Mycology and diagnostics Flashcards Preview

Virology, Parasitology, Mycology > Mycology and diagnostics > Flashcards

Flashcards in Mycology and diagnostics Deck (98):
1

What are the characteristic of Fungi as a kingdom?

eumycota, eukaryotic, ergosterol cell membrane, cell wall- glucans and chitin, heterotrophic metabolism (need to be fed)

2

What are the morphologies of fungi? subclasses?

yeast, mold- fleshy fungi (mushroom- reproductive structure)-> terranean and subterranean and dimorphic- yeast or mold depending on environmental conditions (typically temp)

3

What are the morphologic features of mold?

unicellular, non-filamentous (budding cells- trying to reproduce or pseudohyphae= elongated bud)

4

What are the morphological features of mold (mould)?

multi-cellular, fiamentous- hyphae (septate or non-septate) and mycelium (interwoven mass of hyphae)

5

What is a conidia? What doe sthe color of mold growing tell you?

a mold spore; white= less likely spores are being released, color change= spores being released

6

What are mushrooms?

aerial reproductive structure, hyohae in soil; basidium with basidiospores

7

What are the morphologic features of dimorphic fungi?

mold at room temp (environmental form), infectious via inhalation, yeast t body temp (37C), diagnostic form, presumptive in vivo, not infectious

8

What is taxonomy?

reproductive structure (basis for ID and classification, which determines pathogenesis and epidemiology, name of disease, only see vegetative in vivo (require in vitro culture to ID by repro struct.), rare to see repro structures in vivo

9

How are fungi named?

generally 2 names: anamorph (asexual name, in vivo-lab) and teleomorph (sexual, prefect state, see both in vitro)

10

what are general features of asexual structures? examples in mold? yeast?

involve mitosis; arthroconidium, macroconidium, microconidium, and sporangiospore; blastoconidium and chlamydoconidium

11

what are the features of a arthroconidium? Characteristic species?

within hyphae, rectangular to barrel-shaped cells; coccidioides immitis

12

What are the features of microconidium? Macrocondium? Characteristic species?

smaller of two; larger of two, usually multicellular; demratophytes

13

What are the features of a sporangiospore? Characteristic species?

produced with a sporangium; rhizopus spp.

14

What are the features of blastoconidium? characteristic species?

produced by yeast cells, "budding"; all yeast

15

What are the features of chlamydoconidium? characteristic species?

tip of psuedohyphae, ID for candida albicans (most common disease causing) and candida dubliniensis

16

what are the general features of sexual forms of reproductive structures? examples?

involve meiosis; can involve mating of two different fungal strains of same species (compatible) or ability to produce structure without mating (hermaphroditic, male and female); acospore, basidiospore, zygospore

17

What are the features of acospores? characteristic mold species? yeast?

spores within an ascus; pseudallescheria boydii, hermaphrodite, sexual name; saccharomyces cerevisiae, hermaphrodite, sexual name

18

What are the features of zygospores? characteristic species?

naked spores; rhizopus spp. requires mating (asexual name same as sexual)

19

What are the features of basidiospores? characteristic species?

formed on basidium (mushroom), amanita spp., hermaphroditic, no asexual state

20

what is the basis of fungal classification?

nature of sexual spores orlack thereof, hyphal characteristic (septate or not)

21

What are the phylum under eumycota? classes under?

Perfect Fungi- zygomycota (produce zygospores), Ascomycota (ascospore and septated hyphae), basidiomycota (mushrooms); and Imperfect Fungi- deuteromycota

22

what are the methods of direct detection in the lab?

gram stain, calcofluor white stain, KOH prep, Wet mount, Woods Lamp, India Ink stain; and histopathology

23

what are the features of gram staining fungi?

yeasts- gram (+), mold- stain poorly

24

What are the features of calcofluor white stain?

stains chitin in fungal cell wall, need fluorescence microscope

25

What are the features of KOH?

same as draino, chews up proteins, use with keratinized tissues- skin, hair nails, look for dermatophytes (ringworm)

26

What are the features of Wet mount?

oral or vaginal secretions, budding yeast= usually thrush; turn light down to see

27

What are the features of Wood's Lamp?

UV light, fluoresce dermatophytes and demratophytosis (ringworm, esp in hair)

28

What are the features of india ink stain?

CSF, encapsulated yeast, cryptococcosis (cryptococcal meningitis from cryptococcal neoformans, very common in immune compromised)

29

What are the features of histopathology?

GMS (gemori methenamine silver) stain= mold w/ hyphae; Mayer's mucicarmine stains yeast pink (mucin capsule, Cryptococcus neoformans); PAS (periodic acid-Schiff) stain- yeats and mold inernal structures (pink)

30

What medium is selective for fungi? fetaures of it?

Sab (Sabouraud dextrose agar), low pH, nutrionally deficient, 2+ days yeast, 7+ days mold, may take 4 wks, forces sporulation, and weeds out B

31

What is a biochemical test that can be performed for yeast?

germ tube test, ID candida albicans/dubliniensis, has candida albicans complex, grow culture 48 hrs, put in complex and incubate 2-3 hours, lateral hyphal extension is positive

32

What are the features of mold ID from culture?

culture medium growth characteristics, hyphal structure (septate or not), reproductive structures, requires well trained eyes

33

What are the features of serologic diagnosis of fungi?

Ab- not reliable or useful in immunocomprimised or neutropenic; Ag- latex agglutination- cryptococcal Ag in CSF for following treatment, and Serum galactomannan- Ag from aspergillus hyphae, not great, adjunct to follow therapy

34

What are some methods of culture confirmation?

nucleic acid probes (only approved for lab grown culture not tissue specimen, not cheap) and sequence analysis comparison- must have pathogen in mind, undergoing eval

35

What are the different main categories of fungal pathogenesis?

true pathogen- problem with even normal immune system, opportunistic- only problem in immunocomprimised

36

What are the factors behind fungal ability to cause disease?

colonize host, suitable micro-environment niche, avoid or subvert host normal defenses, multiple in environmental niche

37

What are known factors of fungal virulence?

highly researched don't know much;grow at 37C and physiologic pH 7.3, produce proteinases- keratinase, phospholipase

38

What aspects of immune system play a role in fungal infections?

phagocytes primary role (if neutropenia at inc. risk), cell mediated (Tcells major) and humoral (B cells minor)

39

What is mycetismus?

poisoning by ingestion of fruiting bodies (mushroom poisoning)

40

What is mycotoxicosis?

intoxication by eating food contaminated with toxin produced by mold (aflotoxin), big problem as it is heat labile

41

What is hypersensitivity disease?

inhalation of fungal elements induce hypersensitivity (pneumonitis)

42

What is mycoses?

infection caused by a fungus

43

what are the classifications of mycoses?

superficial, cutaneous or mucocutaneous, subcutaneous and systemic

44

What is involved in a superficial mycoses? examples.

restricted to outermost skin layers, stratum corneum; Pityriases (tinea) versicolor (dry scaly ringworm, pigmented), Dandruff

45

What are the etiology, distribution, predisposing factor, clinical picture of Pityriasis?

malassezia furfur (flaky, lipophilic yeast), part of normal flora (endogenous, over grow), oily skin, hypopigmented lesion if tan (dark if fair complected, catheter associated malassezia sepsis),

46

What is the etiology, distribution and predisposing factors of dandruff?

Malassezia globosa, found on human scalp, oily skin - sebaceous secretions, higher levels of M. globosa on scalp, individual susceptibility

47

What are the features of cutaneous mycoses? Examples.

infect keratinized tissues w/o invasion (skin, hair, nails); candidiasis (thrush) and dermatophytes (ringworm-tinea)

48

skin scraping, culture and biochemical features of Pityriasis?

spaghetti and meatball appearance, lipid growth requirement (olive oil overlay), and sugar assimilation tests; dumbbell appearance

49

What is the etiology, distribution, and predisposing factors?

candida albicans most common, normal flora (endogenous to mouth, skin, GI, and vaginal; except mom to baby), endocrine deficiency, immune defect (chemo, steroid, AIDS), follow Ab therapy

50

What are the clinical features of candidiasis in mucous membranes? Vaginal mucosa?

curd-like patchy areas, inflammation and swelling (drool and talk funny); thick milky discharge, inflammation and itching

51

How is candidiasis diagnosed?

wet mount, gram stain, look for yeast; culture- chlamydoconidia to ID C. albicans/dubliniensis, biochemical- germ tube to ID C. albicans/dubliniensis, sugar assimilation tests or thermotolerance, separate species

52

What are the etiologies of dermatophytosis?

epidermophyton floccosum, Trichophyton rubrum, Trichophyton tonsurans, and microsporium canis (all ringworm)

53

What is the distribution and predisposing features of dermatophytosis?

True pathogen, selective association of pathogens (animal, human, soil); exposure to contaminated object

54

What are the clinical presentations of skin dermatophytosis? diagnose?

dry and scaly skin leading to vesicular lesions, tinea corporis (body), tinea pedis (athletes foot), tinea cruris (jock itch); KOH prep

55

What are the clinical presentations of hair dermatophytosis? diagnose?

brittle hair, with or without alopecia, inflammatory response in severe infections, Wood's Lamp

56

What are the clinical presentations of nail dermatophytosis? diagnose?

deformed and/or cracked nail (tinnea anguium), hardest to treat; difficult due to smaple thickness but KOH

57

How is dermatophytosis diagnosis confirmed in general? Features of trichophytun rubrum? microsporum canis? epidermophyton floccosum?

culture, macroscopic features: macrocondium, microconidium, septate hyphae; red pigment in culture; septate hyphae from dogs or cats; flocks (tinea corporis and cruris)

58

What are the general features of subcutaneous mycoses? example.

localized area (SQ or lymphatics, hands or feet most common), traumatic implantation, exogenous fungi (vegetation); sporotrichosis (US, other species in other countries)

59

what is the etiology, distribution and predisposing factor with sporotrichosis?

sporothrix schenkii (dimorphic), moss, hay, soil, decaying vegetation, exogenous source exposure

60

What are the clinical features of sporotrichosis?

lessions at inoculation site (multiple nodules, lymphatics that drain inoculation site), "lymphocutaneous", raised local lymphadenopathy that necrosis over time

61

What is the presumptive diagnosis of sporotrichosis?

clinical picture and/or histopathology (GMS) elongated yeast called cigar bodies

62

What is the confirmed diagnosis of sporotrichosis?

culture at 25c (yeast bud like)and 37c (hyphae)

63

What are the general features of a true systemic mycoses? Examples

normal host immune system, lungs primary inoculation (spore inhaled), disease spectrum widespread (acute, chronic, or systemic), granulomatous, geo restricted (soil), etiologic agents dimorphic; endemic fungal disease- blastomycosis, histoplasmosis, coccidioidomycosis

64

What us the etiology, distribution and predisposing factors of blastomycosis?

blastomyces dermatitidis, endemic soil- Northern missisisspi river basin, exposure to conidia from soil (inhaled), some gentic predisposition affecting severity of disease

65

What are the clinical features of blastomycosis?

primary pulmonary disorder (frequently unrecognized, very mild), potential to disseminate to skin, bone, and GI

66

How is blastomycosis presumptively diagnosed?

clinical picture and/or histopathology, GMS or H&E, broad based budding yeast with double contoured wall

67

How is blastomycosis diagnosis confirmed?

culture 25C (hyphae) and 37C (double contoured wall with broad based budding); slow grow, microscopic observation, DNA probe

68

What is the etiology, distribution, and predisposing factor for coccidioidomycosis?

coccidioides immitis/posadasii (can't distinguish, nationally reportable), soil (SW US), exposure to conidia from soil by inhalation, normal host (haboobs!)

69

What are the clinical features of coccidioidomycosis?

primary pulmonary disease, extrapulmonary brain infection in AIDS (defining)

70

How is coccidioidomycosis diagnosed presumptively?

clinical picture and/or histopathology- spherule with endospores (yeast like but not technically yeast, can look like budding yeast is only find endospores) H&E or GMS

71

How is diagnosis confirmed for coccidioidomycosis?

culture (highly infectious in lab, bio3, capped tubes) microscopic observation (classic arthroconidia), DNA probe, DNA polymorphisms to separate immitis (California clade) from posadasii (non-California clade), noninfectious in hospital (dimorphic)

72

What is the etiology, distribution and predisposing factor for histoplasmosis?

Histoplasma capsulatum (intracellular in histocytes), endemic in soil of Ohio-Missouri river valleyassociated with bird and bat droppings (high nitrogen content in soil), exposure to conidia- inhalation normal host

73

What are the clinical features histoplasmosis?

primary pulmonary (coin lesions bilateral), extrapulmonary- blood (fungemia) and lymph nodes (AIDS defining)

74

How is histoplasmosis presumptively diagnosed?

clinical picture and/or histopathology, characteristic CXR, small intracellular yeast (PAS)

75

How is histoplasmosis diagnosis confirmed?

culture, microscopic observation (characteristic tuberculate macroconidia at 25C, small budding yeast at 37C), DNA probe

76

what are the features of opportunistic systemic mycoses in general?

invasive infection (fungi low virulence), immune defect (aggressive cancer therapy older population, solid organ transplant, AIDS)

77

Examples of opportunistic systemic mycoses.

true yeast or yeast like - systemic candidiasis, cryptococcosis, pneumocystis pneumonia; true mold- mucomycosis (zygomycosis) and invasive aspergillosis; (same in vivo and in vitro, any temp for all)

78

What is the etiology and distribution of invasive candidiasis?

canidida albuicans/dubliniensis, C. glabrata (resist std antifungals), C. Krusei (intrinsic resist fluconazole), C. lusitaniae (intrinsic resist amphotericin B), C. tropicalis, and C. parapsilosis; endogenous flora

79

What are the clinical features of invasive candidiasis?

any organ system (Resp- AIDS def., Wound- pulm or peritoneal, and Esophageal- AIDS def.), Candidemia (blood, diagnose with blood culture)

80

How is invasive candidiasis presumptively diagnosed?

clinical suspicion, gram stain blood culture and or histopathology- budding yeast with pseudohyphae

81

How is the diagnosis of invasive candidiasis confirmed?

culture, biochemical testing (germ tube to rule out C. albicans/dubliniensis

82

What is the etiology, distribution, and predisposing factor for cryptococcosis?

Cryptococcus neoformans (encapsulated yeast), environment assoc. w/ pigeons, exogenous- inhalation dried fecal material from colonized pigeons, immunosupression

83

What are the clinical features of cryptococcosis?

primary pulmonary, extrapulmonary (AIDS def.)- blood (fungemia), brain (meningitis), and Cutaneous

84

How is cryptococcosis presumptively diagnosed?

clinical suspicion, india ink stain of CSF, histopathology- PAS, encapsulated budding yeast, irregular sizing

85

How is the diagnosis of cryptococcosis confirmed?

culture- mucoid colonies, biochemical tests

86

What is the etiology, distribution, and predisposing factor for Pneumocystis Pneumonia?

Pneumocystis jirovecii (formerly P. carinii f.sp. hominis), human derived, environmental source not recognized, immunosuppression (AIDS)

87

What are the clinical features of Pneumocystis Pneumonia?

primary pulmonary (AIDS def.)- nonproductive cough, chest tightness, CXR- diffuse bilateral interstitia and bilateral perihilar interstitia

88

How is Pneumocystis Pneumonia presumptively diagnosed?

clinical picture (characteristic CXR) and compromised host

89

How is diagnosis of Pneumocystis Pneumonia confirmed?

histopathology (lung biopsy- crescent shaped cysts), can't culture, immunoflourescent stain (bronchoalveolar lavage, monoclonal Ab against surface epitopes)

90

What is the etiology, distribution, and predisposing factor for mucormycosis (zygomycosis)?

Rhizopus spp. or Rhizomucor spp., environment saprophytes (everywhere!), sever immune suppression, uncontrolled diabetes (low blood pH encourages growth)

91

What are the clinical features of mucormycosis (zygomycosis)?

primary sinus orbital (have to cut out), disseminate to any organ system (extremely deadly)

92

How is mucormycosis (zygomycosis) presumptively diagnosed?

clinical suspicion and/or histopathology- irregular sized non-septate hyphae, angioinvasive

93

How is the diagnosis of mucormycosis (zygomycosis) confirmed?

culture, microscopic appearance- aspetate hyphae with sporangium containing sporangiospores and rhizoids (roots), and species ID- mating studies and molecular sequencing

94

What is the etiology, distribution, and predisposing factor for invasive aspergillosis?

aspergillosis fumigatus complex, A. Flavus complex, and A. terrus complex, environmental contaminate- sparophyte (breath in), immune suppression (neutropenia)

95

What are the clinical features of invasive aspergillosis?

primary pulmonary and cutaneous (under tape), sino-orbital, disseminated

96

How is invasive aspergillosis presumptively diagnosed?

clinical suspicion, histopathology- 45 degree angle branching, irregular size, septate hyphae

97

How is the diagnosis of invasive aspergillosis confirmed?

culture, microscopic features- 45 degree angle branching, irregular size, septate hyphae, vesicle, phialides, conidia; molecular sequencing

98

What is the etiology, presentation, and predisposing/distribution of fungal meningitis/septic arthritis?

exserohium rostratum- opportunistic fungus, black pigmented (phaeohypomycosis), contaminated steroid injection (compounded solution)