, dsRNA – Rotavirus: infantile gastroenteritis; villous destruction and atrophy leads to decreased absorption for Na and water

63 Flaviviruses – HCV, Yellow Fever, Dengue, SLE, West Nile – Yellow Fever: transmitted by Aedes mosquito, causes high fever, black vomitus, jaundice; councilman bodies in liver (hepatocytes undergoing apoptosis) Orthomyxovirus – Segmented – Influenza – hemagglutinin (viral entry), neuraminidase (progeny release) – Genetic shift = reassorment (pandemics) – Genetic drift = minor changes based on random mutations (epidemic)


65 Togavirus – Rubella, EEE, WEE – Rubella: German measels, 3 days, fever, lymphadenopathy, arthralgias; TORCH Paramyxoviruses – Paraflu, RSV, Rubeola, Mumps – Measles: Koplik spots, 3 C’s (cough, coryza, conjunctivitis), rash spreads head to toe – Mumps: Parotitis, orchitis, aseptic meningitis Rhabdovirus – Rabies – Negri bodies (cytoplasmic inclusions in neurons); bullet shaped; long incubation; retrograde migration – Fever, malaise  agitation  photophobia, hydrophobia  paralysis, coma  death


67 Hepatitis Viruses HAV – Fecal-oral, short incubation, no carriers, usually asymptomatic HBV – Parenteral, sexual, materal-fetal transmission; long incubation, carriers HCV – Blood transmission, resembles HBV in course and severity (Chronic, cirrhosis, HCC); carriers; post-transfusion hepatitis; IVDA HDV – Requires HBV surface Ag; co-infection or superinfection; carriers HEV – Enteric transmission; water-borne epidemics; course similar to HAV; high mortality in pregnant women

68 Hepatitis Serology Markers IgG HAV Ab = prior infection, protective IgM HAV Ab = active HAV infection HBsAg = active disease, carrier state HBsAb = immunity; recovered (dz or exposure) HBcAg = New dz HBcAb = positive during window pd; IgM is sign of recent disease, IgG signifies chronic disease

69 HIV Diagnosis – ELISA = RULE OUT TEST Positive test is confirmed with Western Blot (Rule In test) Falsely negative test in first 1-2 months of infection – HIV PCR/viral load Monitor effects of therapy – AIDS diagnosis is CD4 count ≤200, or presence of AIDS defining illness

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