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EOS Principles of diseases > special bacteria & fungi > Flashcards

special bacteria & fungi Flashcards

1
Q

what are some characteristics of spirochaetes?

A
  • long, thin spiral-shaped bacteria
  • gram negative
  • anaerobic
  • classical ultrastructure
  • ancient lineage
  • ubiquitous
  • most are living, few are pathogenic
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2
Q

how can spirochaetes cause chronic infections?

A
  • evade immune system

- hypersensitivity reactions develop

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3
Q

what are the 3 basic elements of the Spirochaete ultrastructure?

A
  • outer sheath
  • endoflagella (between cell wall & outer sheath & enables motility)
  • protoplasmic cylinder (composed of cell wall & cell membrane)
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4
Q

what makes spirochaetes different to conventional bacteria?

A
  • distinguished by the location of their flagella which runs lengthwise between cell wall & outer sheath
  • endoflagella are an important virulence factor for Spirochaetes
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5
Q

what are the characteristics of Rickettsiales bacteria?

A
  • small obligate intracellular parasites
  • minute coccobacili
  • gram negative bacteria but stain poorly
  • energy parasites - have an ATP transport system that allows them to steal host’s ATP
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6
Q

describe the maintenance of Rickettsiales?

A
  • maintained in reservoirs (animals, insects & humans)
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7
Q

what is the mode of infection for Rickettsiales?

A
  • use arthropod vectors
  • parasites of vascular epithelium
  • enter endothelial cells & cause necrosis of vascular lining
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8
Q

how can Rickettsiales be cultured?

A
  • Rickettsiales will grow in cell cultures & embryonated eggs but not on artificial media due to being intracellular parasites
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9
Q

describe the lifecycle of Rickettsia rickettsi

A
  • R.rickettsi infects a tick feeding on blood of an infected animal
  • it invades a host cell & reproduces & infects more host cells
  • female tick transmits it to her eggs by transovarial transmission
  • infected larval tick gets onto a new host
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10
Q

which bacteria causes spotted fever?

A

Rickettsia

  • R.rickettsia causes Rocky Mountain Spotted Fever
  • R.australis causes Queensland Tick Typhus
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11
Q

which bacteria causes Epidemic typhus?

A
  • Rickettsia prowazekii
  • louse-borne disease
  • domestic animals are incidental hosts
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12
Q

name the disease Orientia tsutsugamuchi bacteria cause?

A
  • scrub typhus
  • mite-borne disease
  • dogs are incidental hosts & only have subclinical infection
  • primarily a human pathogen
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13
Q

Features of Coxiella brunetti? What disease it causes, mode of transmission, vectors?

A
  • causes sporadic abortion in ruminants & Q fever in humans
  • obligate intracellular pathogen
  • produces an endospore-like form
  • aerosol transmission occurs in domestic animals & humans
  • arthropod vectors
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14
Q

what makes Rickettsiae & Coxiella different from conventional bacteria & Chlamydiales?

A
  • host-cell dependence AND poor affinity for basic dyes AND requirement for an invertebrate vector distinguishes Rickettsiae & Coxiella from conventional bacteria & Chlamydiales
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15
Q

list 6 features of chalmydia

A
  • small obligate intracellular parasites
  • true energy parasites (cannot make ATP so must steal ATP from host)
  • contain DNA, RNA & ribosomes
  • contain an inner & outer membrane
  • no peptidoglycan
  • no vectors
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16
Q

what type of infections does Chlamydia cause?

A
  • causes chronic infections of the epithelial of the mucous membranes
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17
Q

brief describe the lifecycle of chlamydia

A
  • complicated lifecycle

- alternates between non-infectious proliferation & infectious non-proliferation stages

18
Q

what are elementary bodies?

A
  • infectious form of chlamydia
  • non-replicating, non-metabolically active form
  • extracellular form
19
Q

what are reticulate bodies?

A
  • non-infectious form of chlamydia
  • metabolically active & replicating form
  • intracellular form, more fragile
20
Q

What are Mollicutes?

A
  • a class of bacteria characterised by the absence of a cell wall
  • genus Mycoplasma (contain most the animal pathogens)
  • genus Ureaplasma (associated with reproductive disorders)
21
Q

key characteristics about Mycoplasmas

A
  • pleomorphic & LACKS A CELL WALL
  • resistant to penicillin bc it does not have a peptidoglycan cell
  • smallest self-replicating organism
  • fried egg appearance
22
Q

describe the pathogenicity of mycoplasma

A
  • infect a wide host range
  • mycoplasmas are extracellular pathogens that adhere to epithelial surfaces using adherence proteins
  • produce toxic metabolic products
  • causes immunopathogenesis
  • cause chronic low-grade infections
  • close contact required for transmission
  • clinical manifestations = respiratory & urogenital tract infections, arthritis, mastitis & septicemia
23
Q

what is enzootic pig pneumonia?

A
  • chronic respiratory disease
  • affects respiratory tract
  • chronic non-productive cough, polyarthritis, poor growth & high morbidity
24
Q

what us mycoplasma haemofelis?

A
  • a parasite of red blood cells

- transmission through arthropods/bite wounds

25
Q

what are fungi?

A
  • eukaryotic organisms
  • do not contain chlorophyll
  • have cell walls of chitin, filamentous structures & produce spores
  • mostly cause opportunistic infections
  • can tolerate acids, osmotic pressure & dehydration
  • aerobic or facultative anaerobes
26
Q

what are the 3 categories fungi?

A
  • yeasts (appear more bacteria-like in colony morphology & consistency)
  • mould or hyphae (fuzzy appearance)
  • dimorphic fungi (can appear as yeast or mycelium depending on environmental conditions)
27
Q

how can fungi be identified?

A
  • can be identified based on microscopic appearance in tissue or on routine culture media
28
Q

features of yeasts

A
  • unicellular fungi
  • non-filamentous
  • typically oval or spherical cells
  • reproduce by mitosis
  • yeasts are facultative anaerobes - allows them to grow in a variety of environments
29
Q

features of moulds

A
  • multicellular
  • filamentous fungi
  • identified by physical appearance, colony characteristics & reproductive status
30
Q

define thallus

A
  • body of a mould or fleshy fungus, consisting of many hyphae
31
Q

define hyphae

A
  • long filaments of cells joined together
  • grow by elongating at the tips (each part of a hyphae is capable growth)
  • vegetative hyphae = portion that obtains nutrients
  • reproductive or aerial hyphae = portion connected with reproduction
32
Q

define mycelium

A

large, visible, filamentous mass made up of many hyphae

33
Q

define septate hyphae

A

cells divided by septa

34
Q

define coenocytic hyphae

A

long continuous cells that are not divided by septa

35
Q

describe dimorphic fungi

A
  • can exist as both multicellular fungi (moulds) or yeasts

- many species are pathogenic

36
Q

describe the lifecycle of fungi

A
  • filamentous form can reproduce asexually by fragmentation of their hyphae
  • fungal spores are formed from aerial hyphae & are used for both sexual & asexual reproduction
37
Q

compare sexual spores and asexual spores?

A
  • asexual spores - are formed by the aerial hyphae of one organism & new organisms are identical to parent
  • sexual spores - formed by fusion of nuclei from 2 opposite mating strains of the same species
38
Q

what are dermatophytes

A
  • cause fungal infections of the skin, hair & nails

- secrete keratinise (an enzyme that degraded keratin)

39
Q

how do subcutaneous mycoses cause fungal infections

A
  • fungal infections beneath the skin
  • caused by saprophytic fungi that live in soil or on vegetation
  • infections occur by implantation of spores or mycelial fragments into a skin wound
  • can spread into lymph vessels
40
Q

how do systemic mycoses cause fungal infection?

A
  • fungal infections deep within the body
  • can affect a number of tissues & organs
  • usually caused by fungi that live in the soil & are inhaled
  • not contagious
41
Q

what are conidospores, clamydospores, sporangiospore?

A
  • condiospores - unicellular or multicellular spore that is not enclosed in a sac
  • clamydospores - thick-walled spore formed within a hyphae segment
  • sporangiospore - asexual spore formed within a sac

EOS Principles of diseases (12 decks)

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